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Tampa Convention Center • Tampa, Florida
Redox Flow Batteries for Grid Scale Energy Storage.
Energy Storage
Vincent SprenklePacific Northwest National Laboratory
August 15, 2017
Energy Exchange: Connect • Collaborate • Conserve2
Challenge for Grid Scale Energy Storage
The value(s) energy storage provides
The ownership cost of the energy storage system over its lifetime
Improving the cost-benefit relationship of energy storage
Energy Exchange: Connect • Collaborate • Conserve
• Grid Scale Energy Storage requires longer cycle life than EV systems
• Grid Scale Energy requires deeper discharge to serve multiple grid applications
• Lithium ion best suited to meet transportation and grid power requirements
• Many chemistries can compete for grid-scale applications
Challenge 1: Reduce Energy Storage Cost
$0
$100
$200
$300
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$500
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$900
$1,000
$1,100
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
BATT500
Syst
em C
apita
l Pric
e ($
/kW
h)
# Deep Cycles
EV 2022
1Energy Storage Systems Cost: GTM/ESA US Energy Storage Monitor: Q2 2016
Lead-acid
Li-ion
NaS
LFP
Redox Flow Battery
2030 Stationary Storage Target
Transportation Targets
3-8 X reduction in lifecycle cost required to address multiple grid
storage applications
Energy Exchange: Connect • Collaborate • Conserve
Challenge - Over 300O utilities Different grid reliability, resiliency, flexibility, renewable integration
challenges Different Market Structure Different cost of electricity Other competing solution approaches besides energy storage
What is needed Requires regional and local analysis of deployed storage technologies
in diverse markets to develop full understanding of monetized and unmonetized benefits
Development of industry standard design tools with fidelity to capture the multi-use value of storage in transmission, distribution, and behind the meter applications.
New business models
Challenge 2: Monetizing Energy Storage Benefits for Multiple Grid Applications
Office of Electricity Delivery and Energy Reliability 5
Strategic Goal:
Mission: To enable energy storage to provide multiple benefits for critical grid applications, DOE is accelerating adoption of energy storage through: improving the technology, field demonstrations, and innovative market design.
Challenges:• Cost competitive energy
storage technologies– Targeted scientific investigations
of key materials and systems
• Validated reliability & safety– Independent testing of
prototypic devices and understanding of degradation.
• Equitable regulatory environment– Enable Industry, Utility,
Developer collaborations to quantify benefits provide input to regulators.
• Industry acceptance – Highly leverage field
demonstrations and development of storage system design tools
Smart Grid
Resiliency
Reliability
Renewables IntegrationAsset Utilization
EV deployment
DOE OE Energy Storage Program
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Vanadium Redox Flow Battery
IT Sodium Metal Halide Batteries
Aqueous Soluble Organic RFBsSafety Standards
ESS Performance Protocols
Component Cost Analysis
PNNL – OE Energy Storage Program Activities that support these Challenges
Cost Competitive Technologies
• Mixed acid increases Top by 80%, energy density 70%.
• Additives for sulfate V/V shows similar Top
• 5X stack power without decreasing efficiency
• At higher performance levels, Vanadium 55% of cost.
• Developing engineered molecules that can be drop in replacement for V/V systems
• Decreased Top from 350°C to 190°C improving lifetime.
• DOE-KETEP MOU to leverage PNNL IT chemistry with RIST/POSCO scale-up efforts.
Sodium-ion Batteries• Analog to Li-ion utilizing existing
production capabilities.• Offers potential for longer cycle-life and
lower cost.
Storage use-case analysis• 7MW/15MWh - WA CEF I • EWEB – Eugene, OR (w/ Sandia)• MA DOER - Northampton, MA• WA CEF II (AVISTA, OPALCO) GMLC –
PGE (Salem, OR), GMP (Rutland, VT), EPB (Chattanooga, TN), LMC (Los Alamos, NM)
• Leading OE Safety Codes and Standards Working Group• CSR 101• CSR Inventory • ESS Compliance Guide
• Rev 2 released April - 2016• 8 performance metrics developed for
ESS Applications.• International adoption TEC 120• Basis for new standards from NEMA,
IEE.
Regulatory Support• PNW PUC Workshop July - 2015• Supporting WA and OR dockets on ESS
Market Acceptance
Energy Exchange: Connect • Collaborate • Conserve
Redox Flow Battery#
Energy Exchange: Connect • Collaborate • Conserve
Power and Energy are separate enabling greater flexibility and safety. Suitable for wide range of applications 10’s MW to ~ 5 kw Wide range of chemistries available.
