FAYETTEVILLE - One of the most promising alternative fuels growing on U.S. farms is already found in many agricultural and commercial fuel tanks. Biodiesel made from soybeans is easy to produce and requires no conversion of existing diesel engines.

"Many premium brand diesel fuels include biodiesel because of its superior lubrication properties," said Pat Manning, agricultural economist at the Arkansas Agricultural Experiment Station. "This will become especially important when new laws, anticipated in some states, will require reduced sulfur emissions in diesel fuels.

"Reducing sulfur in conventional diesel also reduces lubrication in the engine," he said. "Biodiesel has no sulphur, but has excellent lubrication properties, so it makes an excellent additive."

Manning and UA agricultural economist Michael Popp are studying the economic benefits of biodiesel production.

"Right now, pure biodiesel costs significantly more than conventional diesel, as much as $1.92 per gallon from one supplier," Manning said. "But blends of conventional and biodiesel run about 5 cents a gallon more than straight conventional diesel."

He said blends can be mixed in any proportion, but 5 percent to 20 percent biodiesel content are most common. Such blends are now used by many bus fleets, government agencies and private fleets.

"Because it's more expensive than conventional diesel, those most likely to use some form of biodiesel now will fall into one of three groups," he said, "those who are mandated to use it by emissions restrictions; those who have self-interest, such as soybean farmers trying to encourage new markets for their crops; or environmentally conscious persons who want to do their part to reduce polluting emissions."

Biodiesel significantly reduces nearly all regulated pollutants, including carbon monoxide and particulate matter, as well as some that are not yet regulated.

While many feedstocks can be used to produce it, the majority of biodiesel is produced from soybean oil, he said. Biodiesel also can be produced from other vegetable oils, animal fats and recycled cooking oil.

Manning said wide development of biodiesel will help raise the price of soybeans for Arkansas farmers, but the real impact on the state's economy would come from producing biodiesel in a plant in Arkansas. "For the state's economy, the real added value is in production," he said.

Producing biodiesel from soybeans is cleaner and uses less energy than conventional fuels, he said. "The energy ratio for biodiesel is 3.24 to 1," he said. "That means biodiesel provides 3.24 times more energy than it takes to produce it. That's better than ethanol, which provides only 1.24 times more energy than it requires to convert it from corn."

He added that biodiesel and ethanol are not in competition with each other, since biodiesel is a substitute or additive for diesel fuel and ethanol is a substitute or additive for gasoline.

Biodiesel won't be available at local gas stations any time soon, Manning said, but farms and other individuals or businesses can buy it in bulk through their fuel suppliers or directly from suppliers in Arkansas, Missouri or Iowa. More information is available from the National Biodiesel Board's Web site: http://www.biodiesel.org/

Fred Miller, Science Editor, Arkansas Agricultural Experiment Station.