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Annual Report 2018

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SCCER HaE-Storage – Annual Activity Report 2018

Published by

Swiss Competence Center for Energy Research – Heat and Electricity Storage

Concept by

Thomas J. Schmidt

Technical Review

Thomas J. Schmidt, Jörg Roth

Editorial work, design and layout by

Peter Lutz, lutzdocu.ch, Uster

Astrid Busa

Printed by

Paul Scherrer Institut, Villigen

Available from

Swiss Competence Center for Energy Research Heat and Electricity Storage (SCCER HaE-Storage) c/o Paul Scherrer Institute 5232 Villigen PSI, Switzerland

Phone: +41 56 310 2381 E-Mail: [email protected] Internet: www.sccer-hae.ch

Copying is welcomed, provided the source is acknowledged and an archive copy is sent to SCCER HaE-Storage.

DOI: 10.3929/ethz-b-000324873 © SCCER HaE-Storage, 2019

1

Table of Contents

Editorial

3 SCCER Networked Research – From the Lab to the Market

Heat – Thermal Energy Storage

5 Sensible Thermal-Energy Storage Systems Optimized for AA-CAES Plant Operation7 AA-CAESPlantModellingImprovementsandLayoutDefinition10 Numerical Phase Change Study and Optimization of High-Temperature Encapsulated Metal

Phase Change Materials for Energy Storage13 High-Temperature Latent Heat Storage System: Heat Transfer Enhancement Using

Ceramic Porous Media15 Direct Contact Latent Heat Storage Using Esters as New Phase Change Materials18 Closed Sorption Seasonal Thermal Energy Storage with Liquid Sorbent Solutions20 Closed Liquid Sorption Seasonal Heat Storage Using Aqueous Sodium Hydroxide22 Thermal Insulation Materials for Thermal Energy Storage

Batteries – Advanced Batteries and Battery Materials

26 Strategies to Improve Na-Ion Batteries28 Development of Ionic Liquids as Electrolyte Additives and a Cathode Material for Lithium

Ion Batteries30 Stabilizing NMC811 in Full Cells with High Areal Capacity32 Pilot Line Modules for Lithium-Ion Battery Cell Assembly and Advantages of Laser

Processing34 Ultra-High Mass Loading Graphite Anodes for Li-Ion Batteries

Hydrogen – Production and Storage

38 Hydrogen Storage in Hydrides40 Performance and Stability of Iron-Cobalt-Nickel Alloys for Water Oxidation42 Titanium-Manganese-Vanadium Electrolytes, Redox Solid Boosters and Copper

Contamination of an All-Vanadium Redox Flow Battery45 Hydrogen storage and delivery in CO2 – formic acid – methanol systems

Synthetic Fuels – Development of Advanced Catalysts

48 Catalyst Developement for the Transformation of CO2 into Fuels and Value-Added Chemicals

50 Development of Selective Catalysts for the Conversion of CO2 to Fuels via Surface Organometallic Chemistry

53 Synthesis and Characterization of Degradation Resistant Cu@CuPd Nanowire Catalysts for theEfficientProductionofFormateandCOfromCO2

55 (Co)-Electrolysis at Paul Scherrer Institut

2

Assessment – Interactions of Storage Systems

60 InvestigationofAA-CAESPlantConfigurationsandGridIntegration64 Calculation of Heat Demand for the Assessment of Storage Potential on System Level 66 Assessment of Energy Storage at the Technology and Energy System Level69 Technology Assessment of Energy Storage72 Assessment of Energy Storage at the Socio-Economic Level 74 IncreasingtheEfficiencyofthePower-To-MethaneTechnology76 ESI – Energy System Integration Platform

Appendix

81 Conferences82 Presentations91 Publications96 Patents97 Organized Events

Table of Contents

3 Editorial

SCCER Networked Research – From the Lab to the Market

The Swiss Competence Center for Energy Research (SCCER) Heat and Electricity Storage is now in the middle of its second phase. As expected at this stage, the collaboration within the SCCER HaE and the other SCCERs reached maturity. The successful operation of the various Joint Activities, like the generation of the White Paper on Power to Gas, where groups from 5 different SCCER collaborate, or the joint Project SwissStore with groups of SCCER HaE and CREST, on the potential of energy storage on the system level for Switzerland (see page 64) are outstanding examples.

On the international level, the SCCER HaE is well connected. The Competence Center has cooperations with institutions in Germa-ny, Austria, Spain, France, UK, the Netherlands, Greece, Poland, USA, Canada, South Korea, Japan and Abu Dhabi.

With respect of the given scope on energy storage on large scale and on seasonal timeframes, the international collaboration is a valuable asset since changing the current energy system towards a climate friendly and sustain-able system is a tremendous task which needs to be addressed on a global scale. National challenges might differ in details, every region has its indi-vidual settings, like mountains in Switzerland or salt caverns in Northern Germany, but the fundamentals in each climate zone are similar. Thanks to the SCCER Program, the collaboration among different research institutions and groups reached a new quality and synergetic effects become obvious.

Following the lines of our technical roadmap, our progress reached new and higheststandards.Oneofourmostimportantgoalsistobringthefindingsfrom the lab to the market in order to have technologies ready for the En-ergy System 2050. Along these lines, within the framework of the SCCER HaE a prototype of auxiliary power supply unit based on formic acid as a hydrogen storage was developed at EPFL together with an industrial partner. Due to its large hydrogen content, and its simple structure, formic acid can be catalytically decomposed into water and CO2. During the past years this processwasoptimizedandfinallyanindustrialprototypewasdeveloped.

The Energy System Integration Platform reached a major milestone. The Platform not only became fully operational in 2018, but its electrolyzer sys-temalsopassedthequalificationtestfortheprimaryandsecondaryreservemarket.

The focus of the assessment of energy storage was set on batteries this year. The aspects of various battery technologies on life cycle aspects, like metal criticality and greenhouse gas emissions were investigated. Giving one example, it was found that Na-ion based batteries at the moment are less ecologic compared to current Li technology. It also became clear that critical metals like Co or Ni need to be substituted from battery systems in future developments.

Those are just a few selected examples of the progress the SCCER HaE made this year, and I hope you got curious to explore also the other achievements of the 25 groups of the SCCER presented on the next pages.

Prof. Dr. Thomas J. Schmidt Head SCCER Heat and Electricity Storage

List of abbreviations

SCCER Swiss Competence Center for Energy Research

HeatThermal Energy Storage

Illu

stra

tion:

Atr

opat

/ iS

tock

Storage of high-temperature heat in industrial applications

An overarching effort on TES at high temperatures con-cerns our investigations of advanced adiabatic compressed air energy storage (AA-CAES). This effort is rooted in the collaboration with ALACAES during SCCER Phase I and an SNF NRP 70 project, as part of which experiments were car-riedoutwiththeworld’sfirstpilot-scaleAA-CAESplantwitha hard-rock cavern and a combined sensible/latent TES at temperatures of up to 575 °C. To reuse existing turboma-chinery, we are now considering plant layouts with maxi-mum temperatures of about 320 °C.

We have investigated in more detail the economics of an AA-CAES plant in Switzerland using a simple plant model integrated into a model of the Swiss electricity grid. The grid-plant simulations indicate that arbitrage by itself is notprofitableandwearethereforeinvestigatingotherusecases in collaboration with BKW. In these simulations, we have assumed that we do not reuse decommissioned mili-tary caverns based on a closer examination of such cav-erns in conjunction with Amberg Engineering. The simple plant model employed in the grid simulations is based on an assumed constant plant efficiency of 70%. Realisticvaluesoftheplantefficienciesforspecificplantconfigura-tions are provided by detailed plant simulations in which the transient behavior of the turbomachinery, TES, and cavern are included. These simulations consider irregular charging/dischargingcyclesandhavebenefitedfromactualturbo machinery performance data provided by MAN Energy Solutions AG. The TES model in the detailed plant model inturnhasbeenusedtostudymulti-tankstorageconfigu-rations, which are of interest because they may be bet-ter suited to irregular charging/discharging cycles because they allow for thermocline control. The simulations of the multi-tank configurationshave shownbetterperformancethanasingle-tankconfigurationevenundernon-adiabaticconditionsfordropsoftheoutflowtemperatureduringdis-chargingof less than9%,andare thereforeexpected to

enablemore efficient operation of the turbine in an AA-CAES plant.

The high-temperature TES activities include also investiga-tions of the performance of latent TES in which 44Mg-56Si is used as phase-change material (PCM), encapsulated in SiSiC tubes. To enhance the heat transfer between the PCM and the air that is used as heat-transfer fluid, the spacebetweenthetubesisfilledwithareticulatedporousceram-ic. Simulations showed that effectivenesses of more than 92%andenergydensitiesofmorethan220MJ/m3 can be achieved. In a parallel effort, detailed simulations of the melting behaviour of PCMs are used to improve the under-standing of the fundamental unsteady heat-transfer pro-cesses and random macroporous percolating structures are being investigated as encapsulations for PCM. These efforts are expected to be useful for the development of improved combined sensible/latent TES units in an AA-CAES plant.

Seasonal storage of low-temperature heat for space heating and hot water

Parallel research projects investigate closed sorption stor-age for seasonal storage using tube-bundle and spiral-finnedtubeheat/massexchangers(HMX)andhavefocusedon understanding and improving the limited discharge power. To increase the wetting of the tube-bundle surfaces, various hydrophilic coatings developed by CSEM were as-sessed using water. Judging by the maximum wetted width, structured coatings were up to 5 times better than uncoated surfaces. To improve the understanding of the mass trans-fer during absorption and desorption, Raman spectroscopy experiments were performed. Preliminary results confirmreduced mass transfer rates during absorption compared to desorption. The mass transfer was also studied using neutron imaging in the SINQ facility at PSI. More detailed analyses of both experiments are in progress. An upscaled HMXbasedonthespiral-finnedtubeconceptwithanominaldischarge power of 5 kW was designed and will be manu-factured in 2019.

Work Package «Heat Storage» at a Glance

Thermal-energy storage (TES) is expected to play an important role in Switzerland’s future energy system because the generation of heat is responsible for about 50 % of primary energy consumption. The main contri-bution of TES in Switzerland is going to be for seasonal storage of low-temperature heat for space heating and hot water. Seasonal storage is expected to be essential to achieving the objectives of the Energy Strategy 2050 (ES 2050). The storage of high-temperature heat in industrial applications has the potential to play an important role also because process heat accounts for about 50 % of the total energy use in Swiss industry. At present, the potential cannot be quantified in detail yet because little information is available on the amounts and tempera-ture levels of the required thermal energies. Some information has been gathered over the past year as part of the preparation of the Fact Sheet Heat by the Working Group «Thermal Storage» of the Forum for Energy Stor-age Switzerland.

5 Heat

Sensible Thermal-Energy Storage Systems Optimized for AA-CAES Plant Operation

Scope of project

The optimization of thermal-energy storage (TES) systems for advanced adiabatic compressed air energy storage (AA-CAES) plants requires that the operational characteristics of such plants are determinedfirst.Asdescribedinlastyear’sannualactivityreport[1]andconclusionsdrawnfromresultsofgridsimulationsperformedintheSCCERAA-CAESproject[2],theoperatingprofilesofAA-CAES plants are predicted to be very dynamic. Ultimately, the plant and therefore also the TES system have to be capable of dealing with off-design conditions without large decreases in their efficiencies.ThermoclineTESsystemscanrequireupto50cyclestoreturntotheirnominalquasi-steady-statebehaviour followingadisturbance[3].TESsystemsthatconsistofmultiplesmallerstorage units that can be used in combination appear to be better suited to off-design operation [4–6].Theultimateobjectiveofourworkistoassesstheperformanceofmulti-tankTESsystemsrelative to single-tank systems under conditions that are representative of AA-CAES plants. In this report, we summarize the results of an ongoing numerical study where TES systems composed of up to four tanks are assessed for nominal, steady-state operating conditions that are representative of a 100 MW/500 MWh AA-CAES plant. The assessment of TES systems for dynamic operating condi-tions is the subject of future work.

ment is based on keeping the total tank volume constant. The assessment assumes that the total volume is divided equally among the tanks and that the aspect ratios of the tanks are identical. For sim-plicity, the structure and insu-lation thicknesses are identical for all tanks.

The simulations were per-formed with a previously de-veloped and validated quasi-one-dimensional heat-transfer model [7] that was coupledwith an external Matlab rou-tine. This routine called the heat-transfer model for each

tank and divided the flowsthrough the tanks according to the mode of operation. There are two basic modes of opera-tion that can be considered for multi-tank systems. The firstis parallel operation, where all tanks are charged simultane-ously by dividing the total mass flow.Inthesimplestcase,con-sideredhere,themassflowisdivided equally between the TES units. The second mode is serial operation, where the tanks are being charged se-quentially with the same total mass flow. For serial opera-tion, the operation of multi-tank TES systems is equivalent

Figure 1:

SCCER AA-CAES plant lay-

out.

Statusofprojectandmainscientificresultsofworkgroups

Authors

Philipp Roos1 Andreas Haselbacher1

1 ETH Zurich

The operating conditions used in this study are taken from the SCCER AA-CAES plant de-sign shown in Figure 1. The plant contains two caverns to simplify the integration of two-stage turbomachinery. The nominal plant design contains a single-tank TES in each cav-ern. The objective of the work described here is to assess multi-tank TES systems of up to four tanks for the operating conditions of the low-pressure (LP) cavern. The correspond-ing nominal mass flow rates,air inflow temperatures dur-ing charging and discharging, and charging and discharging durations are indicated in Fig-ure 1. To simulate daily stor-age operation, two idle phases of seven hours were added af-ter the charging and discharg-ing phases. Including the idle phases is important because the simulations included the thermal losses from the TES to take into account the larg-er surface area of multi-tank systems. The surface area grows as the number of tanks increases because the assess-


AA-CAES Advanced Adiabatic Compressed Air Energy Storage

TCC Thermocline Con-trol

TES Thermal Energy Storage

LPC HPCM HPT LPTG

TESHP

TESLP

ChargeDischarge

HP: High pressure cavern (70 bar ≤ p ≤ 100 bar) LP: Low pressure cavern (p ≈ 10 bar)

m c,d = 200 kg/sTc = 320◦CTd = 20◦C∆tc,d = 5h

6 Heat

to thermocline-control (TCC) methods[8,9].Inthisreport,the focus lies on the extraction TCC method, which was found to be promising in prior work.

An example of the working principle of the extraction TCC method with a four-tank stor-age during charging is shown in Figure 2. At the start of the charging phase, the chain of TES units is checked from top to bottom to determine the ac-tive inlet and outlet. The ac-tive inlet is chosen to be the inletofthefirsttankthatisnot

fully charged. The active out-let is chosen to be the outlet of the first tankwhere the tem-perature at the bottom is be-low the pre-defined switchingtemperature, which was cho-sen as 50 °C (corresponding to a dimensionless temperature of 0.1 in Figure 2). At time t1, when the switching tempera-ture of TES 2 is reached, TES 3 is also starting to be charged. At time t2, when the switch-ing temperature at the out-let of TES 3 is reached, TES 4 is starting to be charged and the active inlet is moved from

TES 1 to TES 2 to decrease pressure losses and increase theefficiency.Forcomparison,the single-tank storage of the same volume is also shown in Figure 2. With a single-tank system, the outflow tempera-tures are significantly higherat the end of the charging phase. The same strategy is applied during the discharg-ing phase with the difference that the switching temperature is 290 °C (corresponding to a dimensionless temperature of 0.9) at the outlet.

The sample results shown here indicate that with mul-tiple tanks, the thermocline is significantly steeper thanfor a single tank, leading to lowermaximum outflow tem-peratures during charging, and higherminimumoutflow tem-peratures during discharging. Ultimately, this allows smaller total volumes to be used with multi-tank systems compared to a single-tank system for the same performance. It is important to note that despite the increased surface area and therefore increased thermal losses for multi-tank TES sys-tems, the results showed that they are cost-competitive when low temperature drops during discharging (ΔTd,max ≤9%) arerequired. For all the TES sys-tems that were analysed, the total material costs were lower than 15 CHF/kWhth. These re-sults justify further efforts to analyse multi-tank TES sys-tems, especially for more re-alistic dynamic AA-CAES plant operation.

References

[1]SwissCompetenceCenter for Energy Re-search – Heat and Electric-ity Storage, «SCCER HaE-Storage – Annual Activity Report 2017», (2017).

[2] J.Garrison,A.Fuchs,T. Demiray, Technical report, (2017).

[3] J.D.McTigue,C.N. Markides, A.J. White, J. Energy Storage, 19, 379–392 (2018).

[4]R.M.Dickinson,C.A. Cruickshank, S.J. Har-rison, Sol. Energy, 104, 29–41 (2014).

[5]A.Sciacovelli,Y.Li,H.Chen,Y.Wu,J.Wang,S.Garvey,Y.Ding,Appl.En-ergy, 185, 16–28 (2017).

[6] I.Ortega-Fernández,S.A. Zavattoni, J. Rodríguez-Aseguinolaza, B. D’Aguanno, M. Barbato, Applied Energy, 205, 280–293 (2017).

[7] L.Geissbühler,M.Kol-man, G. Zanganeh, A. Hasel-bacher, A. Steinfeld, Appl. Therm. Eng., 101, 657–668 (2016).

[8] L.Geissbühler,A. Mathur, A. Mularczyk, A. Haselbacher, Sol. Energy, accepted for publication (2019a).

[9] L.Geissbühler,A. Mathur, A. Mularczyk, A. Haselbacher, Sol. Energy, accepted for publication (2019b).

Figure 2:

Top: Simulated outflowtemperatures for a TES system consisting of one and four tanks (diabat-ic conditions, constant Vtot = 4300 m3) with the switching times t1 to t3. Bottom left: Thermoclines in the four TES system at times t1 to t3. The TES units in use are indicated by the colored frames. Bottom right: Thermo-clines in the one-tank TES system at the start and end of the charging phase.

Sensible Thermal-Energy Storage Systems Optimized for AA-CAES Plant Operation

7 Heat

AA-CAES Plant Modelling Improvements and Layout Definition

Scope of project

The research efforts were focused to further develop and apply the dynamic numerical model for AA-CAES plants, developed at SUPSI in the Matlab-Simscape environment. Among its features, to accurately describe the thermocline evolution within packed bed thermal energy storage (TES) sys-tems,thismodelembedsa1DFortrancodedevelopedbyETHZ[1].


The plant layout labelled P1, and reported in Figure 1 top left,isafirstexampleofmodelapplication[2].Inthisconfigu-ration, the TES is contained in a chamber that is physically separated from the cavern where the cold air is stored. These two volumes have dif-ferent pressures (LP and HP respectively) and, before the plant discharging phase, they have to be balanced at the same pressure value. The pressure equilibrium between the cavern and the TES cham-ber was modelled comput-ing theunsteady inviscidflowthrough a converging nozzle placed between them. Further-more, this plant layout implies that, after a discharge phase,

the TES chamber has a re-sidual high pressure that has to be discharged to allow the next charge from the LP com-pressor (LPC). In order to not waste the pressurized air left in the TES chamber and part of the thermal energy stored there, the depressurization is performed through an auxil-iary turbine.

A second layout, labelled P2 [2]andshowedatthetoprightof Figure 1, was conceived in order to avoid the pressure balancing actions. This was obtained by keeping constant the pressure in the TES cham-ber and exploiting the thermal energy at the outlet of the HP compressor (HPC). Therefore,

an additional TES was placed inside the cavern and a HP-LP turbine train was added. So, the thermal energy obtained after the HPC is exploited by the HP turbine, that is placed between the cavern and the LP TES chamber.

The two layouts were com-pared under a regular cy-cling schedule composed by 5 hours of charging followed by 5 hours of discharging, both at a constant mass flow rateof 200 kg/s (232 kg/s for the LP compressor in P1 layout to compensate the air expelled through the auxiliary turbine). In the P1 layout additional idle time intervals were added be-tween these main phases in

Authors

Jonathan Roncolato1 Filippo Contestabile1 Simone Zavattoni1 Viola Becattini2 Giw Zanganeh3 Andreas Haselbacher2 Davide Montorfano1 Luca Cornolti1 Maurizio C. Barbato1

1 SUPSI2 ETHZ3 ALACAES SA


HP High Pressure

HPC High Pressure Com-pressor

HPT High Pressure Tur-bine

LP Low Pressure

LPC Low Pressure Com-pressor

LPT Low Pressure Tur-bine


Figure 1:

AA-CAES plant layouts, P1 on the top-left and P2 on the top-right. Blue lines show the charging flowpaths while red lines are the discharging ones. On the bottom, temperature and pressure variations within the TES chambers are reported accordingly.

8 Heat

Figure 2:

Load profiles over oneweek used to simulate ir-regular cycles with the P2 layout. Positive/negative loads correspond to charg-ing/discharging of the plant.

Figure 3:

Turbomachinery power levels resulted from simu-lations (top); daily and average efficiencies of theAA-CAES P2 plant for the simulated week (bottom).

order to allow the pressure ad-justments in the TES chamber. Aconstantisentropicefficiencyof 0.85 was set for all the tur-bomachinery; volumes of cav-ern and TES chamber were set to 177’000 m3 and 18’500 m3 respectively.

The results reported at the bottom of Figure 1 show the TES chamber temperature and pressure evolution during the first10cycles.IntheP1layout,

issues related to the dynamics of the TES chamber were de-tected, namely large tempera-ture variations and time lags required for the pressure ad-justments. The former would likely affect the components life (e.g., probes and electron-ics) while the additional time lags due to pressurization and depressurization of the TES chamber would be detrimental for the plant responsiveness to the grid power demand.

In the P2 layout instead, both temperature and pressure variations in the TES chamber were smaller. This result can be achieved if an adequate regulation of the mass flowrate of compressors and tur-bines is actuated. After the comparison of these results and considering the drawbacks caused by the pressure swings within the TES chamber, the P2 layout was preferred to test a realistic weekly sched-ule based on electric power exchanged with the grid (see Figure 2). This schedule was designed by PSI starting from an economic optimization of the AA-CAES plant operation. For this case, turbomachin-ery efficiencieswere switchedfrom isentropic to polytropic ones: namely LPC was set to

0.85, HPC to 0.88, HPT to 0.86 and LPT to 0.90. The two TESs were pre-charged for 10 hours witha200kg/sflow rateandat the beginning of the week simulation, the cavern was initialized at 85 bar. Feedback controls were activated to keep the cavern pressure within the 80–100 bar range. The HPC was operated in sliding pres-sure mode, assuming the com-ponent to be flexible enoughto follow the cavern pressure increase. On the other hand, considering the limited flex-ibility of turbo-expanders, the pressure at the turbine inlet was throttled to 80 bar.

Top of Figure 3 shows the ac-tual power of all turboma-chinery, from which it is pos-sible to notice that the useful power for the LPC decreases during charges to balance the increasing power request by the HPC. During discharges in-stead, the adoption of a throt-tling pressure helped in having hourly constant power output for both expanders. The ef-fects of higher temperatures at the outlet of HPT caused by the throttling was mitigated by the presence of the LP TES, with-out influenceson theLPTop-eration. The daily and weekly efficienciescalculatedareplot-ted at the bottom of Figure 3.

The simulation of a realistic connection to the grid showed that transients of turboma-chinery and their characteris-tics, especially turbomachines' flexibility, are particularly sig-nificant for the AA-CAES op-eration. Therefore, exploiting data provided by MAN ES AG, realistic turbomachinery char-acteristics were included in the numerical model and tested on a new plant layout called P3.


9 Heat


References

[1] L.Geissbühler,M. Kolman, G. Zanganeh, A. Haselbacher, A. Stein-feld, Applied Thermal En-gineering, 101, 657–668 (2016).[2]M.C.Barbato,«Analysis of AA-CAES Cycles Exploiting Com-bined Sensible/Latent Heat Storage and Novel Materials», NRP70 Project 407040_154017 Final report (2019).[3] J.Roncolato,F.Con-testabile, D. Montorfano, A. Haselbacher, G. Zan-ganeh, P. Jenny, E. Jac-quemoud, M. Scholtysik, M.C. Barbato, «AA-CAES-G2G Advanced Adiabatic Compressed Air Energy Storage grid-to-grid performance modeling», Annual Project Report (2018).

For the P3 layout, based on the P2 plant topology, the com-pression ratio was evenly split between LP and HP compo-nents in order to consider «off-the-shelf» turbomachinery as suggested by MAN ES AG. This technical choice, with respect to P1 and P2, forced a lowering of the maximum temperatures at the LPC outlet.

Furthermore, driven by eco-nomic reasons, constant speed turbomachinery was consid-ered (in fact, this avoids the need for Variable Frequency

Drivers).Theflexibilityoftur-bomachinery performance, whenever possible, was guar-anteed by systems that include variable guide vanes. Further-more, compressors/turbines polytropicefficienciesasfunc-tion of compression ratio and massflowrate/«reducedmassflow rate» were included intothe numerical model (i.e., turbomachinery performance maps).

Moreover, different approach-es were discussed to properly model the transients of tur-

bomachinery, starting from a very accurate physical pro-cedure up to a more simpli-fied approach. The former isbased on specifically devel-oped sub-models that mimic real turbomachinery start-ups accordingly to the character-istics provided by MAN ES AG. The latter consists in just ac-counting for parasitic energies and start-up times based on reliable data gathered from the samemanufacturer[3].

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Numerical Phase Change Study and Optimiza-tion of High-Temperature Encapsulated Metal Phase Change Materials for Energy Storage

Scope of project

Highly conductive, high melting point (above 400 °C) metal alloys can be used as phase change ma-terials (PCMs) for high energy and power density latent heat storage applications, as an alternative to the widely used molten salts. The computational phase change model implemented last year was usedtocomparehigh-andlow-temperaturePCMsduringmelting(i.e.discharging)andsolidification(i.e. charging). A parametric study was conducted with cylindrical stainless steel encapsulations of different sizes and orientations. For the optimization of the encapsulations, we focused on machine learning techniques. Random percolating macro-porous structures – used to increase the convec-tiveheattransferbetweentheheattransferfluid(HTF)andPCM–werecreatedandmeshedin2Dand 3D to serve as encapsulations for the PCMs. In another design, randomly generated porous structuresthatresemblefinsinsideapairofconcentricpipesweregeneratedtoincreasetheheattransfer inside the encapsulation. A de-convolutional neural network was developed to predict the temperature, velocity and heat transfer values in the simulation domain of the porous structures. Once trained with enough simulations, this network will be used to optimize the porous structures dependingonthespecificationsrequiredfortheapplication.


The phase change model should allow to track the melt interface, predict the convec-tion in the melt, capture phase change over a temperature range, account for volumet-ric expansion and contraction, and close contact melting. We developed a transient axisym-metric simulation using the enthalpy-porosity method [1]for phase change inside a cy-lindrical PCM storage unit (Fig-ure 1a and Figure 1b) with an air gap to allow for thermal expansion of the metal. Sim-ulations were performed for low-temperature (Rubitherm RT-27) and high-temperature (Al-12Si) PCMs in vertical and

horizontal cylinders with inner diameters of 1–10 cm, with wall temperatures set so that they have the same Stefan num-bers. Time-depen-dent temperature contours and velocity vectors for one spe-cific case of meltingin a vertical cylinder for Al-12Si are shown in Figure 1c.

Figure 1 (a–c):

Conduction-driven charg-ing/discharging simulation setup of (a) vertical and (b) horizontal encapsulated cylindrical PCM storages. The blue part represents the PCM, and the red part the thermal expansion gap, surrounded by a constant temperature outer wall. (c) Time dependent tem-perature contours and ve-locity vectors within the melting PCM in a 5 cm di-ameter cylinder with wall temperature 30 K above the melting point.

Authors

Nithin Mallya1 Sophia Haussener1

¹ EPFL


HTF Heat Transfer Fluid

PCM Phase Change Material

Parametric Phase Change Study

(a)

(b)

(c)

11 Heat

The corresponding quantifica-tion of multiple modes of heat transfer is shown in the heat transfer variation plot Fig-ure 1d. Initially, conduction is dominating[2]duetothethinlayer of melt next to the wall. A sudden drop is observed in the heat transfer rate due to the lower conductivity of the liq-uid metal where the dominant heat transfer mode changes to convection. Kelvin-Helmholtz instability convection cells form in the molten PCM due to shearingflowsofhotrisingandcold sinking molten fluid thatspeed up the melting process compared to the conduction only case.

In order to guide the design of an actual unit, a non-dimen-sional analysis was performed using

Fourier ,

Stefan and

Grashof

numbers as shown in Fig-ure 1e. Faster melting was achieved with larger Stefan numbers (larger tempera-ture differences) and smaller Grashof numbers (small diam-eters). A comparison with the low temperature PCM is cur-rently performed to obtain a generalized relation.

,

and

Topology Optimization: Porous Encapsulations

Last year, we investigated ge-netic algorithms for optimizing latent heat storage units. But they are limited by the number of parameters and are not suit-able for random macro-porous structures that cannot be ex-plicitly parametrized (such as shown in Figure 2a).

Deep learning neural networks with multiple processing lev-els are well known in learning data representations of vary-ing degree of complexity and are the state-of-the-art tech-niques used for recognizing objects, images, and speech, and have been used in drug

discovery and genomics. Arti-ficialneuralnetworksrequirealarge amount of training data to replicate flows accurately,which makes them suitable for modellingflowsspecifictothetrained geometries and mod-els.

While porous media can be characterized with respect to their morphology with images obtained using tomography data, a parametric description cannot be given. Deep learn-ing optimization is currently applied to such structures, requiring two steps: training and optimization. Encapsu-lated macro-porous structures are currently generated with specific morphologies (poros-


(e)

(d)

Figure 1 (d–e):

(d) Dynamic variation of multi-mode heat trans-fer within the PCM for the case in Figure 1b. (e) Melt fraction and wall heat transfer variation for Al-12Si against non-dimensional time for cases with different non-dimen-sional numbers.

12 Heat


ity, minimum thickness, con-nectivity etc.). For these struc-tures, theflow,phasechangeand heat transfer are modelled (Figure 2c and Figure 3) to train a de-convolutional neural network – an image recogni-tionspecificfeedforwarddeepneural network (Figure 2b) that has been previously suc-cessfully used in image recog-nition and recently been used

to optimize aerofoils [3]. Theoptimization step will then follow using gradient-based methods to conceivably gener-ateapplicationspecificmacro-porous heat storage systems. While training of neural net-works is typically in the order of tens of hours, optimization can be performed in the mat-ter of a few minutes or hours in non-parametrized porous

structures and even to obtain results with boundary condi-tions and porous character-istics beyond the training im-ages.

The combination of these op-timization approaches with latent heat storage modelling shows to be promising for pro-viding guidance of tailored la-tent heat storage units.

Figure 3:

A randomly generated con-centric 3D macro porous latent heat storage unit which is meshed and la-beled. The randomly gen-erated porous structures resemblefinsinsideapairof concentric pipes

References

[1]A.D.Brent,V.R.Vol-ler, K.J. Reid, Numer. Heat Transf., 13, 297–318 (1988).

[2] J.M.Khodadadi,Y.Zhang,Int.J.HeatMassTransf., 44(8), 1605–1618 (2001).

[3]P.Baqué,E.Remelli,F. Fleuret, P. Fua, «Geodesic Convolutional Shape Optimi-zation», https://arxiv.org/abs/1802.04016, (2018).

Figure 2:

(a) A randomly generated periodically repeating cell of a 3D macro porous la-tent heat storage which is meshed and labeled. (b) A de-convolutional neural network with in-put and output as a set of 3D voxels. (c) Temperature distribu-tion output in a single slice of the 3D domain at a spe-cifictime.

13 Heat

High-Temperature Latent Heat Storage System: Heat Transfer Enhancement Using Ceramic Porous Media

Scope of project

The design of a thermal energy storage unit (TESU) with a high-temperature silicon-based phase change material (PCM) is presented. The PCM is encapsulated in a SiSiC tube and air is used as theheattransferfluid(HTF),whichpassesalongtheencapsulation.Theflowpassageisfilledwithreticulated porous ceramics (RPC) to enhance the heat transfer between the encapsulated PCM and theHTF.Akeybenefitofsuchaconfigurationisitsscalabilitybythein-seriesorin-paralleladditionofmultipleunits.Inourwork,weproposeadesignstrategybasedonwell-definedperformancemetrics(i.e.exergyefficiency,energydensity,andeffectiveness).


flow), and on the local ther-mal non-equilibrium formula-tions of the energy equation for the porous media. The P1 approximation was used to consider the radiation in the porous medium and the appar-ent heat capacity method was employed for the energy equa-tion in the phase changing do-main. Radiative and transport properties of the porous me-dium were obtained from the literature[2–4].Theequationswere solved using Comsol Mul-tiphysics package® (v5.3) in-terlinked with Matlab.

A parametric analysis was per-formed for all combinations of 5 different encapsulation diameters, Denc, (2, 4, 6, 8, 10 cm), 5 different encapsula-tion lengths, Lenc, (20, 40, 60, 80, 100 cm) and 3 different po-rous foam morphologies with pore sizes, dpore, (1.25, 2.5, 5 mm) and constant poros-ity (Φ=0.9). For comparison,simulations on empty channels (without porous medium) were also performed. The simula-tions stopped as soon as the HTF average temperature at the outlet fell bellow 1210 K.

As a measure of the storage system performance, the stor-age effectiveness (ε) was de-fined:

D: Net discharged energy by HTFE: Total possible thermal energy that

can be discharged

ε is indicating how effectivethe storage system is extract-ing the maximum possible en-ergy from the storage unit. It would be equal to unity if the temperature of the system at the discharged time is equal to the HTF inlet temperature.

Figure 2 shows the effective-ness of the storage system for different unit designs. For the system with empty channels, the effectiveness increases with decreasing encapsulation diameter. However, manufac-turing such small scale TESU

Mg-Si (wt% 44/56) was con-sidered as the PCM, which has a high melting temperature (1219 K) and heat of fusion (757kJ/kg) [1].Only thedis-charging procedure is consid-ered in this work. The TESU is assumed to be at an initial temperature of 1229 K and it is discharged with HTF entering at the inlet at 1119 K.

The design procedure starts with preliminary calculations: knowing the desired discharg-ing time (set to 1 hour) and thedischargedexergyefficien-cy (set to 0.95) of the system, the mass flow rate and theflowpassageareawerecalcu-lated for a certain porous me-dium and encapsulation size. Theexergyefficiency(ηdis) was definedasfollows:

A: Net discharged exergy output by HTFB: Equivalent thermal exergy for pump-

ingC: Exergy released by TESU

An axisymmetric model (Fig-ure 1) was developed based on the preliminary calculations to analyze the performance of the storage unit with vari-ous RPC morphologies. The multi-physics model was based on the continuity and Brink-man equations (with Forch-heimercorrectionsforthefluid

Authors

Ehsan Rezaei1, 2 Maurizio Barbato1 Alberto Ortona1 Sophia Haussener1

1 SUPSI2 EPFL




RPC Reticulated Porous Ceramics

TESU Thermal Energy Storage Unit

Figure 1:

Axisymmetric model used for the simulations of the latent thermal energy stor-age unit.

References

[1]B.Cárdenas,N.León,Renew. Sustain. Energy Rev., 27, 724–737 (2013).

[2]B.Dietrich,Chem.Eng. Sci., 74, 192–199 (2012).

[3]B.Dietrich,Int.J.HeatMass Transf., 61, 627–637 (2013).

[4] J.Petrasch,P.Wyss,A. Steinfeld, J. Quant. Spectrosc. Radiat. Transf., 105(2), 180–197 (2007).

14 Heat

Figure 2:

The effectiveness of the TESU for different stor-age sizes with two differ-ent foams and without foams. The black dots in-dicate conditions for which the simulations were per-formed. The black diamond in each figure shows thepoint with the highest ef-fectiveness.

is difficult and expensive.Adding the porous medium for larger encapsulation di-ameters increasesthespecificsurface area for the heat ex-change between the storage unit and the HTF. As a result, higher effectiveness can be achieved. For dp = 5 mm, a maximum effectiveness of ~ 0.92 is reached at Denc = 2 cm and Lenc = 100 cm. For the model with dpore =1.25 mm, the maximum effectiveness was ~ 0.93 at Denc = 20 mm and Lenc = 400 mm.

The volumetric energy densi-ties of all configurations areshown in Figure 3. Systems

High-Temperature Latent Heat Storage System: Heat Transfer Enhancement Using Ceramic Porous Media

Figure 3:

Energy densities of the TESUs for different unit sizes and for two different foam morphologies.

with larger encapsulation length generally require larger massflowratesandlargerflowpassage areas to discharge the system in the desired time with the desired exergy efficiency.As a result, the energy density of the storage unit decreases when increasing the encapsu-lation length.

Conclusions and future studies

For small encapsulation diam-eters,thespecificsurfaceareaof the TESUs increased and as a result the system effective-ness increased. However the performance of the system

decreased at larger diameters (Denc≥20mm). For larger di-ameters, the use of porous media enhanced the perfor-mance of the storage unit. The energy densities of these sys-tems were within 30–650 MJ/m3. The best performance of the TESUs showed effective-ness ≥0.92 and energy den-sity≥220MJ/m3.

For future studies, a storage system with variable pore size will be considered with the aim of increasing the performance of the storage unit at larger encapsulation diameters.

15 Heat

Direct Contact Latent Heat Storage Using Esters as New Phase Change Materials

Scope of project

The Direct Contact Energy Storage (abbreviated as DENSE) project started in mid-January 2018 and proposes to investigate the suitability of Esters as a new class of bio-based phase change materials (PCM)tobeusedindirect-contactlatentheatstoragessetups.Atfirst,acomprehensiveinvestiga-tion of esters’ thermal properties and behaviour has been planned. The esters have been studied based on several «classes» such as fatty esters (deriving from fatty carboxylic acids), lactones (cy-clic esters), diesters (esters deriving from dicarboxylic acids), triglycerides (esters of glycerol with carboxylicfattyacids),aromatics(estersofaromaticcompounds).Inparallel,firstexperimentalandnumerical investigations have been conducted aiming at the optimization of the direct contact latent heat storage technology when used with esters or other phase change materials.


The first class analysed wasthat of fatty esters. With this purpose, esters of five differ-ent linear saturated fatty car-boxylic acids (myristic C14, pal-mitic C16, stearic C18, arachidic C20 and behenic C22) coupled with alcohols of different chain length (methanol C1, 1-pen-tanol C5 and 1-decanol C10) have been synthesized, puri-fied and studied. The resultsobtained show that fatty es-ters are promising candidates as bio-based PCM for low-mid temperatures applications. In addition, interesting trends correlating the chemical struc-tures to the thermal properties have been found (Figure 1) [1,2].

The results obtained from fatty esters have been presented at

the International Sustainable Energy Conference (ISEC), Graz.

The second class investi-gated was that of lactones. Here, two commercial lac-tones (ε-caprolactone andγ-valerolactone) and threesynthesized ones (dibenzo-chromen-6-one, 1,2-cam-pholide and oxa-adamanta-none) have been studied. In general, the lactones showed a wide range of phase change temperatures. However, they were also characterized by poor thermal stability, low en-thalpies of fusion and a high degree of supercooling, which mark them as unsuitable PCM. No clear correlation between the chemical structures and the thermal properties could

be observed in this case. A publication on lactones is cur-rentlybeingreviewed[3].

Natural and biodegradable triglycerides have been inves-tigated through commercial samples (glyceryl trioctanoate from coconut oil, glyceryl trili-noleate from lignin, and glyc-eryl trioleate from olive oil). All commercial samples tested showed a strong tendency to form different crystalline states through polymorphism, hence tri glyc erides have been marked as unsuitable com-pounds for latent heat storage, and investigations on this class have been interrupted.

