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PEM Fuel Cells for Submarines
Industrial Solutions and ServicesYour Success is Our Goal
Fuel CellApplications forelectric energy
production
Emergency power supply(PEFC)
Frighter
Emission-free and noiselessoperation (PEFC)
Bus
Delivery trucks
Elektrischer Antrieb
Bahn
Energy storage with gases(PEFC)
Storage system forregenerative energies
Space Shuttle
Grid-independent operation(SOFC, PEFC)
DecentralPower plants
Railroad
H2/O2
Reformer gas/Air
H2/Air
Passenger car
Emission-free and energy-efficient operation (PEFC)
Electrical propulsion(SOFC, PEFC)
Air-independent power supply(PEFC)
Emission-free and noiselessoperation (PEFC)
Gas tanker
Electrical propulsion(SOFC, PEFC)
Air-independent propulsion(PEFC)
Submarine
Reformer gas/Air
Fig. 1: Possible applicationsfor generating electrical energy
Fuel cells allow the direct generation of electricpower from hydrogen and oxygen with a consid-erably better efficiency and no pollutant emissioncompared to conventional combustion engines.Their operation is noiseless.
In addition to these basic advantages, the fuelcell with a solid, ion conducting, polymeric mem-brane (Polymer Electrolyte Membrane – PEM)has further positive properties:
• Quick switch-on, switch-off behavior
• Low voltage degradation and long service life
• Favorable load and temperature cycle behavior
• Overload possibility
• Low operating temperature (80°C)
• Absence of a liquid corrosive electrolyte.
All these characteristics make the PEM fuel cell(PEM FC) an ideal power unit.Aboard submarines they show their outstandingadvantages against conventional AIP systems(Air Independent Propulsion) using oxygen andhydrogen, carried on board.
The new submarines of class U 212 A areequipped with PEM FC modules with an electri-cal output of 30 to 40 kW each, which have beendeveloped since 1985 on behalf of the GermanMinistry of Defense. The new type U 214 classsubmarines will be fitted with 120 kW fuel cell
modules which have been developed bySiemens in a next step.
The basic suitability of fuel celltechnology onboard submarineshas been demonstrated by
installing a 100 kW FC powerplant with alkalinefuel cells on thesubmarine U1 ofthe Federal GermanNavy in 1988.During the tests the
performance of additionalequipment such as H2
and O2 components has beenproven.
Further possible applications of PEM FCs forpower generation are listed below (see also Fig. 1, left side):
Using hydrogen and oxygen
• Operation in spacecrafts
• Component in a long-term energy storage system (consisting of solar cells, an electrol-yser system and a hydrogen/oxygen storagesystem)
Using hydrogen and air
• Zero emission operation of electrically drivenvehicles
Using reformer gas and air
• Power supply far distant from a public powersupply system
• Safe, low emission power supply on cargo vessels especially in harbor
• Utilization of boil-off gases aboard gas tankers
• Power supply e.g. for drives on rail vehicles
Concentrating on manufacture and developmentof fuel cells for AIP applications, Siemensdemonstrated its technological competence inprojects for air-breathing PEM fuel cells, e.g.
– Fork lift truck
– Micro co-generation
– Propulsion systems for busses.
The Siemens R&D activities in the fields of Direct Methanol Fuel Cells (DMFC) and SolidOxide Fuel Cells (SOFC) are not presented in thisbrochure.
Introduction
OxygenHydrogen
Energy
Water
3
Cover photo: 30–40 kW module (top)and 120 kW module (below)
Both the basic function and the designof the PEM FC are very simple (Fig. 2): the electrochemical element at whichthe chemical energy is converted intoelectrical energy is the membraneelectrode unit. It consists of the poly-mer electrolyte, the gas diffusion elec-trodes with a platinum catalyst andcarbon sheets on each side.
After the abstraction of the electronsfrom hydrogen – they flow from theanode via the electrical load to thecathode – the resulting protonsmigrate from the anode to the cathodewhere they combine with oxygen (andthe electrons) to water. The theoreticalvoltage of an H2/O2 fuel cell is 1.48 V(referred to the upper heat value ofhydrogen). At zero load conditions,slightly more than 1 V per cell is avail-able.
