Fuel Cells: Selected Entries from the Encyclopedia of Sustainability Science and Technology

794 Pages·2013·15.069 MB·English

by  Klaus-Dieter Kreuer (auth.), Klaus-Dieter Kreuer (eds.)

Fuel Cells
ThisvolumecollectsselectedtopicalentriesfromtheEncyclopediaofSustainabilityScience
andTechnology(ESST).ESSTaddressesthegrandchallengesforscienceandengineering
today. It provides unprecedented, peer-reviewed coverage of sustainability science and
technology with contributions from nearly 1,000 of the world’s leading scientists and
engineers, who write on more than 600 separate topics in 38 sections. ESST establishes a
foundationfortheresearch,engineering,andeconomicssupportingthemanysustainability
andpolicyevaluationsbeingperformedininstitutionsworldwide.
Editor-in-Chief
ROBERTA.MEYERS,RAMTECHLIMITED,Larkspur,CA,USA
EditorialBoard
RITA R. COLWELL, Distinguished University Professor, Center for Bioinformatics and
ComputationalBiology,UniversityofMaryland,CollegePark,MD,USA
ANDREASFISCHLIN,TerrestrialSystemsEcology,ETH-Zentrum,Zu¨rich,Switzerland
DONALD A. GLASER, Glaser Lab, University of California, Berkeley, Department of
Molecular&CellBiology,Berkeley,CA,USA
TIMOTHYL.KILLEEN,NationalScienceFoundation,Arlington,VA,USA
HAROLD W.KROTO, Francis Eppes Professor of Chemistry, Department ofChemistry
andBiochemistry,TheFloridaStateUniversity,Tallahassee,FL,USA
AMORYB.LOVINS,Chairman&ChiefScientist,RockyMountainInstitute,Snowmass,
USA
LORD ROBERT MAY, Department of Zoology, University of Oxford, Oxford, OX1
3PS,UK
DANIELL.MCFADDEN,DirectorofEconometricsLaboratory,UniversityofCalifornia,
Berkeley,CA,USA
THOMASC.SCHELLING,3105TydingsHall,DepartmentofEconomics,Universityof
Maryland,CollegePark,MD,USA
CHARLESH.TOWNES,557Birge,UniversityofCalifornia,Berkeley,CA,USA
EMILIOAMBASZ,EmilioAmbasz&Associates,Inc.,NewYork,NY,USA
CLAREBRADSHAW,DepartmentofSystemsEcology,StockholmUniversity,Stockholm,
Sweden
TERRY COFFELT, Research Geneticist, Arid Land Agricultural Research Center,
Maricopa,AZ,USA
MEHRDAD EHSANI, Department of Electrical & Computer Engineering, Texas A&M
University,CollegeStation,TX,USA
ALI EMADI, Electrical and Computer Engineering Department, Illinois Institute of
Technology,Chicago,IL,USA
CHARLES A. S. HALL, College of Environmental Science & Forestry, State University
ofNewYork,Syracuse,NY,USA
RIK LEEMANS, Environmental Systems Analysis Group, Wageningen University,
Wageningen,TheNetherlands
KEITH LOVEGROVE, Department of Engineering (Bldg 32), The Australian National
University,Canberra,Australia
TIMOTHY D. SEARCHINGER, Woodrow Wilson School, Princeton University,
Princeton,NJ,USA
Klaus-Dieter Kreuer
Editor
Fuel Cells
Selected Entries from the Encyclopedia
of Sustainability Science and Technology
Editor
Klaus-DieterKreuer
Max-Planck-Institutfu¨rFestko¨rperforschung
Heisenbergstr.1
D-70569Stuttgart
Germany
This book consists of selections from the Encyclopedia of Sustainability Science and
Technology edited by Robert A. Meyers, originally published by Springer Science
+BusinessMediaNewYorkin2012.
