A biofuel is any fuel source that’s made from biological materials. The two most common kinds of biofuels right now are both gasoline alternatives: ethanol and biodiesel.
Ethanol is ethyl alcohol (C2H5OH). It's also known as grain alcohol because it’s often made from the distillation of grain crops like corn or soybeans. Corn is the source material for 90 percent of the ethanol produced in the U.S., but any plant material -- collectively called biomass -- can be used to make ethanol: leaves, woodchips, wild grasses, even trees. Brazil, the world’s second-largest ethanol producer, makes its biofuel from sugarcane.
When used in cars and trucks, ethanol is usually mixed with a little gasoline to improve fuel economy. The resulting fuel is called E85, denoting 85 percent ethanol and 15 percent gas. In 2007, there were 5.5 million Flex Fuel Vehicles on the road in the U.S. that could run on E85 fuel. Unfortunately, there were only 1,208 E85 filling stations -- less than 1 percent of the total filling stations in America.
What if you’re lucky enough to live near one of these ethanol stations? Does that mean you’ll get amazing fuel economy with zero emissions? Not quite. A gallon of E85 ethanol contains 80,000 BTU of energy compared with 124,800 BTU for the same amount of gasoline. That means you would have to buy 1.56 gallons of E85 for every gallon of regular gasoline. But it’s cheaper, right? Again, not quite. Technically, a gallon of E85 costs 19.9 percent less than gas, but since you’ll have to fill up more often, E85 ends up costing you more.
But the good news is that E85 is significantly friendlier to the environment. Not only is E85 clean-burning -- it produces 39 percent less carbon dioxide (CO2) than regular gasoline -- but it’s actually carbon neutral. In other words, the amount of CO2 emitted by the combustion of ethanol equals the amount of CO2 that the corn plant absorbed during its lifetime. The U.S. currently produces 9.2 billion gallons of ethanol a year and consumes 9.6 billion gallons.
Biodiesel is a biofuel made from plant- or animal-based fats and can run in a regular diesel engine. In fact, Rudolf Diesel’s original prototype engine ran on peanut oil. Biodiesel uses a chemical process called transesterification to covert fats like vegetable oil and rendered animal fats into a clean-burning, biodegradable fuel.
Biodiesel packs nearly the same energy content as regular diesel, but burns much, much cleaner. Pure biodiesel (aka B100) produces 75 percent fewer emissions than regular diesel. Purchased biodiesel is as cheap as gas, but if you can find a donated source -- like recycled fryer oil from a restaurant -- it’s potentially free!
One downside to fossil fuels is that farmland that could be used for food production is instead used to grow fuel. Another has to do with availability. For example, there are only 663 biodiesel filling stations in the U.S. and the country currently produces only 700 million gallons a year. By contrast, there are more than 160,000 gasoline filling stations in the U.S. That’s because fossil fuels -- though detrimental to the environment -- are plentiful and cheap. Read more about the pros and cons of fossil fuels on the next page.