Fuels Glossary

Alkylation - A refining process for converting light, gaseous olefins into high-octane gasoline components.

Alternative fuel - Sustainable, non-petroleum fuel.

ASTM - The American Society for Testing Materials is a non-profit organization that has created standards for testing fuels.

ASTM specifications - Standards created for commercial fuels. ASTM's "Standard Specifications for Biodiesel Fuel (B100) Blending Stock for Distillation Fuels," D6751-02, includes results and measurable fuel qualities as well as testing methods.

B20 blend - A biodisel fuel blend. The number after "B" indicates the percentage of biodiesel included in the blend. In B20, there would be 20% biodiesel and 80% petroleum diesel in the fuel blend.

B100 - B100 indicates that the biodiesel is 100% biodiesel with no added petroleum diesel.

Biodiesel - A fuel derived from biological sources that can be used

in diesel engines.

Biodiesel Blend - Blend of biodiesel and diesel fuels. The blend can be with Diesel #1, Diesel #2, or JP8.

Biofuel - A fuel made from renewable biological sources.

Biomass - Organisms or biologically derived material. This includes whole plants, microbes, or plant parts, agricultural waste, etc.

Cetane Number - A measure of ignition quality of diesel fuel. The higher the cetane number, the easier the fuel ignites when it is injected into the engine.

Diesel engine - Named for the German engineer Rudolph Diesel, this internal-combustion, compression-ignition engine works by heating fuels and causing them to ignite. It can use either petroleum or bio-derived fuel.

Diesel fuel - A distillate of fuel oil that has been historically derived from petroleum for use in compression ignition engines. Can also be derived from plant and animal sources.

Diesel number 1 - Diesel #1 is also called kerosene and is not generally used as a fuel oil in diesel vehicles. Diesel #1 has a lower viscosity (it is thinner) than Diesel #2.

Diesel number 2 - the typical diesel vehicular fuel.

E85 - An alcohol fuel mixture containing 85 percent ethanol and 15 percent gasoline by volume.

Energy balance - The difference between the energy obtained from the use of a fuel and the energy required to produce the fuel by adding up all the production requirements; for example: agricultural processes, drilling, refining, transportation, etc.

Energy-efficiency ratio - A number representing the quotient of the energy stored in a fuel divided by the energy required to produce, process, transport, and distribute that fuel.

Flashpoint - The lowest temperature at which a liquid will produce enough vapor to ignite. The lower the flashpoint, the higher the risk of fire. Biodiesel has an abnormally high flashpoint for a fuel, making it relatively safe to handle and store. For example, the flashpoint for petroleum-based diesel number 2 is standardized at 60° - 80°C while that for biodiesel is 100°- 170°C.

Flexible-fuel vehicle ("flex-fuel" vehicle) - A vehicle that can run alternately on two or more sources of fuel.

Fossil fuel - A fuel derived from carbon contained in ancient life on Earth; it is non-renewable.

Gasification - A catalytic, heat-driven process used to convert carbonaceous material, coal, petroleum, or biomass into gaseous materials such as carbon monoxide and hydrogen.

Gas to liquid - The process of refining natural gas and other hydrocarbons into longer-chain hydrocarbons.

Gel point - The point at which a liquid fuel solidifies.

High compression ignition engine - a Diesel engine; air is compressed, increasing the temperature such that it ignites the fuel.

Indirect-injection engine - An older model of diesel engine in which fuel is injected into a pre-chamber, partly combusted, and then sent to the fuel-injection chamber.

Lubricity - The "kinetic viscosity" of a fuel which affects engine life. The higher the lubricity, the easier a fuel can move through an engine. Biodiesel has a relatively high lubricity.

M85 - An alcohol fuel mixture containing 85 percent methanol and 15 percent gasoline by volume.

Nitrogen oxides - Products of combustion that contribute to the formation of smog and ozone.

Straight vegetable oil (SVO) - Any vegetable oil that has not been optimized through the process of transesterification.

Transesterification - The chemical process in which an alcohol reacts with triglyceride esters to produce glycerol and the alcohol esters that constitute biodiesel.

Viscosity - The ability of a liquid to flow. The higher the viscosity, the slower the liquid flows.

VOCs - Volatile Organic Compounds. VOCs contribute to air pollution.