The recent demonstration at UConn used waste vegetable oil from the school's dining facility. The raw used French fry oil was pumped in one end of a labyrinth of holding tanks, pumps, and pipes and finally through a reactor where biodiesel is separated from the glycerol using gravity and a technology Parnas says is proprietary and therefore a secret.
Biodiesel flows out the top, because it is lighter, and glycerol is expelled from the bottom of the 6-foot-long cylindrical aluminum reactor mounted at a 45 degree angle.
Parnas said he couldn't provide specific details of what happens in the various tanks and the tubular reactor because of trade secrets. He said methanol with an acid catalyst is added at the beginning of the process, then removed, and methanol with a base is added near the end to finish the biodiesel.
About half of what goes in is turned into biodiesel. Once the machinery is set up the process is mostly automated and would take minimal work to keep going, he said. "It would be very easy to go into a wastewater treatment plant and make 100,000 gallons of biodiesel a year from their brown grease," Parnas said. "It is a very significant commercial opportunity."
Parnas said biodiesel from brown grease should help with the problem of too little feed stock in the growing renewable fuel market.
The shortage has led producers to go directly to the source of vegetable oil — food — for the supply. Corn, sugarcane, soy beans and even macadamia nuts have been used to make the fuel, Parnas said.
Parnas said that is the wrong approach.
"We absolutely do not want to take any food and make fuel," he said. "That is utterly wrong."
Citing the ethanol industry that uses corn to create ethanol, which is now added to gasoline, Parnas noted that has driven up the cost of corn and reduced the supply of food.
Unlike ethanol, which is mostly made from corn and has only a slight energy return, biodiesel is much more efficient, Parnas said. In its very least efficient method of production, using soy beans, a gallon of biodiesel contains 3.5 times as much energy as required to make it, Parnas said. If it is made from waste oils the energy return jumps to a factor of 15 or 20 times of what it takes for production.
"Biodiesel is a really awesome fuel," he said.