ISBN978-1-4614-5784-8 ISBN978-1-4614-5785-5(eBook)
DOI10.1007/978-1-4614-5785-5
SpringerNewYorkHeidelbergDordrechtLondon
LibraryofCongressControlNumber:2012954279
#SpringerScience+BusinessMediaNewYork2013
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Contents
1 FuelCells,Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Klaus-DieterKreuer
2 AlkalineMembraneFuelCells. . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
RobertC.T.Slade,JamieP.Kizewski,SimonD.Poynton,
RongZeng,andJohnR.Varcoe
3 DirectHydrocarbonSolidOxideFuelCells. . . . . . . . . . . . . . . . . . 31
MichaelvandenBosscheandStevenMcIntosh
4 FuelCellComparisontoAlternateTechnologies. . . . . . . . . . . . . . 77
JuliaKunze,OdysseasPaschos,andUlrichStimming
5 FuelCellTypesandTheirElectrochemistry. . . . . . . . . . . . . . . . . . 97
Gu¨ntherG.Scherer
6 FuelCells(SOFC):AlternativeApproaches
(Electroytes,Electrodes,Fuels). . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
K.Sasaki,Y.Nojiri,Y.Shiratori,andS.Taniguchi
7 MembraneElectrolytes,fromPerfluoroSulfonic
Acid(PFSA)toHydrocarbonIonomers. . . . . . . . . . . . . . . . . . . . . 179
KenjiMiyatake
8 MoltenCarbonateFuelCells. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Choong-GonLee
9 PEMFuelCellMaterials:Costs,Performance
andDurability. . . .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . 249
A.deFrankBruijnandGabyJ.M.Janssen
10 PEMFuelCellsandPlatinum-BasedElectrocatalysts. . . . . . . . . . 305
JunliangZhang
11 PEMFuelCells,MaterialsandDesign
DevelopmentChallenges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341
v
vi Contents
StephenJ.PaddisonandHubertA.Gasteiger
12 PhosphoricAcidFuelCellsforStationaryApplications. . . . . . . . . 369
SridharV.KanuriandSathyaMotupally
13 PolybenzimidazoleFuelCellTechnology. . . . . . . . . . . . . . . . . . . . 391
MaxMolleo,ThomasJ.Schmidt,andBrianC.Benicewicz
14 PolymerElectrolyte(PE)FuelCellSystems. . . . . . . . . . . . . . . . . . 433
JohnF.Elter
15 PolymerElectrolyteMembrane(PEM)FuelCells,
AutomotiveApplications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473
ShyamS.Kocha
16 PolymerElectrolyteMembraneFuelCells(PEM-FC)and
Non-nobleMetalCatalystsforOxygenReduction. . . . . . . . . . . . . 519
UlrikeI.Kramm,PeterBogdanoff,andSebastianFiechter
17 ProtonExchangeMembraneFuelCells:High-Temperature,
Low-HumidityOperation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577
StevenJ.HamrockandAndrewM.Herring
18 SolidOxideFuelCellMaterials:Durability,
ReliabilityandCost. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 607
HarumiYokokawaandTeruhisaHorita
19 SolidOxideFuelCells. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 657
A.Atkinson,S.J.Skinner,andJ.A.Kilner
20 SolidOxideFuelCells,MarketingIssues. . . . . . . . . . . . . . . . . . . . 687
JohnBøgildHansenandNielsChristiansen
21 SolidOxideFuelCells,SustainabilityAspects. . . . . . . . . . . . . . . . 731
K.U.Birnbaum,R.Steinberger-Wilkens,andP.Zapp
Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 793
Chapter 1
Fuel Cells, Introduction
Klaus-DieterKreuer
Fuelcellsaredeviceswhichelectrochemicallyconvertthechemicalfreeenergyof
gaseousorliquidreactantsintoelectricalenergyinacontinuousway.Asinabattery
the reactants are prevented from chemically reacting by separating them with an
electrolyte, which is in contact with electro-catalytically active porous electrode
structures. Apart from effectively separating the anode and cathode gases and/or
liquids,inotherwordsthefuelandair,theelectrolytemediatestheelectrochemical
reactions taking place at theelectrodesby conducting a specific ion atvery high
rates during the operation of the fuel cell. In the simplest case of a fuel cell,
operating with hydrogen (fuel) and oxygen (air) as reacting gases, a proton or
oxideioncurrentequivalenttotheelectroniccurrentpassingthroughtheexternal
load is driven through the electrolyte and parts of the heterogeneous electrode
structures(Fig.1.1).
