Alternating Current (AC)
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The commonly available electric power used in buildings, including homes. The power shifts or alternates back and forth, typically changing direction 50 or 60 times per second.
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Anode
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The hydrogen side of the fuel cell membrane where electrons are stripped from hydrogen atoms.
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Balance of Plant
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Supporting components necessary for the operation of the fuel processor and the fuel cell integrated into a fuel cell system.
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Base-Load
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The usual minimum electrical demand placed on the fuel cell system.
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Catalyst
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A substance that alters the speed of a chemical reaction and does not appear in the final product and undergoes no permanent changes.
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Cathode
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The oxygen side of the membrane where reduction of the oxidant occurs.
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Conductor
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A material such as copper or aluminum which offers low resistance or opposition to the flow of electric current.
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Current
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The movement of an electrical charge (electrons or ions) through a circuit.
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Direct Current (DC)
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An electrical current which flows only in one direction in a circuit. Batteries and fuel cells produce direct current.
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Electrode
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An electrically conductive structure in an electrochemical device, such as a fuel cell, which transfers electrons to or from reactant atoms or molecules.
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Electrolyte
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The medium in a fuel cell that provides the ion transport mechanism between the anode and the cathode necessary to sustain the electrochemical process. In a PEM fuel cell, the electrolyte allows the transport of positively charged hydrogen ions (protons) from the anode, where they are produced, to the cathode, where they react with oxygen molecules and electrons to produce water.
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Electron
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The negatively charged component of an atom and the unit of negative electrical charge that makes up a current.
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Fuel
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Fuel cells need hydrogen, and some systems are run from bottled hydrogen. Systems such as IdaTech’s, however, incorporate fuel processors that produce hydrogen from a variety of alcohol or fossil fuels.
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Fuel Cell
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A device that electrochemically converts the chemical energy of a fuel and an oxidant to electrical energy. The fuel and oxidant are typically stored outside of the fuel cell and transferred into the fuel cell as the reactants are consumed.
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Fuel Processor
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A device that supplies purified hydrogen to a fuel cell, consisting of a reformer coupled to a hydrogen purifier.
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Grid Connected
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A fuel cell system that operates in parallel with the utility power system.
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Grid Isolated/Independent
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A fuel cell system that powers a dedicated load (e.g. a residential home). and is not connected to the utility power grid.
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Gross Power
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The primary power output of a fuel cell stack prior to any conditioning and losses associated with the production of power suitable for the connected load.
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Ion
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An atom or molecule that has acquired an electrical charge by the loss or gain of electrons. When electrons are stripped from hydrogen atoms in the anode side of the fuel cell, the atoms become positively charged hydrogen protons, which are ions.
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Kilowatt
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1,000 watts, which is equivalent to approximately 1.34 horsepower. (A watt is a basic measure of electrical power.)
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Load Following
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Method of operating a fuel cell system to generate a varying amount of power depending on the load demanded.
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Megawatt
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1 million watts
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Net Power
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The difference between the gross power flowing from a fuel cell stack and the sum total of all the power losses (including power needed to operate the balance-of-plant, and losses incurred during power conditioning).
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OEM
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An original equipment manufacturer who incorporates an IdaTech fuel cell system or fuel processor into its equipment.
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Oxidant
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A chemical compound (usually oxygen) that reacts with a fuel to create heat or power through chemical conversion in processes such as burning or electrochemistry.
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Power Conditioning/Power Management
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The subsystem that converts the DC power from the fuel cell stack to AC power that is compatible with requirements of the load. A battery bank and charger may also be part of this subsystem.
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Proton
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The positively charged hydrogen ion that remains when an electron is removed from the hydrogen atom in the anode side of a fuel cell.
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Proton Exchange Membrane Fuel Cell
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A type of acid-based fuel cell in which the exchange of protons (H+) from the anode to the cathode is achieved by a solid, water-swollen membrane electrolyte impregnated with a strong acid. The fuel cells typically run at low temperatures (<100OC) and pressures (<5 atm).
Anode Reaction: H2 Æ 2H+ + 2e-
Cathode Reaction: _O2 + 2H+ + 2e- Æ H2O
Overall Reaction: H2 + _O2 Æ H2O
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Reformate Gas
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The hydrogen-rich gas that exits the fuel reformer.
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Reformer
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A vessel in which fuel reacts with steam and heat, usually in the presence of a catalyst, to produce a hydrogen-rich gas.
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Steam Reforming
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The process for reacting a hydrocarbon or alcohol fuel, such as natural gas or methanol, in the presence of steam to form hydrogen as a product. This is the commonly preferred method of bulk hydrogen generation.
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Stoichiometric Ratio
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The ideal oxidizer-to-fuel ratio in the cathode reaction, wherein all of the oxidizer exactly reacts with all of the fuel.
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Watt
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A basic measure of electrical power.
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