Soybean Fuel Additive Could Help Cut Prices

The researchers said fuel additives made from soybean oil improve the performance of diesel fuel and, in particular, of diesel fuel containing ethanol. When the additive is used in combination with 10 percent ethanol in deisel, significant reductions in emissions can be achieved.

Galen Suppes, KU associate professor of chemical engineering, and Joseph Heppert, KU associate professor of chemistry, developed and evaluated formulas for soybean oil-based cetane improvers with very good results.

"Our goal was to match the ignition value of commercial additives," Suppes said. The research team did just that, and they discovered something more -- their soybean-oil based additives improve fuel lubricity, an important factor in the performance of fuel-injected engines. When paired with the diesel/ethanol fuel blend, soybean-oil cetane improvers help reduce greenhouse gas emissions while stimulating state and local farm economies.

Cetane improvers are commonly added to make the fuel ignite faster, which reduces harmful exhaust emissions. Diesel fuels are given a cetane rating or number that correlates with how long it takes fuel to ignite once it has begun to be injected into the engine's cylinder. This is commonly referred to as ignition delay time. Shorter ignition delay times reduce harmful nitrogen oxide gas emissions, and they result in faster engine startup in cold weather along with smoother engine operation overall. Commercial cetane improvers are derived from petroleum. The soybean oil-based additives developed by Suppes and Heppert are the first of their type.

Suppes and Heppert used a blend of 10 percent ethanol and 90 percent deisel fuel in a Volkswagen test engine. They saw reductions in the amount of particulate matter in the engine exhaust of more than 30-50 percent compared with unblended deisel. The opacity of exhaust smoke dropped too.

Suppes said the fuel blend, sometimes called "diesehol," is tied closely to cetane improvers because when ethanol is added to diesel fuel, the cetane number and the lubricity of the diesel can be compromised. Ethanol fuel releases fewer pollutants into the environment, but it has trouble igniting and burning at low temperatures. That's where the KU team's additives are especially important.

"Soybean oil-based additives are ideally suited to use in deisel to great advantage because they increase lubricity while improving the cetane rating," Suppes said. Commercial petroleum-derived additives do not improve lubricity.

The new additive is effective in very small numbers: It takes only 500 parts per million to have full effect. Suppes said the researchers target the retail cost of their additive at 40 cents per gallon when manufactured at a commercial production level. Currently used additives cost more. In addition, Suppes said the value of the new additive exceeds its cost value because of the benefit of lubricity. Plus soybean oil-based additives are a renewable resource.

Ethanol fuel is manufactured from corn and grain sorghum. Ethanol production is the third largest user of corn in the U.S., behind feed and export uses, according to a report submitted at the Midwestern Governors' Conference.

"Higher diesel and gasoline prices create a real opportunity to start to use ethanol and alternative synthetic fuels," Suppes said. "The use of these fuels has a positive impact because they are cleaner burning, they reduce our dependency on imported crude oil, and they can stimulate farm economies.

"Diesel engines are typically 30 percent more efficient than gas engines. Their use has a more-than 23 percent reduction in fuel consumption," he said. "If you're going to use ethanol, it's by far more advantageous to use it in a more efficient engine because ethanol costs more."

Suppes notes that the cost to consumers of cars and trucks with deisel engines makes them unpopular, but they don't have to be more expensive.

"In Europe the cost of a diesel engine is similar to a gas engine," Suppes said. "Europe maintains a little better quality control on diesel fuel, and they have better diesel engines that they can mass produce. The bottom line is you don't have to pay more; you just need to create a situation where there are enough engines in use."

The team will present its findings at an international conference in Paris in June. The research was supported by the Kansas Soybean Commission, the USDA and MidContinental Chemical Co., Inc., in Leawood.