Nevertheless, a review article on tri glycerides as PCM with additional data from the tri-

Figure 1:

Left: Strategy for the in-vestigation of esters as new PCM through classes toobtainafinaldatabaseoftheir thermal properties. Right: First results of the phase change transition (Tm equals temperature of melting, Tc temperature of crystallization) obtained for the class of linear fatty es-ters (accepted for publish-ingfrom[2])

Authors

Anastasia Stamatiou1 Rebecca Ravotti1 Stefan Krimmel1Jörg Worlitschek1

1 HSLU


DENSE Direct contact EN-ergy StoragE


ISEC International Sustainable Energy Conference

MEPA Methyl Palmitate


16 Heat

glycerides tested will be sub-mitted for publication during 2019.

In parallel to what has been done for linear fatty esters, di-esters deriving from different natural dicarboxylic acids (ox-alic C2, succinic C4, suberic C8, sebacic C10) coupled with lin-ear alcohols of various lengths (methanol C1, 1-pentanol C5 and 1-decanol C10) have been

synthesized and fully char-acterized. The assessment of diesters’ thermal properties is currently ongoing. A publica-tion on diesters is expected during the course of the year.

The last class of esters under investigation is that of aro-matic esters. At present, nine commercial aromatic esters have been characterized, while pentyl and phenyl esters of

terephthalic acid are being synthesized from methyl tere-phthalate via transesterifica-tion. So far, aromatic esters seem to possess a wide range of phase change temperatures, while the enthalpies of fusion vary greatly. The research on aromatic esters will continue, resulting to a publication.

The experimental and numeri-cal investigation of the Direct Contact Latent Heat Storage Concept started as well. The first experimental screeningtests in a 12 l test rig (Fig-ure 2) have been performed in the laboratory of the HSLU and the numerical investiga-tionwithANSYSFLUENTatthepartner university, the Techni-cal University of Vienna. The experiments show, a linear de-crease of the power output un-til a drop of the power occurs for all experiments with differ-ent Re numbers (Figure 3c). These results have been pre-sented at the 12th International Conference on Energy and De-velopment, Environment and Biomedicine, Corfu. One peer-reviewed paper concerning the experimental investigation has

Figure 3:

a) Picture of the so-lidification process witha Reynolds number of 4250 at the nozzle. b) Simulation of tem-perature distribution at an iso-surface of equal grade of turbulence in a liquid-liquidflowofafreejet. c) Dimensionless power-performance (temperature effectiveness vs. grade of load) of the test runs by the screening test.


Figure 2:

Left: Flow chart of direct contact experimental set up: (a) storage tank; (b) HTF outlet; (c) expansion tank; (d) pump; (e) plate heat exchanger; (f) thermostat unit; (g) by-pass; (h) nozzle plate; (i)droplet flow, ascending

against the gravity; (j) insulation; (k) LED strips.

Right: The storage tank is filledwithwater(7l)asPCMand a thermo oil (4 l) as HTF. The droplet flow of theHTFis illuminated by one of the LED strips. It ascends to the interface HTF/PCM and it is pumped out by the tube at the top.

17 Heat


References

[1]R.Ravotti,O.Fell-mann, N. Lardon, L.J. Fischer, A. Stamatiou, J. Wortlitschek, Appl. Sci., 8, 1069–1087, (2018).

[2]R.Ravotti,O.Fell-mann, N. Lardon, L.J. Fischer, A. Stamatiou, J. Wortlitschek, Appl. Sci., 9 (2), 225–240 (2018).

[3]R.Ravotti,O.Fell-mann, N. Lardon, L.J. Fischer, A. Stamatiou, J. Wortlitschek, Mol., Submitted, Under Review (2018)

[4]S.Krimmel,A.Sta-matiou, J. Worlitschek, H. Walter, Int. J. of Mech. Eng., 3, 83–97 (2018).

alreadybeenpublished[4]andone additional paper on the numerical investigation is un-der review.

For the upcoming investiga-tions, two new test-rigs are planned. A new 55 l setup will include improvements out of

the experience with the 12 l test-rig. A new geometry of the test volume, optical ac-cess from four sides and a completely automatic control system are the main improve-ments. A new 2.5 l test-rig will be built to investigate the in-terface interactions between

different phase change materi-alsandheattransferfluids.

Additionally, the models of multi-phase flow and phasechange in ANSYS FLUENTwillbe connected, and validated with experimental observa-tions.

18 Heat

Closed Sorption Seasonal Thermal Energy Storage with Liquid Sorbent Solutions

Scope of project

A closed sorption Thermal Energy Storage (TES) prototype based on water vapour absorption/de-sorption in a high-energy density sorbent like aqueous sodium hydroxide (NaOH-H2O, LiBr-H2O or LiCl-H2O was setup at HSR-SPF (Figure 1). The two processes charging (desorption, D) and discharg-ing (absorption, A) occur under reduced pressure i.e. at sorbate vapour pressure and the exclusion ofnon-condensableair[1,2].Duringthechargingprocessinsummer,thethermalenergyproducedby solar collectors is used to partially vaporize / desorb (in the A/D unit) the water contained in the diluted solution. While this process is running, the resulting concentrated solution (A/D unit) and the water (E/C unit) are stored at room temperature in separate tanks (high concentration (HC) Sorbent tank and H2O Sorbate tank) until the discharging process. In this storing period, no thermal energy is lost as it is in the case of sensible thermal energy storages. During discharging in winter, ground heat is used to evaporate the stored water at its vapour pressure in the evaporator (E: E/C unit). Thus, in the A/D unit, heat is released during the exothermic process of water vapour absorption into theconcentratedsolution.Thereleasedheatistransferredtoaheattransferfluidthatcanbeused,forexample,infloorheatingapplicationswhereasthedilutedsolutionisstoredinthelowconcentra-tion (LC) tank until the next regeneration phase.


is influencing theefficiencyofthe tube bundle heat and mass exchangers from the reaction zone. These parameters were investigated by performing small scale surface wetting ex-periments. The modular design for the absorber/desorber unit allows the replacement of the tube bundle and implementa-tion of the improvements from previous small-scale experi-ments. Thus, testing of several

types of tubes and liquid sor-bent modifications is possible[3].

A series of evaporation/con-densation tests was carried out in order to test the facility in conditions close to the real process conditions. Figure 2 shows temperature and power curves of the first measure-ments. About 1 kW of power is exchanged on both A/D and

Figure 1:

Schematic of the closed sorption thermal en-ergy storage (TES) setup based on water vapour absorption/desorp-tion in a sorbent: a) simplified CAD drawingshowingthefluidloops,b) graphical user interface (GUI).

The applied storage concept (Figure1) allows and benefitsof the liquid sorbent phase, which can be pumped. The 1 kW prototype unit is using thefallingfilmprincipleimple-mented in a tube bundle heat and mass exchanger technolo-gy with a manifold distributing the sorbent and sorbate over the tubes. Sorbent surface wetting and residence time of the sorbent in the water vapour

Authors

XavierDaguenet-Frick1 Mihaela Dudita1 Lukas Omlin1 Paul Gantenbein1

1 HSR (University of Applied Sciences Rap-perswil)


A/D Absorber/Desorber

E/C Evaporator/Con-denser

HC High Concentration


LC Low Concentration


19 Heat

E/C units for a heat transfer fluid (HTF) inlet temperaturesof 13 °C for the A/D and 39 °C for the E/C tube bundle. The E/C unit was run without any fluidpre-heating.Thisexplainsthe first (negative) powerpeak. With the increase of the recirculated water tempera-ture in the E/C loop, this power gradually reaches the designed valueof1kW.Thefluctuationsof the HTF temperature at the inlet of the E/C unit are ex-plaining thesmallfluctuationsof the power curve of this unit.

Process improvement

To increase the wetting of the tube bundle surfaces – com-pared to the previous COM-TES system – a feasibility study regarding the effect of a hydrophilic coating on struc-tured tube samples was car-ried out. The OptoPEG coating was developed by CSEM. The wetting experiments were per-formed in the SPF laboratory with water and the results are shown in Figure 3. The sample code includes the short name of the coating and whether it is textured or not (OPTO_f – OptoPEG coated flat tube,OPTO_t1 to OPTO_t3 – Op-toPEG coated tube with dif-ferent texturing types). The maximum wetted width is the graph from Figure 3 as well as in the inset. In compari-son with the non-coated tube (OPTO_f0), all the samples with hydrophilic coating show a better wetting behaviour expressed as the maximum wetted width. The structured samples may present a bet-ter wetting behaviour than the non-structured[9].

Sorbent materials

Theoretical investigations per-formed showed that the two sorbents NaOH-H2O and LiCl-H2O have the same absorp-tion potential and this is higher compared with LiBr-H2O (Fig-ure 4). These considerations include both liquid and solid

Closed Sorption Seasonal Thermal Energy Storage with Liquid Sorbent Solutions

Figure 2:

Reference measurements with water as operation fluid: temperatureT andpower P in function of time t for the A/D unit used as condenser and the E/C unit used as evaporator.

References

[1]X.Daguenet-Frick,P. Gantenbein, J. Mül-ler, B. Fumey, R. Weber, Renewable Energy, 110, 162–173 (2017).

[2]M.Dudita,X.Da-guenet-Frick, L, Omlin, P. Gantenbein, A. Haeberle, «Compact Seasonal Ther-mal Energy Storage for Solar Energy Systems», Eurosun 2018, Rapperswil, Switzerland (2018).

[3]X.Daguenet-Frick,M. Dudita, L. Omlin, P. Gantenbein, «Seasonal Thermal Energy Storage with Aqueous Sodium Hydroxide – Development and Measurements on the Heat and Mass Exchang-ers», Düsseldorf (2018).

Figure 3:

Left: Structured and coat-ed tube samples Right: DI water wetting performance of tube sur-faces with hydrophilic coat-ing OptoPEG (CSEM).

Figure 4:

Absorption potential com-parison of sorbent-sorbate combinations: LiBr-H2O, NaOH-H2O and LiCl-H2O. The last two have the same potential (both phases – liquid and solid are consid-ered).

phases of sorbents. Although our storage concept follows the application of liquid sor-bents and because of cost rea-sons NaOH-H2O is preferred, these results give a hint for the selection of the second (best) sorbent material.

20 Heat

Closed Liquid Sorption Seasonal Heat Storage Using Aqueous Sodium Hydroxide

Scope of project

Empa is working on different ends to improve heat and mass transfer characteristics in the liquid sorption process using aqueous sodium hydroxide for the purpose of seasonal heat storage. Major challenges are found in the mass transfer of water within the sorbent solution and rate limitations determined by molecular diffusion. Detailed analysis of mass transfer phenomena was performed in 2018 using Raman spectroscopy and neutron imaging. It is the goal to use results from mass transfer studies to improve the core heat and mass exchanger component and to increase its volumetric power density prior to upscaling towards larger thermal discharge power.


Mass transfer analysis

In the absence of significantturbulent mixing, mass trans-fer of water from its gaseous phase to its liquid phase in the liquidsorbentfilmisgovernedby molecular diffusion. The dif-fusion rate is proportional to the concentration gradient in the liquid film, whereby theproportionality factor is the dif-fusioncoefficient.Thediffusioncoefficient again is dependenton the concentration of the liquid sorbent as well as on its temperature.

Absorption and desorption processes are characterized by mass transfer of water in oppo-site directions. During absorp-tion water vapour is driven into the liquid sorbent while dur-ing desorption water is being evaporated from the liquid sor-bent. As previous experiments

Authors

L. Baldini1, B. Fumey1

R. Weber1

1 Empa


HMX HeatandMassExchanger

NaOD Sodiumdeuteroxide

suggested the two processes behave differently, even un-der similar pressure differ-ences between the sorbent solution and the absorbate atmosphere. The desorption process was found to be less critical and could be operated athigherthermalpower[1–3].In desorption mode the trans-portofwaterinthefilmisther-mally driven. Minimum sorbent concentrations are encoun-tered at the heat exchanger surface, increasing towards the liquid-gas interface, in-versely following the thermal gradient in the liquid film. Inabsorption mode an additional barrier to mass transport is assumed at the liquid surface interface. Due to quick initial absorption at the interface a so called equilibrium layer is being formed, acting as a dif-fusion barrier by reducing the local driving force for mass

transfer, i.e. the concentration gradient.

Raman spectroscopy experi-ments were performed to study the mass transfer kinetics dur-ing absorption and desorp-tion under different operating conditions (Figure 1). Raman spectroscopy proved to be appropriate to detect various sodium hydroxide concentra-tions. Using measured calibra-tion curves, sodium concentra-tions could be calculated from Raman signals received for water molecules and OH ions, respectively. Preliminary re-sults confirm the reduction ofmass transfer rates in absorp-tion mode compared to de-sorption mode. More detailed analysis of the measurement campaigns performed is on-going and will be published in ascientificjournal.

Figure 1:

a) Raman spectroscope at Empa with test cell for NaOH sample holding, pressure sensor and valve for vapor control. b) Intensity signals record-ed in initial measurements for different concentrations allowing for separating peaks generated from wa-ter molecules or NaOH.

21 Heat

References

[1]R.Weber,B.Fumey,«NaOH-Speicher für saiso-nale Wärmespeicherung – Final report SFOE», Empa – Swiss Federal Laborato-ries for Material Science and Technology (2016).

[2]R.Köll,W.vanHelden,B. Fumey, «European Union Seventh Framework Program Project COMTES – Combined development of compact thermal energy storage technologies – De-liverable 5.1: Description of experimental systems», J.B. Johansen and S. Fur-bo, Editors (2015).

[3]K.E.N'Tsoukpoe,N.LePierrès, L. Luo, Energy, 53, 179–198 (2013).

Another experiment campaign with reference to mass transfer in the heat and mass exchang-er (HMX) was performed us-ing neutron imaging technique available at the SINQ facility at Paul Scherrer Institute (PSI). In an aluminium test cell NaOD solution is brought in contact with water vapour during the course of droplet impingement onto the liquid film. The goalwas to observe the effect of surface to bulk mixing during the experiment by monitoring the concentration of hydrogen atoms in the solution. For bet-ter image contrast deuterium was used instead of normal water in the sorbent solution. Figure 2 highlights the pos-sibility of visualizing different sorbent concentrations in the liquid film. At the gas liquidinterface where water vapour is being absorbed neutrons are more strongly attenuated resulting in a darker image. A detailed analysis of the results of this measurement campaign is ongoing and will be made available through publishing activities once consolidated.

Experimental equipment: Lab-scale bulk reactor and upscaled heat and mass exchanger

Another experimental setup used to study mass transfer kinetics at a bulk scale was fur-ther advanced in 2018 and will beavailableforfirstmeasure-ments in 2019 (Figure 3). This lab-scale bulk reactor can be used to determine mass trans-ferkineticsinliquidfilmsunderdifferent turbulence scenarios. It can help to quantify possible absorption rates under either undisturbed or well mixed conditions and therefore give an indication of what transfer

Closed Liquid Sorption Seasonal Heat Storage Using Aqueous Sodium Hydroxide

rates are possible or theoreti-cally achievable.

ThedesignofanupscaledHMXwith nominal thermal output power of 5 kW was further advanced such that manu-facturing can be initiated in 2019. The design features a transparent housing allowing for visual inspection during operation. An appropriate spi-ralfinnedtubeheatexchangercandidate with maximum volu-

metric power density remains tobeidentifiedforupscaling.

Figure 2:

Neutron image of test cell with NaOD droplet imping-ingontoNaODfilminwa-ter vapor atmosphere.

Figure 3:

Picture of assembled lab-scale bulk reactor for ma-terial evaluation under application-like conditions.

22 Heat

Thermal Insulation Materials for Thermal Energy Storage

Scope of project

In combination with thermal energy storage, renewable energy technologies offer a vast potential for the supply of residential space heating and the production of domestic hot water (DHW). The problem of reaching an increased market diffusion of seasonal thermal energy storage is not attrib-utedtoalackofknowledgeofthesetechnologies,butrathertotheirhighcost[1].Particularlyinthe case of hot-water seasonal thermal energy storage (STES), it becomes of paramount importance to minimize the annual heat losses while ensuring the economic feasibility of the storage system. Theseconflictingobjectivesleadtoanoptimizationprobleminwhichthecostsoftheinsulationandthe storage container need to be balanced against the penalty costs associated to the annual heat losses and the space occupied by the storage. The latter is particularly important when the storage is placed inside a residential building.

The focus of this project is the economic optimization of hot-water STES systems for multifamily houses. The simulation-based optimization includes: • the design of the storage system, • optimization of the control strategy, and • optimization of the entire system including peripheral components. Inthisarticle,wepresentasummaryofthefirstphaseofthisproject:theevaluationofthermalinsulation materials suitable for STES. The outcome of this work has recently been published in Re-newable and Suitable Energy Reviews [2].


This article summarizes the ongoing work aiming to achieve goal A through eco-nomic optimization of hot-wa-ter TES systems. Alternative to hot-water storage, we are investigating – in the frame-work of an Innosuisse project – the techno-economic poten-tial of near-surface horizontal borehole thermal energy stor-age. Goal B is actively pursued in another ongoing Innosuisse project directly related to the work presented here. In terms of goal C, a parametric study is being conducted to assess the

economic potential of combin-ing sensible and latent heat storage for STES systems inte-grated in residential buildings.

Scenarios and boundary conditions

In this work, the focus is on STES systems for direct supply of space heating and produc-tion of DHW in single buildings. Storage volumes between 10 and 1'000 m3 are regarded for this application. The learnings from this work can neverthe-less be applied also to larger STES systems suitable for clusters of buildings or dis-trict heating. In larger sys-tems, however, the energetic and economic relevance of the thermal insulation is not as important as in smaller sys-tems. This follows from the smaller surface-to-volume ra-tio of larger systems and con-sequently their fundamentally different thermal behavior and economic characteristics.

Authors

Willy Villasmil1Marcel Troxler1

Ludger Fischer1

Jörg Worlitschek1

1 Lucerne University of Applied Sciences & Arts


DHW Domestic Hot Water

PUR-PIR Polyurethane-Poly-isocyanurate Rigid Foam

STES Seasonal Thermal energy Storage

VIP Vacuum Insulated Panels

In the framework of SCCER HaE, three goals have been definedfortheSTEStask:A. Development and construc-

tion of a seasonal water storage pilot plant with costs below 60 CHF/m3.

B. Identification of a ther-mal insulation method that combines vapor barrier with high thermal resistance.

C. The increase of the stor-age density by combining sensible and latent storage modes.

Figure 1:

The three TES concepts considered in this project. Concept 1: Conventional stor-

age tank (single-wall con-struction) integrated inside the building.

Concept 2: Double-wall vacu-um-insulated storage buried in the ground.

Concept 3: Reutilization of an existing room using water-proof thermal insulation ma-terial.

References

[1]S.M.Hasnain,EnergyCon-vers. Manag. 39, 1127–1138 (1998).

[2]W.Villasmil,L.J.Fischer,J.A Worlitschek, Renew. Sus-tain. Energy Rev. 103, 71–84 (2019).

[3]P.Pinel,C.A.Cruick-shank, I. Beausoleil-Morrison, A.A. Wills, Renew. Sustain. Energy Rev. 15, 3341–3359 (2011).

[4]A.Hesaraki,S.Holmberg,F. Haghighat, Renew. Sustain. Energy Rev. 43, 1199–1213 (2015).

[5]M.Koru,Arab.J.Sci.Eng.41, 4337–4346 (2016).

[6]F.Ochs,W.Heidemann,H. Müller-Steinhagen, Int. J. Heat Mass Transf. 51, 539–552 (2008).

[7]A.A.Abdou,I.M.Budaiwi,J. Build. Phys. 29, 171–184 (2005).

[8]F.Dominguez-Munoz,B. Anderson, J.M. Cejudo-Lo-pez, A. Carrillo-Andres, Energy Build. 42, 2159–2168 (2010).

[9]A.Abdou,I.Budaiwi,Con-str. Build. Mater. 43, 533–544 (2013).

23 Heat

The storage concepts consid-ered here are shown in Fig-ure 1. In these scenarios, the STES system consists of a thermallystratifiedwatertankwith a maximum temperature in the range of 60–90°C [3].Lower storage temperatures may allow a reduction of heat losses, however at the expense of a larger storage volume and the cost of incorporating sup-porting equipment (e.g. a heat pump) to increase the tem-peraturetoauseful level[4].One method to be explored to allow the integration of a STES system in an existing build-ingistheretrofitofanunusedunderground room enclosure (Figure 1, concept 3). The ret-rofit would consist of apply-ing suitable vapor barrier and thermal insulation materials to thewalls,floor,andceilingof the room to allow the entire space to be transformed in a hot water reservoir for STES. The challenges of incorporat-ing the insulation material on the inside wall of the storage are similar to those faced in the construction of hot water pit storages. Identifying suit-able materials for this applica-tion is the subject of an ongo-ing Innosuisse project.

Thermal insulation methods and materials

A selection of thermal insula-tion materials that can be ap-plied on the storage outside wall is presented in Table 1, along with their most relevant thermophysical properties. The selection was made on the basis of commercially available materials with maximum ser-vice temperatures adequate for thermal energy storage in the range of 60–90 °C. From theperspectiveofenergyeffi-

ciency, the thermal conductiv-ity is typically the most impor-tant property to be considered in the evaluation of insulating materials. The thermal con-ductivity, λ, largely depends on the density, internal struc-ture (pore fraction and pore size), temperature, and mois-ture content of the insulation material.[5–9]Forthesakeofproviding a concise overview, thermal conductivity values re-ported here correspond to dry materials at 20 °C.

The thermal performance of insulation materials can be evaluated by comparing either the thermal conductivity (λ) or the material thickness (L) re-quired to provide a given ther-mal resistance (R-value = L/λ). Here, a reference R-value of 10 m2 K W–1 (deemed suitable for STES) is used to allow a direct cost comparison of the various insulation materials. This comparison is presented in Figure 2, in which the re-quired material thicknesses (L) were computed using mean thermal conductivities values of those listed in Table 1.

The work conducted in this project has allowed identify-ing thermal insulation materi-als suitable for STES. Our eco-nomicanalysis[2]showsthatthe use of novel thermal insu-lation materials (such as VIP or PUR-PIR) can be favorable

when the economic value of saving living space outweighs the extra cost of the thermal insulation itself. Alternative-ly, the method of evacuated powders (widely used in cryo-genics) can offer significantadvantages for STES. First, it can allow the storage to be buried underground (Figure 1, concept 2), thereby eliminat-ing the need for valuable living space inside residential build-ings. In contrast to VIP, the use of evacuated powders in a double-wall tank construc-tion can allow maintaining the low thermal conductivity of the insulating jacket through a periodic re-evacuation of the vacuum chamber.

Table 1:

Thermophysical properties of thermal insulation mate-rials. λ: thermal conductivity at

20 °C, dry material;ρ: bulk density; Tmax: maximum service tem-

perature. σcc: compressive stress at

10%deformation;VIP: vacuum insulation panels; XPS:extrudedpolystyrene;EPS: expanded polystyrene; PUR-PIR: polyurethane-polyiso-

cyanurate foam.

Figure 2:

Material cost (top) and insulation thickness (bot-tom) required to achieve an R-value of 10 m2 K W–1 with various thermal insu-lation materials. Solid dots represent average cost val-ues, while the bars indicate the range found in the lit-erature.

Thermal Insulation Materials for Thermal Energy Storage

BatteriesAdvanced Batteries and Battery Materials

Illu

stra

tion:

tol

okon

ov /

iSto

ck

The guiding principles of the work were • to show solutions for future cost-effective energy stor-

age, especially for the grid and mobility; • tomaintainandfurtherdeveloptheknow-howinthefield

of batteries and battery materials, to support both Swiss industry and Swiss authorities to master the energy tran-sition;

• to educate students and experts in the field of energystorage in batteries;

• to select, develop, and demonstrate materials and sys-tems for future batteries, in favor of the Swiss industry;

• to keep jobs in Switzerland.

The following picture shows the roadmap of the activities.

Battery materials and electrodes

AtETHZandEmpatheactivitiesinthefieldofbatteryma-terials and electrodes were focused mainly on the develop-ment of high area capacity electrodes for Li-ion batteries and their demonstration in full cells. A negative graphite electrode was developed jointly with Belenos Clean Power Holding, our industrial partner. It exhibits high areal ca-pacity of 5.4 mAh/cm2,highcoulombicefficiencyof99.8%,and shows low average charge voltage of 0.2 V vs. Li+/Li atC/2rate.Theinitialcoulombicefficiencyofthegraphiteelectrodewas 93.7%. A capacity retention of 75% after200 cycles was demonstrated at C/5 rate in an NMC111/graphite full cell with high mass loading electrodes (areal capacity of 4.3 mAh/cm2). Based on the measured data we projected to enable > 220 Wh/kg in a pouch cell with a stack of 11 anodes and 10 cathodes according to an xls calcu-lation sheet developed at Empa. Further, the shape-con-trolled synthesis of cathode powders on multi-gram scale was extended to Co-poor and Ni-rich NMC811 using the co-precipitation system built in 2017. Finally, a selection of the best electrolyte to stabilize NMC811 in full cells against graphite anodes is underway. To this point, capacity reten-tionof91%after200cyclesatC/3ratewasdemonstratedin a NMC811/graphite full cell with intermediate mass load-ing (i.e., lower areal capacity).

At the University of Fribourg research on a more fundamen-tal level was performed. Electrolyte additives based on ionic liquids (IL) with different sizes of crown ethers are promising showing enhancement in the cationic transference number. For instance,byadding1wt%of IL-crown-5 intoacom-mercial aprotic electrolyte LP71 (1M LiPF6 in EC/DEC/DMC) a transference number of 0.62 was obtained while that of pure LP71 was only 0.44. The electrochemical stability window is up to 4.9 V, while the ionic conductivity is about

Work Package «Batteries and Battery Materials» at a Glance

One of the options for decentralized storage of electrical energy is the use of batteries. This direction was further investigated within WP 2 of this SCCER. The main efforts are now focused on the advancement of two selected prospective battery systems, the high-end lithium-ion battery and the potentially cost-effective sodium-ion bat-tery. These two main directions were pursued with focus on material-related activities, and all partners were in-volved in the different topics. The core group here comprised the teams of Maksym V. Kovalenko from ETH Zürich and Empa, Katharina M. Fromm from University of Fribourg, Claire Villevieille from PSI, and Corsin Battaglia from Empa. The production processes for the electrodes and cells from the new materials needed to be understood as well. These activities were pursued under the lead of Axel Fuerst from Berner Fachhochschule Biel (BFH). Need-less to stress, that all groups provided their core expertise wherever needed and demonstrated close collabora-tion and interacted together via the exchange of researchers and materials.

5.3 mS/cm. Also, some alternative cathode materials were tested. Efforts were made to increase the rate capability of LiMnPO4(LMP)byFedoping;theLi-iondiffusioncoefficientof Fe-doped LMP electrodes increased to ~ 5 x 10-9 cm2/s compared to that of pure LiMnPO4 (10–11 ~ 10–12 cm2/s).

Na-ion batteries are the targeted system for stationary ap-plications since their cost is expected to be lower than that of Li-ion batteries whereas their energy density could be only 20–30% less. Still, novelmaterials and electrolytesneed to be developed keeping in mind the cost criteria. On the materials side, we successfully developed some carbo-naceous materials using biowaste sources. Those negative electrodes for Na-ion batteries delivered up to 280 mAh/g at a cycling rate of C/3 for more than 100 cycles with a load-ing close to the one used in an industrial application. For the positive electrode, the challenges are bigger. We opted for the investigation of the phases Na2/3Mn0.6Fe0.25Co0.15O2 and Na2/3Mn0.6Fe0.25Al0.15O2 since both of them are reported to be good for Na diffusion (allowing thus fast cycling rates). We found out that it is possible to increase the Na content oftheP2phasebyusingsacrificial template/Nareservoircomposed of the organic material Na2C6O6. On the engi-neering side, several home-made cylindrical cells were as-sembled with high loaded positive electrodes (> 15 mg/cm2, ratioofactivematerials>90wt%)andourcarbonaceousnegative electrodes as a proof-of-concept. The fading is more pronounced with such loadings however. On the elec-trolyte side, activities related to water-in-salt electrolytes were started to assess the viability of such a system prom-ising both higher safety and a cost reduction.

Battery cell production research

The team at the BFH focuses on battery cell production research, and potential implementation partners were in-

volved right from the start. We are aware of challenges of significantoperatingexpensesassociatedwithacompletemanufacturinglineandthechallengesdefiningabusinessmodel for such a line. For this reason, the hardware based partoftheprojectlimitsitselftospecificstepsinthepro-cess (mainly laser cutting, Z-folding, and quality control) where the highest potential for cost reduction is seen. The main activity of the project is, however, not the hardware but the holistic (computer) model based analysis of manu-facturing. In the end, a complete cost model of the manu-facturing process is built and optimization is done. This ap-proachshowedapotentialof60%costreductionforpouchcellsand25%costreductionforcylindricalcells,basedoncurrent material sets used in industry.

In more detail, a complete holistic model of the pre-pro-duction pilot line at an industrial partner including the elec-trode production was already developed. As novelty, it is dynamicandincludessimultaneouslyproductflow,productquality, process flowwith production parameters, workermodel,machinelevelwithconsumptionandallcost(CAPEXand OPEX) in contrast to the today’s static product flowmodels. The main research objective is to optimize the pro-duction with new technique and «Industrie 4.0» approach-es.

The combination of focusing on critical parts of the manufac-turing process in hardware and the cost modeling approach is well suited to educate students to become specialists in thiscriticalfieldononehand.Ontheotherhand,itserveswell to answer urgent questions from the implementation partners.Asanadditionalbenefitacademiaandotherscannow be provided with application sized cells produced of this pilot line with today’s and new chemistries for testing. First functional cells were already built from commercial electrodes (NCA and NMC111).

26 Batteries

Strategies to Improve Na-Ion Batteries

The P2-Na0.67Mn0.6Fe0.25Al0.15O2 phase, used as cathode ma-terial,providesahighspecificcharge of 160 mAhg-1 in half cell. It might be due to the higher sodiation level of the material during the discharge at 0.8 instead of the initial 0.67.Inhalfcellconfiguration,the excess of Na comes from the Na metal counter electrode whereas no additional Na is present in full cell.

The use of an organic com-pound, the disodium rhodizo-nate (called thereafter SR), as Na reservoir in full cell was investigated. The material was mixed with different ratio of a standard P2 cathode pre-viously developed in the lab (P2-Na0.67Mn0.6Fe0.25Co0.15O2 or P2-NaMFC) and tested versus a carbonaceous material. The electrochemical performance (Figure 1a) showed that the

specificchargeincreasedfrom77 mAhg-1 to 90 mAhg-1 with an 80/20 at the 1st cycle. The benefit was kept for 8cyclesbut the electrochemical per-formance faded and became similar after 10 cycles. The operandoX-raydiffractionex-periment (XRD) (Figure1b)reveals the vanishing of the SR Bragg reflection at 26.4°suggesting that the SR decom-posed during the 1st charge. Interestingly, the decompo-sition of SR coincided with a negative shift of the P2- NaMFC peak at ca. 36° whereas a positive shift was expected during the desodiation. It in-dicates that a sodiation of the P2-NaMFC material occurred due to the decomposition of SR, showing that the organic molecule is playing the role of Na reservoir. Unfortunately, the formation of water during its decomposition is detrimen-

tal for long-term cycle, mean-ing that the organic molecule needs to be further optimized.

O3-phase with a layered oxide structure material possesses a Na content allowing high spe-cificcharge in full cell systembut the material suffers from a faster fading. Therefore, the reason of this fading requires deeper investigation. The O3-NaNi0.5Mn5/16Sn1/16Ti1/8O2 phase (O3-NNMST) loses 25 % ofits initial specific charge af-ter 15 cycles whereas a bet-ter stability is reached for the next cycles. The evolution of the O1s core level spectra ob-tained from the X-ray photo-electron spectroscopy analysis (Figure 2) showed that a peak at 530 eV, assigned to the anionic redox activity, is de-tected during the charge and vanished at the end of the dis-charge. After 10 cycles, the re-

Scope of project

Due to the abundance of Na, Na-ion batteries (NaB) are considered as a serious alternative to the dominant Li-ion technology for stationary applications. All along this project, new electrode materi-alswereinvestigatedandtwowereselected:acarbonaceousmaterialproducedfrombiowaste[1]and the layered oxide P2-Na0.67Mn0.6Fe0.25Al0.15O2.[2]Thecombinationofthesematerialsallowedtoreachaspecificchargeofca.100mAhg-1 at C/10 resulting in an energy density of 170 Whkg-1 (after 5 cycles). This report exposes the strategies employed to improve the electrochemical performance, the cost and the safety of NaB.


Figure 1:

a) Electrochemical perfor-mance of P2-NaMFC with different ratio of SR at C/10 and b) Operando XRD of P2-NaMFC:SR (80:20) (con-tour plot) and correspond-ing galvanostatic curve. The P2-NaMFC peaks are labelled specifying the phase changes (P2)O2) upon cycling.

References

[1][1]C.Marino,J.Caba-nero, M. Povia, C. Villevieille, Journal of The Electro-chemical Society, 165 (2018) A1400-A1408.

[2]E.Marelli,C.Villevieille,S.Park,N.Hérault,C.Marino,ACS Applied Energy Materials, 1 (2018) 5960-5967.

[3]C.Marino,E.Marelli,S.Park, C. Villevieille, Batteries, 4 (2018) 66.

[4]L.Suo,O.Borodin,Y.Wang,X.Rong,W.Sun,X.Fan,S.Xu,M.A.Schroeder,A.V.Cresce,F.Wang,C.Yang,Y.-S.Hu,K.Xu,C.Wang,Advanced Energy Materials, 7 (2017) 1701189.

[5]H.Chen,Q.Hao,O.Zivkovic, G. Hautier, L.-S. Du, Y.Tang,Y.-Y.Hu,X.Ma,C.P.Grey, G. Ceder, Chemistry of Materials, 25 (2013) 2777-2786.

Authors

Cyril Marino¹ Elena Marelli¹ Maximilian Schuster¹ Claire Villevieille¹

¹ PSI


CMC Carboxymethyl-cellulose

NaB Na-Ion Batteries

NaMFC Na0.67Mn0.6Fe0.25

Co0.15O2

NMP N-Methyl-2-Pyrrol-idone

NMPC Na3MnCO3PO4

NNMST NaNi0.5Mn5/16Sn1/16-

Ti1/8O2

NTP NaTi2(PO4)3

SR Disodium Rhodizon-ate

XRD X-RayDiffractionSpectroscopy

27 Batteries

Strategies to Improve Na-Ion Batteries

versibility of the anionic redox is not present anymore since the peak at 530 eV is seen both in the charge and the dis-charge spectra. Combined with on-line electrochemical mass spectroscopyandXRD, itwasconfirmedthattheanionicre-dox failure is responsible of the capacity fading.

The electrode processing is an important part in the overall cell cost. In a standard pro-cedure, electrodes of layered oxide materials are prepared in the toxic solvent, N-methyl-pyrrolidone (NMP), which is a drawback for industrial pro-cessing. Water-based elec-trodes of P2-NaMFC using carboxymethylcellulose (CMC) binder were tested and limited electrochemical performances at 90 mAh·g-1 were obtained comparedtoaspecificchargeof 145 mAh·g-1 for the NMP-based electrode (Figure 3a).[3] This difference can beexplained by the protons ex-change in the structure, oc-curring when the material is mixed into water, which dis-rupts the Na ions extraction duringthecharge.Thisfindingindicates that water cannot be used as solvent in the prepa-ration of such electrodes if a high energy density battery is targeted.

In order to improve the safety of the NaB, a new research line was opened in the laboratory using aqueous-based electro-lyte. The use of water-in-salt electrolyte (highly concentrat-ed electrolyte) instead of con-ventional aqueous electrolyte widens the stability window of water (from 1.23 V to > 2 V) and enables the usage of elec-trode materials adapted to this new potential limit in aqueous system.[4]

The material NaTi2(PO4)3 (NTP), widely used as negative electrode material in aque-ous NaB, was selected to be the counter electrode. On the cathode side, the first focuswas on the carbonophospho-nate material Na3MnCO3PO4 (NMPC), successfully tested in organic-based electrolytes. [5] NMPC was tested in fullcell with NTP as anode and an aqueous 15 m NaFSI elec-trolyte with a voltage window between 1.8 V to 0 V at C/15 rate (Figure3b). A specificcharge of 100 mAh·g-1 was reachedforthefirstdischargeand, for the following cycles, a continuousdecreaseinspecificcharge from 140 mAh·g-1 to 50 mAh·g-1 can be observed. The evolution of the coulombic efficiencyreachedamaximumof95%afterthe5th cycle indi-

cating that a good passivation is formed preventing the water decomposition.

Figure 2:

X-ray photoelectron spec-troscopy spectra of the O1s core level acquired on O3-NNMST electrodes at different states.

Figure 3:

Electrochemical perfor-mance of a) P2-NaMFC electrodes prepared in NMP and in water at C/10 and b) the full cell NMPC vs. NTP cycled in 15 M NaFSI aqueous electrolyte at C/15.

28 Batteries

Development of Ionic Liquids as Electro-lyte Additives and a Cathode Material for Lithium Ion Batteries

Scope of project

Electrolyte additives: Crown-ether based ionic liquids (IL) have been developed as additives for electrolytes to enhance the battery properties. As critical parameters, the cation transference num-ber, ionic conductivity, electrochemical voltage window, cycleability, and rate capability have been investigated.

Cathodes: A nanostructured composite of LiMnPO4/C had shown promising electrochemical proper-tiesasacathodematerialin2017[1].Inordertoincreasetheratecapability,wenowtestedFe-doped LiMnPO4 (LMP), whose stoichiometry was determined by ICP analysis.


Electrolyte additives

The cation transference num-ber (TLi

+) increased from 0.44 for the pure commercial elec-trolyte to 0.62 upon addition of 1wt%ofaspecificionicliquid(Figure 1a). The crown-ether based ionic liquid decomposed at ca. 4.3 V vs. Li+/Li and sup-pressed the decomposition of the solvent. Furthermore, stripping/plating of lithium is significantlyreducedatlowpo-tential when the ionic liquid is present. The ionic conductivity oftheelectrolytewith1wt%ILprovided 5.7 mS/cm at 25 °C

(Figure 1b). No degradation occurred during 100 cycles at a constant current of ± 20 and ± 50 µA per cm2 of electrodes holding for 1 h at each ± cur-rent (Figure 1c).

The electrolytes with IL have been tested on cathodes (NMC111 and NMC811) of Li-ion batteries in collaboration with Empa. The capacity re-tention of NMC111 with IL ad-ditivewas>65%upon200cy-cles at C/3, while it dropped rapidly after 140 cycles with-out IL additive in the electro-lyte (Figure 2a). On the other

hand, the capacity retention of the Ni-rich cathode NMC811 was slightly lower with an IL additive than that without an IL additive upon 160 cycles. The rate capability of NMC111 with an IL additive was superi-or to that without the additive at low C-rates between C/10 and 1C but then it decreased at 5C compared to that without the additive.

The new electrolyte addi-tives have also been tested on carbon anodes and NaMFC cathodes of Na-ion batteries in collaboration with PSI. The

Authors

Jihane Hankache1 Nam Hee Kwon1 Katharina M. Fromm1

1 University of Fribourg

Figure 1:

(a) Li+ transference num-bers of electrolytes with and without an IL ad-ditive (averaged over 3 measurements). (b) The ionic conductivi-ties of an electrolyte with 1wt% of IL additive atvarious temperatures. (c) Cycling at constant current ±20 and ±50μAper cm2 of electrodes hold-ing for 1 h at each ± cur-rent.

Figure 2:

The specific capacities ofNMC111 cathode of Li-ion batteries (a), carbon anode (b) and NaMFC cathode (c) of Na-ion batteries with and without an IL additive in the electrolyte upon cy-cling.

