Occasionally a fresh idea breaks into such mundane activities as developing improved motor vehicle fuels. Such was the case when "McDiesel", a biodiesel fuel made from used oil from fast food restaurants, was added to the array of alternative fuels. Then, in 1997, Joshua and Kaia Tickell of Louisiana embarked on a 10,000-mile tour of the United States in their three-ton motor home, "Veggie Van." Tickell had been making homemade biodiesel in what he calls his Green Grease machine, and the " Veggie Van" towed a portable Green Grease Machine. Stopping at fast food restaurants to collect used oil for making the biodiesel which was their only fuel, the Tickells and their "Veggie Van" got media attention and caught the popular imagination.
Biodiesel, composed of alkyl esters of fatty acids, is manufactured from new and used vegetable oils and animal fats and recycled grease, by a process of transesterification. The oil most commonly used in the U.S. is soybean oil. Soybeans have been overproduced, surpluses exist, and prices are declining. To make biodiesel, the oil or fat is filtered, then treated with alkali to break it down into fatty acids and glycerol. Then it is combined with methanol or ethanol, which reacts with the fatty acids to form methyl or ethyl esters. The two are separated, the esters being used for fuel and the glycerol for pharmaceuticals and cosmetics.
Biodiesel can be used by itself to fuel diesel engines (100 % biodiesel) or, more commonly, as an additive to petroleum diesel, usually at the 20 percent level (B20). Engines do not need to be modified to burn biodiesel. Biodiesels made from different oils will consist of different esters, depending upon the fatty acid compositions of the oils. However, the energy content is roughly the same, which is slightly lower than that of petroleum diesel, meaning that it delivers fewer miles per gallon. Because biodiesel has a higher flash point and, hence, is less flammable, it is safer to handle and store than petroleum diesel.
The Department of Energy's Office of Fuels Development is working through the National Biofuels Program to make biofuels, which are manufactured from renewable resources, a significant part of the nation's energy market. The National Renewable Energy Laboratory's Biodiesel Project is conducting research to develop fuel standards, test performance, improve technologies, and increase the market share for biodiesel.
Beginning in April 2001, federal, state, and alternative fuel provider fleets that are required under the federal Energy Policy Act (EPAct) to purchase alternative fuel vehicles may be given credit for using biodiesel. EPAct's intent is to replace 30 percent of petroleum-based fuels in the transportation sector with domestically produced alternative fuels by 2010. The goal is to decrease the nation's dependence on foreign oil and to increase energy security.
Like other alternative fuels, biodiesel emits less air pollution than petroleum fuels. The emissions reductions are roughly proportional to the amount of biodiesel in the fuel. Biodiesel contains no sulfur and therefore emits no sulfur oxides or sulfate aerosols. It has a higher cetane rating (analogous to octane ratings for gasoline) than petroleum diesel. Because of its oxygen content, it not only burns more completely, but enhances the combustion of petroleum diesel. This tends to reduce emissions of hydrocarbons, carbon monoxide, soot and other particulate matter, and toxics such as benzene. Smoke, soot deposits, and odors are reduced. Nitrogen oxides emissions, however, are slightly increased because the high temperature and more complete combustion of the fuel causes more nitrogen from the air to be burned. Reliable quantitative data have not yet been developed, and some information on environmental effects is anecdotal. Nonetheless, the evidence points to substantial clean air and health benefits from using biodiesel.
In the Bay Area, biodiesel is most widely used as a fuel for sailboat auxiliary engines. In the future, the marine market is expected to extend to other types of vessels. When used in marine engines, biodiesel is faster starting than petroleum diesel and emits less unburned fuel into the water. In the case of spills, biodiesel is biodegradable and contains no soluble toxics, unlike petroleum diesel. Waterfowl, mammals, and fish, however, can suffer from being coated with biodiesel. The U.S. Environmental Protection Agency considers it to be an oil, like petroleum diesel, and harmful to marine wildlife.
On dry land, San Francisco International Airport is experimenting with four biodiesel vehicles, two using 100% biodiesel and two using the B20 mixture. Berkeley's Ecology Center is using 100% biodiesel for its 10- truck fleet of recycling trucks. In May, a San Francisco gas station opened a biodiesel pump for retail customers.
In the last few years, the biodiesel industry has grown dramatically, largely on its own, without government subsidies such as those received by the ethanol industry. As it is, the cost of biodiesel is about 50 percent above that of petroleum diesel. Mass production could lower the cost, as could the development of oilseeds with a higher content of oil. Soybeans contain 20 percent oil; rapeseed (canola), which is used in Europe, contains 40 percent.
In spite of its higher cost, biodiesel has a loyal market. Its users are drawn by its environmental benefits and its aesthetic qualities, its cleanness and its pleasant aroma—"like doughnuts or french fries."
Adelia Sabiston
For more information: The best sources of information are online. We recommend typing "biodiesel" into a Web browser such as Google. To go directly to a Google search on biodiesel, follow this link.