The cooling units or bipolar plates incombination with carbon diffusion lay-ers distribute the reactants uniformlyacross the area of the cell, conduct theelectrons across the stack, remove theheat from the electrodes and separatethe media from each other.
PEMfuel cell
Fig. 3: Components of cell Fig. 5: Comparison of cells: 120 kW type (front)30–40 kW type (back)
4
Fig. 3 shows the two core compo-nents of a cell with outside dimen-sions of 400 mm x 400 mm. As usedin 30–40 kW modules.
Fig. 5 compares the bipolar plate ofthe 30–40 kW modules to the 120 kWtype. Two cells of the 120 kW typeproduce about twice the power of onecell of the 30–40 kW type with nearlythe same active area.
The in principle high developmentpotential in regard to the membranematerial is shown in Fig. 4. Withimproved materials the power densitycan nearly be doubled.
The voltage of a PEM FC referred tothe operating time is stable, degrada-tion rates are less than 2 µV/h for the30–40 kW module (Fig. 6).
Cooling unit
Membraneelectrode unit
Cooling unit
400 mm
1500
1000
500
Cel
l out
put
Pz
0
W
1.1
V
0.9
0.7
0.5
Cel
l Vol
tage
Uz
0 500 1000 1500 2000ACurrentI
TKW
pO2
pH2
pK
Aact
= ~80°C= 2.3 bar abs.
= 2.0 bar abs.
= 5.0 bar abs.
= 1163 cm2
Dow (G 29)
Naf 115 (D 14)
Naf 117 (A 37)
Dow
Naf 115
Naf 117
60
56
54
52
50
Modulevoltage
[V]
Degradation of voltage (single cell):(55.75-55.56V)/72cells/1.500h = 1.76µV/h
1000
500
0
ModuleCurrent [I]
55.75V 55.56V
Operating time [h]2000 600400 800 1500
pO2: 2,3 bar apH2: 2,0 bar aTemp.: 80° CFakt.: 1163 cm2
Zellenzahl: 72
Electrical load
Polymerelectrolyte
Product waterH2O + O2
OxygenO2
HydrogenH2
Waste heat
4e–
H+
Anode Cathode
H+
H+
H+
O2+4e–=
2H2O
20- -
20- -+4H+=
4e–=2H2–4H+
Fig. 2: Functional principle
Fig. 4: Potential output increase when using various electrolytes
Fig. 6: Voltage degradation referred to operating time(measurement from 30–40 kW module)
Fuel cell modules
Fuel cellpower plant
The fuel cells need additional auxiliariesfor their operation. The FC stack,valves, piping and sensors form the FCmodule, the corresponding moduleelectronics controls the proper opera-tion of the FC process. The ancillariescomprise the equipment for supplyingH2, O2 and N2, for reactant humidifica-tion, for product water, waste heat andresidual gas removal. The FC stack andthe ancillaries are installed in a contain-er which is filled with inert gas (N2) at3.0 bar abs. to prevent a release of H2
and/or O2 in the case of leakage.
The FC module can be operated at vari-ous static load currents. Currentsbelow 650 A for 30–40 kW modules orbelow 560 A for 120 kW modulesrespectively can be applied in continu-
ous operation. The output power/cur-rent characteristics for 30–40 kWmodules are shown in Fig. 7.
For currents above the rated currentthe loading time is limited due to theinsufficient heat removal at such work-ing points. Even loads up to the doubleof the rated current can be applied fora short time.
At the rated operating point, the over-all efficiency is approximately 59%referred to the lower heat value of H2
(LHV). It increases in the part loadrange, reaching a maximum of approxi-mately 69% at a load factor of some20% of the rated current (approx. 100 A) (Fig. 8).
The properties of the 30–40 kW and120 kW modules are listed in thetable.
Suitable operating conditions for fuelcell modules are provided for subma-rine application by a fuel cell system inwhich fuel cell modules are connected
• to the hydrogen and oxygen supply• to disposal units such as for
– cooling – residual gas– reaction water
• to auxiliary systems such as for– inert gas drying– nitrogen supply– evacuating system
• to the propulsion/ship’s system asthe purpose of the whole FC system.