References

[1]N.H.Kwon,H.Yin,T. Vavrova, W. Lim, U.Steiner,B.Grobéty,K.M. Fromm, J. Power Sources, 342, 231–240 (2017).


IL Ionic Liquids

NaMFC Na0.67Mn0.6Fe0.25

Co0.15O2

LMP LiMnPO4

29 Batteries

Figure 3:

(a) The rate capability of LiMnPO4 and Fe-doped LiMnPO4 cathodes of Li-ion batteries at various C-rates. (b) The cycleability of Fe doped LiMnPO4 electrode at the C-rate of C/5.

anodes showed no change in performance with and with-out IL (Figure 2b), while the capacities of NaMFC cathodes were 110 and 107 mAh/g at C/10 and C/5, respectively, with the IL additive, and 135 and 130 mAh/g at the same rates as above without an IL additive as shown in Figure 2c.

Cathodes

TheLi-iondiffusioncoefficientof Fe-doped LMP electrodes increased significantly from 10–11 ~ 10–12 cm2/s (pure LMP) to 4.4 ~ 7.3 x 10–9 cm2/s. The rate capability of Fe-doped LMP provided 157 and 142 mAh/g at C/10 and 1C, respectively,

while pure LMP gave 123 and 90 mAh/g at the same C-rates, respectively. This corresponds toa30–60%increaseinspe-cificcapacities(Figure3a).

Good cycling stability until ~ 20 cycles was observed with ca. 120 mAh/g at C/5 of C-rate in Figure 3b.

Development of Ionic Liquids as Electro-lyte Additives and a Cathode Material for Lithium Ion Batteries

30 Batteries

Stabilizing NMC811 in Full Cells with High Areal Capacity

References

[1] J.VidalLaveda,J.E. Low, C. Battaglia, in preparation.

[2]R.Dubey,K.Kravchyk,M. Kovalenko, in prepara-tion.

Scope of project

Lithium-ion batteries enabled the success of portable electronics and are recognized as a promising technologyforelectricmobilityandstationaryenergystorage.InthefirstyearofphaseII,weestab-lished an automated co-precipitation setup for the shape-controlled synthesis of LiNi0.33Mn0.33Co0.33O2 (NMC111) cathode materials and developed a NMC slurry preparation and coating process enabling high mass loadings (up to 29 mg/cm2)andhighactivematerialcontents(96%)intheelectrodes.In the second year of phase II, we extended this work towards full cells coupling high-mass-loading NMC111 cathodes with 4.3 mAh/cm2 areal charge capacity with balanced high-mass-loading graph-ite anodes with 4.8 mAh/cm2, provided by SCCER partner Prof. Kovalenko's group at ETH/Empa, demonstratingacapacityretentionof63%after300cyclesatC/5.Thislabcellisprojectedtoreachstate-of-the-art 220 Wh/kg, when scaled to pouch cells developed by SCCER partner Prof. Fürst's group at BFH.


To go beyond the state-of-the-art, we extended our co-precipitation capabilities to the synthesis of Ni-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode materials. NMC811 of-fersalmost30%highergravi-metric capacity than NMC111 and reduces the amount of critical and expensive cobalt. Nevertheless, NMC811 still poses multiple fundamental challenges, such as irrevers-ible structural rearrange-ments, transition metal disso-lution, high surface reactivity,

and parasitic oxidation of the organic electrolyte at the sur-face when delithiated, severely limiting its long-term cycling stability. Exploring electrolyte additives, we were able to stabilize NMC811 electrodes with a high areal capacity of 4.3 mAh/cm2 against bal-

anced graphite electrodes with 5.2 mAh/cm2 in a full cell dem-onstrating a capacity retention of74%after300cyclesatC/5.This cell is projected to reach 245 Wh/kg when scaled to pouch cell format. Future work needs to focus on improving the Coulombic efficiency dur-ingthefirstcyclesandreducecell impedance growth during long-term cycling.

Layered (NMC811) cath-ode powders were syn-thesized by co-precipita-tion of Ni0.8Mn0.1Co0.1(OH)2 hydroxide precursor followed by high temperature solid-state calcination with LiOH.H2O at 800 °C under O2flow.Pow-der X-ray diffraction (XRD)analysis confirms the phasepurity of the NMC811 powder, showing a layered structure belonging to the R-3mH space group (Figure 1a). Moreover, no presence of impurity phases is detected. Scanning electron microscopy (SEM) imaging re-veals that the NMC811 pow-ders consist of ~ 3–7 µm quasi-spherical secondary particles composed of 150–300 nm primary particles (Figure 1b). NMC811 powders display a tap density of around 2.2 g/cm3

with a BET surface area of ap-proximately 2.1 m2/g.

Galvanostatic cycling in half cells of the NMC811 vs. Li metal at room temperature demonstrates initial discharge capacities of 203 mAh/g, 197 mAh/g and 190 mAh/g at rates of C/10, C/5 and C/3, re-spectively. Long-term cycling reveals a discharge capacity retentionof86%and51%af-ter 100 and 240 cycles at C/3, respectively (data not shown here). A high areal charge ca-pacity is key to reach high en-ergy density on cell and pack level, as it reduces the weight and volume fraction of inactive materials in the cell. There-fore, we developed a NMC slurry preparation and coating process enabling high mass loadings (up to 29 mg/cm2) and high active material con-tents(96%)intheelectrodes,reaching a high areal capacity of ~ 5.2 mAh·cm-2 at a rate of C/10 in NMC811 vs. Li metal half cells (Figure 2a). Due to a high active material content and the high mass loading, our electrodes can reach sig-nificantlyhigherarealcapacitythan commercial NMC111 and NMC811 reference electrodes

Authors

Josefa Vidal Laveda¹ Jia En Low¹Corsin Battaglia¹

¹ Empa


NMC111 LiNi0.33Mn0.33Co0.33O2

NMC811 LiNi0.8Mn0.1Co0.1O2

SEM Scanning Electron Microscopy

XRD PowderX-RayDif-fraction

Figure 1:

a)PowderXRDpatternandb) SEM image of NMC811 powders.

31 Batteries

Figure 2:

a) Rate performance in half cells of NMC811 and NMC111 electrodes with different mass load-ings vs. Li metal. b) Discharge capacity vs. cycle number of high mass loading NMC811 vs. Li metal.

Figure 4:

Projected energy density for pouch cells vs. num-ber of anode sheets for NMC111 and NMC811 vs. graphite.

(also shown for comparison in Figure 2a). High-mass-loading NMC811 delivers initial dis-charge areal capacities of up to 5.2 mAh/cm2 at a rate of C/10, but at such a high mass load-ing of almost 30 mg/cm2 stable cycling is limited to rates up to C/5. At lower, but still high, mass loadings near 20 mg/cm2, the performance of our NMC811 electrodes is compa-rable to commercial reference electrodes. Extended cycling in half cells with high mass load-ing NMC811 electrodes at C/5 shows 4.7 and 2.6 mAh/cm2 after 50 and 100 cycles at C/5, respectively (Figure 2b).

Next, high-mass-loading NMC111 (~ 29 mg/cm2) and NMC811 (~ 24 mg/cm2) elec-trodes were cycled in balanced full cells against a high-mass-loading graphite electrode (~ 15 mg/cm2) provided by SCCER project partner Prof. Kovalenko´s group [2] em-ploying an electrolyte formu-lation developed by us spe-cifically to stabilize NMC811[1]. Galvanostatic cycling ofthe NMC111/graphite and NMC811/graphite full cells at a rate of C/5 demonstrates initial gravimetric discharge capacities of approximately 145 mAh/g and 175 mAh/g, re-spectively. These cells exhibit similar areal discharge capaci-ties of 4.3–4.5 mAh/cm2, but NMC811 displays more rapid fading during the first cyclescompared to NMC111. How-ever, NMC811 demonstrates better capacity retention prob-ably due to the lower mass loading required with NMC811 in order to balance graphite electrode with an equal mass loading of 15 mg/cm2 (practi-cal capacities at low rates are 200 mAh/g vs. 160 mAh/g for

Figure 3.

a) Gravimetric discharge capacity and b) areal dis-charge capacity vs. cycle number of NMC111 and NMC811 vs. graphite full cells at high mass loadings.

Stabilizing NMC811 in Full Cells with High Areal Capacity

NMC811 vs. NMC111). The NMC811/graphite cell deliv-ers a discharge capacity re-tention of 74% after 300cy-cles at C/5 corresponding to 3 mAh/cm2 after 300 cycles (Figure 3). Cell energy den-sity projections for a stacked pouch cell based on our high areal capacity NMC111/graph-ite and NMC811/graphite cells result in estimated 220 Wh/kg and 245 Wh/kg, respectively, when using 11 anode sheets and 10 cathode sheets. Our projections also indicate that when increasing the NMC811 electrode mass loading to 29 mg/cm2 and the gravimet-ric capacity to 200 mAh/g, and cycling it against 18 mg/cm2 graphite electrode, ~ 275 Wh/kg could be attained (Fig-ure 4), which corresponds to the energy density target for the SCCER project.

Conclusions

We presented results on the synthesis and characterization of high capacity NMC811 cath-odes in half and full cells. We established a slurry process-ing and coating process for the preparation of electrodes with high areal capacity reach-ing ~ 5.2 mAh·cm-2 in half cells vs. Li metal. NMC811/graphite full cells delivered a discharge capacity reten-tion of 74% after 300cycles

at C/5 reaching 3 mAh/cm2 employing an electrolyte for-mulation developed specifi-cally to stabilize NMC811. Cell energy density projections for a stacked pouch cell based on the presented NMC111/graphite and NMC811/graphite lab cells estimate that energy densities of 220 Wh/kg and 245 Wh/kg, respectively, could be reached when using 11 an-ode and 10 cathode sheets. To reach the project target of 275Wh/kg,Coulombiceffiencyduringthefirstcyclesneedstobe improved and impedance growth during long-term cy-cling needs to be mitigated.

32 Batteries

Pilot Line Modules for Lithium-Ion Battery Cell Assembly and Advantages of Laser Processing

Authors

Michael Stalder1 Aysegül Haktanir1 Axel Fuerst1

1 BFH (Bern University of Applied Sciences)

Scope of project

The main goal of the «Batteries and Battery Materials» work package at the SCCER program is to produce battery cells with a gravimetric energy density of 275 Wh/kg, whereas current state-of-the-art cells exhibit energy densities of around 220–240 Wh/kg. The goal shall be reached by improv-ing material synthesis and slurry formulation, thicker electrodes and cell assembly with optimized inactivematerials.[1]TheteamatBFHhasestablishedavirtualpilotlineandhardwaremodulesfor pouch cell assembly, which are used to build test cells for research and industry and investigate currentchallengesinbatterycellproduction.[2]Inparticular,theapplicationoflaserprocessingforcutting, ablation and electrode conditioning are in focus.



NMC LiNixMnyCo1-x-yO2

Figure 2 shows performance results of a stacked test bat-tery for formation and for cy-cling at different C-rates. In each cycle the cell is charged to 4.2 V at constant current followed by a constant voltage phase and discharged to 2.75 V at constant current. One can see that the design capacity is reached. Further reduced capacity at higher c-rates is in the expected range. Addi-tionally, a life cycle test at 1C was executed with the same potential window: The battery reached80%ofinitialcapacityat about 200 cycles, which is in line with current state-of-the-art for NMC-based lithium-ion materials.

The test of the cell with 6 anode sheets and 5 cathode sheets each sized 65 x 85 mm indi-cated that the design capac-ity of 1100 mAh was reached (Figure 2). The cell weighs 19.2 grams and has a mea-sured capacity of 1054 mAh which equals to a discharge energy of 3846 mWh at C/5. This is close to the current state-of-the-art even without further design optimizations.

Above results show that the BFH team is capable to assem-ble application-sized pouch cells with required quality.

Figure 1:

Pilot line modules: (A) laser cutting unit, (B) stacking unit, (C) ultrasonic welding station and (D) glove box.

References

[1]C.Battaglia,«MaterialsInnovation for Next-Gen-eration Batteries», SCCER HaE Annual Symposium 2018 (2018).

[2]A.Kwade,etal.,Nature Energy, 3(4), 290–300 (2018).

[3]W.Pfleging,Nanopho-tonics, 7(3), 549 (2018).

Production of test cells on pilot line modules

Since August 2018 the team produces test batteries on its battery manufacturing pilot line modules.

Anode and cathode sheets are cut by pulsed fiber laser andstacked automatically. Current collector tabs and electrode foils are bonded by ultrasonic welding. Before further treat-ment the stacks are dried un-der vacuum to remove residual moisture. Subsequently, the cells are manually processed in a glove box under nitrogen atmosphere, where electrolyte is filled, and cells are evacu-ated and sealed. The arrange-

ment of the pilot line modules is shown in Figure 1.

Test cells with 6 anode sheets and 5 cathode sheets each sized 65 x 85 mm, have been built. The electrode material in use has been purchased: • The anode is made of graph-

ite coating at 2.2 mAh/cm2 (approx. 50 µm thickness) and 18 µm copper current collector.

• The cathode is made of a NMC532 coating at 2.0 mAh/cm2 (approx. 60 µm thickness) and 20 µm alu-mina current collector.

Size and used material re-sult in a design capacity of 1100 mAh.

33 Batteries

At BFH the functionality of the laser has been extended to ablation of active materials where the same equipment as for cutting is used. In ablation of active material, the mate-rial is removed from the cur-rent collector with the goal of removing all the active mate-rial in a defined area withoutaffecting the current collector (alumina or copper foil).

This process can be used to manufacture electrode sheets from foils of coated material wherethecoatingprofileisnotconstant towards the edge or edge quality is poor. By using ablation, a coated foil without welldefinedboundariescanbeused to produce a usable elec-trode sheet by removing active material in the tab area, see Figure 3.

Pilot Line Modules for Lithium-Ion Battery Cell Assembly and Advantages of Laser Processing

In the future, further applica-tion of laser ablation of active material shall be investigated, e.g., for correcting the thick-ness of electrodes if quali-tatively insufficient sectionsare detected or perforating electrodes to create electrode channels for improved ion transport in thick coatings.

Further, practical knowledge gained from building test bat-teries is used to continuously optimize the construction of the pilot line modules. Besides the technical optimization studies, the team continuously improves the production qual-ity.

Advantages of laser processing

Lasers have the potential to be used in various steps in lithi-um-ion battery cell production such as cutting of electrodes, structuring and modificationof electrodes, cutting and welding of tabs and cutting of pouchcelllaminate.[3]

At BFH the laser unit is used to cut electrodes and for ablation of active materials.

Laser foil cutting provides several advantages over me-chanical foil punching: Laser cutting has minimal tool wear which makes it more cost-ef-fective in terms of operational costs because there are no re placement tooling and out-age times. Due to tool wear in mechanical punching the edge quality degrades over time, an issue which is not present in laser cutting. Further La-ser cutting is highly flexiblein geometrical shapes, such that different electrode sizes can be cut on the same equip-ment with much shorter setup times and no additional tool-ing compared to mechanical punching.

Figure 3:

Illustration of laser cutting and tab ablation: B coated raw electrode foil with poor edge quality. C Electrode sheet cut, and tab area cleaned by laser.

Figure 2:

Performance of a multilay-ered test battery at differ-ent C-rates.

34 Batteries

Ultra-High Mass Loading Graphite Anodes for Li-Ion Batteries

Author

Romain Dubey1,2

Kostiantyn Kravchyk1,2

Maksym V. Kovalenko1,2

1 ETHZ2 Empa

Since the commercialization of LIBs in 1991 by Sony Corpo-ration, graphite remains the most prominent anode mate-rial for LIBs. When comparing it with other anode materials such as Si, Sb, Sn or Li4Ti5O12 (LTO), most important advan-tages of graphite are its low cost, non-toxicity, safety, low de-lithiation potential of 0.2 V vs. Li+/Li, high coulombic/en-ergy efficiencies, as well aslong operation life span over hundreds to thousands charge/discharge cycles.

In the context of further im-provement of graphite an-odes for LIBs, great research efforts are presently focused on the development of high areal capacity graphite elec-trodes of > 3.5 mAh cm-2 with high rate capability (maintain-ing the gravimetric capacity of > 350 mAh g-1 at C/2 rates or higher).

We have developed a graphite anode (jointly with an indus-trial partner) with an ultra-high areal capacity of 5.4 mAh cm-2,

Scope of project

At present, rechargeable Li-ion batteries (LIBs) became a key energy storage technology, which served mankind for the past two decades in a variety of applications, e.g. portable electronic de-vices and electric vehicles, owing to its high energy density, long cycling lifetime, and high power performance[1-5].Thepracticalenergydensityofpresent-dayLIBscomposedofelectrodeswithareal capacities of 3.5 mAh cm-2, however, is approaching its limit of 220–250 Wh kg-1. In this con-text, the development of anodes and cathodes with higher areal capacities has been considered as the main objective within this SCCER project, enabling to increase the energy density of LiBs by up to5–15%.

StatusofprojectandmainscientificresultsofworkgroupsReferences

[1] J.B.Goodenough,K.S. Park, J. Am. Chem. Soc., 135 (4), 1167–1176 (2013).

[2]N.Nitta,F.X.Wu,J.T.Lee,G.Yushin,Mater.Today, 18 (5), 252–264 (2015).

[3]M.Armand,J.M.Tar-ascon, Nature, 451 (7179), 652–657 (2008).

[4]H.Chen,T.N.Cong,W.Yang,C.Tan,Y.Li,Y.Ding,Prog.Nat.Sci.,19 (3), 291–312 (2009).

[5]P.Fairley,Nature,526 (7575), S102–S104 (2015).

Figure 1:

a) Galvanostatic charge/discharge curves and b) cyclic stability of a graphite anode (cells were cycled at different C rates (1C rate is 372 mAh g-1) in the potential range of 0.01–1.5 V using constant current-constant voltage (CCCV) protocol at 5 mV; Specificcapacitiesandcur-rents correspond to the mass of graphite active material.


LIB Lithium-Ion Battery

LTO Li4Ti5O12

thehigh initialcoulombiceffi-ciency of 93.7% and the lowaverage charge voltage of 0.2 V vs. Li+/Li at C/2 rate (Fig-ure 1). The developed graphite anode delivers a capacity of ~350 mAh g-1 for 35 cycles at a C/2 rate and shows high cou-lombicefficiencyof99.8%.

The galvanostatic measure-ments of full cells in combi-nation with LiNixMnyCo1-x-yO2 (NMC) cathodes are in prog-ress.

35

HydrogenProduction and Storage

Work Package «Hydrogen Production and Storage» at a Glance

The energy economy based on renewable energy is developing very quickly and produces a large demand for energy storage. Seasonal storage requires storing approximately half of the annual energy demand and is, there-fore, a challenging materials science and technology task. In Switzerland the average annual electricity demand is approx. 10 MWh/capita and the energy demand slightly less than 60 MWh/capita incl. nuclear, jet fuel, and embedded energy. A seasonal storage if the energy is produced from renewable is in the range of 5–30 MWh/capita (corresponds to 500–3000 l of oil). In WP 3 new materials for energy storage with hydrogen are inves-tigated. The carbon free hydrogen cycle is based on purely technical means and is a closed materials cycle, be-cause the water released into the atmosphere precipitates spontaneously. The energy is stored by splitting of water into hydrogen and oxygen and the hydrogen is stored. The combustion of the hydrogen with air releases the energy in the form of heat and electricity. In this work package the research concentrates on two methods to produce hydrogen, i.e. the alkaline electrolysis and the hydrogen evolution from the electrolyte of a redox-flow-battery, and two methods to store hydrogen in hydrides and in formic-acid.

Hydrogen production by alkaline electrolysis

Water splitting by electrolysis is limited to a few MW in pow-er, which is 3 orders of magnitude less than current power stationsareoperating.Thegoalistosignificantlyincreasetheefficiencyandthepower(current)densityinelectrolys-ers in order to increase the hydrogen production rate.

Examining the electrocatalytic performance of naturally-occurring metallic minerals is of interest for energy con-version applications given their unique atomic composition and formation history. Herein, we report the electrocatalytic function of an iron-based Gibeon meteorite for the oxygen evolution reaction (OER). After ageing under operational conditions in an alkaline electrolyte, an activity matching or possibly slightly superior to the best performing OER cata-lysts emerges, with stable overpotentials as low as 270 mV (for 10 mA·cm−2) and Tafel slopes of 37 mV decade−1. The Faradaicefficiency for theOERwasunityandnodeterio-ration in performance was detected during 1000 hours of OER operation at 500 mA·cm−2. Mechanistic studies suggest anoperandosurfacemodificationinvolvingtheformationofa 3D oxy(hydroxide) layer with a metal atom composition of Co0.11Fe0.33Ni0.55, as indicated by Raman and XPS stud-ies and trace Ir as indicated via elemental analysis. The growth of the catalyst layer was self-limiting to < 200 nm after ca.300hoursofoperationas indicated throughXPSdepthprofilingandcyclicvoltammetry.Theuniquecompo-sition and structure of the Gibeon meteorite suggest that further investigation of Ir–Co–Ni–Fe systems or other al-loys inspired by natural materials for water oxidation are of interest.

Hydrogen production by Dual Circle Redox Flow Battery

Alternatively, electricity is stored in a redox-flow batterywithahighflexibility inchargeanddischargepower.Theelectrolyte containing the storage material reacts on a cata-lyst and splits water, i.e. chemical discharge of the battery into hydrogen. This method allows to split water without the need of electrodes nor gas separator and has the potential to reach very high power densities. In the particular case of a RFB dual circuit, the electrolytes are conventionally charged but are then chemically discharged over catalytic beds in separate external circuits. The catalytic reaction generates hydrogen gas as secondary energy carrier. For demonstration, indirect water electrolysis was performed generating hydrogen and oxygen in separate catalytic reac-tions. Hydrogen was generated from V(II) using an abun-dant and low cost Mo2C catalyst and achieved a production yieldof96±4%.WateroxidationwasachievedoverIrO2 and RuO2 nanoparticles from positive electrolytes compris-ingCe(IV)invariousacidsolutions.A78±8%O2 yield was obtained in 1 M H2SO4 and a partially hydrated RuO2 cata-lyst.Thissystemisunique inthefieldofenergystorage,merging two highly pursued technologies: renewable elec-trochemical energy storage and renewable power-to-gas.

This approach is designed to complement electrochemical energy storage and may circumvent the low energy density of RFBs especially as hydrogen can be produced continu-ously whilst the RFB is charging. The novel technique al-lows surplus electricity to be stored as hydrogen beyond the limited energy density of the RFB electrolytes, with rapid discharge of the electrolytes also possible to provide

Illu

stra

tion:

Jef

f Ku

bina

an immediate sink for excess electricity. As water oxidation is not of commercial interest, alternative discharge reac-tions for the anolyte must be investigated. With commercial all- vanadium RFBs the chemical discharge of the positive (V(V)) species may also be envisaged, such as reduction by hydrazine to produce protons and N2, SO2 oxidation to produce H2SO4, or the oxidation of wastewater pollutants.

Further investigation into optimizing the catholyte dis-charge and to further characterize the catalytic reactions are in progress. For instance, the use of Mn(II) electrolyte to replace Ce(IV) in the positive electrolyte is under prog-ress.

Hydrogen storage in complex hydrides

Among the potential hydrogen storage materials, the borohydrides exhibit a high gravimetric and volumetric hydrogen storage capacity, up to 20mass% of hydrogenwith 150 kg H2/m3. However, the challenge for borohydrides is the high enthalpy for hydrogen desorption and the kinetic barrier for re-hydrogenation.

These materials have been combined with ionic liquids in or-der to destabilize the borohydride. The hydrogen desorption temperaturewasloweredsignificantly.Anew3Dstructureof carbon based on graphene oxide and carbon nanotubes linked together exhibits a large hydrogen storage capacity. Thematerialabsorbsmore than5mass%ofhydrogenatroom temperature and desorbs the hydrogen with almost no hysteresis. Metal hydrides can be used to compress hy-drogen. The increase of the temperature to 200 °C allows to compress hydrogen to 200 bar without any moving parts.

Large scale hydrogen storage has been developed and built with a capacity of 2 kg of hydrogen (80 kWh of en-ergy). The hydrogen is stored in an intermetallic compound ((La0.74Ce0.24)Ni4.21Co0.68Mn0.10) with an equilibrium hydro-gen pressure of 3 bar at 20 °C. The storage is installed in thesmallscaledemonstratorforSionandfilledbyaPEMelectrolyzer. The modular design of the storage allows up-scalling and a several storage system for 1 MWh (25 kg of hydrogen) to 3 MWh is currently built.

Hydrogen storage in Formic acid

Formic acid (FA) and methanol (CH3OH) are considered as effective liquid chemicals for hydrogen storage as being easier to handle than solid or gas materials. This work sum-marizes the recent progress of research on the develop-ment of homogeneous catalysts mainly focusing on formic acid and CH3OH and the reports on the catalysts based on both precious and non-precious metals which are rapidly increasing in the past few years.

Formicacid(FA)contains~4.4wt%ofhydrogen(or53g/L)which can be catalytically released and converted to elec-tricity using a proton exchange membrane (PEM) fuel cell. Although various catalysts have been reported to be very selective towards formic acid dehydrogenation (resulting in H2 and CO2), a side-production of CO and H2O (formic acid dehydration) should also be considered, because most PEM hydrogen fuel cells are poisoned by CO.

In this research, a highly active aqueous catalytic sys-tem containing Ru(III) chloride and meta-trisulfonated triphenylphosphine (mTPPTS) as a ligand was applied for formic acid dehydrogenation in a continuous mode. CO concentration (8–70 ppm) in the resulting H2 + CO2 gas stream was measured using a wide range of reactor operating conditions. The CO concentration was found to be independent on the reactor temperature but increased with increasing formic acid feed. It was concluded that unwanted CO concentration in the H2 + CO2 gas stream was dependent on the current formic acid concentration in the reactor which was in turn dependent on the reaction design.

Next,preferentialoxidation(PROX)onaPt/Al2O3 catalyst was applied to remove CO traces from the H2 + CO2 stream. It was demonstrated that CO concentration in the stream could be reduced to a level tolerable for PEM fuel cells (~ 3 ppm).

An industrial prototype has been built and presented on 19.03.2018,theworld'sfirstformicacid-basedpowersup-ply unit, using PEM fuel cell for electricity production.

38 Hydrogen

Hydrogen Storage in Hydrides

Scope of project

The storage of hydrogen in hydrides offers many advantages over the conventional compressed or liquid hydrogen storage. The density of the hydrogen in the solid material can reach twice the den-sity of liquid hydrogen at room temperature in the equilibrium with the gas phase. The equilibrium pressure is moderate and, therefore, the storage is safe, reversible and compact. Beside the well-known interactions of hydrogen with solids i.e. physisorption, chemisorption and ionic compounds new interactions like the pore condensation in nanomaterials and the Kubas interaction are of great interest for the development of new storage materials. Some of the new carbon materials, e.g. graphene oxide, exhibit unique gas sorption properties. These materials can be functionalized, e.g. Boron and Nitrogen, are low cost and easy to produce in large quantities. The start-up company GRZ Technologies SA has developed large scale solid hydrogen storage systems with a capacity of > 1 MWh and sold several hydrogen compressors (HyCo) based on metal hydrides as well as the advanced gas analysing system (AGAS).



AGAS Advanced Gas Ana-lysing System

GO Graphene Oxide

GONT Graphene Oxide Nanotube Material

HyCo Hydrogen Compres-sors

IL Ionic Liquid

NaBH4 Sodium Borohy-dride

Authors

Andreas Züttel1,2 HeenaYang1,2 Loris Lombardo1,2 Noris Gallandat1,2 YannickBaehler1,2

1 EPFL, Valais/Wallis2 Empa

Figure 1:

Schematic synthesis of the borohydride with the ionic liquid[1].

Figure 2:

Hydrogen release of 3 dif-ferent BH4-IL combinations [1].

References

[1] L.Lombardo,H.Yang,A. Züttel, «Destabilizing sodium borohydride with an ionic liquid», Materials Today Energy 9, 391–396 (2018).

[2]H.Yang,A.Züttel,«First Hydrogen Storage Beyond Physisorption in Carbon Nanostructures», to be submitted to Science (2019).

[3]A.Züttel,N.Gallandat,«Metal hydride hydrogen compressor», to be sub-mitted to IJHE (2019).

Study of borohydride ionic liquids as hydrogen storage materials

(IL), vinylbenzyl trimethylam-monium chloride, was applied to modify the charge distribu-tion in BH4 and promote the dehydrogenation of NaBH4 (Figure 1).

The effect of IL concentration as well as particle size on the amount of desorbed hydrogen was investigated. The dehy-drogenation reaction of the ILeNaBH4 complex was exo-thermic (negative enthalpy), which is in contrast to the en-dothermic hydrogen desorp-tion reaction for pure NaBH4 (positive enthalpy). The en-thalpy of the ILeNaBH4 com-plex for dehydrogenation was lower than NaBH4 due to the interactions of the cation, the IL, and the borohydride. De-hydrogenation of the mixture (mass ratio of NaBH4 : IL 1 : 4 and 1 : 2) started below 160 °C, with a maximum hydrogen de-sorption capacity of 2.1wt%(Figure 2). The strong amine cation in the IL led to destabi-lization of the borohydride by polarization, thus resulting in improved dehydrogenation of the complex hydride. The en-thalpy of the dehydrogenation reaction is 4.8 kJ mol–1 of hy-drogen. The exothermic nature of the reaction was caused by deformation of the lattice and

destabilization from the IL.

Sodium borohydride (NaBH4) is a complex hydride containing 10.5% of its mass as hydro-gen; however, it is too stable to desorb hydrogen at room temperature. A ionic liquid

39

Figure 3:

Schematic synthesis meth-od for the preparation of the graphene oxide nano-tubematerial(GONT).[2]

Hydrogen Storage in Hydrides

First hydrogen storage beyond physisorption in carbon nanostructures

Hydrogen storage in carbon materials has been intensive-ly investigated, adsorption of hydrogen on the surface of carbon due to Van der Waals interaction is only observed at low temperatures. As a consequence, the equilibrium pressure is low and limits the application of the hydrogen storage material. A new 3D structure of carbon based on graphene oxide (GO) and car-bon nanotubes linked together (Figure 3) exhibits a large hy-drogen storage capacity. The material absorbs more than 5wt% of hydrogen at roomtemperature (Figure 4) and desorbs the hydrogen with almost no hysteresis. The 3D carbon material shows a stron-ger interaction with Hydrogen as compared to physisorption on carbon nanotubes. The 3D carbon material was inves-tigated for the adsorption of various gases H2, Ar, N2, He. International Patent applica-tionwasfiled.

Metal hydrides for hydro-gen compression (HyCo)

The thermodynamic properties of metal hydrides can be used to compress hydrogen. Accord-ing to the Van't Hoff equation (-R·ln(p/p0)=ΔH/T–ΔS) thehydrogen pressure depends on the temperature (Figures 5, 6).

The intermetallic compound (La0.74Ce0.24)Ni4.21Co0.68Mn0.10 from Baotou Santoku Battery Materials Co., Ltd. absorbs hy-drogen at 20 °C and 3 bar and releases hydrogen at 100 °C and 25 bar and at 225 °C and 200 bar.

Figure 5:

Schematic description of the hydrogen absorp-tion and desorption pro-cess in the MH compres-sor. The entropy change is in good approximation equal to the standard en-tropy of hydrogen: S0(H2) = 130 J·mol–1·K–1.[3]

Figure 4:

Gravimetric hydrogen ca-pacity of the components andtheproductGONT.[2]

Figure 6:

Energy required for the compression of hydro-gen gas from 1 to 100 bar by mechanical isother-mal compression and by MHcompressor.[3]

40 Hydrogen

Performance and Stability of Iron-Cobalt-Nickel Alloys for Water Oxidation

Scope of project

Hydrogen, foreseen to replace fossil fuels as energy carrier in the future, can be produced electro-chemically from water and renewable and abundant energy sources through water electrolysis. The water oxidation half reaction is considered as a bottleneck due to larger required overpotentials (>0.35V)ascomparedtowaterreduction(~0.1V).[1]Oureffortshavebeenconsequentlyfocusedtowards understanding and improving the oxidation half reaction (OER).


Nickel-iron-colbalt alloys have evidenced state-of-the-art cat-alytic activity for the OER, with overpotentials below 0.3 V. Electrodes made from these relatively inexpensive and abundant metals (compared to Ir or Pt) can be prepared synthetically or as we have re-cently shown, can also be de-rived from naturally occurring minerals, such as the Gibeon Meteorite.[2,3]

This active catalyst can also be formed in situ during OER operation on mass-produced inexpensive materials, such as Ni-containing stainless steel but the stability both in terms of performance and compo-sition remains unclear.[4]Indeed, the composition of stainless steel is not tuned for such application and the over-

potential and stability is not ideal. In our recent efforts to understand the performance and stability of iron-based an-odes for water oxidation we have prepared alloys of Iron, Cobalt and Nickel of different compositions. The procedure used to prepare the electrodes was using an arc melting sys-tem at EPFL Sion. Photographs showing the electrode prepa-ration procedure are shown in Figure 1.

The compositions of Nickel-iron-colbalt alloy electrodes prepared are shown in Figure 2 (left) and their performance and stability for OER in alkaline conditions were investigated using standard electrochemi-cal techniques (1 M NaOH at 0.5 A/cm2 current density for 200 hours). The samples

of this experiments showed promising performances. The samples FeCoNi-33-33-33-H and FeCoNi-55-22.5-22.5-H of the first batch displayedthe best overall overpoten-tials,with246and248[mVat10 mA/cm2]respectively.

The second batch of sam-ples, used to qualitatively compare the performance of the electrodes, showed that FeNi-50-50 displayed the best overpotential among the compositions tested, with an overpotential of 284[mV at10 mA/cm2]. As it was thecase for the first batch, thebest trimetallic samples were FeCoNi-33-33-33 and FeCo-Ni-55-22.5-22.5 with 314 and 318[mV at 10mA/cm2] re-spectively (see Figure 2 right).


ICP-MS Inductively Coupled Plasma Mass Spec-trometry

OER Oxygen Evolution Reaction

XPS X-rayPhotoelectronSpectroscopy

References

[1]F.LeFormal,W.S.Bou-rée,M.S.Prévot,K.Sivula,Chimia, 69(12), 789–798 (2015).

[2] M.Gong,H.Dai,NanoRes, 8(1), 23–39 (2014).

[3] F.LeFormaletal., Energy Environ. Sci., 9, 3448 (2016).

[4] H.Schaferetal.Energy & Environ. Sci., 8, 2685–2697 (2015).

Figure 1:

Photographs of alloy elec-trodes at different prepa-ration steps: Pure metal pellets (a), alloy lump (b), unpolished alloy slice (c), polished alloy slice (d), un-oxidized unused electrode (e), and oxidized electrode (f).

Authors

Florian Le Formal¹ LucasYerly¹Nestor Guijarro¹ XavierPereiraDaCosta¹ Kevin Sivula¹

¹ EPFL

41

Figure 2:

Left: Ternary phase dia-gram of Fe, Ni, Co. The red dots represent the compo-sition of the samples pre-pared for this work. Right: Overpotential (mV) to drive a water oxidation current density of 10 mA/cm2.

Performance and Stability of Iron-Cobalt-Nickel Alloys for Water Oxidation

The Tafel slopes calculated for the samples of the second batch were homogeneous, with values around 40[mV/dec].Thesevaluesarepromis-ing for the performance of the electrodes and they might also give a hint about the active site of the catalyst, as cobalt-based catalysts usually display Tafel slopes in this range.

The density of nickel active site was found to increase with the nickel content in the sample, as expected. More in-terestingly, no correlation was found between the active site density and the overpotential of the samples, which might prove that cobalt playing an im portant role in the OER ca-talysis.

Inductively coupled plasma mass spectrometry (ICP-MS), Raman spectroscopy and X-ray photoelectron spectros-copy (XPS) measurement allpointed to a reduction in iron content on the surface of the electrode during the oxidation process. However, it was found that the overpotential was low-er for samples with higher iron concentration on their surface after oxidation.

Two hypothesis were made to explainthisbehavior.Thefirstis that iron promotes the cata-lytic activity of the samples, but is etched out of the sam-ple. The samples with better performance would continue to etch iron and progressively lose their activity as their com-position rejoins the one from the less active samples. The second hypothesis is that the samples displaying a better overpotential are the ones that initially had a higher iron con-tent. During the etching, they therefore release more mate-rial, making them more porous and thus more active for OER.

The overall score, combin-ing the overpotential and the metal etching density of the electrode to rank the sam-ples on both performance and stability, showed that the two best samples were FeCoNi-55-22.5-22.5 and FeCoNi-33-33-33. Additional experiments were performed on these two compositions, to assess the two hypothesis arising from the previous mea-surements. The performance after 200 hours of oxidation showed no significant drop inperformance for both samples,

whichtendstodisprovethefirsthypothesis. However, the mea-surement of the capacitance density of the samples did not prove the second hypothesis either, as FeCoNi-55-22.5-22.5 displayed a lower capacitance, and therefore lower porosity, despite its superior perfor-mance.

These hypotheses could be further assessed by thoroughly analyzing the change in per-formance of the samples of all the different compositions, as well as their capacitance den-sity in order to obtain a trend on amore significant numberof sample. Other techniques could also be used to try to determine the porosity of the samples,andXPSatdifferentdepths could be performed on the samples, in order to try to identify the depth of the active layer. This work could also be repeated for other trimetal-lic compositions, with metals such as chromium, manga-nese or molybdenum, which are found in the catalytically active stainless steel samples, or copper, which is known to promote the activity of cobalt. These concepts will be consid-ered in future work.

42 Hydrogen

Titanium-Manganese-Vanadium Electrolytes, Redox Solid Boosters and Copper Contamination of an All-Vanadium Redox Flow Battery

Scope of project

Redoxflowbatteries(RFBs)aresufferingfromlowenergydensitycomparedtootherenergystor-agedevices.[1–5]Toovercomethisweakness,anewconceptwasdevelopedbyAmstutzandco-workers which includes a second pathway to discharge chemically the RFB. This pathway allows the system to generate hydrogen and oxygen using catalytic beds as heterogeneous catalyst, without affecting the functioning of the RFB. It was found that the positive half-cell of V-Ce RFB suffered from degradation due to the high oxidizing properties of cerium electrolyte. As an alternative, we in-vestigated the use of another positive electrolyte composed of titanium, manganese and vanadium.

Another way to increase the energy density of the RFB is to add solid phase materials with high energy storage capacity in the electrolyte tanks in order to increase the whole capacity of the RFB. Polyanilinewasthefirstmaterialstudiedasproof-of-conceptinacidicmedia.[1]Wewentfurtherbyscreening a variety of solid phase storage materials working at neutral pH, such as potassium and sodium intercalation compounds or redox conducting polymers.

IntheframeworkoftheMartignydemonstrator,acommercialvanadiumredoxflowbattery(VRFB)operates for 3 years now. Stack leakage was observed, advanced corrosion of the carbon electrodes and cracks of the bipolar plates on several stacks were discovered. The cracks enabled the elec-trolyte to leach the copper current collectors and contaminated the entire electrolyte solution with copper ions. Here we present a method to purify the contaminated electrolyte

Statusofprojectandmainscientificresultsofworkgroup

Authors

Danick Reynard¹ Solène Gentil¹ Elena Zanzola¹ Vimanshu Chanda¹ Sunny Maye¹ Pekka Peljo¹ Christopher R. Dennison¹Alberto Battistel¹ Heron Vrubel¹ Hubert H. Girault¹

¹ EPFL Valais/Wallis


CNT Carbon Nanotubes

EV Ethylviologen

HER Hydrogen Evolution Reaction

RFB Redox Flow Battery

VRFB Vanadium Redox Flow Battery

References

[1]F.Pan,Q.Wang,Mol-ecules, 20, 20499–20517 (2015).

[2] J.Bartolozzi,J.PowerSources, 27, 219–234, (1989).

