HydRail Conference Birmingham, 3 & 4 July 2012

A Fuel Cell System for Railbus Application

Robert Steinberger-Wilckens, Arvin Mossadegh Pour Hydrogen & Fuel Cells The Hydrogen & Doctoral Training Centre & Fuel Cell Research Centre

Hydrogen production, PEFC & HT-PEFC storage & handling SOFC Systems & Modelling Slide 2 RSt, 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 3 RSt, 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 4 RSt, 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 5 RSt, 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 6 RSt, 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 7 RSt, July 2012 Solid Oxide Fuel Cell - Principle

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

Slide 8 RSt, July 2012 Metal Hydride Concepts

Sodium Alanate:

T ~ 125 °C 6 NaH + 6 Al + 9 H 2 Na AlH + 4 Al + 6 H 6 NaAlH 2 3 6 2 4 5.6 wt% Reactive Hydride Composite:

T ~ 350 °C – 400 °C MgH2 + 2 LiBH4 MgB2 + 2 LiH + 4H2 7.8 – 11.4 wt%

MgH2 + 2 NaBH4 MgB2 + 2 NaH + 4H2

MgH2 + Ca(BH4)2 MgB2 + CaH2 + 4H2

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

Slide 9 RSt, July 2012 Storage Alternatives

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

H2-gas 700 bar Weight 133 kg Composite shell Volume 260 litre

92 kg liquid H 2 167 l 130 kg LiBH / MgH metal hydrides 4 2 92,9 l 285 kg NaAlH 4 167 l 175 kg MgH 2 73 l Hydralloy C® 462 kg (GKSS Tank f. SAX3) 200 l

(compact vehicle: 9 l petrol or 1.2 kg H2 for 100 km) Status: 22.1.2009 Slide 10 RSt, July 2012 Hydrogen Sorption of a Reactive Hydride

Composite 2LiBH4+MgH2  2LiH+MgB2

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

Slide 11 RSt, July 2012 Metal Hydride Tanks (Sodium Alanate)

Absorption Desorption Slide 12 RSt, July 2012 Metal Hydride Tanks (Sodium Alanate) (2)

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

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

Slide 13 RSt, July 2012 System Concept

start up

Aux. Hydrogen Tank heat via burner

H2 Anode MH Tank heat Cathode

400°C questions: - balance700°C of heat flow - balance of gas flows SOFC - sizing of tank for application during start up phase

Slide 14 RSt, July 2012 Start Up Phase

Aux. Hydrogen Tank

Air 800°C 27 m^3/h Air 20ºC Anode λ=8 MH Tank Cathode 800ºC +50 mbar

Slide 15 RSt, July 2012 Operational Phase

Aux. Hydrogen Tank

Air 20ºC Anode λ=8 MH Tank Cathode 400ºC, 5 bar

700ºC 600ºC +30 mbar +50 mbar

Air

Slide 16 RSt, July 2012 Stack and Tank Modelling

stack considered as heat exchanger during start-up

tank is heated by air in the

outer hull and releases H2 when heated to core

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

Slide 17 RSt, July 2012 Start-up of Metal Hydride Tank

Slide 18 RSt, July 2012 Start-up of SOFC Stack

Slide 19 RSt, July 2012 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 20 RSt, July 2012 Acknowledgments go to: IEK-PBZ – Fuel Cell Project at Forschungszentrum Juelich Klaus Taube, Jose Bellosta von Colbe Helmholtz-Zentrum Geesthacht

Thank you for your attention!

Slide 21 RSt, July 2012