Glossary
Use this comprehensive glossary to define terms commonly used in the alternative fuels and advanced vehicles industry. If you have questions about specific technologies or fuels, contact the Technical Response Service at 1-800-254-6735.
Click on the appropriate letter. · A · B · C · D · E · F · G · H · I · J · K · L · M · N · O · P · Q · R · S · T · U · V · W · X · Y · Z ·· A · ASTM InternationalA nonprofit organization that develops and delivers international standards. ASTM standards, test methods, specifications, and procedures are recognized as definitive guidelines for fuel quality. Advanced Technology VehiclesA vehicle that combines new engine, power, or drivetrain systems to significantly improve fuel economy. This includes hybrid power systems and fuel cells, as well as some specialized electric vehicles. Alternative Fuel VehiclesA dedicated, flexible fuel, or dual-fuel vehicle designed to operate on at least one alternative fuel. Alternative FuelsThe Energy Policy Act of 1992 defines an alternative fuel as:
Anaerobic DigestionAnaerobic digestion is series of processes in which microorganisms break down biodegradable material in the absence of oxygen. Autoignition TemperatureThe lowest temperature at which a flammable gas vapor will ignite spontaneously, without a source of ignition, after several minutes of exposure to sources of heat. BatteryThe battery provides electricity to start the engine and power vehicle electronics/accessories. Battery (auxiliary)In an electric drive vehicle, the auxiliary battery provides electricity to start the car before the traction battery is engaged and to power vehicle accessories. Battery packStores energy generated from regenerative braking and provides supplemental power to the electric traction motor. BiochemicalChemical reactions in living organisms. Biochemical ConversionUsing enzymes and catalysts to change biological substances chemically to produce energy products. An example is digestion of organic wastes or sewage by microorganisms to produce methane. BiomassPlant matter such as trees, grasses, agricultural residue, algae, and other biological material. Blender PumpA fuel dispenser that draws fuel from two separate storage tanks and can dispense preprogrammed blends of those two fuels. Cetane NumberCetane number relates to the fuels susceptibility to self-ignite. The higher the cetane number, the greater the fuel's tendency to self-ignite. Charge portThe charge port allows the vehicle to connect to an external power supply in order to charge the traction battery pack. Clean Air Act Amendments of 1990Amendments to the Clean Air Act of 1970 creating two gasoline standards to reduce vehicle emissions in highly polluted cities by requiring gasoline to contain cleaner-burning additives, such as ethanol. DC/DC converterThis device converts higher-voltage DC power from the traction battery pack to the lower-voltage power needed to run vehicle accessories and recharge the auxilliary battery. Diesel exhaust fillerThis port is for filling the diesel exhaust fluid tank. Diesel exhaust fluid tank (SCR)This canister holds diesel exhaust fluid, which is injected into the exhaust stream during selective catalytic reduction. Diesel oxidation catalystThis device uses a chemical process to break down pollutants in the exhaust stream, turning them into less harmful components. Diesel particulate filterThis device removes diesel particulate matter or soot from the exhaust gases of a diesel engine. E85A high-level gasoline-ethanol blend containing 51% to 83% ethanol, depending on geography and season. Electric GridAn interconnected system that maintains an instantaneous balance between supply and demand (generation and load) while moving electricity from generation source to customer. Electric generatorGenerates electricity from the rotating wheels while braking, transferring that energy back to the traction battery pack. Some vehicles use motor generators that perform both the drive and regeneration functions. Electric traction motorUsing power from the traction battery pack, this motor drives the vehicle's wheels. Some vehicles use motor generators that perform both the drive and regeneration functions. ElectricityElectric current used as a power source. Electricity can be produced from a variety of feedstocks, including oil, coal, nuclear, hydro, natural gas, wind, and solar. ElectrolysisElectrolysis is a method by which an electric current splits water into hydrogen and oxygen. If the electricity used is from renewable sources, such as solar or wind, the resulting hydrogen will be considered renewable as well. Electronic control module (ECM)The ECM controls the engine's performance, fuel efficiency, and emissions; safeguards the engine from abuse; monitors the operation of the vehicle; and troubleshoots mechanical problems. Electronic control module (ECM) - (gasoline)The ECM controls the engine's performance, fuel efficiency, and emissions; safeguards the engine from abuse; monitors the operation of the vehicle; and troubleshoots mechanical problems. Electronic control module (ECM) - (natural gas)The ECM controls the engine's performance, fuel efficiency, and emissions; safeguards the engine from abuse; monitors the operation of the vehicle; and troubleshoots mechanical problems. Electronic control module (ECM) - (propane)The ECM controls the engine's performance, fuel efficiency, and emissions; safeguards the engine from abuse; monitors the operation of the vehicle; and troubleshoots mechanical problems. Emission Control TechnologiesEquipment used in diesel-powered vehicles to reduce exhaust emissions, such as particulate matter and nitrogen oxides. New engines and vehicles can be designed with these technologies, and used engines can be retrofitted to use this equipment. Energy Policy Act of 1992Passed by Congress