[3]C.PoncedeLeon,A.Frıas-Ferrer,J.Gonzalez-Garcıa,D.A. Szanto, F.C. Walsh, J. Power Sources, 160, 716–732 (2006).

[4]Z.G.Yang,J.L.Zhang,M.C.W. Kintner-Meyer, X.C.Lu,D.W.Choi,J.P. Lemmon, J. Liu, Chem. Rev., 111, 3577–3613 (2011).

[5]M.Skyllas-Kazacos,M. H. Chakrabarti, S.A. Ha-jimolana, F.S. Mjalli, M. Saleem, J. Electrochem. Soc., 158, 55–79 (2011).

[6]V.Amstutz,K.E. Toghill, F. Powlesland, H. Vrubel, C. Comninellis, X.HubandH.H.Girault,Energy Environ. Sci., 7, 2350–2358 (2014).

[7]H.J.Lee,S.Park,H. Kim, Journal of the Electrochemical Soci-ety, 165(5), A952–A956 (2018).

[8]F.Q.Xue,Y.L.Wang,W.H.Wang,X.D.Wang,Electrochim. Acta, 53, 6636 (2008).

[9]G.Davies,Coor-din. Chem. Rev., 4, 199 (1969).

[10]Y.R.Dong,H.Kaku,K. Hanafusa, K. Moriuchi, T. Shigematsu, ECS Trans-actions, 69 (18), 59–67 (2015).

[11]E.Zanzola,C.R.Den-nison, A. Battistel, P.E. Peljo, H. Vrubel, V. Amstutz, H.H. Girault, Electrochimica Acta, 235, 664–671 (2017).

[12]T.Janoschka,N. Martin, M.D. Hager, U.S. Schubert, Ange-wandte Chemie Interna-tional Edition, 55 (46), 14427–14430 (2016).

[13]D.Reynard,H. Vrubel, C.R. Denni-son, A. Battistel, H. Gi-rault, ChemSusChem, https://doi.org/10.1002/cssc.201802895, Accepted paper (2019).

• At the Cathode: VO2+ + H2O D VO2+ + 2H+ + 2e− E° = +0.991V vs. SHE

Mn3+ + e− D Mn2+ E° = +1.51V vs. SHE

• At the Anode: V3+ + e− D V2+ E°=−0.225Vvs.SHE

• Disproportionation reaction at high potential: 2Mn3+ + 2H2O D Mn2+ + MnO2 + 4H+

To overcome the low energy density of RFB,[1–5] a newconcept was developed by Am-stutz and co-workers which includes a second pathway to discharge chemically the RFB. This pathway allows the sys-tem to generate hydrogen and oxygen using catalytic beds as heterogeneous catalyst, with-out affecting the functioning of the RFB. The concept of dual-circuit redoxflowbatterywasstudied for a V-Ce RFB, using Ce(IV)/Ce(III) and V(III)/V(II) as positive and negative redox

couples, respectively. Ce(IV) is chemically discharged through the oxidation of water to oxy-gen on RuO2 catalyst and V(II) is chemically discharged through proton reduction to hydrogen on Mo2Ccatalyst.[6]

The positive half-cell of V-Ce RFB suffered from degrada-tion due to the high oxidizing properties of cerium electro-lyte. As an alternative, we in-vestigated a V-Mn RFB. The main redox reactions are de-scribed below:

Investigation of titanium-manganese-vanadium electrolytes as catholyte for dual-circuit redox flow batteries

43

Figure 1:

Boosters and redox me-diators used in the organic aqueous redox flow bat-tery.

Mn(III) is known for its dispro-portionation at 1.5 V vs SHE, leading to the formation of MnO2 solid particles and Mn2+. It was previously reported that Mn(III) can be stabilized by increasing the concentration of acid.[7–9] However, thismethodwasnotsignificantasthe energy density of Mn(III) redox species was still low. Dong et al reported a novel Ti-Mn RFB wherein they real-ized that upon mixing TiO2+ ions with Mn(II) in H2SO4 so-lution, they prevent the oxida-tion of Mn(III) to MnO2.[10]Inorder to understand the exact redox mechanism behind the inhibition of MnO2 formation by addition of TiO2+ in the elec-trolyte, electrochemical and surface characterizations were intensively investigated. It was shown that 1:1:1 of Ti/V/Mn in 5 M H2SO4 was the best compromise to reduce the for-mation of MnO2 and maintains the reversibility of Mn(III) to Mn(II) reduction. As a per-spective, a dual V-Ti-Mn RFB will be studied.

ated as booster and redox mediator (–0.7 and 0.9 V vs SHE) respectively (Figure 1). [12]Fromourpreviouswork,we demonstrated that a high electronic conductivity of the booster was necessary in or-der to prevent insulating path upon cycling. To that purpose, carbon nanotubes (CNT) were investigated as electronic supporting material for both CuHCNFe and polyimide. Gal-vanostatic cycling of both car-bon nanotubes based boosters (ratio 30% of CNT and 70%of booster) have been investi-gated in 1M KCl solution lead-ingtospecificcapacitiesof150and300mAh∙g-1 for polyimide and CuHCNFe, respectively. As a perspective, a near neu-tral pH booster-based RFB will be designed. As expected from the standard redox potential of the redox mediators, an open-circuit voltage of 1 V should be reached at pH 5 and room temperature.

In order to increase the energy density of the RFB, one pos-sibility is to add solid phase materials with high energy storage capacity in the electro-lyte tanks in order to increase the whole capacity of the RFB. Starting in 2017, with our work on polyaniline [11], we wentfurther by screening a variety of solid phase storage materi-als, i.e boosters, and near neu-tral pH aqueous electrolytes i.e redox mediators. One im-portant challenge is to match the fermi level of the boosters with the standard potential of the redox mediators in order to drive the interfacial charge-transfer. The positive electrolyte con-sists of the use of a K+ interca-lation compound, CuHCNFe as booster, and TEMPTMA, a tem-po derivative, as soluble redox mediator (+0.9 V vs SHE). At the negative side, polyimide derivatives and amino ethylvi-ologen (EV) have been evalu-


Redox solid boosters for aqueous redox flow batteries

44 Hydrogen

After 3 years of operation, stack leakage was observed on the 10 kW / 40 kWh commercial vanadiumredoxflowbatteries(VRFB) installed in the frame-work of the Martigny demon-strator. Advanced corrosion of

the carbon electrodes and bi-polar plates on several stacks were discovered. It led to the failure of the VRFB. Moreover, cracks through bipolar plates enabled the electrolyte to leach the copper current col-

lectors and contaminated the entire electrolyte solution with copper ions.

The deleterious effects of cop-per contaminants were firsthighlighted on the operation of a VRFB. It was observed that metallic copper improved the parasitic hydrogen evolution reaction (HER) on the negative side. To tackle the problems related to copper pollution, a simple, eco-friendly and cost-effective procedure to identify copper contamination on-site and to purify the electrolyte was developed.

A classical VRFB stack was used to plate out the copper removing from the solution. The optimal cathode poten-tial for copper deposition onto carbon felt electrode was de-termined to be –100 mV vs SHE. Moreover, the stack can be regenerated after the puri-fication.Theprocessdescribedhere was successfully used to purify 6000 L of vanadium electrolyte (V+3/V+4 mixture). At theendof thepurification,the stack was regenerated by flashing20–30Lofelectrolyte.That represents only a fraction of what would have been nec-essary to dispose the contami-nated electrolyte. This work has been accepted as a full pa-perinChemSusChem.[13]


Figure 2:

Schematic illustration of thepurificationprocessde-veloped to remove copper from the vanadium elec-trolyte.

Purification of copper-contaminated vanadium electrolytes using vanadium redox flow batteries

45

Authors

GáborLaurenczy¹Nordahl Autissier2

¹ EPFL2 GRT GROUP SA, Orbe

Hydrogen storage and delivery in CO2 – formic acid – methanol systems

Formic acid (FA) contains ~4.4wt% of hydrogen (or53 g/L) which can be catalyti-cally released and converted to electricity using a proton ex-change membrane (PEM) fuel cell. Although various catalysts have been reported to be very selective towards formic acid dehydrogenation (resulting in H2 and CO2), a side-production of CO and H2O (formic acid de-hydration) should also be con-sidered, because most PEM hy-drogen fuel cells are poisoned by CO.

In this research, a highly ac-tive aqueous catalytic system containing Ru(III) chloride and meta-trisulfonated triphe-nylphosphine (mTPPTS) as a ligand was applied for formic acid dehydrogenation in a con-tinuous mode. CO concentra-tion (8–70 ppm) in the result-ing H2 + CO2 gas stream was measured using a wide range of reactor operating condi-tions.

The CO concentration was found to be independent on the reactor temperature but increased with increasing for-mic acid feed. It was concluded that unwanted CO concentra-tion in the H2 + CO2 gas stream was dependent on the current formic acid concentration in the reactor which was in turn dependent on the reaction de-sign.

Scope of project

Formic acid (HCOOH) and methanol (CH3OH) are considered as effective liquid chemicals for hydro-gen storage as being easier to handle than solid or gas materials (Figure 1). This work summarizes the recent progress of research on the development of homogeneous catalysts mainly focusing on formic acid and CH3OH and the reports on the catalysts based on both precious and non-precious metals which are rapidly increasing in the past few years.

Statusofprojectandmainscientificresultsofworkgroup

Next, preferential oxidation (PROX) on a Pt/Al2O3 cata-lyst was applied to remove CO traces from the H2 + CO2 stream. It was demonstrated that CO concentration in the stream could be reduced to a level tolerable for PEM fuel cells (~ 3 ppm).

An industrial prototype has been built and presented on 19.03.2018, the world's firstformic acid-based power sup-ply unit, using PEM fuel cell for electricity production (Fig-ure 2).

Figure 1:

Reversible hydrogen stor-age and delivery.


CH3OH Methanol

HCOOH Formic Acid (FA)

mTPPTS meta-Trisulfonated Triphenylphosphine

PEM Proton Exchange Membrane

Figure 2:

Article in 24 heures about the presentation of the world's first formic acid-based power supply unit, using PEM fuel cell (indus-trial prototype).

Synthetic FuelsDevelopment of Advanced Catalysts

Work Package «Synthetic Fuels» at a Glance

The work package «Synthetic Fuels» is devoted to exploring and developing efficient processes to convert carbon dioxide – using excess energy obtained from renewable intermittent energy sources – into fuels, with a specific focus on methanol and hydrocarbons. This work-package is sub-divided in two main parts, addressing catalytic (Part 1) and electrocatalytic (Part 2) processes. A short summary of the 2018 highlights is provided below.

Part 1: Catalytic conversion of CO2

The hydrogenation of CO2 to methanol is investigated at ETHZ, where selective supported Cu catalysts are being developed. ETHZ has shown that introducing Lewis acid dopants at the periphery of supported copper nanoparti-cles using Surface Organometallic Chemistry dramatically improved the methanol activity of Cu-based catalysts with selectivityabove80%.Thisapproachhasshowntobegen-eral and providing guidelines to improve CO2 hydrogenation catalysts – that includes converting poor catalysts such as Cu/TiO2 into highly efficient systems by dispersing Ti(IV)sites on silica. In addition, silica-supported Ag-based cata-lysts have been developed to convert CO2 in the presence of methanol into methyl formate with high selectivity. Detailed operando spectroscopic studies have shown that interfacial sitesareessentialfortheefficiencyofthattransformation.Allthesefindingsarecurrentlybeingusedtodevelopmorerobust catalysts amiable to scale-up.

EPFL has investigated alternative approaches, where CO2 from biogas (gas produced from organic wastes, typically 35 : 65 CO2 : CH4) is separated and catalytically incorpo-rated into cyclic carbonates using ionic liquids (ILs) as the catalyst. The process is being scaled-up and discussions to implement a reactor at a biogas plant are underway. The resulting cycling carbonate can be used in pure form in many applications or converted into glycols and methane/methanol using a heterogeneous Ru catalyst.

Furthermore, EPFL has also uncovered another promising way of CO2 conversion using frustrated Lewis pairs (FLPs) by designing, for instance, a water stable and heteroge-neous MOF catalyst – SION-105 – that converts CO2 to val-ue-added benzimidazoles.

Part 2: Electrocatalytic conversion of CO2

Regarding CO2-reduction, the electrocatalytic conversion of CO2 to alcohols is an intense research area, where Cu-based catalysts are particularly appealing. Detailed studies atPSIonthinfilmspreparedviaDCmagnetronsputteringhave shown that Cu0 is the active species causing the en-hanced alcohol selectivity of (reduced) copper oxides.

In parallel, ETHZ has shown that highly dispersed Cu parti-cles supported on carbon are formed under electro reduction conditions yielding high Cu-normalized CH4 currents and UniBern has successfully transferred their work on Cu foam to technical substrates such as 2D meshes and 3D skel-eton supports that show superior performances for C2 and C3alcohol formation reaching total alcohol efficienciesof25%.UniBernhasalsoshownthathighFaradaicefficien-cies for alcohol production can be maintained for more than 8 hours. Besides Cu, UniBern has shown that Ag-foams are alsoefficientelectro-catalysts for the reductionofCO2 to CH4withFaradaicyieldsreaching55%.Thisunexpectedlyhigh hydrocarbon production has been shown to be due to the high bond strength of CO on Ag foam which prevents the parasitic hydrogen evolution reaction. The loss of Farad-icefficiencyovertimeinthesecatalystshasbeenrelatedtoasignificantpoisoningthroughcarbonspeciesdeposition.

In parallel, EPFL has investigated novel approaches for the reduction of overpotential in CO2 electro-conversion by tuning the electrolyte. Using choline chloride (ChCl) and its derivatives in combination with the concept of deep eutectic solvents (DES) provided active media for the CO2 electroreduction to CO with low onset poten-tials and good selectivities (Faradaic efficiencies). A very versatile approach has been devised that combines DES

Illu

stra

tion:

Beh

oldi

ngEy

e /

iSto

ck

and IL approaches that allows high-throughput screening of co-catalysts that should accelerate the discovery of new, moreefficientsystems.

The CO2–to–CO electro-reduction process in co-electrolys-ers, best carried out in alkaline solution, is also being inves-tigated at PSI. While the state-of-the-art anodic electrodes in alkaline water electrolysers (AWEs) have been based on NiO for several decades, PSI has shown that the stabiliza-tion by the incorporation of Fe is due to the inhibition of the transformation of the compact and crystalline rock salt structure of Ni1-xFexOy into more layered and disordered polymorphs. Furthermore, alternative transition metal ox-ides catalysts based on perovskite-related structures have been investigated because of the immense compositional possibilities. Detailed structure-activity relationships have been found using a combined experimental and computa-tional approach based on OER/multi-descriptor relation-ships that will help the design of highly active oxygen evo-lution catalysts forefficientanodes forAWEs. Inparallel,highlyefficientOERIr-basedcatalystsforacidmediahavebeen developed at ETHZ following earlier studies with PSI, showing that only few (down to one) Ir atoms are enough to obtain highly active OER catalyst.

Moving to co-electrolysis studies, a process mostly limited by the low solubility of CO2 in aqueous solutions and asso-ciated CO2 transport-limited current densities, PSI has de-veloped a bipolar-like membrane assembly to facilitate this process. Using Au black as cathode catalyst shows that this novelconfigurationsuccessfullysuppressed the formationof CO2 on the anode side, while maintaining similar Faradaic efficiencyasthealkalineelectrolytesystem.

48

Catalyst Developement for the Transformation of CO2 into Fuels and Value-Added Chemicals

Scope of project

CO2 can be reduced and incorporated into organic scaffolds by catalysis and/or electrocatalysis. Effective catalysts include ionic liquids (ILs), organic salts and frustrated Lewis pairs (FLPs). Here, we present a status overview of our main results related to catalytic CO2 conversion.


Electrochemical reduction of carbon dioxide

Electrochemical reduction of carbon dioxide (ERC) provides a sustainable alternative to transform CO2 into valuable products. However, electro-reduction occurs through high-energy intermediates, result-ing in large overpotentials, which can be reduced by em-ploying ionic liquids (ILs).[1]It was also found that pres-ence of hydroxyl groups in the proximity of reaction centres further promotes the ERC.[2]Combining these two ideas, we decided to employ choline chloride (ChCl) and its deriva-tives as promoters and media for the ERC (Figure 1) in the form of deep eutectic solvents (DESs) in order to obtain ho-

mogeneous systems, suitable for application as electrolytes. The novel systems are active media for the reduction, pro-viding low onset potentials and good selectivities (Faradaic ef-ficiencies) for the productionof CO (Table 1). Moreover, this concept of employing DESs in-stead of ILs can be broadened to the cations other than cho-line, for example, imidazolium chlorides, which are precur-sors to conventional ILs. This approach avoids additional synthetic steps and affords cheap co-catalytic systems of high purity and enables high-throughput experimenta-tion (currently ongoing) that should accelerate the discov-ery of superior electrolytes for this important reaction.

Heterogenious catalysis

Another promising way of con-verting CO2 harnesses frus-trated Lewis pairs (FLPs), com-prising Lewis acids and bases sterically hindered in such a way that the acid-base ad-duct is not formed as in clas-sical Lewis pairs, and exhibit outstanding ability to activate CO2. Progress in FLP-chemistry includes efforts to improve the moisture stability of FLPs and transfer this concept from ho-mogeneous to biphasic IL and heterogeneous environments.

Following this latter strat-egy, we have designed a wa-ter stable heterogeneous MOF catalyst – SION-105 – for the metal-free and FLP-mediated conversion of CO2 to value-added benzimidazoles. The introduction of Lewis acidic B centers within the MOF struc-ture provides steric protection, suppressing irreversible bind-ing and deactivation with bas-es and water. The high stability of SION-105, CO2-responsive-ness, recyclability, tolerance against a wide variety of func-tional groups, and catalytic activity, achieved through the in situ formation of FLPs with o-diamine aromatic substrates as complementary bases, highlight the utilization of MOF catalysts for CO2 conversion. Ourfindingsopenthewayforthe next generation of hetero-geneous catalysts, which are intricately designed via direct

Author

Paul J. Dyson¹

¹ EPFL


DES Deep Eutectic Sol-vent

ERC Electrochemical Re-duction of Carbon Dioxide

FLP Frustrated Lewis Pair

IL Ionic Liquid

Figure 1:

A concept of employing DESs by benefitting fromthe ionic part of choline and an OH-group.

Table 1:

Reduction onset potentials for the ERC and product distribution at optimal potentials for chrono-amperometrical experi-ments employing DESs or DES-like systems (neat or as an additive in various solvents).

Catholyte FECO %**

FEH2

%**EAg/AgCl V

ChCl-Urea (1:2) 15.8 17.0 -1.40

ChCl-Urea (1:2) + H2O(15%vol) 59.0 26.3 -1.38

ChCl-EG (1:2) 78.0 9.9 -1.43

BMImCl-EG (1:2) 95.8 6.8 -1.44

1M ChCl + 2M EG in H2O 23.3 75.6 N/A*

1M ChCl + 2M EG in MeCN 98.8 4.7 -1.52

1M ChCl + 2M EG in 3EOH 92.3 8.4 -1.4

1M ChCl + 2M EG in PC 101.5** 0.5 -1.5

1M ChCl in EG 71.1 28.2 -1.42

1M ChCl in PEG-200 83.2 7.9 -1.40

1M BMImCl in PEG-200 85.9 3.7 -1.41

1M EMImOHCl + 2M EG in PC 101.8** 1.6 -1.45

1M EMImOHCl + 2M EG in MeCN 98.9 0.8 -1.45

* Cannot be determined due to concomitant HER.** Theexperimentalerrorisintheorderof+/-5%(GC)Experimental conditions: U-type divided cell, Ag polished disc cathode, Pt wire anode,

Ag/AgCl reference, anolyte – H2SO4 (aq, 0.5 M), catholyte – depictedintheTable,Nafion117membraneseparator.

49

References

[1]B.A.Rosen,A.Salehi-Khojin, M.R. Thorson, W. Zhu, D.T. Whipple, P.J.A. Kenis, R.I. Masel, Sci-ence, 334, 643–644 (2011).

[2] L.Zhang,N.Wu,J.Zhang,Y.Hu,Z.Wang,L.Zhuang,X.Jin,ChemSus-Chem, 10(24), 4824–4828 (2000).

[3]F.D.Bobbink,F.Menoud,P.J. Dyson, ACS Sustainable Chem. Eng., 6, 12119–12123 (2018).

[4]W.-T.Lee,A.P.vanMuyden, Z. Huang, F.D. Bob-bink, P.J. Dyson, Angew. Chem, Int. Ed., 131, 567–570 (2019).

[5]M.Hulla,G.Laurenczy,P.J. Dyson, ACS Catal., 8, 10619–10630 (2018).

Figure 2:

Reaction of aromatic o-diamines with CO2 as a C1-source. Atom color code: Eu – green; C – grey; O – red; B – magenta; H – white.

Figure 3:

Indirect CO2 reduction to fuels via catalytic biogas upgrader.

Catalyst Developement for the Transformation of CO2 into Fuels and Value-Added Chemicals

assembly and functionalization for the activation of small mol-ecules. We are also working towards the direct synthesis of methane from CO2 and H2 using FLP-chemistry.

Wehaveidentifiedbiogas(gasproduced from organic wastes, typically 35 : 65 CO2 : CH4) as a CO2 source for our catalytic CO2 extractor from gas streams, in which the CO2 is removed and catalytically incorporated into cyclic carbonates. To this end, we have revealed the intrica-cies of the reaction catalyzed by homogeneous ILs, which in turn will lead to the develop-ment of very robust catalysts.

This novel scrubbing approach is relevant since biogas up-grading methods into biometh-ane are expensive, and are only suitable for large scale biogas plants. The result-ing cycling carbonates can be used in pure form (solvent, electrolyte in batteries, etc.) or processed into a variety of different chemicals, including polymers and glycols. In this

context, we have reported two simple approaches to convert cyclic carbonates into glycols and methane/methanol, using a heterogeneous Ru catalyst/H2 combination and a metal-free F– salt/hydrosilane combi-nation,respectively.[3,4]

With respect to a two-step re-duction of CO2 to methanol via formamides, the mechanism of amine N-formylation with CO2 and hydrosilane reduc-ing agents was investigated in detail. [5] Formation of a car-

bamate was identified as therate-determining step of the reaction. Catalyst pKa-activity relationship (Figure 4) con-firmstheroleofsaltcatalystsas bases required for carba-mate stabilization similarly to the related quinazoline-2,4-dione formation investigated previously.

Figure 4:

Reaction yield dependency on the pKa of the catalyst.

50

Development of Selective Catalysts for the Conversion of CO2 to Fuels via Surface Organometallic Chemistry

Authors

XingHuang¹ Nicolas Kaeffer¹ Erwin Lam¹ Hsueh-Ju. Liu¹ Christos Mavrokefalos¹ Gina Noh¹ Kim Larmier¹ Dmitry Lebedev¹ Shohei Tada¹ Patrick Wolf¹ ChristopheCopéret¹

¹ ETHZ


EDX EnergyDispersiveX-RaySpectroscopy

EPR Electron Paramag-netic Resonance

FE FaradaicEfficiency

GC-MS Gas Chromato-graph-Mass Spec-trometer

HAADF-STEM High Angle Annular Dark Field Scanning Transmission Elec-tron Microscopy

HER Hydrogen Evolution Reaction

ITO Indium Tin Oxide

OtBu (CH3)3CO−


SOMC Surface Organo-Metallic Chemistry

UV-Vis Ultraviolet-Visible

XAS X-RayAbsorptionSpectroscopy

XPS X-RayPhotoelec-tron Spectroscopy

Scope of project

The conversion of CO2 to fuels, such as methanol, using hydrogen produced from alternative ener-gies or directly via electroreduction is a dynamic research area, in view of the constant increase of CO2 emission and the abundant excess of unused intermittent and renewable energy sources available today due to the increase availability of wind and solar power sources. This research area posesses several technical challenges and in particular the development of stable and selective thermo- and electrocatalysts. This work package focuses on the development of improved catalytic materials via rational design for the selective • hydrogenation (Part 1) and • electroreduction of CO2 coupled with the oxygen evolution reaction (OER) (Part 2).


Towards the selective hydrogenation of CO2 to CO3OH

In the recent years, we have worked on developing selec-tive CO2 hydrogenation cata-lysts to methanol. In particu-lar, we have investigated the effects of ZrO2 as a Lewis acid-ic support for Cu nanoparticles to promote CH3OH synthesis. This finding resulted in thedevelopment of active cata-lystspreparedbyflame-spraypyrolysis, with similar activity and higher selectivity than the

state-of-the art Cu/ZnO/Al2O3

catalysts.[1] In addition, wegenerated a library of supports consisting of isolated surface metal sites (Zr, Ti, Ga, Zn etc.) on SiO2 (denoted as M@SiO2) via a surface organometallic chemistry (SOMC) approach (summarized in Scheme 1). Cu nanoparticles dispersed on these supports (denoted as Cu/M@SiO2) show enhanced activity and selectivity for CH3OH synthesis compared to Cu dispersed on SiO2 alone.

In 2018, we further investi-gated the nature and role of these different promoters to mediate CH3OH synthesis by using ex situ and in situ spec-troscopic investigations.

We determined that supported Cu nanoparticles on SiO2 con-taining surface Zr sites (Cu/Zr@SiO2, Scheme 1) promoted CH3OH synthesis with a se-lectivity of 77% by providing

Lewis acidic coordination sites. These findings confirmed ourconclusions as to the nature and role of Zr in our previous work on Cu/ZrO2; furthermore, the understanding garnered from this work enables the ra-tionaldesignofmoreefficientcatalysts by increasing the dis-persionofZr.[2,3]

By using electron paramag-netic resonance (EPR) and ultraviolet-visible (UV-Vis) spectroscopy, the structure

and role of Ti sites for Cu/Ti@SiO2 could be unraveled: Ti in its +4 oxidation state provides Lewis acidic surface sites that promote the selective conver-sion of CO2 to methanol as found for Zr. These findingsdemonstrate that Ti effectively promotes CH3OH synthesis, in spite of the poor activity and selectivity observed for Cu/TiO2. This shows that isolated Ti sites in an inert matrix like

silica behaves quite differently from Ti sites on the surface of titania; it opens new avenues in (re)exploring previously dis-carded promoters for CH3OH synthesis.[4]

In parallel, we have investi-gated the role of interfaces in alternative CO2 conversion processes such as the hydro-genation of CO2 in the pres-ence of methanol that provides methyl formate and showed that the Ag-supported on silica

Scheme 1: Schematic procedure for grafting of [Zr(OSi(OtBu)3)4] onSiO2-700 followed by ther-mal treatment at 500 °C, grafting and reduction of [Cu(OtBu)]4.

51


isoneofthemostefficientcat-alysts for that transformation and that the interface plays an essential role for the selectivity ofthattransformation.[5]

evolved is H2, which we identi-fiedasarisingfromcatalysisatthe carbon black support itself.

We further analysed the CuOx/CB material after a 4-hour electrolysis at –1.0 V vs. RHE. TEM images do not show the presence of well-dispersed Cu NPs in the range 1–10 nm, as compared to the starting ma-terial. Instead, Energy Dis-persive X-Ray Spectroscopy(EDX) elemental mappingreveals that Cu is present on the post-electrolysis material with some Cu-rich regions to-gether with discrete Cu species (single sites or small clusters) dispersed all over the carbon support, pointing to Cu NPs reconstruction under electro-catalytic conditions. Interest-ingly, under these conditions large Cu particles (several tens of nanometers) are not formed upon turnover as reported typically for other catalysts. Here, the presence of highly dispersed Cu species also cor-roborates with the high Cu mass-activity observed for CH4 evolution. We are now investi-gating the origin for the recon-struction of Cu nanoparticles under electrocatalytic condi-tions and the precise nature of the active sites formed.

Water electrolysis is comple-mentary to CO2 electroreduc-tion and the most direct way for generating hydrogen – a green alternative to fossil fuels. While in acidic media the cathodic process (hydrogen evolution

reaction, HER) proceeds with small overpotentials, the con-comitant anodic process (oxy-gen evolution reaction, OER) requires high overpotentials, which translates into signifi-cantenergyloss[7].Moreover,the harsh reaction conditions limit the pool of possible an-odic catalysts to the expen-sive and scarce noble metals, namely Ru and Ir. Therefore, decreasing the noble metal content while maintaining high catalytic activity is a critical re-quirement for the anodic water oxidation catalysts.

Decreasing the noble metal loading can be achieved via synthesis of high surface area noble metal oxides[8] or bydispersing the noble metal ac-tive species on the surface of a support[9]aswehaveshownearlier. In the present work, we prepared indium tin oxide (ITO) supported Ir species and

Figure 1:

Total current density (squares, left scale) and potential dependence for Faradaic efficiencies ofCO2-reduction gas-phase products (dots, right scale) for CO (blue), C2H4 (purple) and CH4 (green) at CuOx/CB/GDL. Condi-tions: CO2-saturated 0.5 M KHCO3 aqueous electrolyte (pH = 7).

CO2 reduction and water oxidation electrocatalysts

Copper is of major interest for CO2 electroreduction, since it has a unique ability to electro-catalyze the formation of high-ly reduced, energetically dense fuels. Achieving high disper-sion of copper on an electrode substrate thus constitutes a possible route to access highly active copper-based electro-catalysts. Here, we used a surface organometallic chem-istry approach to generate small copper nanoparticles (4.0 ± 1.4 nm) well dispersed onto an activated carbon black support (4.2Cuwt%).[6] Af-ter air oxidation, the material was filtered on gas diffusionlayer to obtain CuOx/CB/GDL electrodes. Cyclic voltamme-tryatthiselectrodeconfirmedthe presence of electro active Cu species in a density of 1.6·10–8 mol·cm–2. Electrocata-lytic performance of the elec-trode was then assessed under aqueous conditions (KHCO3 0.5 M) with constant CO2 stream (20 mL·min–1).

The on-line analysis of volatile products by a gas chromato-graph-mass spectrometer (GC-MS) demonstrated the evolu-tion of CO2-reduction products (Figure 1), namely CO at lower overpotentials (starting from –0.6 V vs. RHE) with Faradaic efficiency (FE) up to 5% at–1.1 V vs. RHE. When poten-tials are scanned downward, C2H4 and CH4 are also detect-ed with CH4FEreaching13%at –1.6 V vs. RHE. Besides, the major gas phase product

In relation to these studies, we are currently exploring the effects of different promoters as well as further understand-

ing different oxide supports to obtain a structure-activity re-lationship by using ex situ and in situ spectroscopic studies.

52

metallic, while the surface be-comes oxidized into the form of an oxo-hydroxide layer, which is likely responsible for the high catalytic activity. The Irsinglesitesshowsignificant-ly higher activity as compared to the supported nanoparticles because all the Ir atoms par-ticipate in catalysis, while only a portion of Ir is accessible for the particles (<60% of Ir ison the surface of 1.5 nm par-ticles).

Taking advantage of our elec-trode design we were able to couple electrochemical studies with spectroscopy to probe re-action intermediates and eval-uate possible reaction mecha-nisms for the Ir single site catalyst. XPS and in situ XASshow that the catalyst original-ly existing as Ir(III) oxidizes to Ir(IV) (0.89 V vs. RHE) and Ir(V) (1.35 V vs. RHE) with in-creasing anodic potential. The in situ XAS studies suggestthat Ir(V) is a resting state of the catalyst under OER condi-tions and that the O-O bond formation takes place upon water nucleophilic attack on the high valent Ir-O interme-diate.

addressed the question of how small can these active species be (down to atomically dis-persed sites), while still being efficientincatalyzingOER.

Iridium nanoparticles or Ir sin-gle sites were prepared on po-rous conductive ITO electrodes via colloidal or SOMC ap-proachesrespectively[10,11].High Angle Annular Dark Field Scanning Transmission Elec-tron Microscopy (HAADF-STEM), X-ray Photoelectronand Absorption Spectroscopies (XPS and XAS) were used tocharacterize the catalysts pri-or to and after catalysis and in situ. HAADF-STEM images (Figure 2) of these materials show homogeneous distribu-tion of 1.5 ± 0.2 nm metallic Ir

nanoparticles on the one hand or atomically dispersed Ir on the ITO support on the other hand (bright dots highlighted with yellow circles) with the total Ir loading of 4.1wt%or0.86wt%,respectively(deter-mined via elemental analysis).

Electrochemical studies of these materials were per-formed in 0.1 M HClO4 using a standard three-electrode set-up. We find that bothcatalysts are highly active in OER, reaching the current of 35 ± 3 A·gIr

−1 (Ir nanoparticles) or 156 ± 13 A·gIr

−1 (Ir single sites) at 1.51 V vs. RHE. In the case of Ir nanoparticles, XPStogetherwiththeHAADF-STEM studies show that the core of the particles remains

References

[1]S.Tada,K.Larmier,R.Büchel,C.Copéret,Catal. Sci. Tech., 8, 2056 (2018).

[2]E.Lam,K.Larm-ier, P. Wolf, S. Tada, O.V.Safonova,C.Copéret,J. Am. Chem. Soc., 140, 10530 (2018).

[3]E.Lam,K.Larm-ier, P. Wolf, S. Tada, O.V.Safonova,C.Copéret,under revision.

[4]G.Noh,E.Lam,J.Alfke, K. Larmier, P. Wolf, K.Searles,C.Copéret,under revision.

[5] J.J.Corral-Pérez,A. Bansode, C.S. Praveen, A. Kokalj, H. Rey-mond, A. Comas-Vives, J. VandeVondele, C. Co-péret,P.VonRohr,A. Urakawa, J. Am. Chem. Soc., 40, 13884 (2018).

[6]N.Kaeffer,H.-J.Liu,C.M. Mavrokefalos, C. Co-péret,inpreparation.

[7]E.Fabbri,T.J.Schmidt,ACS Catal., 8, 9765 (2018).

[8]D.F.Abbott,D.Leb-edev, K. Waltar, M. Povia, M. Nachtegaal, E. Fabbri, C.Copéret,T.J.Schmidt,Chem. Mater., 28, 6591 (2016).

[9]E.Oakton,D.Leb-edev, M. Povia, D.F. Ab-bott, E. Fabbri, A. Fedorov, M.Nachtegaal,C.Copéret,T.J. Schmidt, ACS Catal., 7, 2346 (2017).

[10]D.Lebedev,C.Co-péret,ACSAppl.EnergyMater. 2019, in press. doi: 10.1021/acsaem.8b01724.

[11]D.Lebedev,R.Ezhov,N. Kaeffer, M. Willinger, X.Huang,Y.Pushkar,C.Copéret,inpreparation.

Figure 2:

HAADF-STEM images of the OER catalysts: Ir nanopar-ticles (left) and Ir single sites (right) dispersed on ITO. The Ir single sites ap-pear as bright dots on the ITO surface (highlighted in yellow circles). The inten-sity profile line scan (bluetrace) is shown as the in-set.


53

Synthesis and Characterization of Degradation Resistant Cu@CuPd Nanowire Catalysts for the Efficient Production of Formate and CO from CO2

Scope of project

In the focus of this part of the SCCER is the conversion of the environmentally unfriendly green-house gas CO2 into high value products (e.g. ethylene, ethanol, propanol, carbon monoxide, formic acid, etc.) by means of electrochemical processing. The particular technological challenge is related to the extraordinary stability of the CO2 molecule thus requiring extremely high over-potentials for its electrochemical reduction at acceptable reaction rates. Only by the use of proper catalysts the CO2 reduction can be accelerated so that the process might become feasible from an economic point of view. Up to now, Sn and Ag based materials have been mainly used as catalysts for the production of formate and CO at high and medium overpotentials, respectively. In this study, we introduce a new synthesis approach towards Pd-based bimetallic CO2RR catalysts which show not only excellent activity and selectivity towards formate at particularly low overpoten-tials and towards CO at medium overpotentials but demonstrate at the same time superior resis-tance to chemical and mechanical degradation.


Bimetallic Pd45Cu55 catalysts were synthesized by a con-trolled galvanic displacement reaction in the presence of a Pd(II) source starting from Cu nanowire (Cu-NW) templates (Figure1).[1] Such formedPd-modifiednanowires(denot-ed as Cu@CuPd-NWs) dem-onstrate a high Faradaic effi-ciency (FE) towards formate at particularly low overpotentials (e.g., FEformate~80% at -0.3Vvs. RHE) close to the thermo-dynamic potential of formate formation (Figure 2). This is rationalized by an ‹anomalous› CO2 reduction pathway which involves an initial CO2 hydroge-

nation reaction step from the formed metal hydride, a cata-lytic effect that is so far known only from pure Pd nanopar-ticles (Pd-NPs).[2] Our elec-trolysis results clearly indicate that the binary Pd45Cu55 al-loy also forms metal hydrides as crucial prerequisite for the CO2 hydrogenation pathway. In contrast to the pure Pd-NPs the novel Cu@CuPd-NW cata-lysts demonstrate in addition a high resistance against ir-reversible CO poisoning which forms as a minor by-product of the formate at low overpo-tentials thereby degrading the catalyst.

The product distribution of the CO2 electrolysis switches at medium overpotentials (from -0.6 V to -1.0 V vs. RHE) from predominant formate forma-tion to selective CO produc-tion with Faradic efficienciesnever falling below FECO=86% (Figure 2). Long-term electro-

Author

YuhuiHou¹ Aline Bornet¹ Abhijit Dutta¹ Motiar Rahaman¹ Roland Widmer2 Roman Fasel2 Rolf Erni2 Peter Broekmann¹

¹ University of Bern2 Empa


Cu-NW Copper Nanowire

FE FaradaicEfficiency

IL-HAADF-STEM Identical Location High-Angle Annular Dark-Field Scanning Transmission Elec-tron Microscopy

IL-SEM Identical Location Scanning Eelectron Microscopy

Pd-NP Palladium Nano-particle

Figure 1:

Identical location high-an-gleannulardark-fieldscan-ning transmission electron microscopy (IL-HAADF-STEM) and spatially re-solved EDX analysis of asingle Cu@CuPd-NW prior to (a–e) and after (f–j) 1 h CO2RR at -0.8 V vs. RHE. Panels (d) and (i) show the 2D-EDXmapping (Pd: redand Cu: green) of the Cu@CuPd-NW. 1D-EDX cross-sections shown in panels (e) and (j) are indicated by the cyan lines in panels (d) and (i), respectively.

Figure 2:

Product distribution of the CO2RR on Cu@CuPd-NWs catalyst at different applied potentials.

54

lysis experiments demonstrate CO efficiencies which remainat a high level of 85%±5%for up to 20 h electrolysis time (Figure 3). The bimetallic Cu@CuPd catalyst remains active even under massive CO pro-duction conditions.

This excellent electrochemi-cal catalyst stability could be further confirmed by identi-cal location high-angle annu-lar dark-field scanning trans-

mission electron microscopy (IL-HAADF-STEM), energy-dispersive X-ray spectrometryand identical location scanning electron microscopy (IL-SEM) applied to the catalyst before and after the CO2 electroly-sis (Figure 1). The HAADF-STEM and SEM inspection did not reveal severe structural and compositional changes of the catalyst after the CO2 electrolysis.

Conclusions and next steps

This study clearly demon-strates that Pd-based binary alloy nanomaterials are prom-ising candidates in particular for the production of formate at exceptionally low overpo-tentials. Co-alloying of Cu to the Pd leads to an increase in the resistance of the catalyst against irreversible CO poison-ing.

Figure 3:

Potentiostatic catalyst stressing experiments car-ried out in CO2-sat. 0.5 M KHCO3 at -0.8 V vs. RHE (CO formation regime); (a) Current density/time plot of continuous 20 h electrolysis and (b) Corresponding CO2RR product distribution rep-resented as FE vs. time plot; (c) Current density/time plot composed of 5 indi-vidual consecutive stress-ing as indicated by the numbers. (d) Corresponding CO2RR product distribution repre-sented as FE vs. time plot.

