Glossary of fuel cell terms

The Glossary of fuel cell terms lists the definitions of many terms used within the fuel cell industry. The terms in this fuel cell glossary may be used by fuel cell industry associations, in education material and fuel cell codes and standards to name but a few.

A

; Activation loss
; Adsorption
; Alkali
; Alkali anion-exchange membrane
; Alkaline fuel cell
; Alloy
; Alternator
; Alternating current
; Ambient Air
; Ambient temperature
; Ampere
; Anion
; Anode
; Aqueous phase reforming
; Artificial membrane
; Atmospheric pressure
; Atom
; Autothermal reforming
; Auxiliary power unit
; Availability factor

B

; Back pressure
; Baffle
; Balance of plant
; Battery
; Biofuel
; Biogas
; Bioreactor
; Biosensor
; Bipolar plate
; Black start
; Beta-alumina solid electrolyte
; Boiling point
; Borax
; British thermal unit
; Busbar

C

; Capacity
; Capacity factor
; Capital cost
; Carbon
; Carbon black
; Carbon dioxide
; Carbon dioxide sensor
; Carbon monoxide
; Carbon monoxide detector
; Carbon paper
; Carnot cycle
; Catalysis
; Catalyst
; Catalyst poisoning
; Catalytic partial oxidation
; Cathode
; Cation
; Celsius
; Centimeter
; Centrifugal governor
; Ceramic
; Cermet
; Chemical thermodynamics
; Circuit
; Circuit diagram
; Circulation
; Climate change
; Cogeneration
; Combustion
; Combustion chamber
; Composite material
; Compressed hydrogen
; Compressed natural gas
; Concentration
; Condensate
; Condensation
; Condenser
; Contamination
; Coulomb
; Countercurrent exchange
; Cryogenic liquefaction
; Current
; Current collector

D

; DC-to-DC converter
; Density
; Desiccant
; Detection limit
; Dew point
; Diffusion
; Direct borohydride fuel cell
; Direct carbon fuel cell
; Direct current
; Direct-ethanol fuel cell
; Direct methanol fuel cell
; Dispersion
; Distributed Generation
; Doping
; Downtime
; Dry basis

E

; Effluent
; Electrical Balance of Plant
; Electricity
; Electrical conductivity
; Electrical efficiency
; Electrical insulation
; Electrical resistance
; Electric circuit
; Electric current
; Electricity generation
; Electric power conversion
; Electrochemistry
; Electrochemical cell
; Electrochemical gas sensor
; Electrode
; Electro-galvanic fuel cell
; Electroosmotic flow
; Electroosmotic pump
; Electrolysis
; Electrolyte
; Electron
; Emission
; Emission standard
; Endothermic
; Energy
; Energy carrier
; Energy content
; Energy security
; Energy storage
; Engine
; Energy conversion efficiency
; Energy density
; Energy transformation
; Enthalpy
; Enthalpy of vaporization
; Ethanol
; Evaporation
; Exergy
; Exergy efficiency
; Exhaust gas
; Exothermic
; Expansion ratio

F

; Fan
; Fahrenheit
; Failure mode and effects analysis
; FCEV
; FCV
; Feedstock purification
; Flammability
; Flammability limit
; Flash point
; Float valve
; Flow battery
; Flow measurement
; Flue gas
; Flue-gas desulfurization
; Fluid dynamics
; Fluid mechanics
; Flux
; Formic acid
; Formic acid fuel cell
; Fossil fuel
; Fouling
; Frequency changer
; Fuel
; Fuel cell
; Fuel cell poisoning
; Fuel cell vehicle
; Fuel efficiency
; Fuel efficiency in transportation
; Fuel processor
; Fuel processing system
; Fuel pump
; Fusible plug

G

; Gadolinium doped ceria
; Gas
; Gas compressor
; Gas detector
; Gas diffusion
; Gas diffusion electrode
; Gasification
; Gasoline gallon equivalent
; Gibbs free energy
; Graphite
; Greenhouse effect
; Greenhouse gases
; Grid connection
; Grid-tied electrical system
; Grid tie inverter
; Guard bed
; Guard catalyst bed

H

; Half-reaction
; Heat exchanger
; Heat pipe
; Heat transfer
; Heating value
; Heat of combustion
; Higher heating value
; High-temperature shift
; Hybrid electric vehicle
; Hydride
; Hydride ion
; Hydrocarbon
; Hydrocarbon dew point
; Hydrodesulfurization
; Hydrogen
; Hydrogen anion
; Hydrogen purity
; Hydrogen-rich fuel
; Hydrogen sulfide sensor

I

; Impurity
; Influent
; Interlock
; Internal combustion engine
; Inverter
; Ion
; Ion exchange
; Ion-exchange resin
; Ionomer
; Islanding

