Robert Steinberger-Wilckens, Arvin Mossadegh Pour

A Fuel Cell System for Railbus Application

HydRail ConferenceBirmingham, 3 & 4 July 2012

Slide 2RSt, July 2012

Hydrogen & Fuel Cells Doctoral Training Centre

The Hydrogen & Fuel Cell Research Centre&

Hydrogen production, storage & handling

PEFC & HT-PEFCSOFCSystems & Modelling

Slide 3RSt, July 2012

Introduction

• hydrogen storage on board vehicles remains sub-optimal• increase of storage pressure to 70 MPa to reduce size and/or

extend range• metal hydrides can offer an alternative – the tank is practically

pressure-less, H2 losses are low and handling simple• high weight of metal hydride tank itself and low adsorption

figures (~5% hydrogen) are a problem for mobile applications• new materials allow loading up to 14% but require high

temperatures in desorption process

Slide 4RSt, July 2012

The Project Idea

• combine high-performance metal hydride tank with SOFC system and use the exhaust heat for discharging the tank

• possible applications:- rail transport- marine vessels

• in both applications weight is of minor importance or even welcomed

• preferably (in first instance) aplication to Auxiliary Power Units for on-board electricity production

• test objects:- APU for diesel rail buses- APU for harbour vessels, service vessels, marine research vessels

Slide 5RSt, July 2012

Application Rail Bus

• diesel-driven vehicles

• travel medium distances in shuttle service

• i.e. hydrogen supply easily accomplished

• energy demand suitable for metal hydride tank

• environmental benefit through reduction of diesel exhaust gases in stations etc.

• possibility to extend functions from APU to diesel-electric drive or hybrid drive train

Slide 6RSt, July 2012

Mid-Range Rail Transport

• Wilhelmshaven –Osnabrueck approx. 200 km single distance

• sufficient time at terminals to refill

• replacement of on-board electricity generation by APU

• optional combination with diesel-electric drive to avoid fumes when accelerating

Slide 7RSt, July 2012

Travel Requirements

• re: Siemens Desiro

• total electric power on-baord: 15 kW

• SOFC system net efficiency 50%

• 75 kWh of hydrogen for 2 hours travel + ½ hour of stops

• 2,5 kg of H2

Slide 8RSt, July 2012

Solid Oxide Fuel Cell -Principle

characteristics:- 700 deg.C operating temperatureadvantages:- high electrical efficiency- high value heat- relatively insensitive to fuel impurities

Slide 9RSt, July 2012

G. Barkhordarian et al. (GKSS, EP1824780, Dec.2004, Deutschland 10 2004 061286.9)

MgB2 + 2 LiH + 4H2MgH2 + 2 LiBH4

MgB2 + CaH2 + 4H2MgH2 + Ca(BH4)2

MgB2 + 2 NaH + 4H2MgH2 + 2 NaBH4

Metal Hydride Concepts

Reactive Hydride Composite:

T ~ 350 °C – 400 °C

7.8 – 11.4 wt%

Sodium Alanate:

2 Na3AlH6 + 4 Al + 6 H26 NaH + 6 Al + 9 H2 6 NaAlH4

T ~ 125 °C

5.6 wt%

Slide 10RSt, July 2012

Volume 260 litre

(compact vehicle: 9 l petrol or 1.2 kg H2 for 100 km)

73 l

167 l

175 kg

H2-gas 700 barComposite shell

liquid H2

MgH2

Tank weight and volume for 500 km range (6 kg H2 = 200 kWh)m

etal hydrides

Storage Alternatives

NaAlH4

LiBH4 / MgH2

285 kg

92,9 l130 kg

Weight 133 kg

92 kg

167 l

Status: 22.1.2009

200 l462 kgHydralloy C®

(GKSS Tank f. SAX3)

Slide 11RSt, July 2012

Hydrogen Sorption of a Reactive Hydride Composite 2LiBH4+MgH2 2LiH+MgB2

loading, 350°C, 50 bar H2unloading, 400°C, 5 bar H2

Slide 12RSt, July 2012

Absorption Desorption

Metal Hydride Tanks (Sodium Alanate)

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Internal Hull External Hull

Improvements with respect to the previous model:

Weight: 1,58 (up to 2.4 possible) instead of 0,865 wt. %; + 83 % ( up to +178 %) by light weight hull materials

Volumen: 31,2 instead of 21 kgH2/m3; + 49 % by compaction of the storage material

Metal Hydride Tanks (Sodium Alanate) (2)

Slide 14RSt, July 2012

AnodeMH Tank

Cathode

System Concept

400°C700°C

SOFC

heat

Aux. Hydrogen Tank

heat via burner

start up

H2

questions:- balance of heat flow - balance of gas flows- sizing of tank for applicationduring start up phase

Slide 15RSt, July 2012

AnodeMH Tank

Aux. Hydrogen Tank

Air

20ºC

λ=8

Cathode800ºC

+50 mbar

Air

800°C

27 m^3/h

Start Up Phase

Slide 16RSt, July 2012

Anode

MH Tank

Aux. Hydrogen Tank

Air

20ºC

λ=8

Cathode

600ºC

+50 mbar

700ºC

+30 mbar

Air

Operational Phase

400ºC, 5 bar

Slide 17RSt, July 2012

Stack and Tank Modelling

stack considered as heat exchanger during start-up

• zero-dimensional SOFC model during operation• no flow fields• no transient behaviour, apart from temperature dependance

tank is heated by air in the outer hull and releases H2when heated to core

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Start-up of Metal Hydride Tank

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Start-up of SOFC Stack

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Conclusions and Outlook

• system can be started within one hour• heat flux and gas flows can be balanced• hydrogen release rate is in balance with stack fuel

requirements

• design needs further refinement - reduction of start-up time- proper temperature control

• further work to be done on - system transients- adaptatoin to application requirements

Slide 21RSt, July 2012

Thank you for your attention!

Acknowledgments go to:

IEK-PBZ – Fuel Cell Project at Forschungszentrum Juelich

Klaus Taube, Jose Bellosta von ColbeHelmholtz-Zentrum Geesthacht