Synthesis and Characterization of Degradation Resistant Cu@CuPd Nanowire Catalysts for the Efficient Production of Formate and CO from CO2

References

[1]Y.Hou,A.Dutta,M.Ra-haman, R. Widmer, R. Fasel, R. Erni, P. Broekmann (sub-mitted).

[2]A.Dutta,M.Rahaman,P. Broekmann, ChemSus-Chem, 10, 1733–1741 (2017).

55

(Co)-Electrolysis at Paul Scherrer Institut

Scope of project

Thedevelopmentof cleanenergy storageand conversion systemsandefficientmethodsofCO2 capture are absolutely necessary to reduce the steadily increasing levels of atmospheric greenhouse gases, which are the primary contributors to destructive climate change. Within this scenario, water electrolysistechnologieshavebeenatthecenterofthespotlightowingtotheirabilitiestoefficientlyconvert renewable energy surplus into hydrogen, which can then be reconverted into electricity via fuel cell or converted into other useful fuels. Therefore, water electrolyzers appear to be central to the development of a clean, reliable and emissions-free hydrogen economy. Additionally, the electrochemical reduction of CO2 gas via co-electrolysis is a rather attractive option for minimizing theatmosphericcarbondioxidelevels.Byefficientelectrochemicalreduction,CO2 can be converted into fuels and other useful chemicals. In the following, the main approaches undertaken at the Paul Scherrer Institut towards the development of highly active and durable OER electrodes for electroly-sis applications, the development of cathode catalyst materials for CO2 reduction, and the rational design and engineering of the co-electrolysis device will be described.


ments,wefindthattheincor-poration of Fe leads to an over-all stabilization of the initially compact and crystalline rock salt structure of Ni1-xFexOy and thereby inhibits the transfor-mation to more layered and disorderedpolymorphs.[2]

Beyond the state-of-the-art NiO-based catalysts, transition metal oxides with perovskite-related structures have re-cently emerged as promising electrocatalysts for the OER in AWEs.[1,3] Given the im-mense compositional possibili-ties offered by the perovskite structure and the many open questions about the mecha-nism at the origin of their electrocatalytic activity, the research has been mostly fo-cused on identifying catalytic descriptors able to predict the optimal physicochemical prop-erties for maximizing the OER activity. In our recent work [4], the correlation betweenex situ electronic conductiv-ity, oxygen vacancy content, flat-band potential (Efb), and the OER activity for a wide range of perovskite composi-tions have been investigated

experimentally and theoreti-cally. It has been found that all of these parameters can affect the OER activity; however, none of them alone plays a crucial role in determining the electrocatalytic activity. The correlation of one single physi-cochemical property with the OER activity always presents deviationpoints,[4] indicatingthat a limitation does exist for such 2-dimensional correla-tions. Nevertheless, these de-viations can be explained con-sidering other physicochemical properties and their correlation with the OER activity. The nov-el concept of the OER/multi-descriptor relationship that we have recently introduced in our study[4] (see Figure1e) rep-resentsa significantadvance-ment in the search and design of highly active oxygen evolu-tion catalysts and in the quest forefficientanodesforAWEs.

Moving on to our activities dealing with CO2-reduction electrocatalysis, the appealing electrochemical transformation of CO2 into methanol or ethanol has preponderantly been car-ried out using catalysts based

State-of-the-art anodic elec-trodes in alkaline water elec-trolysers (AWEs) have been based on NiO for several de-cades due to this material’s relatively high activity and stability for the oxygen evolu-tion reaction (OER) in alkaline media. More recently, howev-er, the effect of Fe doping on the OER has been the subject of many intensive investiga-tions since the incorporation of small amounts of Fe into NiO can greatly enhance its OER activity.[1] In a recent work,we have produced highly crys-talline Ni1-xFexOy nano-powders byflame-spraysynthesis (seeFigure 1a, b) with different Ni-to-Fe ratios to investigate how Fe incorporation influencesthe surface electronic prop-erties and local coordination structures of Ni catalysts and how this impacts the electro-chemical stability and OER ac-tivity.[2]OperandoXASmea-surements (see Figure 1c, d) show that the incorporation of Fe greatly stabilizes the Ni electronic structure and local coordination environment un-der OER conditions. Combined with electrochemical measure-

Author

Daniel F. Abbott¹ Emiliana Fabbri¹ Bernhard Pribyl¹ AlexandraPătru¹ Juan Herranz¹ Thomas J. Schmidt¹

1 PSI


AWE Alkaline Water Elec-trolyser

BSCF Ba0.5Sr0.5Co0.8Fe0.2O3-d

CA Chronoamperomet-ric

CO2RR CO2 Reduction Reaction

EXAFS ExtendedX-RayAbsorption Fine Structure


RHE Reversible Hydrogen Electrode

TF Thin FilmXANES X-rayAbsorption

Near Edge Structure Spectroscopy

XAS X-rayAbsorptionSpectroscopy

XPS X-rayPhotoelectronSpectroscopy

56


on copper oxides (CuOx),[3]for which the (surface) oxida-tion state in the course of the reaction and its concomitant effect on the product selec-tivity remain controversial. To study this effect, we used DC magnetron sputtering to pre-pare low roughness Cu2O thin films (TFs) with a controlledoxide thickness of 100 nm, and

used these as electrocatalysts for the reduction of CO2 [5].The TFs were characterized prior to and after chronoam-perometric (CA) CO2-reduction at−1.0Vvs.thereversiblehy-drogen electrode (RHE) using X-ray photoelectron spectros-copy(XPS)andAr-sputtering.Chiefly, sample re-oxidationupon disassembly of the elec-

trochemical cell and/or trans-fertotheXPSwereavoidedbyperforming the electrochemi-cal measurements in a N2-filled glovebox and transfer-ring the sample in an air-tight chamber, respectively. As il-lustrated in Figure 2, this re-sulted in clear changes in the Cu-2p and -LMM spectra spe-cifically.Whereasintheformer

Figure 2:

Cu-2p and -LMM spectra (left vs. right) of 100 nm thick Cu2O thin film elec-trodes before and after 30 minutes of chrono-amperometry (CA) at –1.0 V vs. RHE in CO2-sat-urated 0.05 M Cs2CO3.

Figure 1:

TEM (a) and high resolution (HR) TEM (b) micrographs of Ni0.9Fe0.1Oy catalysts. Normalized XANES spec-tra (c) and Fourier trans-formed Ni EXAFS spectra(d) recorded in operando for Ni1–xFexOy over a range of applied potentials. All Ni X(k) functions were Fourier transformed over a k-range of 2.6–12.5 Å. Reproduced from Reference[2] withpermission from The Royal Society of Chemistry. Cor-relation between OER ac-tivity, conductivity, amount of oxygen vacancies, and flat-band potential forLaMO3–δ, La0.8Sr0.2CoO3–δ and, BSCF electrode pro-cessed with acetiylene black carbon (BSCF/ABf) (e). Reproduced from Ref-erence[4]withpermissionfrom The American Chemi-cal Society.

57

Figure 3:

Schematic of the novel cell configurationusedforCO2RR from gas phase.

References

[1]E.Fabbri,A.Ha-bereder, K. Waltar, R. Kotz, T.J. Schmidt, Catal. Sci. Technol., 4, 3800–3821 (2014).

[2]D.F.Abbott,E.Fab-bri, M. Borlaf, F. Bozza, R. Schäublin, M. Nachtegaal, T. Graule, T.J. Schmidt, J. Mater. Chem. A, 6, 24534–24549 (2018).

[3] J.Herranz,J.Durst,E.Fabbri,A.Pătru,X.Cheng,A.A.Permyakova,T.J. Schmidt, Nano Energy, 29, 4–29 (2016).

[4]X.Cheng,E.Fabbri,Y.Yamashita,I.E.Castelli,B. Kim, M. Uchida, R. Hau-mont, I. Puente-Orench, T.J. Schmidt, ACS Catalysis, 8, 9567–9578 (2018).

[5]A.A.Permyakova,J.Her-ranz, M. El Kazzi, M. Povia, M.Horsiberger,A.Pătru,T.J. Schmidt, submitted (2018).

[6]A.Pătru,T.Binninger,B. Pribyl, T.J. Schmidt, J. Electrochem. Soc., 166 (2) F34–F43 (2019).

[7]A.Pătru,T.Binninger,B. Pribyl, T.J. Schmidt, EP17182823.

[8]T.Binninger,B.Pribyl,A.Pătru,P.Rüttimann,S.Bjelić,T.J.Schmidt,J. Mass Spectrom., 53, 1214–1221 (2018).


nosignificantdifferenceswereobserved when the post-CA samples were transferred in air or N2 (see blue v. green lines, respectively), likely due to the identical Cu-2p spectra exhibit-ed by Cu0 and Cu2O, the Auger spectra were much more sen-sitive to the transfer means. Moreover, the excellent agree-ment between the spectrum of the N2-transferred sample and reports for Cu0 confirmedthe complete reduction of the TF upon CO2-electroreduction, probing that Cu0 is the active species causing the enhanced alcohol selectivity of (reduced) copperoxides[5].

While such co-electrolysis studies in liquid electrolytes are of great fundamental in-terest, the process is limited by the low solubility of CO2 in aqueous solutions, resulting in CO2 transport-limited current densities of 30 mA/cm2. In or-der to scale the process up to larger scales, direct use of CO2

from gas phase in a polymer electrolyte membrane cell con-figurationcanbeused.While,generally, an alkaline environ-ment promotes the CO2 reduc-tion reaction (CO2RR) at the cathode, a secondary effect in such a system is the transport of carbonate and bicarbonate towards the anode side, where they form CO2 via oxidation. Because of this, for each CO2 molecule reduced at the cath-

ode, one or two CO2 molecules are formed at the anode, con-tributingtoalossinefficiencyof the overall system. To solve this issue, while maintaining high selectivity for CO2RR, we recently started working on a system using a bipolar-like membrane assembly [6,7].However, unlike a bipolar membrane system, our system does not contain two rigid and connected ionomer layers of similar thicknesses, but rather itcontainsa thinfilmalkalineionomer layer, which is sprayed onto the cathode catalyst layer and Nafion® XL membraneseparating the cathode from the anode side (see Figure 3). By employing only a thin alka-lineionomerfilm,theCO2 and

H2O molecules formed at the interface of the two layers can more easily diffuse towards the cathode and participate in thereactionsoncemore.[6]

Our preliminary results us-ing Au black as the cathode catalyst show that this novel configuration successfullysuppressed the formation of CO2 on the anode side, while maintaining similar Faradaic efficiencyasthealkalineelec-trolyte system. In order to be able to detect the produced gases online during the tests, we developed a new versatile multivariate calibration meth-od for mass spectrometers, which was employed during ourexperiments.[8]

Work Package «Assessment of Storage Systems» at a Glance

The assessment of energy storage is applied at three nested levels: technology, energy system, and socio-eco-nomic impact. It is furthermore supported by a holistic assessment of demonstrators. Feedback for other work packages (WPs) of the SCCER HaE, for different SCCERs, and towards industry, society & politics is the main goal. The approaches of the work package «Assessment – Interactions of Storage Systems» include a combined methodology for life cycle analysis (LCA) and techno-economic analysis, while new pathways for socio-economic assessment are meant to aid understanding the broader societal impact. The challenges and risks of succeed-ing in this work package have previously been identified mainly in the direction of data acquisition and data uncertainty. When employing scenarios and assumptions, which is inevitable for providing an assessment of energy systems (containing storage technologies) to an unknown future of 2035 and 2050 (a horizon the federal «Energy Strategy» is aiming at), sensitivities of capacities, efficiencies, and prices have a strong impact on the results. Therefore, in cooperation with SCCER «Joint Activity Scenarios and Modelling» (JASM) we push forward to have a homogenized setting of scenarios, share data on load profiles and technology descriptions as well as having a common agreement on data sources.

Choices of scenarios and system boundaries for heat (tech-nology) modelling turned out to be rather complex and dif-ficult to deal with in comparison to electricitymodelling,whereas the time dependency and resolution poses lesser constraints, due to the very high inertia of building masses and thermal systems in general. This opens new modes of sectoral coupling between electricity, heating and cooling, giving thermal storage technologies a massive potential for compensating for intermittent renewable (electrical) energy production from any source. In order to meet the challenges on the technological level, the theoretical assessments are based and validated on demonstrator systems for energy storage and expertise developed in this and other SCCERs, namely the power to gas plant HEPP, the AACAES demon-strator of WP 1, but also in battery research. The groups working on the technologydirectly benefit from theoreti-cal assessment since the relevant boundary conditions for the systems and systemic research questions are provided. Therefore, the team is strongly interlinked with the Joint ActivitiesCEDA,JASMandtheWhitePaperPowertoX.

The assessment of batteries was a major focal point in this reporting period and assessed on all three nested levels:

• On the technology level, a comparison of carbon and life-cycle costs of storing electricity in battery systems for various regions was made. It turned out that the envi-ronmental characteristic of electricity generation (to be stored) is primarily influencing the result. The type ofbattery system is less important with the exception of leadacidandvanadiumredoxflowbatterieswhicharemost problematic in this sense. The study on material criticality indicated that lead acid batteries are especially problematic as well due to Zinc, Lead and Iron. All batter-ies containing Co also have an issue with regard to metal

criticality. Additionally, the economic & environmental as-sessment of Lithium-Ion vs. Sodium-Ion cells came to the conclusion that at the current state of development the Sodium system lacks behind the state of the art Lithium system in terms of cost and environmental impact due to their still significantdifference inenergydensityat thecurrent state. These assessments were done in close col-laboration with the battery work package team, which is implementing the results in their future research strat-egy.

• Onenergysystemlevel,thelong-termevaluationofflex-ibility options for the Swiss energy system was evalu-ated with the Swiss TIMES energy model by PSI and it was found that under continuation of the current policy mainly pump storage and low voltage battery are needed in 2050. In case of a policy to meet the Swiss climate targets in the Paris Agreements, the additional capacity includes also medium and high voltage batteries. At the local energy system level, an additional model has been already developed by UniGeneva to optimize a battery schedule in 24 h framework, assuming perfect day-ahead forecast of the electricity demand load and solar PV gen-eration. The objective function is to minimize the elec-tricity bill including energy and power components. The model considers as well four consumer applications (PV self-consumption, avoidance of PV curtailment, demand load-shifting and demand peak shaving), different tech-nologies and locations.

• At the socioeconomic level, the inter-sectoral learning in value chains for lithium-ion batteries was assessed in order to inform innovation policy makers on useful next steps. It was found, based on expert interviews and pat-ent search that a focus should be set on facilitating trans-

Illu

stra

tion:

AF-

Stu

dio

/ iS

tock

AssessmentInteractions of Storage Systems

fer of tacit knowledge between chemical sector, cell man-ufacturers and users. At the same level, the questions on how the battery industry responded to the emergence of new markets, and what is opportunity for latecomers in the lithium-ion battery industry, could be addressed. Based on publication- and patent-analysis, as well as by expert interviews it was found that industry responded by branching the chain of innovations following the new direction, while the former line of development still pro-gressed.

In the area of demonstrators two new units can be re-ported. For the power to gas system (HEPP) at HSR, the majorityof2018’sworkwasthespecificationandprocure-ment of plant components which lead to completion and the formal start of operation was in October 2018. The specialty of this system lies in the reactor scheme which allows for regeneration operation of the catalyst (developed in the large consortium of the Pentagon and Store to go (both EU projects) with partners from ZHAW) and the installation of a high temperature, solid oxide electrolyser, also devel-oped in the consortium. The second demonstrator, formally put into operation, is the small scale demonstrator at Sion. This demonstrator represents a combination of PV system with battery storage (different types) and hydrogen as a long term storage option, scaled to the needs of a single family home. The SCCER teams look forward to the insights the new demonstrators will give. On the level of existing demonstrators, progress was made at the Energy System Integration Platform (ESI) it was possible to demonstrate the combined operation of electrolyser, methanation and fuel cellalongadaypowerprofile,proving thedynamicsand readiness. The COSYMA direct methanation passed1’000 hours of operation at an industrial site (SCCER Biosweet). At the grid to mobility demonstrator an analysis

of conversion losses in grid to mobility pathways was done and design and sizing recommendations based on renew-ableprofileswerederived.Itwasinvestigatedhowstation-ary storage systems for local businesses can be optimized.

The contribution of SCCER HaE in the Joint Activities (JA)in this reporting period was the model implementation of a new methodology for estimating building energy demand in the residential sector for heating and cooling, used in JA Simulation and Modelling (JASM). Going along the same line, in the collaboration with CEDA the residential heating loadprofilesfromheatingdayswereelaborated.FinallytheJAWhitePaperPowertogaswasputforwardsignificantlyby support of the assessment team and it is close to com-pletion by now. In terms of collaborations, the application for an joint project (SwissStore) with groups from CREST was successful. This project started at end of 2017 and investigates the role of competing and/or complementary electric, thermal and chemical energy storage technologies for Switzerland and runs till October 2021.

In summary, the interlinkage between this and the other WPshasstrengthenedsignificantly.Thisresultsinfeedbackloops into the research strategies of the technical WPs in particularofWPs1and2basedonrecentfindings.Regard-ing the full roadmap, the overall picture of the assessment is supported on the one hand by working through groups of storage technology assessments (high power electricity storage options in 2016, batteries in 2018, thermal storag-es 2019) and planning to publish those on a Web Platform. On the other hand by the intense work on adding storages into new and existing energy system models like Swiss-Times and Energy System Models from CREST and fur-thermore supplying the models and data within the JASM framework.

60 Assessment

Investigation of AA-CAES Plant Configurations and Grid Integration

Scope of project

In Phase I of this project, the focus was primarily on technical aspects, culminating in experiments withtheworld’sfirstAA-CAESpilot-scaleplant,constructedandoperatedbyALACAESwithsupportfrom the SFOE, SNF, and CTI in an unused tunnel near Pollegio, Switzerland. The plant was charac-terized by an unlined rock cavern and experiments were carried out with both sensible and combined sensible/latentthermal-energystorage(TES)units,attainingplantefficienciesof63–74%[1,2].

In Phase II, the focus has shifted to the analysis of AA-CAES plants on three levels: • the plant layout, its siting, and costs, • the plant performance in the electricity grid, and • detailed plant simulations and life-cycle analyses. TheoverarchinggoalofPhaseIIistodeterminewhetheranAA-CAESplantcanbeoperatedprofit-ably in Switzerland’s future energy system.


to consist of a high-pressure and a low-pressure turbine. The main motivation for these changes was to be able to use existing turbomachinery by MAN Energy Solutions AG. Re-using existing turbomachinery is the only feasible way for-ward because the market for AA-CAES plants is unlikely to ever be large enough to justify the very costly development of turbomachinery that can oper-ate at both high temperatures and high pressures. Using two turbines in turn meant that it was natural to incorporate two thermal-energy storage (TES) units and two caverns. Simula-tions of the SCCER plant layout will be shown below.

Regarding the siting of an AA-CAES plant in Switzerland, our original objective was to reuse decommissioned military cav-erns. The rationale was that depending on the volumes of military caverns, the cost of excavating a cavern could be at least reduced and perhaps even entirely eliminated. How-ever, the investigation of a list of decommissioned military caverns provided by Arma-suisse showed that none were

large enough for our target cavern volume of 170’000 m3. Most of them were so small that the cost savings were not significant compared to thetotal plant capital costs [3].Furthermore, several disad-vantages of reusing unused military caverns became ap-parent. • First, the caverns do not

have the required overbur-den of about 1000 m to con-tain the maximum cavern pressures of about 100 bar.

• Second, the caverns typi-cally have multiple entranc-es and exits, all of which represent potential paths for air leakages.

• Third, the caverns are typi-cally highly branched, lead-ing to large surface-to-volume ratios, which would increase heat losses from the air to the surrounding rock.

• Fourth, the cross-section of most of the caverns is horseshoe-shaped, which may lead to stress concen-trations and consequent fracturing and air leaks.

• Finally, few caverns were lo-cated in regions with high-quality rock (such as in

Authors

P. Roos1 J. Roncolato2 F. Contestabile2 S. Zavattoni2 M. Barbato2 J. Garrison1 A. Fuchs1 T. Demiray1 C. Bauer3 W. Schenler3 P. Burgherr3 A. Haselbacher1 G. Zanganeh4 P. Jenny5 M. Scholtysik5 E. Jacquemoud5 F. Amberg6 F. Pacher6 J. Mühlethaler7 M. Arnal8

1 ETHZ2 SUPSI3 PSI4 ALACAES SA5 MAN Energy Solutions AG 6 Amberg Engineering 7 Swissgrid 8 BKW



CAES Compressed Air Energy Storage

LCA Life Cycle Assess-ment


During the first two years ofPhase II, the modelling frame-work for the three levels and the interfaces between the levelsweredefinedandimple-mented.More specifically, theAA-CAES plant model has been improved by adding more ac-curate component represen-tations including transient effects. The grid model was used to assess the impact of AA-CAES plants of different power and capacity ratings on the Swiss electricity market in one specific location andshowed that there was a ben-efitofadding thisstorageca-pacity to the grid. This report gives a brief overview of the current state of our efforts and describes future work.

Level 1: Plant layout, siting, and costs

Compared to earlier studies of an AA-CAES plant in the SNF NRP 70 project, the plant lay-out considered in the SCCER project was adapted in two respects: The maximum tem-peratures were lowered from about 600 °C to 320 °C and the expansion train was extended

61 Assessment

the Aare massif), and they would therefore likely have required costly measures to render them airtight.

For these reasons, the plant- siting study has shifted at-tention to excavating entirely new caverns, which gave us theflexibilitytopickplantsitespurely on the rock quality and the vicinity to nodes in the Swiss electricity grid. Based on these considerations and results from previous simula-tions with the grid model de-scribed in the next section, our current investigations assume that the AA-CAES plant is lo-cated in the vicinity of the grid node near Bitsch in the canton of Valais.

With the information on the plant layout and siting, it is possible to construct simple models for the capital costs [3]. Our model includes, forexample, the costs of the cav-ern, the turbomachinery, the TES units, the electrical equip-

ment, and the transmission line to the nearest grid node.

Level 2: Plant performance in the Swiss electricity grid

The objective of the simula-tions with the coupled grid-plant model is to evaluate the profitability of severalplant power and capacity rat-ings for various use cases. The evaluation is based on a simple AA-CAES plant model that assumes a constant plant efficiencycoupledwithamod-el of the Swiss electricity grid [4]. Over the past year, thecoupled plant-grid model was extended in two ways. First, the fidelity of the grid modelwas improved. It now includes the full 2025 AC grid model of Swissgrid as well as an aggre-gated model of the neighbor-ing countries, see Figure 1, in which Bitsch is indicated by a blue circle. Load demand, generator costs, and produc-

tion availability were projected from historical data to match the 2025 model (collaboration with the SNF NRP 70 project AFEM). The second extension is that the evaluation now makes use of the abovementioned cost estimates, thereby allow-ingtheprofitstobeestimatedfor various use cases.

To evaluate the use case of electricity price arbitrage, an


Figure 1:

Grid model including the 2025 AC grid model of Swissgrid as well as an aggregated model of the neighboring countries. Bitsch is indicated by a blue circle.

Figure 2:

Estimated annual revenues of AA-CAES plants minus the costs for the use case of arbitrage only.

62 Assessment

Figure 3:

Schematic plant layouts that have been simulated with the detailed plant model.

Figure 4:

Load profiles over oneweek used to simulate ir-regular cycles with the second plant layout shown in Figure 3. Positive/nega-tive loads correspond to charging/discharging of the plant.


optimal power-flow model[5,6] was used to quantifyand compare the annual elec-tricity costs with and with-out the AA-CAES plant with a time-coupled 48-hour rolling horizon optimal dispatch. For simplicity, we assumed a plant efficiencyof70%andthattheplant construction costs were annualized over 50 years for the turbomachinery and 100 years for the cavern.

The results presented in Fig-ure 2 indicate clearly that arbi-tragealone isnotaprofitableuse case irrespective of the power and capacity ratings. Therefore, additional use cas-

es, e.g., reserve markets and other flexibility services, willbe considered in future work. Furthermore, the plant model will be extended to better re-flect the unsteady plant op-eration by including the power consumption and the reduced efficienciesduringthestart-upand shut-down transients.

Level 3: Detailed plant simula-tions and coupled LCA assessment

The coupled plant-grid simu-lations in Level 2 rely on as-sumed plant efficiencies. Pro-viding realistic values of these

efficiencies for specific plantconfigurationsisoneobjectiveof the detailed plant simula-tions carried out in Level 3. The detailed model, imple-mented in Matlab-Simscape, now contains submodels for the unsteady operation of the turbomachinery, the temporal evolution of the pressure and temperature in the caverns, the behavior of the TES units, and allows for temperature-dependent air properties. The TES units are modelled using a previously developed heat-transfer model that accounts for the time-dependent tem-peratureprofilesinthestoragematerials as well as the struc-turalandinsulationlayers[7].

The detailed model has been validated with data from the Huntorf CAES plant and the Pollegio AA-CAES pilot plant. The detailed simulations are performed with operational schedules that correspond to eitherregularcycleswithfixedcharging and discharging du-rations or to irregular cycles representing the anticipated operation in the electricity grid.

The detailed plant model was used to analyse the two plant

63 Assessment

Figure 5:

Plant efficiencies obtainedfrom simulations of the second plant configura-tion with the detailed plant model.

References

[1] L.Geissbühler,V.Be-cattini, G. Zanganeh, S. Zavattoni, M. Barbato, A. Haselbacher, A. Stein-feld, J. Energy Storage, 17, 129–139 (2018).

[2]V.Becattini,L.Geissbüh-ler, G. Zanganeh, A. Hasel-bacher, A. Steinfeld, J. En-ergy Storage, 17, 140–152 (2018).

[3]T.Motmans,Masterthesis, ETH (2017).

[4]SwissCompetenceCen-ter for Energy Research – Heat and Electricity Storage, Annual Report 2017 (2017).

[5]A.Fuchs,T.Demiray,IEEE Eindhoven PowerTech, 1–6 (2015).

[6]D.Kourounis,A.Fuchs,O. Schenk, IEEE Trans. Pow-er Systems, 33, 4005–4014 (2018).

[7] L.Geissbühler,M.Kol-man, G. Zanganeh, A. Hasel-bacher, A. Steinfeld, Appl. Thermal Eng., 101, 657–668 (2016).


layouts depicted in Figure 3 for regular cycles. Both plants contain low- and high-pressure compressors and two caverns. As indicated in the figure,the low-pressure compres-sor takes ambient air to about 33 bar and the high-pressure compressor charges the cav-ern up to 100 bar. The main difference between the two plantsisthatthefirsthasonlyone TES located in the low-pressure cavern and one tur-bine, whereas the second has two TES and high- and low-pressure turbines.

The simulations indicated that the first layout suffers froma lack of operational flex-

ibility arising from the pres-sure equilibration of the two caverns prior to discharging. The equilibration introduces a time scale that may prevent the plant from being able to react to power demands. The second plant layout does not require pressure equilibra-tion and hence does not suf-fer from a lack of operational flexibility. We have thereforeinvestigated this layout also for the irregular charging-dis-charging cycles covering one week of operation depicted in Figure 4. The daily and weekly plantefficienciesareplottedinFigure5, confirming that theplant efficiency of 70% usedin the plant-grid simulations

in Level 2 can be regarded as realistic.

We have since progressed to the analysis of a third plant layout that is similar to the second but for which both the low- and high-pressure compressor have pressure ra-tios of 10, allowing the use of existing turbomachinery by MAN Energy Solutions AG as well as realistic compressor performance data.

The plan for the coming year is to use the detailed plant simu-lations of this third plant lay-outtodeviseasimplifiedplantmodel for the plant-grid simu-lations in Level 2.

64 Assessment

Calculation of Heat Demand for the Assessment of Storage Potential on System Level

Scope of project

The assessment of energy storage within WP 5 of the SCCER HaE employs a nested-level approach, where storage is studied on the level of technologies, on level of the system, and on level of the socio-economic impact. To understand the potential of energy storage on the system level, Univer-sity of Basel, University of Geneva and the Lucerne University of Applied Sciences and Arts teamed up in the SNF research project SwissStore. One of HSLU’s tasks, which is a joined deliverable with SCCER, includes the development of demand curves for space heating (residential, commercial and industry sectors). Those load curves are later on used in a social planner model, which basically fol-lows the standard approach of large scale energy system models.


tion would be sectoral coupling with the (residential and com-mercial) space heating sector, asdecribedin.[1]Ahighshareof non-renewable heat genera-tion for space heating could be adapted towards low or zero carbon emissions. This would be a major move towards the fulfilmentoftheratifiedKyototargets for Switzerland. Anoth-er opportunity is given by the usage of thermal energy stor-ageasaflexiblesinkforelec-tricity generation regulation. Three independent storages canbeidentifiedinahouse:• its thermal mass and iner-

tia, • the storage for domestic hot

water at 65–70 °C and • a new storage for space

heating.

Coming back to Figure 1, the SNF project SwissStore re-quires load curves for heat de-mand.Thedifficultyislocatedat the unavailability of true data about the energy end use for space heating, the demand.

What is given is data about the consumption of all kind of energy carriers (fuel oil, natu-ral gas, wood pellets etc.) for heating. The Swiss Federal OfficeforEnergyhasasounddatabase on those. Data from Prognos would suggest a one-to-one translation from fuel consumption to energy end use, which in many cases is not realistic: Considering e.g. a given case of a single-family house, with given insulation and therefore given seasonal

As described in Figure 1, the key features of electricity modelling are a spatial aggre-gation (only differentiating on the grid level) and a very high temporal resolution of the di-urnal electricity demand curve.

Electricity grids have little in-ertia or intrinsic storage ca-pacity, consequently the gen-eration of electricity has to match the consumption ex-actly. More intermittent elec-tricity sources from wind and solar power would make this endeavour more challenging. Energy storage technologies are one strategy to deal with this problem, sectoral coupling between electricity and e.g. mobility another. For Switzer-land, a promising combina-



CAES Compressed Air Energy Storage



Authors

Matthias Berger1

Stefan Frehner1

Marco Meier1

Jörg Worlitschek1

1 Lucerne University of Applied Sciences & Arts

Figure 1:

Top-down vs. bottom-up modelling of heat demand in conjunction with bot-tom-up electricity models for integrated energy sys-temmodels.Source:[1].

65 Assessment

heat losses, and finally givendemand of heat to compensate these losses per day.

There are many technologi-cal options for realizing the heat production, for instance an air-water heat pump feed-inga35°Cunderfloorheating,compared to a state-of-the-art condensing boiler supplying ra-diators at 70 °C. While the con-densing boiler is usually oper-ated in direct response to the occupancy and daytime (night setback, peaks in morning, evening and during weekend hours), an underfloor heatinghas a large time constant, it would most of the time make sense to run on constant level.

As it is clearly visible with this example, a given heat de-mand is not per se resulting to an universal demand curve. The scientific answer in [2]is hence based on a different methodology: the combination of maps of the distribution of population and climate, both in high spatial resolution and for the climate, in daily mean temperature levels. For model-ling and simulation, this means the solver has the freedom to pick a technology and deliver the heat for the day at any time; the thermal mass of the building and assuming the in-creased proliferation of under-floorheatingarethejustifica-tion.

When looking into distant fu-ture of 2035, 2050 or 2099, the big question is how climate change would potentially al-ter our heating (and cooling)

demand in Switzerland in the long run. For a historic bench-mark period of 1981 to 2017, a trendofwarmingandtheinflu-ence on heating demand has been proven with data from MeteoSwiss in Reference[3].Figure 2 and Figure 3 are giv-ing an idea of the spatial distri-bution and the deviation from average for Switzerland. For the future perspective, we ob-tained data from MeteoSwiss and C2SM for the CH2018 climate scenarios for Switzer-land.

Calculation of Heat Demand for the Assessment of Storage Potential on System Level

References

[1]M.Berger,«Heat-ing and cooling future of Europe and interactions with electricity», IEEE - European Public Policy Committee, 2018.

[2]M.Berger,J.Wor-litschek, Energy, 159, 294–301, 2018.

[3]M.Berger,J.Wor-litschek, «Feedback between anthropogenic factors and climate: energy consumption for space heating», 17th An-nual CMAS Conference, Chapel Hill, NC, USA.

Figure 2:

Map of the relative difference in heat-ing degree days between 2015, the warmest year be-tween 1981–2017, and the norm period 1981–2010. Source: [3].

Figure 3:

Map of the relative difference in heat-ing degree days between 1984, the coldest year be-tween 1981–2017, and the norm pe-riod 1981–2010. Source:[3].

66 Assessment

Assessment of Energy Storage at the Technology and Energy System Level

Scope of project

On the technological scale, the University of Geneva (UNIGE) examines which electricity storage technologiescansupportPVandwindtechnologiestomeetvarioustypeofdemandprofiles(e.g,peak and base load) depending on the scale of deployment, namely residential, utility and bulk, as well as how they compare with traditional power generators on a levelised cost basis. UNIGE also collaborates with PSI-LEA, ETHZ and HSLU in the assessment of storage technologies for different applications, e.g., batteries and thermal storage.

ThemainobjectiveontheenergysystemlevelistodefinetheroleandtherequirementsofenergystoragewithindefinedenergysystemscompliantwiththeSwissEnergyStrategy2050.Tothisend,we model energy systems and the value proposition of energy storage for those systems at high temporalresolution(≤1hour).• At the local scale, UNIGE is, so far, focusing on individual dwellings and analysing PV-coupled bat-

tery systems and PV-coupled heat pump systems, including both thermal and electric storage and performing various applications from the consumer perspective (i.e. reducing the electricity bill). Wethenanalysetrade-offsbetweenconsumersbenefitsandelectricitygridimpacts.

• At the national scale, we have built a dedicated optimisation model of the Swiss power sector includingneighbourswithatemporalresolutionof1hour.Finally,inordertogetdataanddefinescenarios, we are collaborating with utilities and other SCCERs (including joint SCCER activity on modelling and scenarios).


• during generation hours, re-ferred to as «Generation»;

• during the maximum two peak period, referred to as «Bi-peak»;

• during generation and peak hours, referred to as «Gen-eration and peak»,

• during time-of-day hours, referred as «Time-of-day»;

• during 24 hours, referred to as «Baseload«.

We develop a model with a temporal resolution of 10 min-utes and run it on a daily ba-sis to calculate the required size and schedule of the stor-age technology as well as the levelised cost of the hybrid system (LCOHS). This subse-quently allows us to discuss the most optimal hybrid sys-tems and compare them with conventional power generation technologies. Furthermore, we determine the sensitivity of the LCOHS to the size of the storage system in both power

and energy terms. Finally, we also examine the competitive-ness of these hybrid systems vis-à-vis conventional electric-ity generators based on future cost reduction trajectories of renewable energy and storage technologies.

Wefindthattheoptimalchoicefor energy storage technology in a hybrid system depends on the scale rather than the supply mode or the renewable energy technology. Our results show that Li-ion batteries prove to be the most optimal storage option at the residential scale (0.58 to 1.22 EUR/ kWh with PV), I-CAES at the utility scale (0.23 to 0.50 EUR/kWh with PV) and PHS at the bulk scale (0.10 to 0.13 EUR/kWh with PV), irrespective of the type of supply mode or renewable generation supply (the rang-es in brackets represent the impact of the type of supply mode on the LCOHS).

Authors

M. Soini1 A. Pena-Bello1

R. Gupta1

M.K. Patel1D. Parra1

1 University of Geneva


AA-CAES Advanced Adia-batic- Compressed Air Energy Storage

ALA Advanced-Lead Bat-tery

I-CAES Isothermal-Com-pressed Air Energy Storage

LCOHS Levelised Cost of Hybrid Systems

LFP Lithium Iron Phos-phate

Li-ion Lithium-ion

LTO Lithium Titanium Oxide

NCA Lithium Nickel Co-balt Aluminum Oxide

NGCC Natural Gas Com-bined Cycle

NMC Lithium Nickel Man-ganese Cobalt Oxide

P2M2P Power to Methane to Power

Pb-Acid Lead Acid

PHS Pumped Hydro Stor-age

PV Solar Photovoltaics

UNIGE University of Geneva

VRE Variable Renewable Energy

VRLA Traditional Valve Regulated Lead-Acid

ToD Time of Day

Research outputs on technological level

Energy Storage can play an enabling role to tackle the problem of intermittency as-sociated with solar and wind generation. However, the tech-no-economic performance of these hybrid systems depends on a large number of param-eters, including wind and so-lar production profiles, thewidely varying performance along the two dimensions of energy and power costs, as well as type of electric-itydemandprofile tobemet. In our study, we assess the operation of hybrid systems including renewable and stor-age technologies supplying constant electricity to various types of electricity demand profiles at different scales,namely, residential, utility and bulk across Switzerland. In particular,wedefined5differ-ent supply modes:

67 Assessment

mayinfluencethechoiceoftheoptimal battery technology, re-main unclear.

We develop an optimization framework to determine the best-suited battery technol-ogy and size depending on the applications combined, includ-ing PV self-consumption, de-mand load-shifting, demand peak shaving and avoidance of PV curtailment. Moreover, we evaluate the impact of the annual demand and electricity prices by applying our method to some representative dwell-ings in Switzerland and the U.S. in collaboration with the Massachusetts Institute of Technology (MIT). Finally we determine the break-even point for all battery technolo-gies and compare the results when only PV self-consump-tion is included and when all applications are combined (see Figure 2). We conclude that residential batteries may reach profitability (without subsi-dies) in both countries in the next decade if all applications are combined according to the expected cost reduction trajec-tories for battery technologies.

Given the PV potential to si-multaneously decarbonize other sectors such as heating and cooling, a second ongo-


The comparison with conven-tional technologies in Figure 1 shows, that further cost re-duction in renewable energy and storage technologies is needed for hybrid systems to supply electricity on demand at competitive cost. Sensitivity analysis shows that reduction in cost of both renewables and storage technologies as well as the energy storage size by al-lowing some distortion in the required supply strategy hold a key towards future cost-competitive of hybrid systems.

Research outputs energy system related

Local scale

UNIGE focuses on individual dwellings with solar photo-voltaics (PV) and residential battery storage given the in-creasing penetration of PV in the built environment and the growing interest in energy storage systems located very closely to consumers.

Since residential batteries are not economically viable yet, combining applications has been suggested as a way to increase their attractiveness, but the extent to which this can be achieved, as well as how the different applications

Figure 1:

LCOHS for all combinations of solar, wind and combi-nation of solar and wind hybrid systems at the bulk scale and their comparison with the generation costs of conventional technolo-gies (National Level). Nu-clear (EP) represents the Nuclear (Existing Plants) in Switzerland and Nuclear (NP) represents Nuclear (New Plants) outside Swit-zerland (New Gen III/III+ reactors as primarily built in Asia (China, South Ko-rea) today). Generation costs of new nuclear plants are not applicable in the Swiss case since the con-struction of new nuclear power plants in Switzer-land is no longer allowed after the agreement on the energy strategy 2050 (May 25, 2017) (values of generation costs of con-ventional technologies are taken from PSI, 2017).

ing study in collaboration with HSLU focuses on PV-coupled heat pump systems deliver-ing cooling, heating and hot water on individual dwellings, including residential storage, both thermal and electric. These systems can be used to increase PV self-consump-tion, but also to simultane-ously provide other residen-tial applications (i.e., demand load-shifting, avoidance of PV curtailment and demand peak-shaving), ultimately helping to reach economic viability.

We focus on different Swiss dwellings in terms of electricity and heat demand, with roof-top PV generators and com-pare which type of storage, namely electric and thermal, offers more benefits for theconsumer and the electricity grid. In particular, we discuss trade-offsbetweenbenefitsforconsumers (e.g., bill minimiza-tion) and grid impacts (e.g., maximum grid relief) depend-ing on the type of consumer, building characteristics and technologies. Additionally, we analyse the differences be-tweenfloorheatingandtradi-tional radiators.

