Cleaner, greener jet fuels made from formulas that contain part soybean oil could clean up the air and give added profits to the nation's 400,000 soybean growers.
Now that biodiesel fuel is being used in ground transportation, research efforts at the National Center for Agricultural Utilization Research in Peoria, Illinois, are helping lay the groundwork for new, winterized formulas of jet fuel blended with esters of soybean oil.
With winterization processing, biodiesel fuel can be safely blended with jet fuel used in commercial and military aircraft. ARS chemical engineer Robert O. Dunn found that small amounts of methyl soyate (SME)—esters from fatty acids of soybean oil—could be blended with jet fuel (JP-8) with little or no effect on aircraft operation, based on established jet fuel specifications.
Dunn has developed a three-step winterization process for biodiesel fuel that involves mixing in additives, chilling the fuel, and filtering out solids. In laboratory tests, researchers have produced biodiesel fuels capable of starting engines at temperatures as low as 5°F, making them comparable to petroleum-based diesel fuels.
In laboratory tests, Dunn checked winterized blends having between 10 and 30 percent methyl soyate (SME) by volume to determine their compatibility with JP-8 and tested the fuels under cold temperatures. Using unwinterized biodiesel fuel blends could mean limiting the ability of aircraft to fly at high altitudes, where cold temperatures can cause crystal formation, which blocks fuel filters and plugs fuel lines.
"The most promising aspect of this work was finding that winterized SME did not form solid particles when exposed to a range of slightly below zero to –52°F in the laboratory," says Dunn.
But eventually even winterized SME blends will form solid particles when the temperature is low enough. "Our work will continue to focus on expanding the lower limits of temperature so that winterized, blended biodiesel fuels can function safely in commercial and military aircraft," says Dunn.
Biodiesel fuel has been shown to reduce harmful exhaust emissions—particulate matter, volatile organic compounds, hydrocarbons, smoke, and carbon dioxide. Another plus: Biodiesel is nonflammable, making it relatively safe to store and handle. It's also biodegradable.—By Linda McGraw, Agricultural Research Service Information Staff.
Robert O. Dunn is in the USDA-ARS Oil Chemical Research Unit, National Center for Agricultural Utilization Research, 1815 N. University St., Peoria, IL, 61604; phone (309) 681-6101, fax (309) 681-6340.
"Biodiesel Jet Fuels" was published in the July 2001 issue of Agricultural Research magazine.