Tel: 01980 613072 E-mail: djbrowning@dstl. · PDF fileTel: 01980 613072 Fax: 01980 613521 ... (AIP) systems can provide increased endurance to conventional submarines – Fuel cell

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Darren BrowningTel: 01980 613072Fax: 01980 613521E-mail: [email protected]

January 7, 2005 Dstl is part of theMinistry of Defence

© Crown copyright 2004. Published with the permission of the Defence Science and Technology Laboratory on behalf of the Controller of HMSO

• Dstl Introduction• Hydrogen storage• Focus on solid state storage• Military applications for hydrogen• Specific military examples• Conclusions



• Dstl is part of the UK Ministry of Defence• Our role is to:

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MalvernCluster

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2001



Specific Weight, % H2

Metal hydride systems ambient temperature

Advanced compressed composite

Liquid Hydrogen

Advanced metal hydridehigh temperature

CarbonNanofibres

& novel sorbents

Reformed Methanol

Reformed Diesel

5

10

20

50

100

200

0.5 1 2 5 10 20

Spec

ific

Volu

me,

kg

H2/m

3

Current Compressed Technology

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• AB2 and AB5 alloys– Typically operate at ambient

temperature– Capacities between 1-2 wt.%– Good volumetric storage– Typically low pressures

• High temperature alloys– typically Mg, Li & Na based– better gravimetric capacities– operate at high temperatures– T being lowered by catalysts etc

HERA



• Carbon nanoabsorbants– Potential to have very high gravimetric capacity– A lightweight refillable hydrogen store would help enable fuel

cells for the military and elsewhere– Much further work required

• Metal organic frameworks (MOFs), Zeolites• Chemical hydride systems

– Higher specific energy but not rechargeable– Hydrolysis e.g. NaBH4, LiH etc

• Used in Hydrogenics HYPORT-C– Thermal decomposition e.g. NH3BH3

• Under development by QinetiQ Hyport C - Hydrogenics



• Great need for high energy density & specific energy storage• Could be met by fuel cell with high performance H2 store• Most pressing for man-portable applications such as IST

(UK) and Land Warrior (US)• Future combat vehicles have increasingly reliance on electric

systems– Silent watch - power without the engine– Exportable power

• All-electric ship• Submarine, UUV applications



• Increasing need for portablepower in the battlefield

– MoD IST (Integrated soldiertechnology)

– US DoD Land warrior

• Battery lifetimes can limit missionendurance

• Soldiers need better powersources with better specificenergies (Wh/kg)

• Weight the biggest issue

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• IST requires around 20 W for 52 hr in less than 2 kg– 520 Wh/kg (1040 Wh in 2 kg)

• Land Warrior requires operation for 72 hr– 720 Wh/kg (1440 Wh in 2 kg)

• Current rechargeable batteries can’t meet targets• Fuel cells under consideration but mostly liquid fuelled

– Direct methanol, direct sodium borohydride

• Compact reformers - methanol, gasoline, JP-8• Would need a leap in solid state storage to meet these

goals• Hydrides have been used for demonstrators



• Vehicles need additional electrical power– silent watch– exportable power, battery charging etc

• Fuel cells not seriously being considered for completepropulsion of military vehicles

• Under consideration for APUs• Ideally on-board JP-8 reforming

– difficult to achieve

• Could solid state storage provide buffer or meet nicheapplications?



• Submarines require long submerged endurance• Nuclear plants lead to large, expensive vessels• Air Independent Propulsion (AIP) systems can provide

increased endurance to conventional submarines– Fuel cell– Stirling engines– Closed- Cycle Diesel– Mesma

• Also potential for fuel cells on nuclear boats to increaseendurance if reactor goes offline



• Unmanned Underwatervehicles

• Require increased endurance• Fuel Cells could offer

improvements over batterysystems

• Volume restricted• Weight also important

– less free volume than amanned submarine

• Urashima uses metal hydride

Urashima

commercial Fuel Cell UUV

(JAMSTEC)



• Move by many Navies towards more-electric and all-electric ships

• Fuel cells could play a part in this• US ONR has two ship service fuel cell programmes

– PEMFC– MCFC

• Aim to operate from logistic fuel• Will a hydrogen buffer be needed?



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• Hydrogenics HYPORT-E system• Investigated as APU by Canadian and US

Army• 1-5 kW, 3 kW av, 15kWh stored energy per

charge• Fuel cell, Electrolyser, Hydrogen store• Hydrogen stored in low pressure metal

hydride, ~1wt% H2 for storage tank• No external fuel connections

– Only connection is to vehicle electrics viaNATO standard

• 4 complete cycles before needs further water• Water is also an issue should be captured Light Armoured Vehicle (LAV)

Hyport E- Hydrogenics



• The US Army is investigating the viability of Ni-H2 batteries– H2 is stored in a metal hydride canister rather than a pressure vessel

• Similar to the Ni-H2 batteries used in satellite systems• Perceived advantages will be the ability to manually isolate

hydrogen supply and therefore render a battery system safeuntil required

• Army concerned about dangers of engineers working on future42V vehicle systems



• German shipbuilder HDW has builtthe U-212 submarine

• Uses a fuel cell AIP system• Siemens PEM fuel cell• Oxygen stored as LOX• Hydrogen stored in metal hydride• Fuel cell lower oxygen demand

than other AIP systems– Important for UW applications U212 Cross-section - HDW



• Submarine contains 18 metal hydride cylinders• Each cylinder stores 1 MWh H2

– weight 4.4T, vol 1200 L– 55kg , 620 m3 H2

– 1.25 wt %, 46 g H2/L– 227 Wh/kg, 833 Wh/L @ 0.7 V/cell

Dimensions of tank: ½ m diameter x 6 m length



• Unlike many land applications volume is critical insubmarine applications

• Weight is less important, in many cases ballast needs tobe added to maintain neutral buoyancy

– can’t be too heavy or additional flotation volume will be needed

• Enclosed environment so safety is paramount– low pressure storage an advantage

• Heat of fuel cell used to desorb hydrogen– reduces thermal signature



• Example of a commercial military application of solid-state hydrogen storage

• German submarine U-33 undergoing sea trials• HDW have agreements to sell the AIP submarines to

numerous foreign navies– Italy– South Korea– Greece

• Retrofittable fuel cell/hydride/LOX plug also available



• Biggest limiting factor of solid state storage to the militaryis the weight

– Need to improve the wt % of hydrogen stored by roomtemperature alloys

– or reduce temperature of operation of high temperature alloys

• Charge and discharge rates an issue,– but not for all applications– e.g many batteries can not be recharged quickly

• Develop alternative storage media– carbons, MOFs



• MoD needs lighter weight, more efficient power sources• A better hydrogen storage system could enable fuel cells

to achieve this• Hydrogen is not the only issue• The whole system including; H2, fuel cell, ancillaries and

air/oxygen must give a significant capability advantageover existing technology (batteries, engines, etc.)



Documents

Tel: 01980 613072 E-mail: djbrowning@dstl. · PDF fileTel: 01980 613072 Fax: 01980 613521 ... (AIP) systems can provide increased endurance to conventional submarines – Fuel cell