Our methodology includes an open-source mixed-integer linear programming optimisa-

68 Assessment

tion to solve the residential energy management problem. It minimises the cost of the daily electricity bill as a func-tion of the electricity and heat demand, PV generation, bat-tery, heat pump and water tank characteristics as well as various types of storage ap-plications and their combina-tions. The storage schedule is optimised with a temporal resolution of 15 minutes on a daily basis and we assume perfect day-ahead forecast of the electricity demand and PV generation to determine the maximum economic potential of batteries regardless of the forecast strategy used.

National scale

A national-scale dispatch model was developed to an-

swer questions centred on the role of bulk electric storage in Switzerland and its neighbour-ing countries. This model opti-mises the power production for each hour of the year. Stylised power plants are represented by linear cost supply curves. This allows to approximate power plant fleets comprisingunits with varying efficiencyand therefore varying specificcosts of power production. The model is calibrated with respect to the electricity price profiles and the power pro-duction in the reference year 2015.Within each of the fivecountries, transmission con-straints are neglected. Cross-border power exchange is sub-ject to optimization within a certain capacity range.

In a first step, this model isused to assess the impact of large volumes of electric stor-age on the replacement of con-ventional dispatchable capac-ity. This is done by optimising the power system for future scenarios with high solar and wind power production. The cases with and without addi-tional storage capacity are ana-lysed separately. This allows to determine the relative impact of bulk storage on the opera-tion and retirement of conven-tional power plants. Since this study relies on an optimisation

framework, it represents the situation in a free market set-ting with rational power plant retirement decisions.

This study thus answers the question to what extent elec-tric storage counteracts or amplifies the replacement ofconventional power plants due to rising variable renewable electricity (VRE) generation. It is found that this strongly depends on both the level of VRE production and the tech-nical properties of the storage. In the most general case, ad-ditional storage capacity in-creases dispatchable power production (e.g. nuclear, coal) for small VRE shares. This is due to charging from these sources for both the replace-ment of more expensive gen-erators and the optimization of capacity utilization. For larger VRE shares storage decreases the produced amount of dis-patchable power, for example due to charging from otherwise curtailed energy. This general pattern strongly depends on the technical storage param-eters. For certain VRE shares long-term storage with low round-trip efficiency causesgreater production from nu-clear power plants, while the opposite holds for battery-type storage with higher efficiency(see Figure 3).


Figure 3:

Impact of bulk storage on the production of nuclear power in high-VRE sce-narios. The storage power share is expressed as a fraction of average electric-ity demand.

Figure 2:

Break-even point of a 7 kWh battery for all bat-tery technologies depend-ing on the type of com-bination of applications, PV self-consumption only (blue), the full combina-tion of applications (green) and for comparison, the in-stalled cost per kWh used in this study (red), for the U.S. (right) and Switzer-land (left). The size of the PV system corresponds to the median installed ca-pacity across both loca-tions.

69 Assessment

Technology Assessment of Energy Storage

Scope of project

Activities of PSI’s LEA team (Laboratory for Energy Systems Analysis) within WP 5 of the SCCER Heat and Electricity Storage in 2018 focused on the environmental and techno-economic assessment of batteries, both on the technology as well as on the energy system level. Alternative energy storage technologies such as power-to-gas options were mainly investigated in the context of increasing the (seasonal)flexibilityoftheSwissenergysystem.


and application specific costsand life cycle inventories – shows that, for a base case as-sumption of social costs of car-bon emissions of 70 €/ tonCO2, the GHG emission related costs are much lower than the direct technology costs (Fig-ure1).[2]

Hence,ouranalysisfinds that– other than in alternative low-carbon passenger vehicles – there seem to be only very few cases with major trade-offs along the two dimensions of GHG emissions costs and life cycle costs (LCC). The fact that

we do not find major trade-offs between the LCC and life cycle emissions (LCE) of differ-ent technologies implies that even in the absence of a car-bon price, choosing a battery technology purely based on LCC will also pick the socially optimal technology. This can inform the debate on the de-sign of battery-support policy, which – based on our results – does not have to differentiate between technologies.

Addressing potential future battery technologies, our economic and environmental

Authors

Christian Bauer1 XiaojinZhang1

Simon Schneider1

Evangelos Panos1

Laurent Vandepaer1, 2

T. Kober1

K. Ramachandran1

Tom Terlow1, 3

1 University of Geneva2 Sherbrooke University,

Canada3 Utrecht University,

Netherlands


GHG Greenhouse Gas


LCC Life Cycle Costs

LCE Life Cycle Emis-sions

On the technology level, we established a comprehensive basis for the environmental as-sessment of indirect («conse-quential») impacts of electric-ity storage within the energy system by integrating new and updated long-term marginal electricity mixes into the eco-invent life cycle assessment (LCA)database.[1]

Together with ETHZ and the University of Geneva, we quantified greenhouse gas(GHG) emissions and cost from storing electricity in stationary batterysystems.[2]Wedevel-oped a modelling framework to assess performance, costs and environmental impacts of Li-ionandNa-ionbatteries.[3]We evaluated material critical-ity in home-based battery sys-tems[4]andanalysedoptimalbattery application in various localcontexts.[5,6]

On the energy system level, we quantified the environ-mental effects of integrating batteries in the future Swiss electricity supply system ap-plying a consequential LCA approach [7] and contributedto the evaluation of flexibilitymeasures for the Swiss energy supplysystem.[8,9]

Our analysis of various battery technologies for various appli-cations used in different coun-tries – based on tech nology

Figure 1:

Comparison of GHG emis-sions cost and lifecycle costs (LCC) of storing one kWh of electricity in bat-tery systems under differ-ent social cost of carbon assumptions. Each dot represents one country-technology application combination which forms the clusters (but overlap): wholesale arbitrage (left), transmission & distribution, increase of self-consump-tion, demand peak shaving and area & frequency reg-ulation (right). The sloped grey lines represent differ-ent ratios of GHG emission cost over LCC. SCC: Social Costs of Carbon

emissions[2];VRFB:Vanadium-Redoxflow

battery, VRLA: Lead-Acid battery, NCA: Nickel-Cobalt-Aluminum, LTO: Lithium-Titanium-Oxide, NMC: Nickel-Manganese-Cobalt, LFP: Lithium-Iron-Phosphate.

70 Assessment


evaluation of Na-ion vs Li-ion batteries shows that – based on the current status of tech-nology development – Li-ion batteries outperform their Na-ion counterparts both in terms of costs and production related GHG emissions (Figure2).[3]However, fundamental battery chemistries suggest that espe-cially for high power applica-tions future Na-ion batteries might become competitive in terms of specific energy andtherefore also in terms of pro-duction costs and associated GHG emissions.

Our evaluation of metal criti-cality for different batteries – based on the life cycle inven-tory data established in [2]– shows that vanadium-redox-flowbatteriesaswellasLi-ionbatteries perform much better than lead-acid batteries and that «bulk-materials», i.e. ma-terials used in comparatively large quantities such as copper and aluminium, primarily de-termine performance regard-ing metal criticality (Figure 3).

However, also few other met-als used in small quantities,

but associated with large sup-ply risks such as cobalt con-tribute to criticality scores. We also show that the concept of metal criticality requires fur-ther developments to become more useful. Overall, metal criticality can be reduced by improving energy density of batteries, reducing the use of rare metals (e.g., Co) and es-tablish large-scale battery re-cycling industries.

Flexibility within the Swiss energy supply system will be-come a key factor as soon as

Figure 2:

Production costs (left) and associated GHG emissions (right) of Na-ion and Li-ion batteriestoday.[3]

Figure 3:

Metal criticality scores of the batteries through-out the system lifetime, per kWh stored, applying three different assessment methods («Graedel et al.», NSTC,EC)[4].VRFB: Vanadium-Redoxflow

battery, VRLA: Lead-Acid battery, NCA: Nickel-Cobalt-Aluminum, LTO: Lithium-Titanium-Oxide, NMC: Nickel-Manganese-Cobalt, LFP: Lithium-Iron-Phosphate, C: Carbon.

71 Assessment

References

[1] L.Vandepaer,K.Treyer,C. Mutel, C. Bauer, B. Amor, The International Journal of Life Cycle Assessment, doi: 10.1007/s11367-018-1571-4 (2018).[2]T.S.Schmidt,M.Beuse,X.Zhang,B.Steffen,S. Schneider, A. Pena Bello, C. Bauer, D. Parra, Environ-mental Science and Tech-nology, doi:10.1021/acs.est.8b05313 (2019).[3]S.Schneider,C.Bauer,E. Berg (2019), submitted to Environmental Science and Technology.[4]T.Terlouw,X.Zhang,C. Bauer, T. Alskaif, Journal of Cleaner Pro-duction, doi:10.1016/j.jclepro.2019.02.250 (2019).[5]T.Terlouw,T.AlSkaif,C. Bauer, W. van Sark, Ap-plied Energy, doi:10.1016/j.apenergy.2019.01.227 (2019).[6]T.Terlouw,T.AlSkaif,C. Bauer, W. van Sark, submitted to Applied Energy (2019).[7] L.Vandepaer,J.Cloutier,C. Bauer, B. Amor, Journal of Industrial Ecology, doi: 10.1111/jiec.12774 (2018)[8]M.Friedl,T.Kober,K. Ramachandran, J. Müh-letaler, «Saisonale Flexibil-isierung einer nachhaltigen Energieversorgung der Sch-weiz», Fokusstudie, Forum Energiespeicher Schweiz (2018).[9]R.Frischknecht,C.Bau-er, C. Bucher, L. Ellingsen, L. Gutzwiller, B. Heimbach, R.Itten,X.Liao,E.Panos,The International Journal of Life Cycle Assessment, https://doi.org/10.1007/s11367-018-1496-y (2018).[10]© Springer Interna-tional Publishing AG, part of Springer Nature 2018, G. Giannakidis et al. (eds.), «Limiting Global Warming to Well Below 2 °C: Energy System Modelling and Policy Development», Lecture Notes in Energy 64, https://doi.org/10.1007/978-3-319-74424-7_10.

large quantities of intermittent renewable energy (e.g., elec-tricity from photovoltaics and wind power) will be part of the supply system.

Ourevaluationofvariousflex-ibility options for the Swiss energy system, i.e. different electricity storage technolo-gies, but also energy conver-sion pathways such as power-to-gas, shows that seasonally balancing production and de-


Figure 4:

Electricity production dur-ing summer that enters into the power-to-X path-way in 2050 (PJ/yr.) in the lowcarbonscenario.[10]

mand will not only require en-ergy storage, but also conver-sion of electricity into other energy carriers; those can be used in other sectors, i.e. for heating and mobility purposes (seealsoFigure4).[8]

Other important flexibility op-tions are the integration of Switzerland in the European electricity grid and measures on the demand side (e.g., tem-poral shifts).

To which extent specific flex-ibility options will have to be implemented in the future will primarily depend on po-litical issues: Key aspects will be the level of GHG emission reduction Swit-zerland is aiming at and the question to which extent do-mestic energy supply will rep-resent a priority for security of supply.

72 Assessment

Figure 1 (left):

Projected electricity stor-age technology market shares for a 4 h duration, 1.75 cycles per day utility-scale electricity sector ap-plication across different EV uptake scenarios.

Assessment of Energy Storage at the Socio-Economic Level

Scope of project

In 2018, the activities of ETH Zurich’s Energy Politics Group (EPG) for the SCCER HaE covered the techno-economic assessment of different battery types, the CO2 emissions impact of operating bat-teries in different European grids, the dynamic competition between different storage types, and the role of new applications in triggering innovation in lithium ion batteries. These activities are described in more detail below.

In a common project with PSI and the University of Geneva, we compared the life-cycle cost and emissionsofsixdifferentbatterychemistriesacrossfivestationaryapplicationsandthreecountries(CH, DE, PL). The analysis reveals that, assuming carbon prices of up to 180 EUR/ton, no major tradeoffs between the emissions and economic cost dimensions exist – in other words, the least cost technologiesaretypicallyalsotheleastcarbonemittingtechnologies[1,2].Formoredetailsonthisproject, please see «Technology Assessment of Energy Storage» (page 69).


On the socio-economic level, as reported in last year’s annu-al report, EPG has developed a system-dynamic simulation model to assess competitive-ness of different battery tech-nologies over time. In 2018, we finalized this model andanalyzed the effect of electric vehicle (EV) uptake on the competitiveness of station-ary storage technologies. The model projects future mar-ket shares by technology un-der different scenarios of EV adoption. Results have been finalized and the study is un-der peer-review.[3] Model-ling projects Li-ion batteries to gain highest market shares

across electricity sector appli-cations by 2030, unexpectedly outcompeting even pumped-hydro storage plants, with the timing of this change depend-ing on EV uptake. This devel-opment is driven by cost re-ductions of 60–70% in Li-ionbattery packs and a reduction of about 60% in balance-of-system cost from 2017 to 2030, based on experience curves.

By focusing on technology competition, our work goes beyond individual battery stor-age cost projections and con-tributes to the policy debate on how to actively manage

resilienceandavoidinefficien-cies in future electricity sys-tems. Exemplary results can be viewed in Figures 1 and 2.

In a new project, EPG devel-oped a model to assess the impact of storage operation on the CO2 imprint of electric-ity systems. Our newly devel-oped approach couples energy system modelling with storage dispatch optimization. This al-lows to assess the effect of battery dispatch on CO2 emis-sions across electricity system contexts, storage applications and various policy scenarios. Currently, no such modelling approach exists, which is why

Authors

Tobias S. Schmidt1

Martin Beuse1

Matthias Dirksmeier1

Abhishek Malhotra1 Bjarne Steffen1

Huiting Zhang1

1 ETHZ


EPG Energy Politics Group

EV Electric Vehicle

Figure 2 (right):

Li-ion battery pack and balance-of-system cost re-duction for an 4 h duration, 1.75 cycles per day utility-scale electricity sector ap-plication across different EV uptake scenarios.The brown bar represents thebatterypack,thefleshtint represents the bal-ance-of-system costs.

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Figure 3:

Network of lithium-ion bat-tery patents.

past studies paint an overly negative and less nuanced pic-ture on the abovementioned effects. First results indicate that impacts differ strongly across the analyzed dimen-sions and show potential of higher CO2 prices to improve emissions footprints across ap-plications.

Finally, ongoing research at EPG is analysing windows of opportunity for latecomers in the lithium-ion battery indus-

try. Thus far, little is known how changing applications for lithium-ion batteries have in-fluenced the knowledge baseof the industry, and whether they provided windows of op-portunity for latecomers.

To investigate this, we con-ducted a patent-citation net-work analysis to analyse the trajectory of evolution of the knowledge base of the lithium-ion battery industry. The anal-ysis is based on 56'996 patents

covering the period 1970–2018 from 140 countries, which was retrieved from the European Patent Office PATSTAT data-base using keyword and clas-sificationcodebasedsearches.

Early results indicate that the increasing emphasis in focus of patenting activity on electric vehicles was accompanied by a shift in knowledge sourcing strategies.[4] Figure3 showsan exemplary result of the analysis.

References

[1]T.S.Schmidt,M.Beuse,Z.Xiaojin,B. Steffen, S.F. Schneider, A. Pena Bello, C. Bauer, D. Parra, Environmental Science and Technol-ogy (accepted: https://doi.org/10.1021/acs.est.8b05313) (2019).

[2]R.Frischknecht,C. Bauer, C. Bucher, L.A.W. Ellingsen, L. Gutz-willer, B. Heimbach, R.Itten,X.Liao,E.Panos,S.Pfister,T.Schmidt,TheInternational Journal of Life Cycle Assessment, 1–6 (2018).

[3]M.Beuse,B.Steffen,T.S. Schmidt, under review (2019).

[4]A.Malhotra,H.Zhang,M. Beuse, T.S. Schmidt, Poster presented at Ad-vanced Automotive Battery Conference (AABC) Asia, Osaka/Japan (2018).

Assessment of Energy Storage at the Socio-Economic Level

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Figure 1:

HEPP Project Partners.

Increasing the Efficiency of the Power-To-Methane Technology

Scope of project

TheUniversityofAppliedSciencesRapperswil(HSR)contributestotheSCCERHaEwithaHighEffi-ciencyPower-to-MethanePilot(HEPP).ThemainaimoftheHEPPprojectistoincreasetheefficiencyof the power-to-methane technology. This task is achieved through thermal coupling of a catalytic methanation and a solid oxide electrolysis (SOE). This coupling is realized with the development of a new heat management and a steam generator as key components. This steam generator uses the waste heat from the catalytic methanation to evaporate water and supplies the steam to the SOE.


HEPP demonstrator and to construct the plant mechani-cally (see Figures 2 and 3). Furthermore, the major part of the electrical design and wiring was done in 2018 and should befinishedbytheendofJanu-ary 2019.

The newly developed mem-brane from our research part-nerAPEXhasbeencharacter-ized. The results show, that the required separation effi-ciency can be achieved, so that the synthetic natural gas SNG can be fed unlimited into the natural gas grid.

The newly developed sensors from our research partner MEMS AG have also been char-acterized. During these tests in comparison with a mass spec-trometry, it was found that the sensors work very well for gas mixtures consisting of three different gases. After imple-menting a correction factor in the evaluation software, the sensors were found to give ac-curate results.

Thermal coupling of SOE and methanation

The thermal coupling of a catalytic methanation and a SOE is a key element and is investigated in the new proj-ect HOTCAT4STEAM. The key component for this coupling is the steam generator making use of the waste heat from the catalytic methanation to evap-orate water and supplies the SOE with steam. In contrast to similar projects in our proj-ect, the heat is directed from the methanation to the steam generator by a heat manage-ment system using thermal oil asheattransferfluid(seeFig-ure 4).

Extensive tests with the steam generator prototypes were done showing that generating steam in using thermal oil at theverylowpressurefluctua-tions required by the SOE is a


HEPP HighEfficiencyPower-to-Methane Pilot

HSR University of Applied Sciences Rapperswil

NG Natural Gas

SNG Synthetic Natural Gas

SOE Solid Oxide Elec-trolysis

Focus in 2018: Project partnerships and plant erection

Authors

Markus Friedl1Sandra Moebus1

1 HSR (University of Applied Sciences Rapperswil)

About 20 institutions support the HEPP project with knowl-edge,materialorfinancialcon-tributions (Figure 1). In 2018 we could win two new part-nerships for the HEPP project, ARBOR Fluidtec AG (Swagelok) and Emerson Automation So-lutions. Furthermore, the work was carried out on behalf of and with the support of the SwissFederalOfficeofEnergyin the new project HOTCAT-4STEAM.

In 2018 the focus of the HEPP team was to procure all mate-rial and components for the

75 Assessment

Increasing the Efficiency of the Power-To-Methane Technology

Figure 3 (right):

Project member Christoph Steiner constructing the HEPP demonstrator.

Figure 2 (left):

Outside the HEPP demon-strator.

Figure 4 (left):

Conceptual layout of proj-ect HOTCAT4STEAM.

challenge. In close co-opera-tion with Dr. MER Jan Van her-le's Group of Energy Materials GEM at EPFL Sion, who deliver the SOE, the thermal coupling is realized during 2019.

Natural Gas Filling Station

The natural gas (NG) station on the HEPP site was approved by the TISG in April 2018 and has been operating since then. The NG station supplies around 10 vehicles with biogas with a consumption between April and November 2018 of around 1'000 kg CH4. The Directorate General of Customs (Oberzoll-direktion) has granted the li-cense for the tax-free feed-in of the SNG produced by the HEPP plant.

Events

Beside the scientific work atthe demonstrator, the HSR team has hosted several events and welcomed guests: • Expert Discussions Power-

to-Gas, June 2018, with around 100 participants.

• Delegation of the full project meeting of the EU project Pentagon, September 2018, with around 30 participants.

• Inauguration of the HEPP facility, October 2018, with around 70 participants.

• Hosting the SCCER HaE An-nual Conference, November 2018, with around 130 par-ticipants.

• Guided tours on the HEPP facility, September until De-cember 2018, around 300 participants.

Publications

In 2018, the focus was to in-form the public about our re-search activities, because scientific publications are ex-pected after the construction of the HEPP demonstrator in the years 2019–2020. Many articles about project HEPP have been published by jour-nalists and by ourselfs in the following media: Aargauer Zeitung,

Aqua&Gas, Bulletin.ch, die Baustellen, ee-news, Erdgas, ET Elektronik,

Folio, Höfner Volksblatt, Leader Special, Linth-Zeitung, NZZ am Sonntag, Panorama – Bildung/Bera-tung/Arbeitsmarkt, Punkt 4 Info, Rundschau Ausgabe Süd, Schweiz am Wochenende, St.Galler Tagblatt, Südostschweiz, Youtility,ZugKultur, Zürichsee Zeitung.

Goals for 2019 – 2020

In 2019 the electrical installa-tions and the gas infrastruc-ture for the HEPP demonstra-tor will be completed in early 2019. Afterwards the HEPP demonstrator can be run and the produced SNG can be fed into the natural gas grid un-limitedly. The measuring cam-paignforthehighefficiencyofthe HEPP demonstrator will be executed in 2019 and 2020.

Figure 5 (right):

Daniela Decurtins and Markus Friedl refuel a natural gas vehicle at the inauguration of the HEPP research facility in October 2018 in Rapperswil.

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ESI – Energy System Integration Platform

Scope of project

The Energy Systems Integration (ESI) Platform at the Paul Scherrer Institute (PSI) provides a basis for research and technology transfer activities for the SCCERs «Heat and Electricity Storage» (HaE) and «Biomass for Swiss Energy Future» (BIOSWEET). Main topics so far are Power-to-Gas processes and conversion of biomass.


In 2018 final details of thebasic platform infrastructure (support structure for indi-vidual sub-systems, supply of media-gases, cooling-water, electricity, safety system & controls) have been completed and all sub-systems (electroly-sis, fuel cells, methane synthe-sis, wet biomass conversion) became operational.

One of the issues resolved for the platform infrastructure was related to the purity of oxygen

being fed into the storage tank. In a joint effort together with the supplier of the gas cleaning equipment for H2 & O2, the root cause for insufficient catalyticconversion of trace amounts of H2 in O2couldbeidentifiedandmeasures be taken to achieve low ppm-levels of impurities for the gas to be fed into the pressure tanks.

Joint activities have been con-tinued between the technology oriented sub-systems (repre-

sented with hardware on the ESI platform) and the teams working on cross-cutting sci-entifictopicssuchascatalysisresearch (synthesis and char-acterization), process diagnos-tics tools (sampling, analysis, process validation) and ener-gy system modelling (energy scenarios, technology assess-ment, life cycle analysis).Author

Peter Jansohn¹ Marcel Hofer¹ Tilman Schildhauer¹

¹ PSI


BIOSWEET Biomass for Swiss Energy Future

HaE Heat and Electricity Storage

CHP Combined Heat and Power

CH4 MethaneSCCER Swiss Competence

Center for Energy Research

Figure 1:

Energy conversion path-ways.

77 AssessmentAssessment 7777 Assessment

ence on the overall system performance.

The fuel cell container system on the ESI platform (based on PEM technology and suit-ed for H2/O2 re-electrificationwithhighefficiency, i.e.upto70%)hasbeenequippedwithadditional fuel cell stacks. In total the system will accom-modate up to four (4) fuel cell stacks (50 kWel each). After the commissioning of the fuel cell modules, the system will undergo similar load ramp test campaigns as for the electroly-ser system (see previous para-graph).

A second container for fuel cell system testing is about 60%complete and will be commis-sioned in spring 2019. In this container PEM fuel cell sys-tems (from small scale series production of industrial part-ners) will be exposed to quali-fication tests in order to sup-port the market introduction of commercial systems at about a 100 kW scale.

Thecatalyticfluidisedbed re-actor for methane synthesis (dubbed GanyMeth; output ca-pacity: up to 20 m3/h of SNG, i.e. an energy equivalent of up to 200 kWth) has been under-going cold commissioning tests andhydraulicfluidizationstud-iesinordertoconfirmthede-sign rules applied for the inter-nal heat exchanger tube array. Advance optical techniques as well as pressure probes have been used to characterize the 2-phase (gas/solid) flow re-gime in between the heat ex-changer tubes which are im-mersed in the fluidized bedzone (void fraction, bubble diameters, bubble rise veloci-ties). The system is now being readied for pressurized opera-tion and for heat transfer tests inordertoconfirmthecoolingcapacity of the rig required for subsequent first synthesistests.

In a process study (supported financially by the cantonAar-gau) performed in the 2nd half of 2018 we were able to show that with a scale-up of some of the components available on the ESI platform (electrolyser,

ESI – Energy Systems Integration Platform

Link

https://www.psi.ch/media/overview-esi-platform

Specific achievements in 2018 Figure 2:

Resultsofpre-qualificationtests for 160 KW electro-lyzer for primary (left) and secondary power reserve test (right).

The PEM electrolyser (a pro-totype system from Siemens) has been tested intensively within a project with Swissgrid in order to proof its capabili-ties for primary and second-ary frequency control services (Figure 2). The system turned out to be 100% fit for suchnetwork services even though some optimization still remains in terms of the control scheme (especially the stack manage-ment).

The predefined load profilescould be realized with the sys-tem within the given (narrow) deviation boundaries. Only during load ramps in the part load regime very brief/short term violations of the given boundaries could be observed in some cases (load spikes caused by the stack manage-ment). These issues can be mitigated by an optimized stack management control algorithm, and will be any-how less significant for largerscale systems (MW systems) for which the individual stack management has less influ-

78 AssessmentAssessment7878 Assessment

ESI – Energy Systems Integration Platform

H2 storage, methane synthesis) one could achieve a sufficientsupply of H2forafleetoffuelcell trucks for transportation of goods. With system com-ponents in the single (< 3) MW scale enough electricity can be provided by photovoltaic (PV) panels on an annual basis to secure the H2 demand of a fleet of 20trucks for regionaltransport (Figure 3).

Excess H2 produced in summer time is transformed into meth-ane (CH4) and injected into the natural gas grid. In winter time the same amount of CH4 is re-processed to produce H2 in a C-neutral fashion in order to supplement the reduced pro-duction via electrolysis. This way sufficient H2 production can be guaranteed without ad-ditional burden imposed on the electric grid during winter time when there are frequent peri-ods of time when Switzerland is dependent on electricity im-ports.

With these encouraging results in hand, it will be exploited if a firstdemonstrationprojectcanbe realized within Switzerland based on this concept.

In order to close the gap be-tween SNG production and storage in the gas grid on the one hand, and to demonstrate the flexible re-electrificationof CH4/H2 mixtures in com-bined heat and power (CHP) systems, on the other hand, the ESI platform has been complemented with a micro gas turbine module in 2018. The system is currently quali-fiedfornaturalgas/CH4 but will be subsequently tested with CH4/ H2 mixtures with increas-ing H2 content. If it can be shown – with moderate modi-ficationstotheCHPsystems–that end-use applications are available for CH4/H2 mixtures withsignificantamountsofH2, the transition to a low carbon/hydrogen energy economy can be simplified considerably. ByallowingsignificantadditionofH2 (20 to40vol%) to theex-isting public networks, storage of large amounts of H2 even on a seasonal basis, becomes feasible at moderate cost. Cur-rent legislative limits and fuel specifications of gas turbineOEMs typically allow only very low amounts of H2 (less than 2vol%resp.5vol%)inthefuelgas.

Outlook for 2019

A moderate expansion of the platform activities will continue to happen also in the coming years (2019/2020). The plat-form infrastructure still has significant flexibility and ca-pacity to accommodate addi-tional technologies (e.g., bat-tery storage systems).

Additional features could also be added on a virtual basis within the recently launched project ReMaP (coordinated by the Energy Science Center (ESC) of ETH Zurich). ReMaP has the ambition to link the demonstration platforms at Empa and PSI (and possibly some test hardware at ETHZ) in order to gather experience on the inter-connected opera-tional behaviour of large and diverse energy systems includ-ing elements of the residential, industrial and mobility related energy sectors.

The ReMaP project has been officiallykicked-off justat theendof2018,andthefirsttaskrelated to the ESI platform is now to set up a platform con-trol system which enables all the features of data transfer envisioned in the ReMaP proj-ect.

The efforts are supported by joint activities of several SCCERs (Coherent Energy Demonstrator Assessment — CEDA), which have been start-ing to develop intra-platform data handling procedures and data evaluation standards.

Figure 3:

Setup to operate hydro-gen fueled trucks without increasing electricity con-sumption during winter season.

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Appendix

81 Appendix

Conferences

• 5th Swiss Symposium Thermal Energy Storage, January 26, 2018, HSLU, Horw, Switzerland.

[>130participants;Audienceandpresenterscomposedofamixtureofcompaniesandresearchersgathered

topromotethedisseminationofscientificresultsandfostercollaborationbetweenindustryandacademia.]

• LATSIS Symposium: 12th International Symposium Hydrogen & Energy, February 11–16, 2018, SwissTech

Convention Center, EPFL, Lausanne, Switzerland.

[Hydrogen&EnergyAwardforMichaelGrätzel,BestPosterAwardforStavroula(Alina)Kampouri,organised

byNorisGallandatandAndreasZüttel.]

• AA-CAES Symposium, May 15, 2018, Biasca and Bellinzona, Switzerland.

[About35participantsfromacademia,industry,andfederalagenciesfromAustria,Germany,andSwitzer-

land.]

• Swiss and Surrounding Battery Days, May 22–24, 2018, Baden, Switzerland, organized by SCCER WP 2.

• 1st International Symposium on Solid-State Batteries, May 28–29, 2018, organized by Empa, Dübendorf,

Switzerland.

• Expert Discussions Power-to-Gas, June 2018.

[~100participants]

• Inauguration Symposium «Small Scale Demonstrator for Sion», September 14, 2018, Energypolis, Sion,

Switzerland.

[80participants]

• Delegation of the full project meeting of the EU project Pentagon, September 2018.

[~30participants]

• Inauguration of the HEPP facility, October 2018, Rapperswil, Switzerland.

[~70participants]

• HSR hosting the SCCER HaE Storage Annual Conference, November 6, 2018, Rapperswil, Switzerland.

[~130participants]

• BFH Conference with Swiss Battery Industry, November 12, 2018, Olten, Switzerland.

[20participants]

• Guided tours on the HEPP facility, September until December 2018, Rapperswil, Switzerland.

[~300participants]

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82 Appendix

Presentations

Work Package «Heat – Thermal Energy Storage»

• B.Fumey,R.Weber,L.Baldini,«Liquidsorptionheatstoragespiralfinnedheatandmassexchanger,steps

towards increased rate of absorption», 12th International Renewable Energy Storage Conference (IRES

2018), March 13–15, 2018, Duesseldorf, Germany.

• B.Fumey,«Applicationspecifictemperaturesforstoragematerialandcomponenttesting»,invitedtalk,

3rd IEA SHC Task 58 / ECES Annex 33 Experts Meeting, April 9–11, 2018, Ljubljana, Slovenia.

• S. Krimmel, A. Stamatiou, A. Ammann, L.J. Fischer, J. Worlitschek, «Investigation of Direct Contact Heat

Exchange for High Thermal Power Latent Heat Storage», presentation, EnerSTOCK2018 – 14th International

Conference on Energy Storage, April 25–28, 2018, Adana, Turkey.

• L. Baldini, «Innovationen im NEST – Sind saisonale Speicher bereits einsatzfähig?», invited talk, Fachtagung

Eco Bau und NNBS, May 15, 2018, World Trade Center Zurich, Switzerland.

• L.J. Fischer, S. Maranda, A. Stamatiou, S. von Arx, J. Worlitschek, « Experimental Investigation on Heat

Transfer Characteristics in a Phase Change Dispersions», presentation, 12th IIR Conference on Phase-Change

Materials and Slurries for Refrigeration and Air Conditioning, May 21–23, 2018, Orford, Quebec, Canada.

• A. Stamatiou, R. Waser, L.J. Fischer, J. Worlitschek, «High power thermal energy storage using phase change

material slurries», presentation, 12th IIR Conference on Phase-Change Materials and Slurries for Refrigera-

tion and Air Conditioning, May 21–23, 2018, Orford, Quebec, Canada.

• S. Frehner, A. Stamatiou, L.J Fischer, J. Worlitschek, «Techno-economic analysis of a phase change material

slurry for industrial applications», presentation, 12th IIR Conference on Phase-Change Materials and Slurries

for Refrigeration and Air Conditioning, May 21–23, 2018, Orford, Quebec, Canada.

• J. Worlitschek, A. Stamatiou, «High power thermal energy storage research at Lucerne University of Applied

Sciences and Arts», presentation, 12th IIR Conference on Phase-Change Materials and Slurries for Refrigera-

tion and Air Conditioning, May 21–23, 2018, Orford, Quebec, Canada.

• S. Krimmel, A. Stamatiou, J. Worlitschek, H. Walter, «Experimental Characterization of the Heat Transfer in

a latent Direct Contact Thermal Energy Storage with One Nozzle in Labor Scale», presentation, EDEB´18 –

12th International Conference on Energy and Development, Environment and Biomedicine, Aug. 25–27, 2018,

Corfu, Greece.

• B. Fumey, «Inventory of sorption heat storage component and system designs currently under investiga-

tion by task and annex partners», invited talk, 4th IEA SHC Task 58 / ECES Annex 33 Experts Meeting,

October 1–3, 2018, Graz, Austria.

• R. Ravotti, O. Fellmann, L.J. Fischer, A. Stamatiou, J. Worlitschek, «Synthesis and Characterization of Car-

boxylic Esters as Novel Phase Change Materials (PCM) for Latent Heat Storage (LHS) Applications», poster,

ISEC 2018 International Sustainable Energy Conference, October 3–5, 2018, Graz, Austria.

• J.Roncolato,S.A.Zavattoni,G.Zanganeh,A.Haselbacher,M.C.Barbato,«Theworld’sfirstundergroundAA-

CAES pilot plant: modelling and validation», 1st FTAL Conference, October 18–19, Lugano, Switzerland.

• P. Gantenbein, «Thermal Energy Sorption Storage Perspectives: Technical Challenges in the Component De-

velopment», invited talk, 7th Symposium SCCER Heat and Electricity Storage, November 6, 2018, Rapperswil,

Switzerland.

• J. Roncolato, A. Pizzoferrato, V. Becanttini, A. Haselbacher, G. Zanganeh, S.A. Zavattoni, F. Contestabile,

A. Steinfeld, M. Barbato, «AA-CAES Plant Modeling: Advancements on Plant Design», poster, 7th Symposium

SCCER Heat and Electricity Storage, November 6, 2018, Rapperswil, Switzerland.

• P. Roos, A. Haselbacher, «Multi-Tank TES System Analysis», poster, 7th Symposium SCCER Heat and Electric-

ity Storage, November 6, 2018, Rapperswil, Switzerland.

• N. Mallya, S. Haussener, «Numerical Melting Study of Encapsulated High-Temperature PCM Units for Energy

Storage», poster, 7th Symposium SCCER Heat and Electricity Storage, Nov. 6, 2018, Rapperswil, Switzerland.

• E. Rezaei, M. Barbato, A. Ortona, S. Haussener, «High-Temperature Latent Heat Storage Units: Heat Transfer

Enhancement Using Ceramic Porous Media», poster, 7th Symposium SCCER Heat and Electricity Storage,

November 6, 2018, Rapperswil, Switzerland.

• R. Ravotti, O. Fellmann, L.J. Fischer, A. Stamatiou, J. Worlitschek, «Investigation of Bio-based Esters as

Novel PCM for LHS Applications», poster, 7th Symposium SCCER Heat and Electricity Storage, November 6,

2018, Rapperswil, Switzerland.

• R. Ravotti, O. Fellmann, L. Müller, J. Worlitschek, «Analytical techniques for characterization of PCM thermal

properties», poster, HSLU Thermal Energy Storage Workshop, December 14, 2018, Horw, Switzerland.

83 Appendix

• W. Delgado, A. Stamatiou, S. Maranda, R. Waser, J. Worlitschek, «Comparison and Assessment of Available

Latent Heat Storage Solutions for High Power Applications», poster, 7th Symposium SCCER Heat and Electric-

ity Storage, November 6, 2018, Rapperswil, Switzerland.

• R. Waser, F. Ghani, S. Maranda, T.S. O’Donovan, P. Schuetz, M. Zaglio, J. Worlitschek, «Numerical Inves-

tigation on a Cascaded Latent Storage Heat Pump Water Heater», poster, 7th Symposium SCCER Heat and

Electricity Storage, November 6, 2018, Rapperswil, Switzerland.

• S. Ammann, D. Schiffmann, W. Villasmil, L. Fischer, J. Worlitschek, «Horizontally Drilled Near-Surface Geo-

thermal Energy Storage», poster, 7th Symposium SCCER Heat and Electricity Storage, November 6, 2018,

Rapperswil, Switzerland.

• L. Baldini, B. Fumey, R. Weber, «Absorption-based Long-term Thermal Energy Storage – Understanding Mass

Transfer in Aqueous Sodium Hydroxide Solutions», poster, 7th Symposium SCCER Heat and Electricity Stor-

age, November 6, 2018, Rapperswil, Switzerland.

• S. Krimmel, A. Stamatiou, J. Worlitschek, H. Walter, «Direct Contact Latent Heat Storage», poster, HSLU

Thermal Energy Storage Workshop, December 14, 2018, Horw, Switzerland.

Work Package «Batteries – Advanced Batteries and Battery Materials»

• K.V. Kravchyk, S. Wang, L. Piveteau, F. Krumeich, M.V. Kovalenko, «Non-Aqueous Aluminium-Graphite Bat-

teries: Status, Prospects and Future», MRS Spring Meeting & Exhibit, April 2–6, 2018, Phoenix, USA.

• L. Duchêne, R.-S. Kühnel, E. Stilp, E. Cuervo Reyes, A. Remhof, H. Hagemann, C. Battaglia, «A Stable 3 V

All-Solid-State Battery Based on a Closoborate Electrolyte», invited talk, MRS Spring Meeting, April 4, 2018,

Phoenix, USA.

• 1st International Symposium on Solid-State Batteries, May 28–29, 2018, Empa, Dübendorf, Switzerland.

• C. Marino, «Is there a future for Na-ion batteries?», invited talk, 1st Swiss and Surrounding Battery Days,

May 23–25, 2018, Baden, Switzerland.

• E.Marelli,«HowtoovercometheP2-phasesNadeficiency:aproofofconcept»,talk,1st Swiss and Surround-

ing Battery Days, May 23–25, 2018, Baden, Switzerland.

• M. Schuster, «Investigation of carbonophosphonates as cathode material for water-in-salt sodium-ion batter-

ies», talk, 1st Swiss and Surrounding Battery Days, May 23–25, 2018, Baden, Switzerland.

• C. Marino, M. El Kazzi, E.J. Berg, M. He, C. Villevieille, «Interface and safety properties of Phosphorus-based

negative electrodes for Li-ion batteries», poster, 1st Swiss and Surrounding battery days, May 23–25, 2018,

Baden, Switzerland.

• K.V. Kravchyk, «Anode Materials with High Areal Capacities for Lithium-Ion Batteries», Swiss and Surround-

ing Battery Days, May 23–25, 2018, Baden, Switzerland.

• J. Conder, C. Villevieille, «How reliable is the Na metal as a reference electrode?», poster, 19th International

Meeting on Lithium Batteries, June 17–22, 2018, Kyoto, Japan.

• C.Battaglia,«ForschungEnergiespeicherunganderEmpa»,invitedtalk,BriefingKantonsratZürich,July2,

2018, Zurich, Switzerland.

• K.M. Fromm, Plenary lecture entitled of «Mixed metal precursors for oxides and their applications», Annual

Meeting of the French Crystallographic Association, July 10–13, 2018, Lyon, France.

