Coffee isn't just a fuel for people anymore.
MU researchers have found a way to convert the coffee grounds commonly found in beverages into biodiesel fuel.
Most biodiesel fuel in the U.S. is made from soybean oil, but the researchers developed an efficient process for extracting oil from used coffee, biological engineering assistant professor Bulent Koc said.
"The extraction process is one of the most energy-intensive processes in biodiesel production," Koc said. "Once you have the oil, no matter where you get it, you can convert it into biodiesel."
Koc and his staff spent six months drying used coffee grounds, extracting oil from them and converting that oil into biodiesel. They used grounds from the faculty cafeteria and from Starbucks, he said.
Professor Leon Schumacher said coffee grounds are a better source of oil than soybeans because soybeans could be used for food instead.
"The goal here, then, is to take a product that we would otherwise simply throw away and actually capture the oil that remains in that product," Schumacher said. "The amount of oil that's in the coffee is very similar to the amount of oil that's in a soybean."
Ground coffee contains 10 to 18 percent oil by weight, said Mudhafar Abdullah, a post-doctorate fellow at MU's biofuel lab.
The process of turning coffee grounds into biodiesel fuel is not new, Abdullah said. But the MU team found a way to extract the oil without drying the grounds, which saves time and energy.
Wet coffee grounds contain 70 percent water and can take up to eight hours to dry, Koc said. The drying process also uses a lot of energy.
"In our system, we developed a method that would allow us to extract oil from materials like coffee grounds without drying," Koc said.
The system devised by the researchers should save money, as well as time.
"If you use soybeans, you have to pay for the raw materials," Koc said. "That is one of the reasons for high biodiesel costs. If we can recycle some of the materials that we are consuming on a day-to day basis, we might reduce the biodiesel production costs."
For the next few months, the team will test the biodiesel from coffee grounds, as well as other alternative fuels, on a small engine in the biofuel lab. Koc said they will determine how well the engine performs and how each fuel is different from regular diesel fuel.
Schumacher said anyone can start using the process at any time, but it will only be cost-efficient if they have a system in place to collect the coffee grounds.
"If you wanted to set the systems in place, you could use it, you know, tomorrow," Schumacher said. "(But) we have to first put a system in place that is efficient to collect this product."