Ames, Iowa – A team of researchers from Iowa State University and the University of Hawaii have developed a process that uses fungus in ethanol production leftovers to save energy, recycle more water and improve the livestock feed left over from the process of manufacturing fuel. The researchers won the 2008 Grand Prize for University Research from the American Academy of Environmental Engineers for the project.
The project focuses on using fungi to clean up and improve the dry-grind ethanol production process, which grinds corn kernels and adds water and enzymes to break the starch into sugar. The sugar is then fermented with yeast to produce ethanol. The current process leaves about six gallons (22.7 litres) of leftovers for every one gallon (3.7 litres) of fuel produced.
The leftovers, known as stillage, contain solids and other organic materials that are removed and dried for livestock feed. The remaining liquid, called thin stillage, still contains some solids, but only about 50 per cent of thin stillage can be recycled back into ethanol production. The researchers added a fungus to the thin stillage and found it would feed and grow, removing about 80 per cent of the organic material and all of the solids, and allowing the water and enzymes in the thin stillage to be recycled back into production. The fungus itself is a food-grade organism that can be dried and sold as livestock feed supplement.
At current production levels, the researchers said that the process would eliminate the need to evaporate thin stillage, saving ethanol plants up to US$800 million a year in energy costs; reduce the industry’s water consumption by as much as 10 billion gallons per year; allow producers to recycle enzymes in the thin stillage, saving about US$60 million per year; increase the market for supplemented feed by about US$400 million per year; and improve the energy balance of ethanol production by reducing energy input, creating more of an energy gain.
It is estimated that it would cost US$11 million to start using the process in an ethanol plant that produces 100 million gallons of fuel per year, but that the cost savings would pay off the investment in about six months. The researchers have filed for a patent on the technology.