A new process used to extract soybean oil could reduce the use of chemicals in the production of biodiesel fuel.
Michael Haas, biochemist with the Agriculture Research Service in Wydmoor, Penn., and his colleagues developed a method to eliminate the use of hexane to extract soybean oil, the base material for biodiesel.
Hexane, a hydrocarbon liquid made from crude oil, is used in large industrial operations designed to isolate soybean oil. Hexane is a source of air pollution, spurring an interest in reducing or eliminating its use in biodiesel production.
"To be fair, the industry has done a very good job at controlling hexane emissions, but they are always interested in anything that would allow them to reduce or eliminate the use of hexane," Haas said.
During the experimentation process, which has been in progress for more than two years, researchers also found that reducing the amount of water present in the soybeans drastically cut down the amount of methanol used in the extraction process. By lightly drying the soybeans in an oven, researchers found that smaller quantities of chemicals were necessary for extraction.
Although the reduction of chemicals has lowered the costs for oil extraction, overall production costs for this method may still be higher than the conventional method, Haas said. Without taking into account the price of the soybean oil, the cost of producing biodiesel without hexane is $1.02, while the traditional method costs only 38 cents per gallon, he said. These results are preliminary, and Haas said he is working on a more accurate economic model for the new extraction and conversion method.
A factor that may reduce the cost of the new process is using the dried soybean flakes, a byproduct of oil extraction, for animal feed, he said.
The researchers conducted a small test with chickens and had positive results, but they are looking for collaborators to determine if using the soy flakes for feed is a viable option.
"If the soy flakes aren't suitable as an animal feed, they create a huge solid waste problem and the process doesn't have a future," Haas said.
Haas is researching the possibility of using distillers' dried grains with solubles, which are a byproduct of the production of ethanol, to make biodiesel. Using these could potentially make 200 million gallons of biodiesel per year. Compared to the estimated 30 million gallons of biodiesel produced in the United States last year, this has tremendous potential as a renewable fuel, he said.
A lack of resources and the huge amounts of diesel fuel used in the United States have created difficulties for the biodiesel industry, said Brent Shanks, associate professor of chemical engineering.
"There is very limited production [of biodiesel] so far, but there are a lot of people looking at producing it right now," he said.
Relatively low production of biodiesel has made the availability of the alternative fuel limited in Iowa, he said.
"We consume so much diesel fuel in this country that if you took all the soybeans, cooking oil and animal fat available, you'd still only supply 15 percent of the on-road diesel," he said.
Although the production and availability of biodiesel are still relatively low, the United States has seen a 15 percent increase in 2003 and 2004, said Roger McEowen, associate professor of agricultural law.
A tax incentive program for 2005-06 has been a factor in the increased interest in biodiesel, he said. In October 2004, Iowa lawmakers passed a tax credit that would directly benefit producers of biodiesel.
The credit allows producers one cent of tax credit per percent point of blend per gallon produced. The incentive program could be extended if it receives approval from lawmakers.