Ethanol is a renewable fuel made from a variety of plant materials known as “biomass“.
Ethanol is a clear, colorless liquid, and has one of a group of compounds called “alcohols.” Hence its alternative name, “ethyl alcohol.”
Also known as liquefied petroleum gas (LPG) or propane autogas, propane is a clean-burning alternative fuel that’s been used for decades to power light-, medium-, and heavy-duty propane vehicles.
Propane used in vehicles is specified as HD-5 propane and is a mixture of propane with smaller amounts of other gases. According to the Gas Processors Association’s HD-5 specification for propane, it must consist of at least 90% propane, no more than 5% propylene, and 5% other gases, primarily butane and butylene.
Propane is stored onboard a vehicle in a tank pressurized to about 150 pounds per square inch—about twice the pressure of an inflated truck tire.
Learn more about Propane in the Clean Cities University Online Courses.
Biodiesel is a diesel replacement fuel for use in diesel engines. It is manufactured from plant oils (e.g., soybean oil, cottonseed oil, canola oil, corn oil);
recycled cooking greases or oils (e.g., yellow grease); or animal fats (beef tallow, pork lard); and various combinations of these feedstocks.