Natural Gas: This fossil fuel is mostly comprised of methane and is one of the cleanest burning fuels. There are two forms of natural gas—liquefied natural gas (LNG) and compressed natural gas (CNG)—both which can be used to fuel cars. The advantages of natural gas over gasoline are that is it less expensive and produces a lot less smog. However, the disadvantage is that natural gas gets less miles per tank and is not as readily available.
Ethanol: Made from plant materials such as corn, sugar cane, and grass, this renewable fuel is an alcohol that is commonly used as a gasoline additive. Although it depends on the region, most gasoline in the US contains 10% ethanol. Because it can reduce dependency on oil and greenhouse gas emissions, the use of ethanol as fuel in the United States has increased dramatically over the last 10 years.
Hydrogen: This fuel is environmentally-friendly and can be burned in an internal combustion engine or used in fuel cells to power electric motors. The advantage of hydrogen is that it doesn’t produce any greenhouse gases or air pollutants and that it can be domestically produced.
Propane: This fossil fuel can power internal combustion engines, not just grills, without degrading the performance of the vehicle. The emissions propane creates a less harmful than gasoline and is a less expensive fuel source. However, propane gets less miles to the gallon and is not as readily available.