Crispy, golden french fries are a main part of many American meals. Now, the vegetable oil they are fried in has become the main ingredient in a new alternative diesel fuel known as "biodiesel." And while french fries are known as junk food, the new biodiesel is anything but junk fuel.

Thanks to a new process developed by INEEL researchers Bob Fox and Dan Ginosar, used french fry oil can be converted into an environmentally friendly diesel fuel faster and less expensively than current processes while producing an even higher grade fuel.

The process of converting vegetable oils or animal fats to diesel fuel is nothing new. Biodiesel fuel has been produced and tested for years as an alternative to petroleum-based diesel fuel, or "petrodiesel."

Using biodiesel in place of petrodiesel offers some distinct advantages. First, the biodiesel is much more environmentally friendly. It burns cleaner and more completely, meaning less pollution. Pollutants include hydrocarbons, sulfur, carbon monoxide and particulates, which are responsible for the thick black exhaust clouds that foul the air behind some diesel-powered vehicles.

Biodiesel is also free of aromatic compounds, the substances that give fuel its ‘cetane’ rating (diesel’s equivalent of gasoline’s more familiar octane rating). However, these compounds include toxic chemicals like benzene and toluene and are carcinogenic. Biodiesel actually has a better cetane rating than petrodiesel without using aromatics. Particulates and aromatic compounds lead to the familiar, caustic odor of burned petrodiesel fuel.

Biodiesel has a different, yet probably more familiar odor when it burns, it smells like fried chicken.

Unfortunately, the current method of producing biodiesel is very time-consuming. Making the fuel is not a continuous process. Instead, it is made in batches that take two or three days to complete.

Working in the Idaho National Engineering and Environmental Laboratory Research Center labs, Fox and Ginosar have developed a new method that produces a higher grade biodiesel with less waste at a lower cost. Their technology eliminates the need for a base liquid, which thus eliminates the need for acid to neutralize the base and water to rinse away the acid. The process is continuous, without all the steps and the unnecessary wastewater.

The process also results in a better separation of biodiesel and glycerol, and a cleaner, higher grade of both substances. The high quality glycerol produced by the new process is very valuable. Conservative estimates place high-grade glycerol at close to $10 per gallon. Fox and Ginosar believe sales of the glycerol could pay for the entire process.

Much of the researchers’ study was done with used french fry oil donated by the J.R. Simplot Company. For Simplot and other food processors, the large volumes of used vegetable oils is a real liability. Transporting the oil to landfills or "yellow oil" markets is expensive, so the prospect of turning a waste product into fuel to power its large trucking fleet is appealing.

Fox and Ginosar envision a time when waste-oil-to-biodiesel conversion plants are connected to food processing plants everywhere, giving processors an environmentally sound source of fuel.

Contact: Charles Briggs at (208) 526-0441