Redox Flow Batteries
#
Key Aspects
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Grid Energy Storage Diverse Markets Encourage Bundling and Cost Reduction.
EPRI – Electric Energy Storage Technology Options: A Primer on Applications, Costs & Benefits (2010)
PNNL-23040 Assessment of EnergyStorage Alternatives in the Puget Sound Energy System
Energy Exchange: Connect • Collaborate • Conserve
• Want energy storage systems that can provide for both:– Fast response balancing services and– Longer duration (2+ hr) deferral and outage mitigation.
Bundled Services: High degree of Flexibility needed from Energy Storage?
Energy price ($/MWh)
Arbitrage only
Arbitrage + Balancing
Arbitrage + Balancing + T&D deferral
Pow
er o
utpu
t (M
W)
Arbitrage + Balancing + T&D deferral + volt/var
PNNL-23040 Assessment of EnergyStorage Alternatives in the Puget Sound Energy System
Energy Exchange: Connect • Collaborate • Conserve
RFB - Major Challenges
11
Low energy density Large form factor/footprint Limited application
Limited electrolyte stability Capacity decay during cycling Cost
Zhenguo Yang, et. al. Chemical Reviews, 111, 3577, 2011Wei Wang, et. al. Adv. Funct. Mater., , 23, 970, 2013
Energy Exchange: Connect • Collaborate • Conserve
-1.0 -0.5 0.0 0.5 1.0 1.5 2.0
Standard potential (V) of redox couples
V3+/V2+VO2
+/VO2+
VO2+/V3+
Fe3+/Fe2+
Mn3+/Mn2+
MnO4-/MnO2
Ce4+/Ce3+
Co3+/Co2+
Cu2+/Cu+
TiOH3+/Ti3+
Ti3+/Ti2+
Cr3+/Cr2+
Zn2+/Zn
S/S2-
Br2/Br-
BrCl2-/Br-
Cr5+/Cr4+
Cl2/Cl-
Eo=1.26V
Eo=1.85V
Redox Flow chemistriesOthers:V2+/V3+ vs. Br-/ClBr2
-; Ce4+/Ce3+ vs. V2+/V3+;Fe3+/Fe2+ vs. Br2/Br-;Mn2+/Mn3+ vs. Br2/Br-;Fe3+/Fe2+ vs. Ti2+/Ti4+, …
ZBB: Br-/Br2- vs. Zn2+/Zn
ICB: Fe3+/Fe2+ vs. Cr3+/ Cr2+
VRB: V2+/V3+ vs. VO2+/VO2+
PSB: Br2/Br- vs. S/S2-
Up to 100 kw or multi-MW demonstrated
H2Evolution
O2Evolution
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RFB - Early Development
Fe2+ Fe3+ + e–
Cr2+ Cr3+ + e–
Open Circuit Potential (OCP) 1.2 V
significant crossover
requires electrocatalyst
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All-Vanadium Flow Battery
V2+
V3+ + e–
crossover is less of an issue
Nafion® membrane
temperature sensitivity
low vanadium concentration/low energy density
graphite
Open Circuit Potential (OCP) 1.5 V
electrolytes influence temperature stability and vanadium concentration
carbon felt
Energy Exchange: Connect • Collaborate • Conserve
V/V Mixed Acid Redox Flow Battery#
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New vanadium chemistry based on SO2-/Cl- electrolytes
Mixed-acids All Vanadium Redox Flow Battery (VRB)
Conventional Sulfate VRB
Mixed AcidVRB
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Redox Flow Battery R&D Objectives
Develop the technologies, tools, and system understanding required to move the mixed acid electrolyte chemistry from basic chemistry to cost effective system solution.
Redo
x Sy
stem
Cos
ts
Perf
orm
ance
Energy Exchange: Connect • Collaborate • Conserve
VRFB 5kW Performance
Stack
Test Parameters
• 780 cm2
• 1-20 cell stacks• 15-85% SOC• Mixed acid electrolyte
• 2M V, 2M S, 5M Cl• Nafion membrane
• 212 (~ 2 mil)• j = 160 -320 mA/cm2
• Modified interdigitated flow design
• 5 KW stack• Chillers to control temperature
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Improved Stack Performance can lower parasitic losses
Carbon Felt Electrode
Bipolar Plate
Membrane
Bipolar Plate
Membrane
Bipolar Plate
(Graphite/PP)Outlet
ChannelInlet
Channel
Carbon Felt Electrode
Bipolar Plate
Membrane
Bipolar PlateOutlet
ChannelInlet
Channel
Carbon Felt Electrode
Carbon Felt Electrode
(IDD 1) (IDD 2)(FTD)
SGL TF6Graphite sheet
SGL PPG 86Graphite/PP
PVC
Fram
e
PVC
Fram
e
PVC
Fram
e
Carbon Felt
Flow direction
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Comparison of ID Designs – 320 mA/cm2
IDD 1 IDD 2s
• IDD 2s design attains a higher capacity at a given cut off window.• IDD 1 has a much higher charge/discharge overpotential at a lower capacity
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Develop material and system enhancements to resolve key cost and performance challenges for energy storage devices.