• K.M. Fromm, Plenary lecture entitled of «Mixed metal precursors for oxides and their applications», Interna-

tional Conference on Coordination Chemistry (ICCC), July 29 – Aug. 3, 2018, Japan.

• M.Schuster,C.Villevieille,P.Novák,C.Marino,«ManganeseCarbonophosphateasCathodesforWater-in-

Salt Na-Ion Batteries», poster, 69th Annual Meeting of the International Society of Electrochemistry, Septem-

ber 2–5, 2018, Bologna, Italy.

• C. Marino, «Biowaste lignin-based carbonaceous materials as anodes for Na-ion batteries», talk, 69th Annual

Meeting of the International Society of Electrochemistry, September 2–5, 2018, Bologna, Italy.

• M.Schuster,C.Villevieille,P.Novák,C.Marino,«ManganeseCarbonophosphates–SuitableCathodesfor

Aqueous and Water-in-Salt Na-ion Batteries?», poster, Electrochemistry 2018, September 24–26, 2018, Ulm,

Germany.

• E. Cuervo Reyes, F. Pagani, C. Battaglia, «Ion Transport in (Low-Dimensional) Ionic Conductors», invited

talk, ECS AiMES Meeting, October 3, 2018, Cancun, Mexico.

• «Advanced Li-ion Batteries», ILmac, October 3–4, 2018, Lausanne, Switzerland.

Presentations

84 Appendix

• R. Dubey, K.V. Kravchyk, M.V. Kovalenko, «High Mass Loading Graphite Anodes for Li-ion Batteries», poster,

7th Symposium SCCER Heat and Electricity Storage, November 6, 2018, Rapperswil, Switzerland.

• J. Hankache, N.H. Kwon, K.M. Fromm, «Development of Ionic Liquids as Electrolytes Additives and a Cathode

Material for Lithium Ion Batteries», poster, 7th Symposium SCCER Heat and Electricity Storage, November 6,



Material for Lithium Ion Batteries», poster, 7th Symposium SCCER Heat and Electricity Storage, November 6,


• J. Vidal Laveda, J.E. Low, C. Battaglia, «Stabilizing NMC811 in Full Cells with High Areal Capacity», poster,


• C. Battaglia, «Materials Innovation for Next-Generation Batteries», talk, 7th Symposium SCCER Heat and


• C. Marino, C. Bolli, E. Marelli, E. Kendrick, C. Villevieille, «Though the Electrochemical Mechanisms of the

O3-Na(Ni0.5Mn5/16Sn1/16Ti1/8)02 Phase used as Cathode Material for Na-ion Batteries», poster, 7th Symposium


• M. Schuster, C. Villevieille, C. Marino, «Investigation on the Suitability of Manganese Carbono-phosphate

Compounds as Cathodes in Aqueous Na-Ion Batteries», poster, 7th Symposium SCCER Heat and Electricity

Storage, November 6, 2018, Rapperswil, Switzerland.

• A. Fuerst, A. Glarner, A. Haktanir, M. Stalder, S. Müller, «BFH Research Group Test Batteries», poster,


• A. Fuerst, A. Haktanir, M. Stalder, «Battery Cost Reduction through Production Simulation», poster, 7th Sym-

posium SCCER Heat and Electricity Storage, November 6, 2018, Rapperswil, Switzerland.

• S. Gentil, E. Zanzola, P. Sharma, P. Peljo, H.H. Girault, «Carbon-Based Solid Phase Charge Storage Nano-

material for the Enhanced Energy Storage in Aqueous Redox Flow Batteries», poster, 7th Symposium SCCER

Heat and Electricity Storage, November 6, 2018, Rapperswil, Switzerland.

• D. Reynard, C. Dennison, A. Battistel, H. Girault, «Low-Grade Heat Recovery Using All-Vanadium Redox Flow

Battery», poster, 7th Symposium SCCER Heat and Electricity Storage, Nov. 6, 2018, Rapperswil, Switzerland.

• C. Villevieille, «Electrode materials, electrolyte or the engineering – what is the key to successful develop-

ment of Na-ion batteries?», invited talk, 5th International Conference on Sodium Batteries, November 12–15,

2018, Saint-Malo, France.

• L. Duchêne, R. Asakura, A. Payandeh, R.-S. Kühnel, A. Remhof, C. Battaglia, «All-Solid-State Battery Based

on Closoborate Electrolytes», invited talk, 3rd Bunsencolloqium on Solid-State Batteries, November 18, 2018,

Frankfurt, Germany.

Work Package «Hydrogen – Production and Storage»

• «Energy Storage for Renewable Energy in Switzerland», poster, 12th International Symposium Hydrogen &

Energy, February 11, 2018, SwissTech Center EPFL, Lausanne Switzerland.

• «Energy Storage with Hydrogen and Hydrocarbons», invited plenary talk, 2018 Kick-off Symposium for World

Leading Research Centers –Materials Science and Spintronics–, February 19–20, 2018, Tohoku University,

International Center Sendai, Japan.

• «Renewable Energy Storage in Hydrides and Hydrocarbons», invited seminar talk, March 15, 2018, Seminar

Physikalische Chemie Uni Bern, Switzerland.

• «50th Anniversary of GAZNAT – Gaznat and EPFL a successful collaboration for future energy technology»,

invited talk, May 18, 2018, Rolex Learning Center EPFL, Switzerland.

• E. Zanzola, S. Gentil, C.R. Dennison, E. Smirnoff, P.E. Peljo, H.H. Girault, «Enhanced Energy Storage in

Aqueous Redox Flow Batteries», oral, 1st Swiss and Surrounding Battery Days, May, 2018, Baden, Switzer-

land.

• «From Metal Hydrides to Hydrocarbons», invited talk, The 1st International Workshop on Mechano-chemistry

of Metal Hydrides (WMMH-18), May 30 – June 1, 2018, University of Oslo, Norway.

• «Storage of Renewable Energy by Reduction of CO2 with Hydrogen», invited talk, CIMTEC 2018, 8th Forum on

New Materials, June 10 – 14, 2018, Perugia, Italy.

• «Storage of Renewable Energy by Hydrogen and Reduction of CO2», invited talk, KONKUK University,

June 21, 2018, Seoul, Republic of Korea.

Presentations

85 Appendix

• «Storage of Renewable Energy by Reduction of CO2 with Hydrogen», invited talk, South China University of

Technology, June 19, 2018, Guangzhou, China.

• D. Reynard, C.R. Dennison, A. Battistel, H.H. Girault, «Harvesting low-grade heat using all-vanadium redox

flowbatteries»,oral,TheInternationalFlowBatteryForum,July10–12,2018,Lausanne,Switzerland.

• ««From Renewable Energy to Hydrogen and Hydrocarbons», invited talk, Energy Materials & Nanotechnology

Meetings, July 16, 2018, Berlin, Germany.

• «Achievements on Hydrogen Storage from the Collaboration between Switzerland and Korea», invited talk,

Europe-Korea Conference on Science and Technology (EKC), August 20, 2018, Glasgow, Scotland, Great

Britain.

• «Storage of Renewable Energy by Hydrogen Reduction of CO2», invited keynote, The University of Edinburgh,

School of Engineering, August 21, 2018, Edinburgh, Scotland, UK.

• «Das Ende der fossilen Energie als Chance für eine nachhaltige Entwicklung», invited talk, European Power

Network, Erneuerbare Energien, August 30, 2018, Industrielle Werke Basel IWB Holzkraftwerk II, Basel,

Switzerland.

• «The Future of Renewable Energy Storage», invited talk, Energy Symposium KIT, September 11–12, 2018,

Karlsruhe, Germany.

• E. Zanzola, P.E. Peljo, C.R. Dennison, E. Smirnoff, H.H. Girault, «Safe Aqueous Redox Flow Batteries Based

on Water Soluble Redox Mediators and Solid-State Intercalation Compounds», poster, 69th Annual ISE Meet-

ing, September 2018, Bologna, Italy.

• «Storage of Renewable Energy by Hydrogen and Reduction of CO2», invited talk, Materials.it 2018,

October 22–26, 2018, Area della Ricerca CNR – Centro congressi, Bologna, Italy.

• «Hydrogen storage in solids, analysis and limits», invited talk, The 190th Committee on Hydrogen Function

Analyses in Materials, Tohoku University, Advanced Institute for Materials Research (WPI-AIMR), Sendai,

Japan.

• «The20YearsofComplexHydridesforHydrogenStorage»,invitedtalk,MetalH2018,November1,2018,

Guangzhou, China.

• D. Reynard, C.R. Dennison, A. Battistel, H.H. Girault, «Harvesting low-grade heat using all-vanadium redox

flowbatteries»,poster,7th SCCER HaE Symposium, November 6, 2018, Rapperswil, Switzerland.

• S. Gentil, E. Zanzola, P. Sharma, P.E. Peljo, H.H. Girault, «Carbon-based Solid Phase Storage Nanomate-

rial for the Enhanced Energy Storage in Aqueous Redox Flow Batteries», poster, 7th SCCER HaE Symposium,


• S. Gentil, E. Zanzola, R. Danick, C.R. Dennison, G. Schwend, E. Smirnoff, P.E. Peljo, H.H. Girault, «Redox

SolidBoosterforredoxflowbatteries»,oral,ICESI-PacificPowerSourcesJointMeeting,January5–10,2019,

Kona, Hawaii, USA.

• N. Autissier, G. Laurenczy, «CO2 as Hydrogen Vector & Formic Acid Power Supply Prototype», SCCER HaE

Storage 7th Symposium, November 6, 2018, Rapperswil, Switzerland.

• G. Laurenczy, «Carbon dioxide to formic acid and to methanol: Homogeneous catalytic ways in aqueous so-

lution at room temperatures», Conference: 256th National Meeting and Exposition of the American-Chemical-

Society (ACS), August 19–23, 2018, Boston, MA, USA.

• L.Lombardo,H.Yang,A.Züttel,«IonicLiquidsasEfficientDestabilizingAgentsofSodiumBorohydride»,

poster, 7th Symposium SCCER Heat and Electricity Storage, November 6, 2018, Rapperswil, Switzerland.

• H.Yang,L.Lombardo,A.Züttel,«CarbonBasedMaterialsforHydrogenStorage»,poster,7th Symposium


• L.Yerly,F.LeFormal,K.Sivula,«PerformanceandStabilityofIron-Cobalt-NickelAlloysforWaterOxida-

tion», poster, 7th Symposium SCCER Heat and Electricity Storage, November 6, 2018, Rapperswil, Switzer-

land.

• N.Plainpan,F.LeFormal,K.Sivula,«ASearchforaStable,InexpensiveandEfficientOxygenEvolution

Reaction, Electrocatalyst in an Acidic Media», poster, 7th Symposium SCCER Heat and Electricity Storage,


• D.Lebedev,R.Ezhov,N.Kaeffer,M.Willinger,X.Huang,Y.Pushkar,C.Copéret,«FromNanoparticlesto

Single Sites – Decreasing the Noble Metal Content in Anodic Water Oxidation Catalysts», poster, 7th Sympo-

sium SCCER Heat and Electricity Storage, November 6, 2018, Rapperswil, Switzerland.

• «Gassolidinteraction,thekeyforrenewableenergystorage»,invitedtalk,XIX.WorkshopüberdieCharak-

terisierung von feinteiligen und porösen Festkörpern, November 14, 2018, Niedernhausen, Germany.

Presentations

86 Appendix

• D.F.Abbott,E.Fabbri,M.Borlaf,F.Bozza,R.Schäublin,T.Graule,T.J.Schmidt,«OperandoX-RayAbsorption

Investigations into the Role of Fe in the Oxygen Evolution Activity and Stability of NixFe1-xOy Nanoparticles»,


• D. Aegerter, E. Fabbri, T.J. Schmidt, «The Effect of Fe in Ba0.5Sr0.5CoxFe1-xO3-5 Towards the Oxygen Evolution,

Reaction in Alkaline Media», poster, 7th Symposium SCCER Heat and Electricity Storage, November 6, 2018,


Work Package «Synthetic Fuels – Development of Advanced Catalysts»

• T.J. Schmidt, «Application of Synchrotron Based Methods to Study Electrochemical Energy Conversion Pro-

cesses», invited talk, TU Munich, January 8, 2018, Munich, Germany.

• N.Kaeffer,C.Mavrokefalos,H.-J.Liu,D.Lebedev,Y.Pineda-Galvan,Y.Tokimaru,A.Fedorov,Y.Pushkar,

C.Copéret,«Molecular-BasedSurfaceEngineeringforSolarFuelsProduction»,invitedtalk,MeetingSCCER

Heat and Electricity Storage, January 22, 2018, Villars-sur-Ollon, Switzerland.

• D. Perego et al, «CO2 reduction to valuable products: a Differential Electrochemical Mass Spectrometry

(DEMS) study», contributed talk, SCCER Meeting 2018, January 22–24, 2018, Villars-sur-Ollon, Switzerland.

• C.Copéret,«Molecularunderstandingandcontrolledfunctionalizationofsurfacestowardssingle-sitecata-

lysts and beyond», invited talk, SAOG 2018, February 1, 2018, Fribourg, Switzerland.

• E. Fabbri, «Insights into Perovskite Nano-Catalysts as Oxygen Electrodes for the Electrochemical Splitting of

Water», invited talk, Advanced Materials Seminar, EPFL, February 26, 2018, Lausanne, Switzerland.

• E.Fabbri,M.Nachtegaal,T.Binninger,X.Cheng,B.-J.Kim,F.Bozza,T.Graule,T.J.Schmidt,«Perovskite

Nano-Catalysts as Oxygen Electrodes for the Electrochemical Splitting of Water», invited talk, ModVal 2018

– 15th Symposium on Modeling and Experimental Validation of Electrochemical Energy Devices, April 12–13,

2018, Aarau, Switzerland.

• D.F.Abbott,E.Fabbri,M.Borlaf,F.Bozza,R.Schaublin,N.Nachtegaal,T.Graule,T.J.Schmidt,«OperandoX-

Ray Absorption Investigations into the Oxygen Evolution Activity, Stability, and pH Dependency of Ni1-xFexOy

Nanoparticles», invited talk, 233rd Electrochemical Society Meeting, May 12–17, 2018, Seattle, USA.

• P. Broekmann, «Morphology Matters: Additive-Assisted Metal Foam Deposition for the Electro-chemical CO2

Conversion», invited talk, 233rd Electrochemical Society Meeting, May 12–17, 2018, Seattle, USA.

• M. Rahaman, A. Dutta, A. Zanetti, P. Broekmann, «Towards C3 alcohol formation: Electrochemical conversion

of CO2 on activated Cu mesh catalysts», poster, 14th International Fischer Symposium, May 28, 2018, Kloster

Seeon, Germany.

• A. Dutta, A. Kuzume, V. Kaliginedi, M. Rahaman, S. Vesztergom, P. Broekmann, «Understanding the struc-

tural and chemical changes of SnO2 nanoparticles during CO2electro-catalysisderivedfromoperandoXAS

and Raman Spectroscopy», poster, 14th International Fischer Symposium, May 28, 2018, Kloster Seeon,

Germany.

• A. Comas Vives, «What can Bonding Analysis and Ab Initio Molecular Dynamics tell us from Heterogeneous

Catalysts?»,invitedtalk,YoungFacultyMeetingoftheChemistryPlatformoftheSwissAcademyofSciences,

June 5, 2018, Bern, Switzerland.

• E. Fabbri, «Oxygen Evolution Reaction – The Enigma in Water Electrolysis», invited talk, The 11thYoungFac-

ulty Meeting, June 5, Bern, Switzerland.

• C.Copéret,«IsolatedSitesatSurfacesandInterfacesforEfficientCatalysis»,invitedtalk,GordonConfer-

ence on Catalysis, June 24, 2018, New London NH, USA.

• T.J. Schmidt, «The Oxygen Evolution Reaction – From the Catalyst to the Cell Level», invited talk, Gordon

ResearchConferenceonFuelCells,August2,2018,Smithfield,RI,USA.

• C.Copéret,«Molecularunderstandingandcontrolledfunctionalizationofsurfacestowardssingle-sitecata-

lystsandbeyond»,invitedtalk,TOCAT8,August5,2018,Yokohama,Japan.

• E.Fabbri,M.Nachtegaal,T.Binninger,X.Cheng,B.-J.Kim,F.Bozza,T.Graule,T.J.Schmidt,«Insightsinto

Perovskite Nano-Catalysts as Oxygen Electrodes for the Electrochemical Splitting of Water», invited talk,

69th Annual Meeting of the International Society of Electrochemistry, September 2–7, 2018, Bologna, Italy.

• D.Perego,J.Herranz,S.M.Taylor,A.Pătru,T.J.Schmidt,«DifferentialElectrochemicalMassSpectrometry

(DEMS) for Electrocatalysis», contributed talk, 69th Annual Meeting of the International Society of Electro-

chemistry, September 2–7, 2018, Bologna, Italy.

Presentations

87 Appendix

• Y.Hou,R.Erni,R.Widmer,M.Rahaman,H.Guo,R.Fasel,P.Moreno-García,Y.Zhang,P.Broekmann,«Elec-

trocatalytic CO2 Reduction on Robust Cu@CuPd Core-shell Nanowires», contributed talk, 69th annual meeting

of the International Society of Electrochemistry (ISE), September 3, Bologna, Italy.

• A. Rudnev, K. Kiran, I. Gjuroski, D. Vasilyev, P. Dyson, J. Furrer, P. Broekmann, «Mass transport effects in

Electrochemical CO2 Conversion from Ionic liquids», contributed talk, 69th annual meeting of the Interna-

tional Society of Electrochemistry (ISE), September 3, Bologna, Italy.

• A.Rudnev,K.Kiran,A.CedeñoLópez,A.Dutta,P.Broekmann,«EnhancedElectrocatalyticCO2 Conversion

on Nanostructured Silver Electrodes in Ionic Liquids», poster, 69th annual meeting of the International Soci-

ety of Electrochemistry (ISE), September 3, Bologna, Italy.

• A. Dutta, I. Zelocualtecatl Montiel, M. Rahaman, P. Broekmann, «Compositionally variant CuAg bimetallic

foam: Towards selective electrochemical CO2 conversion into ethanol», poster, SCS Fall Meeting, Septem-

ber 7, Lausanne, Switzerland.

• A.Dutta,C.Morstein,M.Rahaman,A.CedeñoLópez,P.Broekmann,«BeyondCopperinCO2 Electrolysis:

Effective Hydrocarbon Production on Silver Nano-Foam Catalysts», poster, SCS Fall Meeting, September 7,

2018, Lausanne, Switzerland.

• L.Foppa,T.Margossian,S.M.Kim,C.Müller,C.Copéret,K.Larmier,A.Comas-Vives,«TheRoleofNi/Al2O3

Interfaces in Water-Gas Shift and Dry Reforming Elucidated by Multi-Scale First Principles Modeling», oral

presentation, Swiss Chemical Society (SCS) Fall Meeting, September 7, 2018, Lausanne, Switzerland.

• A.Dutta,A.Kuzume,V.Kaliginedi,M.Rahaman,I.Sinev,B.RoldánCuenya,S.Vesztergom,P.Broekmann,

«Understanding the structural and chemical changes of SnO2 nanoparticles during CO2 electro-catalysis

derivedfromoperandoXASandRamanSpectroscopy»,poster,SCSFallMeeting,September7,2018,

Lausanne, Switzerland.

• A. Comas Vives, «Dynamics and Adlayer Effects Drive the CO Activation on Ru-catalyzed Fischer-Tropsch

Synthesis», invited talk, European Materials Research Society Fall meeting, September 17–20, 2018,

Warsaw, Poland.

• J.Herranz,A.A.Permyakova,M.ElKazzi,M.Povia,A.Pătru,T.J.Schmidt,«DisclosingtheOxidationState

of Copper Oxides Upon Electrochemical CO2-Reduction», contributed talk, AiMES 2018 ECS and SMEQ Joint

International Meeting, September 30 – October 4, 2018, Cancun, Mexico.

• A.Pătru,S.Taylor,O.Nibel,D.Perego,C.Borca,M.Bohm,F.Oldenburg,F.Huthwelker,L.Gubler,

T.J.Schmidt,«Insightsintoelectrodesandelectrolytesintheallvanadiumredoxflowbatteries»,contributed

talk, 234th ECS Fall Spring Meeting, October 1–6, 2018, Cancun, Mexico.

• M.Povia,J.Herranz,T.Binninger,D.F.Abbott,B.-J.Kim,M.Nachtegaal,T.J.Schmidt,«ACombinedSAXS

andXASSetupofOperandoElectrocatalystDegradationStudies»,contributedtalk,234th ECS Fall Spring

Meeting, October 1–6, 2018, Cancun, Mexico.

• A.Pătru,B.Pribyl,T.Binninger,T.J.Schmidt,«NewCo-ElectrolysisCellDesignwithImprovedCO2 Reduction

Efficiency»,contributedtalk,234th ECS Fall Spring Meeting, October 1–6, 2018, Cancun, Mexico.

• M. Calizzi, R. Mutschler, N. Patelli, L. Pasquini, A. Züttel, «FeCo Nanoparticles for CO2 Hydrogenation»,


• J. Zhang, W. Luo, A. Züttel, «Electrochemical CO2 Reduction Toward CO and Ethanol», poster, 7th Symposium


• K. Zhao, L. Wang, M. Calizzi, E. Moioli, A. Züttel, «Evolution of Adsorption Species During CO2 Hydrogena-

tion on Ru/AI2O3: Intermediates or Byproducts?», poster, 7th Symposium SCCER Heat and Electricity Storage,


• N.Kaeffer,C.Mavrokefalos,H.-J.Liu,C.Copéret,«SupportingCopperNanoparticlesonCarbonviaSurface

Organometallic; Chemistry: Application in CO2 Electroconversion and Selective Hydrogenation», poster,


• E.Lam,K.Larmier,D.Lebedev,P.Wolf,S.Tada,O.Safanova,C.Copéret,«IsolatedZrSurfaceSiteson

Silica Promote Hydrogenation of CO2 to CH3OH in Supported Cu Catalysts», poster, 7th Symposium SCCER


• G.Noh,E.Lam,K.Larmier,P.Wolf,C.Copéret,«TheRoleofTiSupportingCuNanoparticlesintheSelective

Hydrogenation of CO2 to Methanol», poster, 7th Symposium SCCER Heat and Electricity Storage, November 6,


Presentations

88 Appendix

• A.Bornet,Y.Hou,P.Moreno-Garcia,M.deJesúsGálvezVázquez,I.ZelocualtecatiMontiel,P.Broekmann,

«Degradation Study of Cu Nanocubes in Electrochemical CO2 Reduction», poster, 7th Symposium SCCER Heat

and Electricity Storage, November 6, 2018, Rapperswil, Switzerland.

• A. Dutta, I.Z. Montiel, J. Drnec, M. Rahaman, P. Broekmann, «Bimetallice CuAg Nano Foam Catalyst:

Towards Electrochemical CO2 Conversion into Selective Ethanol», poster, 7th Symposium SCCER Heat and


• Y.Hou,S.Bolat,A.Bornet,Y.Romanyuk,P.Moreno-Garcia,I.ZelocualtecatiMontiel,V.Grozovski,P.Broek-

mann, «Design and Fabrication of Novel Metallic Copper Membrane Catalysts for Electrochemical CO2 Reduc-

tion», poster, 7th Symposium SCCER Heat and Electricity Storage, November 6, 2018, Rapperswil, Switzer-

land.

• Y.Hou,R.Erni,R.Widmer,R.Fasel,P.Broekmann,«SynthesisandCharacterizationofCu@CuPdNanowire

CatalystsfortheEfficientProductiionofFormateandCOfromCO2», poster, 7th Symposium SCCER Heat and


• K.Kiran,A.V.Rudnev,J.Gjuroski,A.CedeñoLopéz,A.Dutta,J.Furrer,P.Broekmann,«EnhancedElectro-

catalytic CO2 Conversion on Nanostructure Silver Electrodes in Ionic Liquids», poster, 7th Symposium SCCER


• P.Moreno-Garcia,Y.Hou,M.Rahaman,P.Broekmann,«TowardsEfficientElectrochemicalN2Reductionat

Room Temperature and Pressure through Hydride Transfer Mechanism on Cu@CuPD Nanowires», poster,


• M.Rahaman,K.Kiran,A.Dutta,P.Broekmann,«TowardsSelectiveC3AlcoholFormation:EfficientCO2 Con-

version on Activated Cu-Pd Catalysts», poster, 7th Symposium SCCER Heat and Electricity Storage, Novem-

ber 6, 2018, Rapperswil, Switzerland.

• A.V. Rudnev, I. Gjuroski, K. Kiran, D. Vasilyev, P. Dyson, J. Furrer, P. Broekmann, «Mass Transport Effets in

Electrochemical CO2 Conversion from Ionic Liquids», poster, 7th Symposium SCCER Heat and Electricity Stor-

age, November 6, 2018, Rapperswil, Switzerland.

• J.Herranz,A.A.Permyakova,M.ElKazzi,J.Diercks,L.Mangani,M.Povia,A.Pătru,T.J.Schmidt,«Disclosing

the Oxidation State of Copper Oxides Upon Electrochemical CO2 Reduction», poster, 7th Symposium SCCER


• D. Perego, J. Herranz, T.J. Schmidt, «Differential Electrochemical Mass Spectrometry (DEMS) for Electro-

catalysis», poster, 7th Symposium SCCER Heat and Electricity Storage, November 6, 2018, Rapperswil,

Switzerland.

• B.Pribyl,A.Pătru,T.Binninger,T.J.Schmidt,«EfficientCO2 Reduction from Gas Phase at low Temperatures

inaBipolarlikeCo-ElectrolysisCellConfigurationandComparisontoLiquidPhaseCO2 Reduction», poster,


• D.Lebedev,R.Ezhov,N.Kaeffer,M.Willinger,X.Huang,Y.Pushkar,C.Copéret,«FromNanoparticlesto

Single Sites – Decreasing the Noble Metal Content in Anodic Water Oxidation Catalysts», poster, 7th Sympo-



Organometallic; Chemistry: Application in CO2 Electroconversion and Selective Hydrogenation», poster,



Silica Promote Hydrogenation of CO2 to CH3OH in Supported Cu Catalysts», poster, 7th Symposium SCCER



Hydrogenation of CO2 to Methanol», poster, 7th Symposium SCCER Heat and Electricity Storage, November 6,


• J. Roth, «Energiespeicherung im Energiesystem von Morgen», invited talk, Aargauer Energie Aperos, Novem-

ber27,2018,Zofingen,Switzerland.

• T.J. Schmidt, «Energiespeicherung im Energiesystem von Morgen», invited talk, Aargauer Energie Aperos,

November 20, 2018, Baden, Switzerland.

• T.J. Schmidt, «Energiespeicherung im Energiesystem von Morgen», invited talk, Aargauer Energie Aperos,

November22,2018,Zofingen,Switzerland.

• D.Perego,J.Herranz,S.M.Taylor,A.Pătru,T.J.Schmidt,«DifferentialElectrochemicalMassSpectrometry

(DEMS) for Electrocatalysis», contributed talk, 2018 MRS Fall Meeting, November 25–30, 2018, Boston, USA.

Presentations

89 Appendix

• T.J. Schmidt, «The Oxygen Evolution Reaction – Properties of IrO2», invited talk, University of Cape Town,

HySA Catalysis, November 29, 2018, Cape Town, South Africa.

• D. Perego, J. Herranz, T.J. Schmidt, «Differential Electrochemical Mass Spectrometry (DEMS) for Electroca-

talysis: An Overview», invited seminar, Politecnico di Milano, December 13, 2018, Milan, Italy.

• P.J. Dyson, «Valorizing waste to produce sustainable chemicals via catalytic routes», European Sustainable

Chemistry Award Lecture, 7th EuCheMS Chemistry Congress, Liverpool, UK.

• P.J. Dyson, «Improving the sustainability of reactions by modifying the environment of the catalyst», Clariant

CleanTech Lecture, University of Basel, Switzerland.

• F.D. Bobbink, «Design of ionic polymer catalysts for the synthesis of carbonates from CO2 and epoxides»,

ACS National Meeting, New Orleans, USA.

• F.D. Bobbink, «A Catalytic CO2 scrubber that generates cyclic carbonates from simple epoxide: ionic liquid

mixtures», SCS Fall Meeting, Lausanne, Switzerland.

• M. Hulla, G. Laurenczy, P.J. Dyson, «N-Formylation of Amines with CO2 and Hydrosilanes Reactivity, Scope

and Mechanism», SCS Fall Meeting, Lausanne, Switzerland.

• D.V. Vasilyev, A.V. Rudnev, P. Broekmann, P.J. Dyson, «Choline-based systems for electro-chemical reduction

ofcarbondioxide»,InternationalSummerSchool«PowertoX:FundamentalsandApplicationsofModern

Electrosynthesis».

Work Package «Assessment – Interactions of Storage Systems»

• M.Beuse,T.S.Schmidt,X.Zhang,B.Steffen,S.F.Schneider,A.PenaBello,C.Bauer,D.ParraMendoza,

«Life Cycle Emissions and Life Cycle Cost Analysis for Stationary Batteries in Different Geographies», EnIn-

nov 2018: 15th Symposium Energieinnovation, February 14–16, 2018, TU Graz, Graz, Austria.

• P. Schütz, D. Gwerder, A. Stamatiou, R. Waser, D. Sturzenegger, M. Aprile, A. Armijo, B. Arregi, P. Elgueza-

bal,R.Scoccia,A.Sivieri,J.Worlitschek,«Fastsimulationplatformforretrofittingmeasuresinresidential

heating», Cold Climate HVAC 2018 – The 9th International Cold Climate Conference Sustainable New and

Renovated Buildings in Cold Climates, March 3, 2018, Kiruna, Sweden.

• A. Malhotra, T.S. Schmidt, J. Huenteler, «Technological Learning in Low-Carbon Innovation Policy», Center

for International Environment and Resource Policy Research Seminar, April 9, 2018, Tufts University, Boston,

USA.

• T.S. Schmidt, M. Beuse, B. Steffen, colleagues from PSI and UNIGE, «Economic and environmental assess-

ment of different battery technologies for different grid network applications», Discussion Forum Life-Cycle

Assessment, April 16, 2018, Zurich, Switzerland.

• P. Schütz, D. Gwerder, A. Stamatiou, R. Waser, D. Sturzenegger, J. Worlitschek, M. Aprile, A. Armijo, B. Ar-

regi, P. Elguezabal, R. Scoccia, A. Sivieri, «Fast Assessment Platform for Energy Consumption of Different

ConfigurationsinResidentialHeatingwithThermalStorages»,Enerstock2018,April24,2018,Çukurova

University, Turkey.

• D. Parra, «Conference de Jeudi: Context, trends and challenges of energy storage», invited talk, University

of Geneva, May 2018, Geneva, Switzerland.

• A. Malhotra, T.S. Schmidt, J. Huenteler, «Interactive learning and technology life-cycles – Explaining the

patterns of innovation and learning in three clean energy technological innovation systems», 9th International

Sustainability Transition Conference, June 12–14, 2018, Manchester, UK.

• J. Roth,Podiumsdiskussion «Revolution oder Evolution: Das vernetzte Energiesystem», Integrated Energy

Plazza, Hannover Fair 2018, April 23, 2018, Hannover, Germany.

• J. Roth, «Experience Exchange: Balancing the feed-in of wind and solar power what is needed», Integrated

Energy Plazza, Hannover Fair 2018, April 26, 2018, Hannover, Germany.

• P. Schütz, R. Durrer, D. Gwerder, M. Geidl, J. Worlitschek, «Operation state recognition for heat pumps from

smart grid monitoring data», International Conference on Energy Engineering and Smart Grids (ESG 2018),

Fitzwilliam College, University of Cambridge, June 25, 2018, Cambridge City, UK.

• A.Malhotra,H.Zhang,T.S.Schmidt,«Theinfluenceofselectionpressuresontechnologicalevolutionincom-

plex artifacts – An analysis of innovation patterns in lithium-ion batteries», Conference of the International

Schumpeter Society (ISS), July 2–4, 2018, Seoul, Republic of Korea.

• M. Patel, Finanz und Wirtschaft Forum «Smart Energy 2018: Welche Energiespeicher sind rentabel? Die öko-

nomische Sicht», invited talk, Gottlieb Duttweiler Institut, July 2018, Rüschlikon, Switzerland.

Presentations

90 Appendix

• M.Beuse,B.Steffen,T.S.Schmidt,«Competitionofstationarybatteries:Influenceofe-mobility»,Strom-

markttreffen ‹Batterien: Kostenentwicklung, Technologien, Anwendungen›, July 27, 2018, Berlin, Germany.

• M. Berger, J. Worlitschek, «Feedback between anthropogenic factors and climate: energy consumption for

space heating», 17th Annual CMAS Conference, October 10, 2018, Chapel Hill, NC, USA.

• A. Malhotra, H. Zhang, M. Beuse, T.S. Schmidt, «Windows of Opportunity in the Lithium-Ion Battery Industry

– A Patent-Citation Network Analysis», Advanced Automotive Battery Conference (AABC) Asia, October 15,

2018, Osaka, Japan.

• A. Malhotra, H. Zhang, M. Beuse, T.S. Schmidt, «Windows of Opportunity in the Lithium-Ion Battery Industry

– A Patent-Citation Network Analysis», 7th SCCER HaE Symposium, November 6, 2018, Rapperswil, Switzer-

land.

• A. Malhotra, T.S. Schmidt, J. Huenteler, «Inter-Sectoral Learning in Technological Innovation Systems»,

7th SCCER HaE Symposium, November 6, 2018, Rapperswil, Switzerland.

• M. Beuse, B. Steffen, T.S. Schmidt, «Competitive Dynamics of Stationary Electricity Storage», 7th SCCER HaE

Symposium, November 6, 2018, Rapperswil, Switzerland.

• P. Roos, G. Zanganeh, E. Jacquemoud, P. Jenny, M. Scholtysik, J. Roncolato, M. Barbato, J. Garrison,

A.Fuchs,T.Demiray,A.Haselbacher,«InvestigationofAA-CAESPlantConfigurationsandGridIntegration»,


• M. Berger, S. Frehner, J. Worlitschek, «Temperature-Derived Heating and Cooling Loads», poster, 7th Sympo-


• R. Durrer, D. Gwerder, M. Geidl, M. Cherepanova, R. Ackermann, J. Worlitschek, P. Schuetz, «Valorisation of

Smart Grid Monitoring Data», poster, 7th Symposium SCCER Heat and Electricity Storage, November 6, 2018,


• P. Schuetz, A Melillo, F. Businger, R. Durrer, D. Gwerder, J. Worlitschek, «Fast Automated Modelling of Build-

ing Dynamics based on Smart Grid Monitoring Data», poster, 7th Symposium SCCER Heat and Electricity

Storage, November 6, 2018, Rapperswil, Switzerland.

• R. Gupta, M Soini, M.K. Patel, D. Parra, «Optimised Electricity Storage Technologies to Supply Renewable

Electricity on Demand under Different Supply Modes and Scales», poster, 7th Symposium SCCER Heat and


• M.C. Soini, D. Parra, M.K. Patel, «Disaggregation of Energy Storage Operation by Time Scales», poster,


• A. Pena-Bello, P. Schuetz, M. Berger, J. Worlitschek, M.K. Patel, D. Parra, «PV-Coupled Heat Pump Systems

Supported by Electricity and Heat Storage: Impacts and Trade-offs for Consumers and the Grid», poster,


• A. Pena-Bello, E. Barbour, M.C. Gonzalez, M.K. Patel, D. Parra, «Optimization of PV-Coupled Battery Systems

for Combining Applications: Impact of Battery Technology and Location», poster, 7th Symposium SCCER Heat

and Electricity Storage, November 6, 2018, Rapperswil, Switzerland.

• S.F.Schneider,E.J.Berg,C.Bauer,P.Novák,«ATechno-EconomicandEnvironmentalAssessmentofFuture

Na-Ion Batteries», poster, 7th Symposium SCCER Heat and Electricity Storage, November 6, 2018, Rapper-

swil, Switzerland.

• T.S.Schmidt,M.Beuse,X.Zhang,B.Steffen,S.F.Schneider,A.Pena-Bello,C.Bauer,D.Parra,«Storing

Electricity with Different Battery Technologies: What are the Associated Life-Cycle Costs (LCC) & Life-Cycle

Greenhouse Gas Emissions (LCE)?», poster, 7th Symposium SCCER Heat and Electricity Storage, November 6,


• X.Zhang,T.Terlouw,S.F.Schneider,C.Bauer,«LifeCycleAssessmentofBatteries–theEnvironmental

Perspective», poster, 7th Symposium SCCER Heat and Electricity Storage, November 6, 2018, Rapperswil,

Switzerland.

• Z.Stadler,S.Moret,T.Damartzis,B.Meier,M.Friedl,F.Maréchal,«CarbonFlowsintheEnergyTransition»,


• M.Friedl,L.C.R.deSousa,S.Moebus,«ProjectHEPP:HighEfficiencyPower-to-MethanePilot»,poster,


• M. Berger, S. Frehner, J. Worlitschek, «HVAC design based on Swiss Climate Scenarios CH2018», 16th Swiss

Geoscience Meeting, November 11, 2018, Bern, Switzerland.

Presentations

91 Appendix

Work Package «Heat – Thermal Energy Storage»

• J. Marti, L. Geissbühler, V. Becattini, A. Haselbacher, A. Steinfeld, «Constrained multi-objective optimization

of thermocline packed-bed thermal-energy storage», Applied Energy, 216, 694–708, 2018.

• L. Geissbühler, V. Becattini, G. Zanganeh, S. Zavattoni, M. Barbato, A. Haselbacher, A. Steinfeld, «Pilot-scale

demonstration of advanced adiabatic compressed air energy storage, Part 1: Plant description and tests with

sensible thermal-energy storage», Journal of Energy Storage, 17, 129–139, 2018.

• V. Becattini, L. Geissbühler, G. Zanganeh, A. Haselbacher, A. Steinfeld, «Pilot-scale demonstration of

advanced adiabatic compressed air energy storage, Part 2: Tests with combined sensible/latent thermal-

energy storage», Journal of Energy Storage, 17, 140–152, 2018.

• S.A. Zavattoni, G. Zanganeh, A. Pedretti, M.C. Barbato, «Numerical analysis of the packed bed TES systems

integratedintothefirstparabolictroughCSPpilot-plantusingairasheattransferfluid»,AIPConference

Proceedings 2033, 090027, 2018.

• L.J. Fischer, S. Maranda, A. Stamatiou, S. von Arx, J. Worlitschek, «Experimental Investigation on Heat

Transfer with a Phase Change Dispersion», Applied Thermal Engineering, 147, 2018.

• R. Waser, F. Ghani, S. Maranda, T.S. O’Donovan, P. Schuetz, M. Zaglio, J. Worlitschek, «Fast and experi-

mentally validated model of a latent thermal energy storage device for system level simulations», Applied

Energy, 231, 116–126, 2018.

• R.Waser,S.Maranda,A.Stamatiou,M.Zaglio,J.Worlitschek,«Modelingofsolidificationincludingsupercool-

ingeffectsinafin-tubeheatexchangerbasedlatentheatstorage»,SolarEnergy,inpress.

• A. Stamatiou, S. Maranda, F. Eckl, P. Schuetz, L.J. Fischer, J. Worlitschek, «Quasi-stationary modelling of

solidificationinalatentheatstoragecomprisingaplaintubeheatexchanger»,JournalofEnergyStorage,

20, 551–559, 2018.

• R. Ravotti, O. Fellmann, N. Lardon, L.J. Fischer, A. Stamatiou, J. Worlitschek, «Synthesis and Investigation

of Thermal Properties of Highly Pure Carboxylic Fatty Esters to Be Used as PCM», Applied Sciences, 8, 1069,

2018.

