The electrode is where reaction of chemical species occurs and electrones are either released or accepted. Typically this will be a metal,such as platinum in PEMFC.

A substance which carries charge via the migration of ions; together with the external connections of a fuel cell, an electrical circuit can be created.

A fuel cell is an electrochemical device, which converts chemical energy to electrical energy without combustion. Unlike a battery, a fuel cell will continuously produce electricity as long as fuel is supplied and the catalyst remains active.

Gas diffusion layers, typically made out of carbon paper or cloth, play a number of important roles in a fuel cell, such as structural support, reactant transport, water removal, and heat conduction.

Hydrogen is the fuel most commonly used in fuel cells.

A variant of the PEMFC which uses a mineral acid based electrolyte rather than an aqueous one and can operate at temperatures up to 200 C. These cells are more tolerant to impurities in the fuel as a result.

Relates to distributed generation where local generators continue to power a location when power from the electricity grid is no longer present. When a fuel cell is grid-connected,islanding(isolation) of the fuel cell is required to allow safe work at that location.

Kilowatt,a unit of power equal to 1,000 watts

Kilowatt electric, a measure of electric power output

Kilowatt-hour,a unit of energy. A device with a power output of one kilowatt running for one hour would generate one kilowatt-hour of energy.

Kilowatt thermal,a unit of thermal(heat) power output.

Low emission vehicles are light duty passenger vehicles meeting strict emissions regulations in California. These can be divided into a number of sub-categories including ultra-low emissions vehicles(ULEV),super-ultra-low emissions vehicles(SULEV), partial zero emissions vehicles(PZEV) or zero emission vehicles(ZEV).

A load-following fuel cell generates variable amounts of electrical power depending on the requirements of the devices it is powering.

Membrane electrode assembly,a structured component in a PEMFC and DMFC,consisting of a membrane with an electrode on each side.

This separates two electrodes of a fuel cell,acting as the electrolyte and allowing passage of ions between the electrodes.