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State crops show promise for biodiesel production
MISSISSIPPI STATE -- High petroleum prices have made biodiesel an attractive option, and research shows that this alternative fuel has benefits beyond reducing the nation's dependence on foreign oil.
Biodiesel can be made from vegetable oils or from animal fats and is blended with petroleum diesel to fuel engines. In Mississippi, soybeans and cottonseed are all being processed into biodiesel, and demand for this fuel is growing.
Federal guidelines require that ultra-low sulfur diesel be available by Oct. 15 nationwide for use in highway vehicles. Sulfur is part of what gives diesel engine exhaust its distinctive odor. Lowering sulfur content reduces much of diesel engines' harmful emissions, but also reduces the lubricating ability of the fuel.
Herb Willcutt, agricultural engineer with the Mississippi State University Extension Service, said biodiesel is uniquely suited to meet this need for engine lubrication.
“Sulfur in diesel lubricates the injector pump and other moving parts in the fuel system,” Willcutt said. “Once fully implemented, the new standards reduce the sulfur content from 2,500 parts per million for off-road diesel and 500 parts per million for on-road diesel to 15 parts per million for both on- and off-road diesel.”
Willcutt said removing sulfur from petroleum drives up the cost 5 to 15 cents per gallon. The lack of lubrication can be solved two ways. Refineries can include an additive in the fuel or the petroleum diesel can be blended with biodiesel.
“Biodiesel at a 2 percent blend has 66 percent more lubricating capacity than the traditional high sulfur fuels that we're burning now,” Willcutt said. “Using biodiesel is a cheap and easy way to get the lubricating quality back into the fuel.”
In Mississippi, soybeans and cottonseeds are used for the production of biodiesel. The Mississippi Soybean Promotion Board funds MSU research efforts to make soybeans an attractive crop for use in the production of biodiesel. A cross-disciplinary team of MSU researchers is trying to find ways to boost the state's production of biodiesel.
Rafael Hernandez, a chemical engineer in MSU's College of Engineering, is studying the oils produced by various crops to determine which are ideal for the production of biodiesel.
“We have to make sure that the fuel we will produce from these crops will meet the standards for biodiesel,” Hernandez said. “These tests determine whether the biodiesel you are producing is going to perform well in a diesel engine.”
Biodiesel must meet the federal ASTM-D6751 standard, which is a measure of the fuel's ability to blend with petroleum diesel, viscosity, sulfur and water content, corrosive properties, flashpoint and more.
Much of the interest in biodiesel stems from its price. Hernandez said it costs about $2.50 a gallon to produce biodiesel, but a federal tax credit takes $1 off the cost of producing biodiesel from first-time used vegetable oils and animal fats, and 50 cents a gallon off the cost of producing biodiesel from previously used oils such as recovered fry oils from restaurants.
“This tax credit goes to biodiesel producers, and is probably one of the main reasons why biodiesel production has increased so amazingly in the last five years,” Hernandez said. “This tax credit is a way to increase the supply of biodiesel and reduce the dependence on foreign oil.”
MSU researchers in plant science, chemical engineering, chemistry, food science and biological engineering have been working together for two years to identify biological sources of oil and turn them into high quality biodiesel.