ThedrivingforceofthisprocessistheGibbsenergy(DG)ofthereaction:
r
H þ1= O !H O
2 2 2 2
andthepotentialdifference(electromotiveforce:emf)formingacrossthecellsimplyis:
emf ¼(cid:2)DG=zF
r
where z is the number of electrons driven through the outer circuit and F is the
Faradayconstant.
The maximum possibleelectric energy E ,which can beharvested from
reversible
suchreactionsinafuelcell,is:
This chapter was originally published as part of the Encyclopedia of Sustainability Science
andTechnologyeditedbyRobertA.Meyers.DOI:10.1007/978-1-4419-0851-3
K.-D.Kreuer(*)
Max-Planck-Institutfu¨rFestko¨rperforschung,Heisenbergstr.1,D-70569Stuttgart,Germany
e-mail:[email protected]
K.-D.Kreuer(ed.),FuelCells:SelectedEntriesfromtheEncyclopedia 1
ofSustainabilityScienceandTechnology,DOI10.1007/978-1-4614-5785-5_1,
#SpringerScience+BusinessMediaNewYork2013
2 K.-D.Kreuer
Fig.1.1 Schematic e–
illustrationofthe
electrochemicalenergy
conversionprocessin
afuelcell
O
2
H+
H
2
H O
2
E ¼(cid:2)DG
reversible r
and,iftheefficiencyZisdefinedastheratiooftheelectricalenergytakenoutofthe
fuelcellandthereactionenthalpyDH (heatofreaction),theefficiencylimit:
r
Z ¼DG=DH ¼1(cid:2)ðTDS=DHÞ
reversible r r r r
can even behigher than unity, providedthe reaction entropy DS is positive (note
r
thatDH isnegativeforanexothermalreaction)likefortheoxidationofcarbon-rich
r
fuels,forexample:
C H þ5O !3CO þ4H O
3 8 2 2 2
The first law of thermodynamics is not violated because a fuel cell is a
nonadiabatic system exchanging heat with the environment; hence, the missing
energycanbetakenfromtheenvironmentbycoolingthesame.
Lookingatfuelcellsinsuchaprinciplewaymayleadonetotheconclusionthat
theyareperfectenergyconversionsystemssuperiortoanyheatengine,forwhich
theefficiencyisstrictlylimitedtothisoftheCarnotcycle.
However,theissueismorecomplex,anditisstillanopenquestionwhichrole
fuelcellswillplayinfuturemoresustainableenergysupplysystems.
Followinguponaboveefficiencyconsiderations,itmustbementionedthatthe
thermodynamic efficiency limits of all relevant fuel cell reactions are actually
below unity (in the range 80–100%) and that irreversibilities (losses) occur in
practically all parts of every fuel cell (e.g., transport losses in the gas diffusion
electrodes, over-potentials associated with the electrochemical reactions taking
placeattheanodeandcathode,IRlossesacrosstheelectrolyteandallinterfaces).
1 FuelCells,Introduction 3
70
with turbine
60
50 posloylmide or xeidleec tfruoelyl dtceiee lmsleel menbrgainnee fuel cellg a s/steam powsteera pmla tnutrbine
ncy / % 40 phosphgoarsico alinceid efunegli nceell gas turbine
e
ci 30
effi
20
expected technological limit
10
current technology
0
0.1 1 10 100 1000
power / MW
Fig.1.2 Efficiencyversuspowerfordifferentfuelcelltypescomparedtootherenergyconversion
technologies
Nonetheless, electric efficiencies of more than 50% have been demonstrated
experimentally, and, considering the fact that heat engines (e.g., steam turbines)
reach such high efficiencies only for very large units, the large fuel efficiency of
smallfuelcellsappearstobeauniquefeature(Fig.1.2).
Together with capital cost and operating cost advantages, this is making fuel
cellsanattractivealternativeespeciallyinthesub-10-MWrange.