to enhance U.S. energy security by requiring federal, state, and alternative fuel provider fleets to implement petroleum-reduction measures. Learn more about EPAct Transportation Regulatory Activities. Exhaust systemChannels the exhaust gases from the engine out through the tailpipe. FeedstocksAny material converted to another form of fuel or energy product. An example is using cornstarch to produce ethanol. Flash PointThe minimum temperature at which a liquid gives off vapor within a test vessel in sufficient concentration to form an ignitable mixture with air near the surface of the liquid. Float assemblyThe float assembly monitors the fuel level in a tank. Flow ImproversA chemical used in fuel to reduce friction and increase performance. Fuel cell stackAn assembly of individual membrane electrode assemblies that use hydrogen and oxygen to produce electricity. Fuel fillerA filler or "nozzle" is used to add fuel to the tank. Fuel filler (gasoline)A filler or "nozzle" is used to add gasoline to the tank. Fuel filler (natural gas)A filler or "nozzle" is used to add natural gas to the tank. Fuel filler (propane)A filler or "nozzle" is used to add propane to the tank. Fuel filterTraps dirt and other particles to prevent them from clogging critical fuel system components, such as fuel injectors. Fuel injection systemThis system inserts fuel into the engine's combustion chambers for ignition. Fuel injection system (gasoline)This system inserts gasoline into the engine's combustion chambers for ignition. Fuel injection system (natural gas)This system inserts natural gas into the engine's combustion chambers for ignition. Fuel injection system (propane)This system inserts propane into the engine's combustion chambers for ignition. Fuel lineA metal tube or flexible hose (or a combination of these) allows for transferring fuel from the tank to the engine's fuel injection system. Fuel line (gasoline)A metal tube or flexible hose (or a combination of these) allows for transferring gasoline from the tank to the engine's fuel injection system. Fuel line (natural gas)A metal tube or flexible hose (or a combination of these) allows for transfering natural gas from the tank to the engine's fuel injection system. Fuel line (propane)A metal tube or flexible hose (or a combination of these) allows for transfering propane from the tank to the engine's fuel injection system. Fuel pumpTransfers fuel from the tank to the engine's fuel injection system via the fuel line. Fuel selector switchOn bi-fuel vehicles, this dashboard switch allows the driver to select between fuels. Fuel tank (biodiesel)Stores fuel on board the vehicle until it's needed by the engine. Fuel tank (compressed natural gas)Stores compressed natural gas on board the vehicle until it's needed by the engine. Fuel tank (diesel)Stores fuel on board the vehicle until it's needed by the engine. Fuel tank (ethanol/gasoline blend)Stores fuel on board the vehicle until it's needed by the engine. Fuel tank (gasoline)Stores gasoline on board the vehicle until it's needed by the engine. Fuel tank (hydrogen)Stores hydrogen on board the vehicle until it's needed by the fuel cell. Fuel tank (liquefied natural gas)Stores liquefied natural gas on board the vehicle until it's needed by the engine. Fuel tank (propane)Stores propane on board the vehicle until it's needed by the engine. Gasoline Gallon EquivalentThe amount of fuel it takes to equal the energy content of one liquid gallon of gasoline where one gasoline gallon equivalent (GGE) equals 120,167 British thermal units (BTUs). Gross Vehicle Weight RatingThe maximum weight of a vehicle, including curb weight (the weight of the vehicle on its own) and payload (the weight of cargo). High pressure regulatorReduces and regulates the pressure of the fuel exiting the tank, lowering it to an acceptable level required by the engine 's fuel injection system. Higher Heating ValueThe heating value is the amount of heat released during the combustion of a specific substance, usually a fuel or food. The higher heating value is determined by bringing all the products of combustion back to the original pre-combustion temperature, condensing any water vapor generated. This value assumes the entire water component is liquid in the products of combustion and that heat can be used. Higher LubricityThe ability to reduce friction—usually in fuel pumps and fuel injectors. Incremental PriceThe additional price of an alternative fuel vehicle over a similar conventional vehicle. Internal Combustion EngineA conventional vehicle motor that burns fossil fuel in a chamber in the presence of air. Internal combustion engine (compression-ignited)In this configuration, fuel is injected into the combustion chamber and ignited by the high temperature achieved when a gas is greatly compressed. Internal combustion engine (spark-ignited)In this configuration, fuel is injected into the intake manifold or combustion chamber and combined with air, and the air/fuel mix is ignited by the spark from a spark plug. IsomerTwo or more compounds with the same formula but a different arrangement of atoms in the molecule and different properties. Kilowatt HoursA measurement for electricity use. Legacy ChargersLegacy electric charging systems such as inductive paddles. Learn more about types of chargers. Load AggregatorsA large group or block (aggregate) of consumers joined together to leverage their combined purchasing power when negotiating rates for energy services. Lower Heating ValueThe heating value is the amount of heat released during the combustion of a specific substance, usually a fuel or food. The lower heating value is determined by subtracting the heat of vaporization of water from the higher heating value for a particular substance, treating any water as a vapor. Manual shut offAllows the vehicle operator or mechanic