America’s 246 million passenger cars burn 380 million gallons of the fossil fuel gasoline every year. To cut down on emissions from fossil fuels, the government and car manufacturers have been pursuing cleaner-burning biofuels, such as ethanol. Unlike fossil fuels, biofuels are considered renewable fuels because they are made from plant materials like corn, soybeans and sugar cane which can be indefinitely replenished.

Fuel Sources

Fossil fuels are carbon-based energy sources like coal, oil and natural gas created over the millennia from decayed plants and sea creatures that accumulated in the oceans. In the United States, 93 percent of the energy we consume comes from fossil fuels, much of it in the form of gasoline and diesel fuel. According to the World Coal Institute, the U.S. has enough coal to last 130 years, while gas proponents say the known resources of natural gas should last 100 years, and experts generally agree that known oil reserves will last only 50 years. A biofuel is any fuel that's made from plant materials. The two most common biofuels that can replace gasoline are ethanol and biodiesel. While any plant material can be used, corn is the source for 90 percent of the ethanol generated in the U.S. The world's second-largest ethanol producer is Brazil, which makes its biofuel from sugar cane. In contrast to the finite supply of fossil fuels, biofuels are considered renewable since corn and other biomass materials can be grown indefinitely.

Energy Output

Ethanol is usually mixed with gasoline to produce a fuel is called E85, which is 85 percent ethanol and 15 percent gasoline. A gallon of E85 contains 80,000 BTU of energy compared to the 124,800 BTU from the same amount of gasoline. This means 1.56 gallons of E85 would be needed to equal one gallon of regular gasoline. Biodiesel produces roughly the same amount of energy as an equal amount of regular diesel. Pure biodiesel, called B100, produces 75 percent less emissions than regular diesel and is as cheap as gasoline to produce.

Environmental Issues

Oil is the most common fossil fuel and produces its energy from hydrocarbons, which are made-up of carbon and hydrogen. When hydrocarbons are burned they produce carbon dioxide, a greenhouse gas that gets trapped in the atmosphere indefinitely and plays a major role in global warming. According to the Energy Information Administration, Americans consume 19.4 million barrels of crude oil every day, which is refined to make gasoline, diesel fuel, jet fuel and propane. American passenger cars alone add 11,450 pounds of carbon dioxide into the atmosphere every year. Biofuel is also a hydrocarbon, creating carbon dioxide and water when it’s burned. But the life cycle of biofuels, in theory at least, does not increase carbon into the atmosphere. E85 produces 39 percent less carbon dioxide than gasoline and is considered carbon neutral because the amount of carbon dioxide emitted equals the amount the corn plant absorbed during its lifetime. Currently, the U.S. consumes 9.6 billion gallons of ethanol a year.