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 See overpotential
Adsorption Adsorption is a process that occurs when a gas or liquid solute accumulates on the surface of a solid or a liquid (adsorbent), forming a film of molecules or atoms (the adsorbate).
Alkali In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element.
Alkali anion-exchange membrane An alkali anion-exchange membrane (AAEM) is a semipermeable membrane generally made from ionomers and designed to conduct anions while being impermeable to gases such as oxygen or hydrogen.
Alkaline fuel cell Alkaline fuel cell (AFC) also known as the Bacon fuel cell.
Alloy An alloy is a solid solution or homogeneous mixture of two or more elements, at least one of which is a metal, which itself has metallic properties.
Alternator An alternator is an electromechanical device that converts mechanical energy to alternating current electrical energy.
Alternating current An alternating current (AC) is an electric current which reverses direction cyclically, as opposed to direct current, the direction of which remains constant.
Ambient Air The air surrounding a given object or system.
Ambient temperature Ambient temperature is the temperature within enclosed space.
Ampere The ampere, in practice often shortened to amp, (symbol: A) is a unit of electric current, or amount of electric charge per second.
Anion A negatively charged ion; an ion that is attracted to the anode.
Anode An anode is an electrode through which electric current flows into a polarized electrical device.
Aqueous phase reforming APR is the production of hydrogen from biomass-derived oxygenated compounds (such as glycerol, sugars and sugar alcohols).
Artificial membrane An artificial membrane, also called a synthetic membrane, is a membrane prepared for separation tasks in laboratory and industry.
Atmospheric pressure Atmospheric pressure is the pressure at any given point in the Earth's atmosphere.
Atom The atom is the smallest unit of an element that retains the chemical properties of that element. An atom has an electron cloud consisting of negatively charged electrons surrounding a dense nucleus. The nucleus contains positively charged protons and electrically neutral neutrons.
Autothermal reforming Autothermal reforming (ATR) uses oxygen and carbon dioxide or steam in a reaction with methane to form syngas.
Auxiliary power unit An auxiliary power unit (APU) is a device on a vehicle whose purpose is to provide energy for functions other than propulsion.
Availability factor The availability factor of a power plant is the amount of time that it is able to produce electricity over a certain period, divided by the amount of the time in the period.
B
Back pressure Back pressure is the pressure exerted on a moving fluid by obstructions or tight bends in the confinement vessel along which it is moving, such as piping or air vents, against its direction of flow.
Baffle A device or construction used to restrain or regulate, e.g. gas, or a fluid.
Balance of plant Balance of plant (BOP) is the infrastructure of a fuel cell, not including the fuel cells. (See also Mechanical Balance of Plant MBOP and Electrical Balance of Plant EBOP).
Battery In electronics, a battery is a combination of two or more electrochemical cells which store chemical energy and make it available as electrical energy.
Biofuel Biofuel is defined as solid, liquid or gas fuel derived from recently dead biological material and is distinguished from fossil fuels, which are derived from long dead biological material.
Biogas Biogas is a gas produced by the biological breakdown of organic matter in the absence of oxygen. Biogas originates from biogenic material and is a type of biofuel.
Bioreactor A bioreactor is any device or system that supports a biologically active environment
Biosensor A biosensor is a device for the detection of an analyte that combines a biological component with a physicochemical detector component.
Bipolar plate A onductive plate in a fuel-cell stack that acts as an anode for one cell and a cathode for the adjacent cell. The plate may be made of metal or a conductive polymer (which may be a carbon-filled composite). The plate usually incorporates flow channels for the fluid feeds and may also contain conduits for heat transfer. See also MEA.
Black start A black start is the process of restoring a power station to operation without relying on external energy sources.
Beta-alumina solid electrolyte Beta-alumina solid electrolyte (BASE) is a fast-ion conductor material used as a membrane in several types of molten salt electrochemical cell.
Boiling point The boiling point of a liquid is the water temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid.
Borax Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid.
British thermal unit The mean British thermal unit (BTU) is 1/180 of the heat required to raise the temperature of of water from at a constant atmospheric pressure. It is about equal to the quantity of heat required to raise one pound of water 1°F (°C).
Busbar In electrical power distribution, a busbar is the strips of copper or aluminium that conduct electricity within a switchboard, fuel cell, distribution board, substation, or other electrical apparatus.
C
Capacity Capacity is the ability to hold, receive or absorb, or a measure thereof, similar to the concept of volume.
Capacity factor The net capacity factor of a power plant is the ratio of the actual output of a power plant over a period of time and its output if it had operated at full nameplate capacity the entire time.