goal
5X increase in power density since start of program while improving energy efficiency at targeted condition.
Vanadium Cost
Mixed Acid VRFB Performance
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Can Flow Batteries provide Frequency Regulation Services?
*DC only
FR duty cycle determined from PJM balancing signal for year 2011
Signals grouped into low, average and high standard deviations
Representative 2-hour intervals with average standard deviation and 2-hour intervals with high standard deviation chosen
• each being energy neutral
Duty cycle consisted of three 2-hour average standard deviation (SD) signals followed by one 2-hour high SD signals, three 2-hour average standard deviation (SD) signals followed by one 2-hour high SD signals and four 2-hour average SD signals
21 cell VRFB stack under Frequency Regulation protocol
Energy Exchange: Connect • Collaborate • Conserve
Remaining Challenges - Cost Reduction#
Energy Exchange: Connect • Collaborate • Conserve
Gritsevski and Nakicenovic, Energy Policy 28 (2000) 907-921
24
Technology Learning rates
• Learning rate (LR) is defined as the % drop in cost as production volume doubles.
• Based on previous development of PV, windmills and gas turbines
• Learning rate of -20% during early stage development/commercialization.
• - 10% LR for full scale manufacturing.
Energy Exchange: Connect • Collaborate • Conserve
Redox Flow and Li-ion Battery Price Projections
Flow2014 - $1200 - 1500/kWh2017 - $600-$800/kWh
LR > 25%
Li-Ion $1200/kWh in 2011 based on ~ 1 GWh in EV/PHEV sales
Li-ion First commercialized 1991
~ 15% LR 2011-2015 all EV/PHEV
• $1200/kWh in 2011 – 1.06 GWh1
• 2014 – projected 7.5 GWh1,2
• ~15% LR
• 2014 – Actual ~ 9 GWh4
To maintain 15% LR requires 27.6 GWhin 2015
Stationary storage market:
• 6.6 GWh by 20253
1. Technology Roadmap, Electric and plug-in electric vehicles, IEA, Updated June 20112. Electric and plug-in hybrid vehicle roadmap, IEA, 20103. Source for stationary storage projected production rates: http://cleantechnica.com/2014/08/26/energy-
storage-market-rises-50-billion-2020-according-lux-research/4. http://evobsession.com/ev-battery-manufacturer-sales-market-share-march-2015/
Redox• @ 20 - 25% LR for redox, can achieve ~ $500 kWh with 4
GWh of installed capacity.
Energy Exchange: Connect • Collaborate • Conserve
0
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2010 2011 2012 2013 2014 2015 2016
$/kW
hr p
roje
cted
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Wh
August 22, 2017
Chemicals36%
PCS10%
Felt8%
Membrane33%
80 mA/cm2
$465/kWhr
Chemicals
51%PCS13%
240 mA/cm2
$347/kWhr
Chemicals
55%
400 mA/cm2
$275/kWhr
Where to Next with Redox Flow Systems
26
Energy Exchange: Connect • Collaborate • Conserve
Advantage: Low-cost redox couple; Low-cost supporting
electrolyte; No resource constraints; Less corrosive and toxic.
A Total Organic Aqueous Redox Flow Battery
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Conclusions
The flexibility of redox flow battery technology offers the potential to capture multiple value streams from a single storage device.
Current research has demonstrated high power conditions can be achieved with minimal impact in stack efficiency.
Next generation RFB technology based on Aqueous Soluble Organics (ASO) being developed to replace vanadium species.
Continued cost reductions in Li-ion technology will be driven by EV/PHEV deployments. RFB maybe able to achieve similar cost targets at ~ 100X lower production volume.
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Acknowledgements
Support from US DOE Office of Electricity Delivery & Energy Reliability - Dr. Imre Gyuk, Energy Storage Program Manager