Operator control and visualization ofthe fuel cell system is effected by theintegrated platform management sys-
tem, or directly by the control panel ofthe fuel cell system.Fig. 10 gives a simplified impression ofthe AIP system.
The fuel cell system in its entirety –the complete fuel cell power plant,especially the supply and disposal sys-tems described above for AIP opera-tion including spatial and functionalintegration on board – has been devel-oped by HDW (HowaldtswerkeDeutsche Werft AG).The new submarine classes U 212 Aand U 214 are equipped with the newfuel cell power plant by HDW with thePEM fuel cell modules by Siemens.
Fig. 9 shows PEM fuel cell modulesassembled in a test rack.
6
Technical data
Rated power 30–40 kW 120 kW
Voltage, about 50–55 V 215 V
Efficiency atrated load 59% 58%
Efficiency at 20% load 69% 68%
Operatingtemperature 80°C
H2 pressure 2.3 bar abs.
O2 pressure 2.6 bar abs.
Dimensions H = 48 cm 50 cmW = 48 cm 53 cmL = 145 cm 176 cm
Weight (without moduleelectronics) 650 kg 900 kg
Propulsion switchboardFeeding of
propulsion/ship’s system
H2 supplyO2 supplyRemoval • Waste heat
• Product water• Residual gas
Integrated PlatformManagement System (IPMS)
FUEL CELLMODULES
Fuel cell systemControl panelModule electronicsControl and monitoring
kW
0
Mod
ule
outp
ut P
M
0 AModule current IM
TKW
pO2
pH2
pK
Aact
n
Membrane: Nafion 117
= ~80°C= 2.3 bar abs.
= 2.0 bar abs.
= 5.0 bar abs.
= 1163 cm2
= 72 Cells
60
200 400 600 800 1000
10
20
30
50
1200
40
%
0
Ove
rall
effic
ienc
y η
o
0 AModule current IM
TKW
pO2
pH2
pK
Aact
n
Membrane: Nafion 117
= ~80°C= 2.3 bar abs.
= 2.0 bar abs.
= 5.0 bar abs.
= 1163 cm2
= 72 Cells
100
100 200 300 400 500
20
40
60
80
600
After the successful developmentthe FC modules are now undermanufacturing. They have proventheir performance and reliability inextensive tests including long termtests. They are an integral part ofan AIP system for modern sub-marines like that of Class U 212 A(30–40 kW modules) and U 214 (120 kW modules).
The field for use of PEM FC willbe widened when suitable reform-ers produce hydrogen from liquidfuels, e.g. methanol. Then it maybe possible that fuel cells canbecome the sole power source of submarines of the future.
Using PEM fuel cells and replac-ing oxygen with air, they are aninteresting alternative for environ-mental-friendly power generation,e.g. for vehicles in cities.
In general: the excellent operatingperformance of PEM fuel cells likehigh efficiency and noiseless oper-ation can lead to a promisingfuture upon further reduction inmanufacturing and operatingcosts.
Fig. 7: Module output referred to load current(measurement from 30–40 kW module)
Fig. 8: Efficiency (measurement from 30–40 kW module)
Fig. 10: Integrated AIP system
Outlook
7
Fig. 9: PEM fuel cell modules assembled in a test rack
Order No. E10001-A930-A35-V3-7600Dispo No. 16600Printed in Germany174D6077 PA 08012.
OurProgram
Systems Engineering andQuality Management
Propulsion Systems
Air-IndependentPropulsion (AIP)
Electrical Systems
Integrated Platform Management System
Auxiliary Systems
Engineering
Logistics
Service
Published bySiemens AGIndustrial Solutionsand ServicesMarine SolutionsP.O. Box 10 56 09D-20038 HamburgTel. +49/40/28 89-27 00Fax +49/40/28 89-36 [email protected]
Siemens AGIndustrial Solutionsand ServicesMarine SolutionsPostfach 32 40D-91050 ErlangenTel. (0 91 31) 7-2 71 79Fax (0 91 31) 7-2 68 [email protected]
www.marine-solutions.de
Siemens Aktiengesellschaft Subject to change without prior notice
© Siemens AG 2001All rights reserved
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