Electricity is an alternative fuel source to conventional gasoline. Vehicles that either partial or fully run on electricity are called electric vehicles and come in a variety of shapes and models. 
Three main types of electric vehicles include fully Electric (EVs), Plug-in Hybrid (PHEVs), and Hybrids (HEVs).

Electric Vehicles (EVs)

They are powered by one or more electric motors that use the energy stored in a battery (larger than the batteries in an HEV or PHEV). EV batteries are charged by plugging the vehicle in to an electric power source and through regenerative braking.

Hybrid Electric Vehicles (HEVs)

An HEV is a conventional vehicle that has an additional electric motor powered by energy stored in a battery. So, HEVs run on an internal combustion engine and an electric motor.
HEVs do not use an external power source to charge the battery. Instead, the battery is charged by the internal combustion engine and through regenerative braking.
The vehicle cannot be plugged in to charge.
HEVs are powered by a traditional gasoline or diesel internal combustion engine and by one or more electric motors that use energy stored in a battery.

Plug-in Hybrid Electric Vehicles (PHEVs)

PHEVs are similar to HEVs but have a larger battery that allows them to travel on electricity alone. The battery can be charged by plugging into an electric power source, through regenerative braking, and by the internal combustion engine.
Unlike EVs, PHEVs don’t have to be plugged in before driving. They can be fueled solely with gasoline, like an HEV. However, they will not achieve maximum fuel economy or take full advantage of their all-electric capabilities without plugging in.


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.” 



Ethanol is available as E85, which is a high-level ethanol blend. E85 fuel can be used in flexible fuel vehicles, which can run on high-level ethanol blends, gasoline, or any blend of these. Another blend, E15, has been approved for use in newer vehicles.


Natural gas is an odorless, gaseous mixture of hydrocarbons—predominantly methane (CH4). It accounts for about one-fourth of the energy used in the United States. Although natural gas is a proven, reliable alternative fuel that has a long history of used to power natural gas vehicles, only about two-tenths of 1% is used for transportation fuel.


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.


Did You Know?

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.