Capital cost Capital cost are costs incurred on the purchase of fuel cells, buildings, construction and equipment to be used in the use of fuel cells or the rendering of it.
Carbon Carbon (C), an atom and primary constituent of hydrocarbon fuels. Carbon is routinely left as a black deposit on engine parts, such as pistons, rings, and valves, by the combustion of fuel.
Carbon black Carbon black is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, ethylene cracking tar, and a small amount from vegetable oil.
Carbon dioxide Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom.
Carbon dioxide sensor A carbon dioxide sensor (CO2) is an instrument for the measurement of carbon dioxide gas. The most common principles for CO2 sensors are infrared gas sensors (NDIR) and chemical gas sensors.
Carbon monoxide Carbon monoxide, with the chemical formula CO, is a colorless, odorless, tasteless yet highly toxic gas.
Carbon monoxide detector A carbon monoxide detector is a device that detects the presence of the toxic gas carbon monoxide (CO), a colorless and odorless compound produced by incomplete combustion and lethal at high levels.
Carbon paper Carbon paper (originally carbonic paper) is paper coated on one side with a layer of a loosely bound dry ink or pigmented coating, usually bound with wax.
Carnot cycle The Carnot cycle is a particular thermodynamic cycle, modeled on the hypothetical Carnot heat engine.
Catalysis Catalysis is the process in which the rate of a chemical reaction is increased by means of a chemical substance known as a catalyst.
Catalyst A catalyst is a chemical substance that increases the rate of a reaction without being consumed; after the reaction it can potentially be recovered from the reaction mixture chemically unchanged.
Catalyst poisoning Catalyst poisoning is the effect that a catalyst can be 'poisoned' if it reacts with another compound that bonds chemically (similar to an inhibitor) but does not release, or chemically alters the catalyst.
Catalytic partial oxidation In catalytic partial oxidation (CPOX) the use of a catalyst for partial oxidation reduces the required temperature to around 800°C – 900°C. The choice of reforming technique depends on the sulfur content of the fuel being used. CPOX can be employed if the sulfur content is below 50 ppm. A higher sulfur content would poison the catalyst, so the TPOX procedure is used for such fuels.
Cathode A cathode is an electrode through which (positive) electric current flows out of a polarized electrical device.
Cation A cation is a positively charged ion.
Celsius The degree Celsius (°C) is a designation for specific temperatures on the Celsius scale as well as units of increment to indicate a temperature interval (a difference between two temperatures or an uncertainty).
Centimeter A centimetre (American spelling: centimeter, symbol cm) is a unit of length in the metric system, equal to one hundredth of a metre, which is the current SI base unit of length.
Centrifugal governor A centrifugal governor is a specific type of governor that controls the speed by regulating the amount of fuel (or working fluid) admitted, so as to maintain a near constant speed whatever the load or fuel supply conditions.
Ceramic Ceramics are inorganic non-metallic materials formed by the action of heat.
Cermet A cermet is a composite material composed of ceramic (cer) and metallic (met) materials.
Chemical thermodynamics In thermodynamics, chemical thermodynamics is the mathematical study of the interrelation of heat and work with chemical reactions or with a physical change of state within the confines of the laws of thermodynamics.
Circuit A circuit is a closed path formed by the interconnection of electronic components through which an electric current can flow.
Circuit diagram A circuit diagram (also known as an electrical diagram, wiring diagram, elementary diagram, or electronic schematic) is a simplified conventional pictorial representation of an electrical circuit.
Circulation In fluid dynamics, circulation is the line integral around a closed curve of the fluid velocity.
Climate change Climate change is any long-term significant change in the “average weather” that a given region experiences.
Cogeneration Cogeneration (also combined heat and power, CHP) is the use of a heat engine or a power station to simultaneously generate both electricity and useful heat.
Combustion Combustion or burning is a complex sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames.
Combustion chamber A combustion chamber is the part of an engine in which fuel is burned.
Composite material Composite materials (or composites for short) are engineered materials made from two or more constituent materials with significantly different physical or chemical properties and which remain separate and distinct on a macroscopic level within the finished structure.
Compressed hydrogen Compressed hydrogen (CGH2, CH2 or CH2) is the gaseous state of the element hydrogen which is kept under pressure.
Compressed natural gas Compressed Natural Gas (CNG) is a fossil fuel substitute for gasoline (petrol), diesel, or propane fuel.
Concentration In chemistry, concentration is the measure of how much of a given substance there is mixed with other substances.
Condensate Condensate, the liquid phase produced by the condensation of steam or any other gas
Condensation Condensation is the change of the physical state of aggregation (or simply state) of matter from gaseous phase into liquid phase.
Condenser