• S. Ammann, A. Ammann, R. Ravotti, L.J. Fischer, A. Stamatiou, J. Worlitschek, «Effective Separation of a

Water in Oil Emulsion from a Direct Contact Latent Heat Storage System», Energies, 11 (9), 2264, 2018.

• S. Krimmel, A. Stamatiou, J. Worlitschek, H. Walter, «Experimental Characterization of the Heat Transfer in

a Latent Direct Contact Thermal Energy Storage with One Nozzle in Labor Scale», International Journal of

Mechanical Engineering, 3, 83–97, 2018.

Work Package «Batteries – Advanced Batteries and Battery Materials»

• R. Hischier, N. H. Kwon, J.-P. Brog, K.M. Fromm, «Early-Stage Sustainability Evaluation of Nanoscale Cathode

Materials for Lithium Ion Batteries», ChemSusChem. 11, 1–10, 2018.

• B.Schönholzer,A.Fuerst,«SteuerungskonzeptfürdiehochflexibleBatteriezellenherstellungSwissEngineer-

ing», ISSN 1660-4121, 5, 12–13, 2018.

• M.G.Fischer,X.Hua,B.D.Wilts,E.Castillo-Martínez,U.Steiner,«Polymer-TemplatedLiFePO4/CNanonet-

works as High-Performance Cathode Materials for Lithium-Ion Batteries», ACS Appl. Mater. Interfaces, 10,

1646–1653, 2018.

• C. Marino, J. Cabanero, M. Povia, C. Villevieille, «Biowaste lignin-based carbonaceous materials as anode for

Na-ion batteries», Journal of the Electrochemical Society, 165, A1400, 2018.

• K.V. Kravchyk, L. Piveteau, R. Caputo, M. He, N.P. Stadie, M.I. Bodnarchuk, R.T. Lechner, M.V. Kovalenko,

«Colloidal Bismuth Nanocrystals as a Model Anode Material for Rechargeable Mg-Ion Batteries: Atomistic and

Mesoscale Insights», ACS Nano, 12, 8, 8297–8307, 2018.

• S. Wang, M. He, M. Walter, F. Krumeich, K.V. Kravchyk, M.V. Kovalenko, «Monodisperse CoSn2 and FeSn2

nanocrystals as high-performance anode materials for lithium-ion batteries», Nanoscale, 10, 15, 6827–6831,

2018.

• K.V. Kravchyk, T. Zünd, M. Wörle, M.V. Kovalenko, M.I. Bodnarchuk, «NaFeF3 Nanoplates as Low-Cost So-

dium and Lithium Cathode Materials for Stationary Energy Storage», Chemistry of Materials, 6, 30, 1825–

1829, 2018.

• M. Walter, K.V. Kravchyk, C. Böfer, R. Widmer, M.V. Kovalenko, «Polypyrenes as High-Performance Cathode

Materials for Aluminum Batteries», Advanced Materials, 15, 30, 1705644, 2018.

Publications

92 Appendix

Publications

• M. Walter, S. Doswald, F. Krumeich, M. He, R. Widmer, N. Stadie, M.V. Kovalenko, «Oxidized Co-Sn Nanopar-

ticles as Long-Lasting Anode Materials for Lithium-Ion Batteries», Nanoscale, 8, 10, 3777–3783, 2018.

• C.P. Guntlin, S.T. Ochsenbein, M. Wörle, R. Erni, K.V. Kravchyk, M.V. Kovalenko, «Popcorn-shaped FexO

(Wüstite) Nanoparticles from a Single-Source Precursor: Colloidal Synthesis and Magnetic Properties»,

Chemistry of Materials Chem. Mater., 4, 30, 1249–1256, 2018.

• S. Wang, K.V. Kravchyk, A.N. Filippin, U. Müller, A.N. Tiwari, S. Buecheler, M.I. Bodnarchuk, M.V. Kovalenko,

«Aluminum Chloride-Graphite Batteries with Flexible Current Collectors Prepared from Earth-Abundant Ele-

ments», Advanced Science, 4, 5, 1700712, 2018.

• E.Marelli,C.Villevieille,S.Park,N.Hérault,C.Marino,«Co-FreeP2–Na0.67Mn0.6Fe0.25Al0.15O2 as Promising

Cathode Material for Sodium-Ion Batteries», ACS Applied Energy Materials, 1, 11, 5960–5967, 2018.

• C. Marino, E. Marelli, S. Park, C. Villevieille, «Impact of Water-Based Binder on the Electrochemical Perfor-

mance of P2-Na0.67Mn0.6Fe0.25Co0.15O2 Electrodes in Na-Ion Batteries», Batteries, 4 (4), 66, 2018.

• K.V. Kravchyk, P. Bhauriyal, L. Piveteau, C.P. Guntlin, B. Pathak, M.V. Kovalenko, «High-energy-density dual-

ionbatteryforstationarystorageofelectricityusingconcentratedpotassiumfluorosulfonylimide»,Nature

Communications, 9, 4469, 2018.

• K.V. Kravchyk, L. Piveteau, R. Caputo, M. He, N.P. Stadie, M.I. Bodnarchuk, R.T. Lechner, M.V. Kovalenko,

«Colloidal Bismuth Nanocrystals as a Model Anode Material for Rechargeable Mg-Ion Batteries: Atomistic and

Mesoscale Insights», ACS Nano, 12 (8), 8297–8307, 2018.

• A.N.Filippin,T.-Y.Lin,M.Rawlence,T.Zünd,K.V.Kravchyk,J.Sastre-Pellicer,S.G.Haass,A.Wäckerlin,

M.V. Kovalenko, S. Buecheler, «Ni–Al–Cr superalloy as high temperature cathode current collector for ad-

vancedthinfilmLibatteries»,RSCAdvances,8,20304–20313,2018.

• J.Liu,S.Wang,K.V.Kravchyk,M.Ibáñez,F.Krumeich,R.Widmer,D.Nasiou,M.Meyns,J.Llorca,J.Arbiol,

M. Kovalenko, A.Cabot, «SnP nanocrystals as anode material for Na-ion battery», Journal of Materials Chem-

istry A, 6, 10958–10966, 2018.

• S. Wang, M. He, M. Walter, F. Krumeich, K.V. Kravchyk, M.V. Kovalenko, «Monodisperse CoSn2 and FeSn2

nanocrystals as high-performance anode materials for lithium-ion batteries», Nanoscale, 10 (15), 6827–

6831, 2018.

• K.V. Kravchyk, T. Zünd, M. Wörle, M.V. Kovalenko, M.I. Bodnarchuk, «NaFeF3 Nanoplates as Low-Cost

Sodium and Lithium Cathode Materials for Stationary Energy Storage», Chemistry of Materials, 6 (30),

1825–1829, 2018.

• M. Walter, S. Doswald, F. Krumeich, M. He, R. Widmer, N. Stadie, M.V. Kovalenko, «Oxidized Co-Sn Nanopar-

ticles as Long-Lasting Anode Materials for Lithium-Ion Batteries», Nanoscale, 8 (10), 3777–3783, 2018.

• C.P. Guntlin, S.T. Ochsenbein, M. Wörle, R. Erni, K.V. Kravchyk, M.V. Kovalenko, «Popcorn-shaped FexO

(Wüstite) Nanoparticles from a Single-Source Precursor: Colloidal Synthesis and Magnetic Properties»,

Chemistry of Materials, 4 (30), 1249–1256, 2018.

• F. Pagani, E. Stilp, R. Pfenninger, E.C. Reyes, A. Remhof, Z. Balogh-Michels, A. Neels, J. Sastre-Pellicer,

M. Stiefel, M. Döbeli, M.D. Rossell, R. Erni, J.L. M. Rupp, D. Battaglia, «Epitaxial Thin Films as a Model Sys-

tem for the Li-Ion Conductivity in Li4Ti5O12», ACS Appl. Mater. Interfaces, 10, 44494, 2018.

• J. Conder, C. Villevieille, «How reliable is the Na metal as a counter electrode in Na-ion half cells?», Chem.

Comm., 55, 1275–1278, 2019 (accepted on the Dec. 20, 2018).

Work Package «Hydrogen – Production and Storage»

• T.N. Nguyen, S. Kampouri, B. Valizadeh, W. Luo, D. Ongari, O.M. Planes, A. Züttel, B. Smit, K.C. Stylianou,

«Photocatalytic Hydrogen Generation from a Visible-Light-Responsive Metal-Organic Framework System:

StabilityversusActivityofMolybdenumSulfideCocatalysts»,ACSAppliedMaterials&Interfaces,10(36),

30035–30039, 2018.

• L.Lombardo,H.Yang,A.Züttel,«Destabilizingsodiumborohydridewithanionicliquid»,MaterialsToday

Energy, 9, 391–396, 2018.

• H.Yang,L.Lombardo,W.Luo,W.Kim,A.Züttel,«Hydrogenstoragepropertiesofvariouscarbonsupported

NaBH4 prepared via metathesis», Int. Journal of Hydrogen Energy, 43 (14), 7108–7116, 2018.

• N.Onishi,G.Laurenczy,M.Beller,Y.Himeda,«Recentprogressforreversiblehomogeneouscatalytichydro-

gen storage in formic acid and in methanol», Coordination Chemistry Reviews, 332, 373–317, 10.1016/j.

ccr.2017.11.021, 2018.

93 Appendix

• C. Fink, L. Chen, G. Laurenczy, «Homogeneous Catalytic Formic Acid Dehydrogenation in Aqueous Solution

using Ruthenium Arene Phosphine Catalysts», Zeitschrift für anorganische und allgemeine Chemie, 644,

740–744, 10.1002/zaac.201800107, 2018.

• Z.Xin,J.Zhang,K.Sordakis,M.Beller,C.-X.Du,G.Laurenczy,Y.Li,«TowardsHydrogenStoragethroughan

EfficientRuthenium-CatalyzedDehydrogenationofFormicAcid»,ChemSusChem,11,2077–2082,10.1002/

cssc.201800408, 2018.

• M. Montandon-Clerc, G. Laurenczy, «Additive free room temperature direct homogeneous catalytic carbon

dioxide hydrogenation in aqueous solution using an iron(II) phosphine catalyst», Journal of Catalysis, 362,

78–84, 10.1016/j.jcat.2018.03.030, 2018.

• I.Yuranov,N.Autissier,K.Sordakis,A.F.Dalebrook,M.Grasemann,V.Orava,P.Cendula,L.Gubler,

G. Laurenczy, «Heterogeneous Catalytic Reactor for Hydrogen Production from Formic Acid and Its Use

in Polymer Electrolyte Fuel Cells», ACS Sustainable Chemistry & Engineering, 6, 6635–6643, 10.1021/

acssuschemeng.8b00423, 2018.

• K. Sordakis, C. Tang, L.K.Vogt, H. Junge, P.J. Dyson, M. Beller, G. Laurenczy, «Homogeneous Catalysis for

Sustainable Hydrogen Storage in Formic Acid and Alcohols», Chemical Reviews, 118, 372–433, 10.1021/acs.

chemrev.7b00182, 2018.

• PhD thesis of Cornel Fink, No 8739 (2018) EPFL, «High-pressure NMR spectroscopic and calorimetric studies

on formic acid dehydrogenation and carbon dioxide hydrogenation».

• PhD thesis of Mickael Montandon-Clerc, No 8594 (2018) EPFL, «Hydrogen storage in the carbon dioxide/for-

mic acid system, using homogeneous iron(II)-phosphine catalysts in aqueous solution».

• M. Spodaryk, N. Gasilova, A. Züttel, «Hydrogen storage and electrochemical properties of LaNi5-xCux hydride-

forming alloys», Journal of Alloys and Compounds, 775, 175–180, 2019.

Work Package «Synthetic Fuels – Development of Advanced Catalysts»

• X.Cheng,E.Fabbri,Y.Yamashita,I.Castelli,B.J.Kim,M.Uchida,R.Haumont,I.O.Puente,T.J.Schmidt,

«Oxygen Evolution Reaction on Perovskites: A Multi-Effect Descriptors Study Combining Experimental and

Theoretical Methods», ACS Catalysis, 8 (10), 9567–9578, 2018.

• S. Luh, S. Budinis, T.J. Schmidt, A. Hawkes, «Decarbonisation of the Industrial Sector by Means of Fuel

Switching,Electrification,andCCS»,ComputerAidedChemicalEngineering;doi:10.1016/B-978-0-444-

64235-6.50230-8, 43, 1311–1316, 2018.

• S.M.Taylor,A.Pătru,D.Perego,E.Fabbri,T.J.Schmidt,«InfluenceofCarbonMaterialPropertiesonActivity

and Stability of the Negative Electrode in Vanadium Redox Flow Batteries – A Model Electrode Study», ACS

Applied Energy Materials, doi:10.1021/acsaem.7b00273, 1, 1166–1174, 2018.

• M. Suermann, T.J. Schmidt, F.N. Büchi, «Comparing the Kinetic Activation Energy of the Oxygen Evolution

and Reduction Reactions», Electrochimica Acta, doi: 10.1016/j.electacta.2018.05.150, 281, 466–471, 2018.

• F.J. Oldenburg, M. Bon, D. Perego, D. Polino, T. Laino, L. Gubler, T.J. Schmidt, «Revealing the Role of Phos-

phoric Acid in all Vanadium Redox Flow Batteries with DFT Calculations and in situ Analysis», Physical Chem-

istry Chemical Physics, doi: 10.1039/c8cp04517h, 2018.

• U. Babic, T.J. Schmidt, L. Gubler, «Contribution of Catalyst Layer Proton Transport Resistance to Volt-

age Loss in Polymer Electrolyte Water Electrolyzers», Journal of The Electrochemical Society, doi:

10.1149/2.0011815jes, 165, J3016-J3018, 2018.

• X.Cheng,E.Fabbri,Y.Yamashita,I.Castelli,B.J.Kim,M.Uchida,R.Haumont,I.PuenteOrench,

T.J. Schmidt, «Oxygen Evolution Reaction on Perovskites: A Multi-Effect Descriptors Study Combining Experi-

mental and Theoretical Methods», ACS Catalysis, 8, 9567–9578, doi: 10.1021/acscatal.8b02022, 2018.

• B.J.Kim,X.Chen,D.F.Abbott,E.Fabbri,F.Bozza,T.Graule,I.E.Castelli,L.Wiles,A.Niedzwiecki,

N. Danilovic, K.E. Ayers, N. Marzari, T.J. Schmidt, «Highly Active Nano-Perovskite Catalysts for Oxygen Evo-

lution Reaction: Insights into Activity and Stability of Ba0.5Sr0.5Co0.8Fe0.2O2+δ and PrBaCo2O5+δ», Adv. Functional

Mater., 28, 1804355, doi: 10.1002/adfm.201804355, 2018.

• E. Fabbri, T.J. Schmidt, «Oxygen Evolution Reaction – The Enigma in Water Electrolysis», ACS Catalysis, 8,

9765–9774, doi: 10.1021/acscatal.8b02712, 2018.

• T.Binninger,B.Pribyl,A.Pătru,P.Ruettimann,S.Bjelic,T.J.Schmidt,«Multivariatecalibrationmethodfor

mass spectrometry of interfering gases such as mixtures of CO, N2, and CO2», Journal of Mass Spectrometry,

53, 1214–1221, doi: 10.1002/jms.4299, 2018.

Publications

94 Appendix

Publications

• S.Erlebacher,B.Pribyl,M.Klages,L.Spitthoff,K.Borah,S.Epple,L.Gubler,A.Pătru,T.J.Schmidt,«Influ-

ence of operating conditions on permeation of CO2 through the membrane in an automotive PEMFC system»,

Int. J. Hydrogen Energy, doi: 10.1016/j.ijhydene.2018.10.033, 2018.

• D.F. Abbott, E. Fabbri, M. Borlaf, F. Bozza, R. Schäublin, M. Nachtegaal, T. Graule, T.J. Schmidt, «Operando

X-RayAbsorptionInvestigationsintotheRoleofFeintheElectrochemicalStabilityandOxygenEvolution

Activity of Ni1-xFexO Nanoparticles», J. Mater. Chem. A, 6, 24534–24549, doi: 10.1039/c8ta09336a, 2018.

• Y.Fu,M.R.Ehrenburg,P.Broekmann,A.V.Rudnev,«SurfaceStructureSensitivityofCO2 Electroreduction on

Low-Index Gold Single Crystal Electrodes in Ionic Liquids», ChemElectroChem, 5 (5), 748, 2018.

• A.Dutta,C.E.Morstein,M.Rahaman,A.CedeñoLópez,P.Broekmann,«BeyondCopperinCO2 Electrolysis:

Effective Hydrocarbon Production on Silver Nano-Foam Catalysts», ACS Catalysis, 8, 8357, 2018.

• A.Dutta,A.Kuzume,V.Kaliginedi,M.Rahaman,I.Sinev,M.Ahmadi,B.RoldánCuenya,S.Vesztergom,

P. Broekmann, «Probing the chemical state of tin oxide NP catalysts during CO2 electroreduction: A comple-

mentary operando approach», Nano Energy, 53, 828, 2018.

• P.Moreno-García,N.Schlegel,A.Zanetti,A.CedeñoLópez,M.deJesúsGálvez-Vázquez,A.Dutta,M.Raha-

man, P. Broekmann, «Selective Electrochemical Reduction of CO2 to CO on Zn-Based Foams Produced by

Cu2+ and Template-Assisted Electrodeposition», ACS Applied Materials & Interfaces, 10, 31355, 2018.

• C. Gütz, V. Grimaudo, M. Holtkamp, M. Hartmer, J. Werra, L. Frensemeier, A. Kehl, U. Karst, P. Broekmann,

S.R. Waldvogel, «Leaded Bronze: An Innovative Lead Substitute for Cathodic Electrosynthesis», ChemElec-

troChem, 5, 2472, 2018.

• D. Vasilyev, E. Shirzadi, A. Rudnev, P. Broekmann, P.J. Dyson, «Pyrazolium Ionic Liquid Co-catalysts for the

Electroreduction of CO2», ACS Applied Energy Materials, 1, 5124, 2018.

• F.Perrin,F.D.Bobbink,E.Păunescu,Z.Fei,R.Scopelliti,G.Laurenczy,S.Katsyuba,P.J.Dyson,«Towardsan

ionic frustrated Lewis pair-ionic liquid system», Inorganica Chimica Acta, 470, 270–274, 2018.

• P.Izák,F.D.Bobbink,M.Hulla,M.Klepic,K.Friess,Š.Hovorka,P.J.Dyson,«Catalyticionic-liquidmem-

branes: the convergence of ionic-liquid catalysis and ionic-liquid membrane separation technologies»,

ChemPlusChem, 83, 7–18, 2018.

• F.D. Bobbink, D. Vasyliev, M. Hulla, S. Chamam, F. Menoud, G. Laurenczy, S. Katsyuba, P.J. Dyson, «Intrica-

cies of cation-anion combinations in imidazolium salt-catalyzed cycloaddition of CO2 into epoxides», ACS

Catalysis, 8, 2589–2594, 2018.

• S. Bulut, S. Siankevich, A.P. van Muyden, D.T.L. Alexander, G. Savoglidis, J. Zhang, V. Hatzimanikatis,

N.Yan,P.J.Dyson,«EfficientcleavageofaryletherC−OlinkagesbyRh-NiandRu-Ninanoscalecatalysts

operating in water», Chemical Science, 9, 5530–5535, 2018.

• F.D. Bobbink, F. Menoud, P.J. Dyson, «Synthesis of methanol and diols from CO2 via cyclic carbonates under

metal-free», ACS Sustainable Chemistry & Engineering, 6 (9), 12119–12123, 2018.

• P.Izák,F.D.Bobbink,M.Hulla,M.Klepic,K.Friess,Š.Hovorka,P.J.Dyson,«CatalyticIonic-LiquidMem-

branes: The Convergence of Ionic-Liquid Catalysis and Ionic-Liquid Membrane Separation Technology»,

ChemPlusChem, 83, 7–18, 2018.

• S.Tada,K.Larmier,R.Büchel,C.Copéret,«MethanolsynthesisviaCO2 hydrogenation over CuO-ZrO2

prepared by Two-Nozzle Flame Spray Pyrolysis», Catalysis Science & Technology, 8, 2056–2060, 2018.

• I.B.Moroz,K.Larmier,W.-C.Liao,C.Copéret,«Discerningγ-Alumina Surface Sites with Nitrogen-15

Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy of Adsorbed Pyridine», Journal of Physical

Chemistry C, 122, 10871–10882, 2018.

• E.Lam,K.Larmier,P.Wolf,S.Tada,O.Safonova,C.Copéret,«IsolatedZrSurfaceSitesonSilicaPromotes

Hydrogenation of CO2 to CH3OH in Supported Cu Catalysts», Journal of the American Chemical Society, 140,

10530–10535, 2018.

• S.-M.Kim,P.Abdala,M.Broda,D.Hosseini,C.Copéret,C.Müller,«IntegratedCO2 capture and conversion

asanefficientprocessforfuelsfromgreenhousegases»,ACSCatalysis,8,2815–2823,2018.

• J.J.Corral-Pérez,A.Bansode,C.S.Praveen,A.Kokalj,H.Reymond,A.Comas-Vives,Aleix,J.VandeVondele,

C.Copéret,P.VonRohr,A.Urakawa,«Decisiverolesofperimetersitesinsilica-supportedAgnanoparticles

in selective hydrogenation of CO2 to methyl formate in the presence of methanol», Journal of the American

Chemical Society, 40, 13884–13891, 2018.

95 Appendix

Publications

Work Package «Assessment – Interactions of Storage Systems»

• M. Berger, J. Worlitschek, «A novel approach for estimating residential space heating demand», Energy, 159,

294–301, 2018.

• A. Hassan, M.K. Patel, D. Parra, «Assessing the impacts of renewable and conventional electricity supply on

the value and cost of power-to-gas», in press, https://doi.org/10.1016/j.ijhydene.2018.10.026

• R. Segundo, D. Parra, N. Wyrsch, M.K. Patel, F. Kienzle, P. Korba. «Techno-economic analysis of battery stor-

age and curtailment in a distribution grid with high PV penetration». Journal of Energy Storage, 17, 73–83,

2018.

• E. Barbour, D. Parra, Z. Alawwad, M. Gonzalez, «Community Energy storage: A smart choice for the smart

grid?», Applied Energy, 212, 489–497, 2018.

• A. Fuchs, D. Parra, «Fokusstudie: Anwendungsfälle und Platzierung von Batteriespeichern in Verteilnetzen –

Technische und organisatorische Aspekte», Forum Energiespeicher Schweiz, https://speicher.aeesuisse.ch/

fokusstudien, 2018.

• L. Vandepaer, K. Treyer, C. Mutel, C. Bauer, B. Amor, «The integration of long-term marginal electricity sup-

ply mixes in the ecoinvent consequential database version 3.4 and examination of modeling choices», The

International Journal of Life Cycle Assessment, doi: 10.1007/s11367-018-1571-4, 2018.

• L. Vandepaer, J. Cloutier, C. Bauer, B. Amor, «Integrating Batteries in the Future Swiss Electricity Supply Sys-

tem – A Consequential Environmental Assessment», Journal of Industrial Ecology, doi: 10.1111/jiec.12774,

2018.

• M. Friedl, T. Kober, K. Ramachandran, J. Mühletaler, «Saisonale Flexibilisierung einer nachhaltigen Energie-

versorgung der Schweiz», Fokusstudie, Forum Energiespeicher Schweiz, 2018.

• R.Frischknecht,C.Bauer,C.Bucher,L.Ellingsen,L.Gutzwiller,B.Heimbach,R.Itten,X.Liao,E.Panos,

«LCA of key technologies for future electricity supply»,, The International Journal of Life Cycle Assessment,

https://doi.org/10.1007/s11367-018-1496-y. 2018.

• M. Friedl, HSR: In 2018, the focus was to inform the public about our research activities, because scien-

tificpublicationsareexpectedaftertheconstructionoftheHEPPdemonstratorintheyears2019–2020.

Many articles about project HEPP have been published by journalists and by ourselves in the following

media: Aargauer Zeitung, Aqua&Gas, Bulletin.ch, die Baustellen, ee-news, Erdgas, ET Elektronik, Folio,

Höfner Volksblatt, Leader Special, Linth-Zeitung, NZZ am Sonntag, Panorama/ Bildung Beratung Arbeits-

markt, Punkt 4 Info, Rundschau Ausgabe Süd, Schweiz am Wochenende, St.Galler Tagblatt, Südostschweiz,

Youtility,ZugKultur,ZürichseeZeitung.2018.

• D. Parra, L. Valverde, J. Pino, M. K. Patel, «A review on the role, cost and value of hydrogen energy systems

for deep decarbonisation», Renewable & Sustainable Energy Reviews, 101, 279–294, 2019.

• T.S.Schmidt,M.Beuse,X.Zhang,B.Steffen,S.Schneider,A.PenaBello,C.Bauer,D.Parra,«Additional

emissions and cost from storing electricity in stationary battery systems», submitted to Environmental Sci-

ence and Technology, 2019.

• S. Schneider, C. Bauer, E. Berg, «A modeling framework to assess performance, costs and environmental

impact of Li-ion and Na-ion batteries», submitted to Environmental Science and Technology, 2019.

• T.Terlouw,X.Zhang,C.Bauer,T.Alskaif,«Towardsthedeterminationofmetalcriticalityinhome-basedbat-

tery systems using a Life Cycle Assessment approach», submitted to Journal of Cleaner Production, 2019.

• T. Terlouw, T. AlSkaif, C. Bauer, W. van Sark, «Multi-objective optimization of all-electric residential energy

systems with heat and electricity storage», submitted to Applied Energy, 2019.

• T. Terlouw, T. AlSkaif, C. Bauer, W. van Sark, «Multi-objective optimization of energy arbitrage in community

energy storage systems using different battery technologies», submitted to Applied Energy, 2019.

96 Appendix

• L. Geissbühler, A. Haselbacher, «A novel thermocline control method for thermal energy storage based on

extracting and mixing HTF streams», EP 18 185902.6.

• E. Moioli, N. Gallandat, A. Züttel, «Design of an optimal reactor for the Sabatier reaction», Innovation Disclo-

sure Form, June 26, 2018.

• F. Bobbink, A.P. van Muyden, W.-T. Lee, P.J. Dyson, «Direct conversion of plastic materials into methane and

liquid fuels», 18207028.4.

Patents

97 Appendix

7th Annual Symposium, SCCER «Heat and Electricity Storage»

The 7th Annual Symposium «SCCER Heat & Electricity Storage» was held on November 6, 2018, in Rapperswil.

Organizers Thomas J. Schmidt, Jörg Roth, Ursula Ludgate,

Astrid Busa, Sandra Moebus, Paul Gantenbein

Speakers Dr. Kerry-Ann Adamson, Jacobs Consultancy, UK

Dr. Enrique Troncoso, Systeng Consulting, UK

Dr. Tom Kober, PSI, CH

Sandra Moebus, HSR, CH

Dr. Luiz Carlos Reichenbach de Sousa, HSR, CH

Dr.AlexandraPătru,PSI,CH

Prof. Dr. Gabor Laurenczy, EPFL, CH

Dr. Nordahl Autissier, GRT, CH

Giorgio Crugnola, FZ Sonick, CH

Dr. Corsin Battaglia, Empa, CH

Cornelia Jahnel, PECEM, D

Klaus Borrmann, PECEM, D

Dr. Paul Gantenbein, HSR, CH

Oral Presentations

• K.-A.Adamson,«GreenHydrogen:Gremlins,FairyTalesandMonsters.TheGrimmtruthaboutEfficiency».

• E. Troncoso, «Hydrogen & Local Energy Systems, a Case Study: The BIG HIT Project».

• T.Kober,«Power-to-XTechnologiesandMarketEnvironmentinSwitzerland».

• S.Moebus,L.C.ReichenbachdeSousa,«ProjectHEPP:HighEfficiencyPower-to-MethanePilot».

• A.Pătru,«DesignPrinciplesofBipolarElectrochemicalCo-ElectrolysisCellsforEfficientReductionofCarbon

Dioxide from Gas Phase at Low Temperature».

• G. Laurenczy, «Carbon Dioxide as Hydrogen Vector».

• N. Autissier, «HyForm-PEMFC 1 kW Demonstrator Unit – Results and Perspectives».

• G. Crugnola, «The Swiss Experience in Cell and Battery Manufacturing for EV, Grid Operation and Back-up

Power».

• C. Battaglia, «Materials Innovation for Next-Generation Batteries».

• C. Jahnel, K. Borrmann, «Heat Storage to Go. We move heat to where it’s needed.»

• P. Gantenbein, «Thermal Energy Sorption Storage Perspectives – Technical Challenges in the Component

Development».

Posters

Thermal Energy Storage

• J. Roncolato, A. Pizzoferrato, V. Becattini, A. Haselbacher,G. Zanganeh, S.A. Zavattoni, F. Contestabile,

A. Steinfeld, M.C. Barbato, «AA-CAES Plant Modeling: Advancements on Plant Design».

• P. Roos, A. Haselbacher, «Multi-Tank TES System Analysis».

• N. Mallya, S. Haussener, «Numerical Melting Study of Encapsulated High-Temperature PCM Units for Energy

Storage».

• E. Rezaei, M. Barbato, A. Ortona, S. Haussener, «High-Temperature Latent Heat Storage Units: Heat Transfer

Enhancement Using Ceramic Porous Media».

• R. Ravotti, O. Fellmann, L. J. Fischer, A. Stamatiou, J. Worlitschek, «Investigation of Bio-based Esters as

Novel PCM for LHS Applications».

• W. Delgado, A. Stamatiou, S. Maranda, R. Waser, J. Worlitschek, «Comparison and Assessment of Available

Latent Heat Storage Solutions for High Power Applications».

Organized Events

Speakers (from left to right):

Giorgio Crugnola, Gabor Laurenczy, Thomas J. Schmidt, Sandra Moebus, Luiz Carlos Reichenbach de Sousa, Tom Kober, Cornelia Jahnel, Klaus Borrmann, AlexandraPătru, Enrique Troncoso, Kerry-Ann Adamson

98 Appendix

Organized Events

• R. Waser, F. Ghani, S. Maranda, T.S. O’Donovan, P. Schuetz, M. Zaglio, J. Worlitschek, «Numerical Investiga-

tion on a Cascaded Latent Storage Heat Pump Water Heater».

• S. Ammann, D. Schiffmann, W. Villasmil, L. Fischer, J. Worlitschek, «Horizontally Drilled Near-Surface Geo-

thermal Energy Storage».

• L. Baldini, B. Fumey, R. Weber, «Absorption-based Long-term Thermal Energy Storage – Understanding Mass

Transfer in Aqueous Sodium Hydroxide Solutions».

Battery and Materials

• R. Dubey, K. Kravchyk, M. Kovalenko, «High Mass Loading Graphite Anodes for Li-ion Batteries».


Material for Lithium Ion Batteries».

• J. Vidal Laveda, J.E. Low, C. Battaglia, «Stabilizing NMC811 in Full Cells with High Areal Capacity».

• C. Marino, C. Bolli, E. Marelli, E. Kendrick, C. Villevieille, «Though the Electrochemical Mechanisms of the

O3-Na(Ni0.5Mn5/16Sn1/16Ti1/8)02, Phase used as Cathode Material for Na-ion Batteries».

• M. Schuster, C. Villevieille, C. Marino, «Investigation on the Suitability of Manganese Carbonophosphate

Compouns as Cathodes in Aqueou Na-Ion Batteries».

• A. Fuerst, A. Glarner, A. Haktanir, M. Stalder, S. Müller, «BFH Research Group Test Batteries».

• A. Fuerst, A. Haktanir, M. Stalder, «Battery Cost Reduction through Production Simulation».

• S. Gentil, E. Zanzola, P. Sharma, P. Peljo, H.H. Girault, «Carbon-Based Solid Phase Charge Storage Nanoma-

terial for the Enhanced Energy Storage in Aqueous Redox Flow Batteries».

• D. Reynard, C. Dennison, A. Battistel, H. Girault, «Low-Grade Heat Recovery Using All-Vanadium Redox Flow

Battery».

Hydrogen Generation and Storage

• L.Lombardo,H.Yang,A.Züttel,«IonicLiquidsasEfficientDestabilizingAgentsofSodiumBorohydride».

• H.Yang,L.Lombardo,A.Züttel,«CarbonBasedMaterialsforHydrogenStorage».

• L.Yerly,F.LeFormal,K.Sivula,«PerformanceandStabilityofIron-Cobalt-NickelAlloysforWaterOxida-

tion».

• N.Plainpan,F.LeFormal,K.Sivula,«ASearchforaStable,InexpensiveandEfficientOxygenEvolution

Reaction, Electrocatalyst in an Acidic Media».

• D.Lebedevc,R.Ezhov,N.Kaeffer,M.Willinger,X.Huang,Y.Pushkar,C.Copéret,«FromNanoparticlesto

Single Sites – Decreasing the Noble Metal Content in Anodic Water Oxidation Catalysts».

• D.Abbott,E.Fabbri,M.Borlaf,F.Bozza,R.Schäublin,Th.Graule,T.J.Schmidt,«OperandoX-RayAbsorption

Investigations into the Role of Fe in the Oxygen Evolution Activity and Stability of NixFe1-xOy Nanoparticles».

• D. Aegerter, E. Fabbri, T.J. Schmidt, «The Effect of Fe in Ba0.5Sr0.5CoxFe1-xO3-5 Towards the Oxygen Evolution,

Reaction in Alkaline Media».

Synthetic Fuels

• M. Calizzi, R. Mutschler, N. Patelli, L. Pasquini, A. Züttel, «FeCo Nanoparticles for CO2 Hydrogenation»

• J. Zhang, W. Luo, A. Züttel, «Electrochemical CO2 Reduction Toward CO and Ethanol»

• K. Zhao, L. Wang, M. Calizzi, E. Moioli, A. Züttel, «Evolution of Adsorption Species During CO2 Hydrogenation

on Ru/AI2O3: Intermediates or Byproducts?».


Organometallic; Chemistry: Application in CO2 Electroconversion and Selective Hydrogenation».


Silica Promote Hydrogenation of CO2 to CH3OH in Supported Cu Catalysts».


Hydrogenation of CO2 to Methanol».

• A.Bornet,Y.Hou,P.Moreno-Garcia,M.deJesúsGálvezVázquez,I.Z.Montiel,P.Broekmann,«Degradation

Study of Cu Nanocubes in Electrochemical CO2 Reduction».

• A. Dutta, I.Z. Montiel, J. Drnec, M. Rahaman, P. Broekmann, «Bimetallice CuAg Nano Foam Catalyst: To-

wards Electrochemical CO2 Conversion into Selective Ethanol».

99 Appendix

• Y.Hou,S.Bolat,A.Bornet,Y.Romanyuk,P.Moreno-Garcia,I.ZelocualtecatiMontiel,V.Grozovski,P.Broek-

mann, «Design and Fabrication of Novel Metallic Copper Membrane Catalysts for Electrochemical CO2 Reduc-

tion».

• Y.Hou,R.Erni,R.Widmer,R.Fasel,P.Broekmann,«SynthesisandCharacterizationofCu@CuPdNanowire

CatalystsfortheEfficientProductiionofFormateandCOfromCO2».

• K.Kiran,A.V.Rudnev,J.Gjuroski,A.CedeñoLopéz,A.Dutta,J.Furrer,P.Broekmann,«EnhancedElectro-

catalytic CO2 Conversion on Nanostructure Silver Electrodes in Ionic Liquids».

• P.Moreno-Garcia,Y.Hou,M.Rahaman,P.Broekmann,«TowardsEfficientElectrochemicalN2 Reduction at

Room Temperature and Pressure through Hydride Transfer Mechanism on Cu@CuPD Nanowires».

• M.Rahaman,K.Kiran,A.Dutta,P.Broekmann,«TowardsSelectiveC3AlcoholFormation:EfficientCO2 Con-

version on Activated Cu-Pd Catalysts».

• A.V. Rudnev, I. Gjuroski, K. Kiran, D. Vasilyev, P. Dyson, J. Furrer, P. Broekmann, «Mass Transport Effets in

Electrochemical CO2 Conversion from Ionic Liquids».

• J.Herranz,A.A.Permyakova,M.ElKazzi,J.Diercks,L.Mangani,M.Povia,A.Pătru,T.J.Schmidt,«Disclosing

the Oxidation State of Copper Oxides Upon Electrochemical CO2-Reduction».

• D. Perego, J. Herranz, T.J. Schmidt, «Differential Electrochemical Mass Spectrometry (DEMS) for Electroca-

talysis».

• B.Pribyl,A.Pătru,T.Binninger,T.J.Schmidt,«EfficientCO2 Reduction from Gas Phase at low Temperatures

inaBipolarlikeCo-ElectrolysisCellConfigurationandComparisontoLiquidPhaseCO2 Reduction».

Assessment of Storage Systems

• P. Roos, G. Zanganeh, E. Jacquemoud, P. Jenny, M. Scholtysik, J. Roncolato, M. Barbato, J. Garrison,

A.Fuchs,T.Demiray,A.Haselbacher,«InvestigationofAA-CAESPlantConfigurationsandGridIntegration».

• M. Berger, S. Frehner, J. Worlitschek, «Temperature-Derived Heating and Cooling Loads».

• R. Durrer, D. Gwerder, M. Geidl, M. Cherepanova, R. Ackermann, J. Worlitschek, P. Schuetz, «Valorisation of

Smart Grid Monitoring Data».

• P. Schuetz, A Melillo, F. Businger, R. Durrer, D. Gwerder, J. Worlitschek, «Fast Automated Modelling of Build-

ing Dynamics based on Smart Grid Monitoring Data».

• R. Gupta, M Soini, M. K. Patel, D. Parra, «Optimised Electricity Storage Technologies to Supply Renewable

Electricity on Demand under Different Supply Modes and Scales».

• M.C. Soini, D. Parra, M.K. Patel, «Disaggregation of Energy Storage Operation by Time Scales».

• A. Pena-Bello, P. Schuetz, M. Berger, J. Worlitschek, M.K. Patel, D. Parra, «PV-Coupled Heat Pump Systems

Supported by Electricity and Heat Storage: Impacts and Trade-offs for Consumers and the Grid».

• A. Pena-Bello, E. Barbour, M.C. Gonzalez, M.K. Patel, D. Parra, «Optimization of PV-Coupled Battery Systems

for Combining Applications: Impact of Battery Technology and Location».

• S.F.Schneider,E.J.Berg,C.Bauer,P.Novák,«ATechno-EconomicandEnvironmentalAssessmentofFuture

Na-Ion Batteries».

• T.S.Schmidt,M.Beuse,X.Zhang,B.Steffen,S.F.Schneider,A.Pena-Bello,C.Bauer,D.Parra,«Storing

Electricity with Different Battery Technologies: What are the Associated Life-Cycle Costs (LCC) & Life-Cycle

Greenhouse Gas Emissions (LCE)?».

• X.Zhang,T.Terlouw,S.F.Schneider,C.Bauer,«LifeCycleAssessmentofBatteries–theEnvironmental

Perspective».

• Z.Stadler,S.Moret,T.Damartzis,B.Meier,M.Friedl,F.Maréchal,«CarbonFlowsintheEnergyTransition».

• M.JFriedl,L.C.R.deSousa,S.Moebus,«ProjectHEPP:HighEfficiencyPower-to-MethanePilot».

Organized Events

100

Contact

Swiss Competence Center for Energy Research Heat and Electricity Storage (SCCER HaE-Storage) c/o Paul Scherrer Institut 5232 Villigen PSI, Switzerland

Phone: +41 56 310 5396

E-mail: [email protected] Internet: www.sccer-hae.ch

Thomas J. Schmidt, Head Phone: +41 56 310 5765 E-mail: [email protected]

We thank the following industrial and cooperation partners:

Documents

Annual Report 2018 - Electricity...2019/03/22 · Imprint SCCER HaE-Storage – Annual Activity Report 2018 Published by Swiss Competence Center for Energy Research – Heat and Electricity