K

; Kröger–Vink notation
; Kilogram
; Kilowatt
; Kilowatt hour

L

; Landfill gas
; Lanthanum carbonate
; LH₂
; Life cycle assessment
; Linear regulator
; Liquid
; Liquid hydrogen
; Liquid–liquid extraction
; Liquefied natural gas
; Liquefied petroleum gas
; Liquefaction
; Liquefaction of gases
; List of chemical purification methods in chemistry
; Load following power plant
; Load profile
; Lower flammability limit
; Lower heating value
; Low temperature shift

M

; Maintenance, repair and operation cost
; Mass flow sensor
; Maximum allowable operating pressure
; Mean down time
; Mean time between failures
; Mean time between outages
; Mechanical energy
; Mechanical Balance of Plant
; Membrane
; Membrane electrode assembly
; Megawatt
; Meter
; Methanation
; Methane
; Methane reformer
; Methanol
; Methanol reformer
; MicroCHP
; Microbial fuel cell
; Micropump
; Miles per gallon equivalent
; Millimeter
; Milliwatt
; Molten-carbonate fuel cells

N

; Nafion
; Nano iron powder
; Nanowire
; Natural gas
; Nernst equation
; Net energy gain
; Nickel
; Nitrogen
; Nitrogen oxide
; Nitrogen oxide sensor

O

; Off board reforming
; Ohm
; Onboard reforming
; Open-circuit voltage
; Original equipment manufacturer
; Output impedance
; Overpotential
; Overpressure
; Overvoltage
; Oxidant
; Oxidation
; Oxygen
; Oxygen sensor

P

; Palladium
; Parallel circuit
; Partial oxidation
; Partial pressure
; Particulate
; Parts per million
; Parts per million by volume
; Pascal
; Peak load
; PEDOT
; Permeation
; Phase transition
; Phosphoric acid
; Phosphoric acid fuel cell
; Photoelectrochemical cell
; Platinum
; Polybenzimidazole fiber
; Polyethylene
; Polymer
; Polymer electrolyte membrane
; Polytetrafluoroethylene
; Polymer electrolyte membrane fuel cell
; Potential difference
; Portable fuel cell applications
; Potassium hydroxide
; Power
; Power density
; Power factor
; Power supply
; Power-to-weight ratio
; Power per unit of mass
; PReferential OXidation
; Pressure regulator
; Pressure relief valve
; Pressure sensor
; Pressure swing adsorption
; Pressure vessel
; Propane
; Proton
; Proton-exchange membrane
; Proton-exchange membrane fuel cell
; Protonic ceramic fuel cell

R

; Reactor
; Reagent
; Rectifier
; Redox
; Reformate
; Reformed Methanol Fuel Cell
; Reformer
; Reforming
; Reformulated gasoline
; Regenerative fuel cell
; Relief valve
; Renewable energy
; Reservoir
; Response time
; Reversible fuel cell
; Reynolds number
; Rupture disc
; Ruthenium

S

; Safety shutoff valve
; Safety valve
; Salt bridge
; Scrubber
; Sensor
; Series circuit
; Service life
; Short circuit
; Sodium borohydride
; Solenoid valve
; Solid oxide electrolyser cell
; Solid oxide fuel cell
; Solubility
; Sorbent
; Sorption
; Specific gravity
; Specific heat capacity
; Specific power
; Specific weight
; Stack
; Standard cubic foot
; Standard electrode potential
; Stationary fuel-cell applications
; Steady state
; SMR
; Steam reforming
; Switched-mode power supply
; Syngas

T

; Tafel equation
; Tail gas combustor
; Tar
; Technology assessment
; Technology life cycle
; Technology readiness level
; Technology validation
; Temperature
; Terbium
; Thermal conductivity
; Thermal efficiency
; Thermal expansion
; Thermal partial oxidation
; Thermoelectricity
; Thermoplastic
; Thermoplastic elastomer
; Transducer
; Transfer switch
; Transformer
; Triple phase boundary
; Triple point
; Turbine
; Turbocharger
; Turbocompressor

U

; Ullage
; Uninterruptible power supply
; Unitized regenerative fuel cell

V

; Vacuum pump
; Vapor–liquid equilibrium
; Vapor pressure
; Vapor recovery
; Voltage
; Voltage converter
; Voltage drop
; Voltage regulator
; Volumetric energy density
; Volumetric flow rate
; Volumetric heat capacity

W

; Water
; Water gas shift reaction
; Water purification
; Water vapor
; Watt
; Wet basis
; W/kg
; Wt.%