Despitetheverydemandingconditionsinautomotiveapplicationsandthemore
than100yearsofoptimizationoftheinternalcombustionengine,therelativelyhigh
fuelefficiencyisoneofthereasonswhyfuelcellshavearealchancetobeapplied
eveninthishighlycompetitivemarket.Foracoupleofnichemarkets(likeoutdoor,
yachting),fuelcellsarealreadywellestablished.
Especiallyformassapplicationssuchasautomotive,afulllifecycleassessment
(LCA) is absolutely critical. Since there are a lot of embedded resources such as
noble metal catalysts and energy for manufacturing fuel cells, LCA very much
depends on aspects such as recyclability and lifetime. For the operation period
itself,cost,performance,anddurabilityissuesareimportant.Butacompletepicture
must also consider aspects of specific applications including how they are
connectedinfutureenergyscenarios.
Since fuel cells are just energy conversion devices, also the availability of
appropriatefuelsisessentialforthepotentialroleoffuelcells.Themostadvanced
fuelcelltypesrelyonnaturalgas(methane)orhydrogenasafuel.
4 K.-D.Kreuer
Due to the high H/C ratio (which gives it some environmental advantage) and
availability, methane (CH ) may play a key role in the broad introduction of fuel
4
celltechnology(DirectHydrocarbonSolidOxideFuelCells).
Hydrogen can be directly obtained by reforming natural gas, but today it is
mainly produced as a by-product only, that is, hydrogen is not being used exten-
sivelyasanenergycarrier.Although,withhydrogen,onecanstorelargeamounts
of energy which can be distributed in relatively easy ways, the hydrogen storage
problemisnotfullysolvedyet.Alsothewaysofproducinghydrogen,includingthe
primaryenergyusedforthis,bearalotofopenquestions.Whilesomecountriesare
evenconsideringtheuseofexcessnuclearenergy(electricityandheat)forproduc-
inghydrogen,otherswanttorelycompletelyonrenewablessuchaswindandsolar.
I hope, these few considerations make it clear that the future of fuel cells may
heavily depend on severe bifurcations. Heat engines and electrochemical energy
storagedevices(mainlybatteries)existedsidebysideinthelatenineteenthandthe
early twentieth century, but the abundance of fossil fuels has later driven the
development of combustion engines and turbines retarding the development of
alternative energy conversion devices such as batteries and fuel cells. It could
wellbethattheexpectedendofthe“oilage”mayalsogoalongwithanincreasing
importanceofalternativeenergyconversiondevices,amongwhichfuelcellshave
the potential toplay an important role. Much will depend on the societies driving
this development. Their understanding of “Sustainability” will be different
dependingonthe relative importanceofitsdifferent aspects,such aspreservation
of natural resources, environmental impact, safety and reliability. Moreover, the
temptationtobenefitfrom short-term“economical advantages”may strongly bias
thedecisionstocome.
Makinglargequantitiesofhydrogenwithsunlight,directlyorindirectly,isstill
far away, but there is no principal physicochemical law preventing this option,
which seems to be one of the long-standing driving forces for the many fuel cell
activitiesaroundtheglobe.
The entries of the following part on fuel cells will strictly keep out of such
aspectswhicharehighlyspeculativeatthisstage.Theyratherfocusonthetechnical
issues comprising descriptions of the state of the art and remaining problems,
approachestosolvethesame,andsomespeculationsaboutfuturedirections.This
volume is meant to provide a solid ground for taking decisions. There is some
redundancy and overlap between entries reflecting different points of view which
naturallyexistevenforthetechnicalissues.
Historically, the fuel cell concept is known for more than 170 years. It was
Christian Friedrich Scho¨nbein who recognized and described the appearance of
“inverse electrolysis” [1], shortly before Sir William Grove, the inventor of the
platinum/zincbattery,constructedhisfirst“gasvoltaicbattery”[2].Grovealready
usedplatinumelectrodesanddilutesulfuricacidasaprotonconductingelectrolyte,
anditisworthmentioningthattoday’slow-temperaturePEM(polymerelectrolyte
membrane)fuelcellsstillmakeuseofrelatedmaterials(carbon-supportedplatinum
and perfluoro-sulfonic-acid (PFSA)-ionomers). The same is also true for high-
temperature fuel cells which are dating back to the 1930s. In an attempt to prove