to manually shut off the fuel supply. Natural gas fuel filterTraps dirt and other particles to prevent them from clogging critical fuel system components, such as fuel injectors. Natural gas sensorsThese monitor the pressure of the fuel supply and relay that information to the electronic control module. Negative Energy BalanceWhen producing a fuel takes more energy than the amount of energy the fuel provides. Onboard chargerTakes the incoming AC electricity supplied via the charge port and converts it to DC power for charging the traction battery. It regulates battery characteristics such as voltage, current, temperature, and state of charge while charging the pack. Overfill protection deviceThis device shuts off the flow of fuel into a fuel tank after 80% capacity has been reached. OxygenateA cleaner-burning additive in a fuel—usually containing hydrogen, carbon, and oxygen. Examples are ethers and alchohols, such as ethanol and methanol. Oxygenated FuelsFuels blended with an additive—usually ether or ethanol—to increase oxygen content, allowing more-thorough combustion for reduced carbon monoxide emissions. Passenger-Miles per GallonPmpg is the vehicle miles per gallon multiplied by the number of passengers traveling in the vehicle. Petroleum Administration for Defense DistrictsThe Petroleum Administration for Defense Districts (PADD) are groupings of U.S. states and the District of Columbia. These districts are defined by the U.S. Energy Information Administration and used to report fuel prices. Positive Energy BalanceWhen producing a fuel takes less energy than the amount of energy the fuel provides. Power electronics controllerThis unit manages the flow of electrical energy delivered by the traction battery, controlling the speed of the electric traction motor and the torque it produces. Pressure gaugeMeasures and displays the fuel pressure within the tank. Pressure relief valveThis device incorporates a valve to limit the pressure within the fuel tank. At a preset pressure level, the valve opens and fuel is vented from the tank. Pump Octane NumberThis number represents the ability of a fuel to resist knocking when ignited in the cylinder of an internal-combustion engine. The number here is the average of the research octane number and motor octane number. Regenerative BrakingA feature of hybrid and plug-in electric vehicles that captures energy normally lost during braking by using the electric motor as a generator and storing the captured energy in the battery. Renewable Fuels StandardA regulation created under the Energy Policy Act of 2005 and implemented by the U.S. Environmental Protection Agency to ensure transportation fuel sold in the United States contains a minimum volume of renewable fuel. Selective Catalytic ReductionSelective catalytic reduction (SCR) is a means of converting nitrogen oxides (NOx) into nitrogen (N2) and water (H20). This is done using a reductant, such as urea or ammonia, and a catalyst. Selective catalytic reductionThe selective catalytic reduction (SCR) system injects diesel exhaust fluid through a special catalyst into the exhaust stream of a diesel engine to break down dangerous NOx emissions into harmless nitrogen and water. Tailpipe EmissionsEmissions produced through fuel combustion during a vehicle's operation. TallowAnimal fat that can be used to produce biodiesel. Tank valveThis primary, manual valve stops fuel from entering or leaving the tank. Technical Response ServiceFor assistance with technical questions about alternative fuels and advanced vehicles, email the Technical Response Service at technicalresponse@icfi.com or call 1-800-254-6735. Thermal system (cooling)This system maintains a proper operating temperature range of the engine, electric motor, power electronics, or other components. ThermochemicalHeat and pressure-based chemical reactions that produce energy. Through gasification (heating biomass by partial oxidation to produce synthesis gas) and pyrolysis (heating biomass in the absence of oxygen to produce liquid oil), biomass feedstocks can be converted to alcohol and hydrocarbon fuels, chemicals, and power. Traction battery packStores electricity for use by the electric traction motor. TransesterificationIn this process, the feedstock chemically reacts with an alcohol (usually methanol) in the presence of a catalyst, like lye. The products are glycerin and the biodiesel fuel or FAME (fatty acid methyl esters). TransmissionTransfers mechanical power from the engine and/or electric traction motor to drive the wheels. Transportation SectorAn energy-consuming sector that consists of all vehicles whose primary purpose is transporting people and/or goods from one physical location to another. Included are automobiles; trucks; buses; recreational vehicles; motorcycles; trains, subways, and other rail vehicles; aircraft; ships, barges, and other waterborne vehicles; and pipelines. Vehicles whose primary purpose is not transportation (e.g., construction cranes and bulldozers, farming vehicles, and warehouse tractors and forklifts) are not included. Vapor PressureVapor pressure is the pressure of the vapor resulting from evaporation of a fuel above a sample of the liquid in a closed container. It is used to measure volatility, an important property of transportation fuels. Vehicle CategoriesA system of classifying vehicles (e.g., passenger cars, commercial vehicles, trailers, off-road vehicles, and special-purpose vehicles). Vehicle Weight ClassThe size of vehicles. Includes light-duty, medium-duty, and heavy-duty vehicles based on their gross vehicle weight rating (the weight of a vehicle on its own plus the weight of cargo). Yellow GreaseSecond-hand cooking oil that can be used to produce biodiesel. well-to-wheelsAnalysis of energy use and emissions from the primary energy source through vehicle operation. |