Y

; Yttria-stabilized zirconia

Z

; Zinc-air battery
; Zinc oxide

Acronyms

Acronym	–
AAEM	alkali anion-exchange membrane
AC	alternating current
AFC	alkaline fuel cell
ATR	autothermal reforming
APU	auxiliary power unit
BASE	beta-alumina solid electrolyte
BOP	balance of plant
BTU	British thermal unit
°C	celsius
C	carbon
C	coulomb
ca. or c.	circa
CGH₂	compressed hydrogen
CH₄	methane
CH₃CH₂OH	ethanol
CH₃OH	methanol
CHP	combined heat and power
CI	chloride ion
CNG	compressed natural gas
CNT	carbon nanotube
CO₂	carbon dioxide
CO	carbon monoxide
CPOX	catalytic partial oxidation
CPS	continuous power supply
DBFC	direct borohydride fuel cell
DC	direct current
DCFC	direct [carbon fuel cell]
DEFC	direct-ethanol fuel cell
DER	distributed energy resource
DFAFC	formic acid fuel cell
DMFC	direct [methanol fuel cell]
E⁰	standard electrode potential
EBOP	electrical balance of plant
EGFC	electro-galvanic fuel cell
EOF	electroosmotic flow
EOP	electroosmotic pump
°F	fahrenheit
FB	flow battery
FC	fuel cell
FGD	flue-gas desulfurization
FMEA	failure mode and effects analysis
FPS	fuel processing system
GDC	gadolinium doped ceria
GEG	gasoline-equivalent gallon
GGE	gasoline gallon equivalent
GHSV	gas hourly space velocity
H₂	hydrogen
H₂O	water
HC	hydrocarbon
HCDP	hydrocarbon dew point
HCOOH	formic acid
HDP	hydrocarbon dew point
HDS	hydrodesulfurization
HEV	hybrid electric vehicle
HHV	higher heating value
HTS	high temperature shift
ICE	internal combustion engine
IMFC	indirect methanol fuel cell
KG	kilogram
KOH	potassium hydroxide
kW	kilowatt
kWh	kilowatt hour
kW/kg	Kilowatts per kilogram
kW/m3	Kilowatts per cubic meter
kW/sq.m	Kilowatts per square meter
LCA	life cycle assessment
LDH	layered double hydroxides
LEL	lower explosive limit
LFG	landfill gas
LFL	lower flammable limit
LH₂	liquid hydrogen
LHSV	liquid hourly space velocity
LHV	lower heating value
LNG	liquefied natural gas
LOD	limit of detection
LPG	liquefied petroleum gas
LSM	lanthanum strontium manganite
LTS	low temperature shift
MAF	mass flow sensor
MAOP	maximum allowable operating pressure
MBOP	mechanical balance of plant
MCFC	molten-carbonate fuel cell
mCHP	micro combined heat and power
MDT	mean down time
MEA	membrane electrode assembly
MeOH	methanol
MFC	microbial fuel cell
mm	millimeter
MPGe	miles per gallon of gasoline equivalent
MRO	maintenance, repair and operations
MSR	methanol steam reforming
MTBF	mean time between failures
MTBO	mean time between outages
MW	megawatt
mW	milliwatt
N₂	nitrogen
NEG	net energy gain
NO_x	nitrogen oxide
O	oxygen
OCV	open-circuit voltage
OEM	original equipment manufacturer
Pa	pascal
PAFC	phosphoric acid fuel cell
PBI	polybenzimidazole fiber
PCFC	protonic ceramic fuel cell
Pd	palladium
p.d.	potential difference
PEC	photoelectrochemical cell
PEDOT	poly(3,4-ethylenedioxythiophene)
PEDT	poly(3,4-ethylenedioxythiophene)
PEFC	polymer electrolyte membrane fuel cell
PEM	polymer electrolyte membrane or proton-exchange membrane
PEMFC	polymer electrolyte membrane fuel cell or proton-exchange membrane fuel cell
PM	particulate matter
POX	partial oxidation
ppm	parts per million
ppmv	parts per million volume
PROX	preferential oxidation
PRV	pressure relief valve
PSA	pressure swing adsorption
PSU	power supply unit
Pt	platinum
PTFE	polytetrafluoroethylene
Pv	power density
Re	reynolds number
RESS	rechargeable energy storage system
RFC	reversible fuel cell
RMFC	reformed methanol fuel cell
RWGS	reversed water-gas shift reaction
s/c	short circuit or steam to carbon ratio
SFC	standard cubic foot or sometimes solid oxide fuel cell
SMPS	switched-mode power supply
SMR	steam methane reforming
SOEC	solid oxide electrolyser cell
SOFC	solid oxide fuel cell
SR	steam reforming
TA	technology assessment
TGC	tail-gas combustor
TOF	turnover frequency
TOS	time on stream
TPB	triple-phase boundary
TPE	thermoplastic elastomers
TPOX	thermal partial oxidation
TRL	technology readiness level
UEL	upper explosive limit
UPS	uninterruptible power supply
URFC	unitized regenerative fuel cell
VHC	volumetric heat capacity
VLE	vapor–liquid equilibrium
W	watt
WGS	water–gas shift reaction
WHSV	weight hourly space velocity
Wt.%	weight percent
YSZ	yttria-stabilized zirconia
ZnO	zinc oxide