Researchers at Iowa State University are exploring the use of ultrasonics to boost ethanol production from corn. The team pre-treated milled corn to break the corn pieces into fine particles, thereby exposing more of the corn’s starch to the enzymes that convert starch to sugars.
Preliminary tests have increased the corn’s release rates of sugars by nearly 30%, promising a greater ultimate ethanol yield per bushel. The research team also plans to see if ultrasonics release some sugars from the fibrous, cellulosic material in corn.
Ultrasound pretreatment generates cavitation in the corn slurry, resulting in strong hydrodynamic shear forces. The shear forces help disintegrate the corn slurry into fine particles, thereby exposing the much larger surface area to enzymatic activity during liquefaction / saccharification.
Not only can the ultrasonic pretreatment facilitate more complete starch conversion, consequently improving the overall ethanol yield, but it could also reduce the total amount of enzymes and nutrient needed, and the processing time.
Preliminary test data showed that the pretreatment resulted in nearly a 50-fold reduction in corn particle size during 40 seconds of sonication, producing the 30% increase in sugar yield. With the advancement in ultrasonic technology in recent years, the energy conversion efficiency of ultrasonic units has improved to > 90%.
This seems to work very well. We’re releasing more of the corn’s stored energy in a shorter period of time with less energy consumption.—David Grewell, Agricultural and Biosystems Engineering
The discovery has led to a patent application and a one-year provisional patent for immediate commercialization of the technology. Grewell is directing the research project. Samir Khanal and Hans van Leeuwen, an Iowa State professor of environmental engineering, are also working on the project. Van Leeuwen has also been leading a research effort on the use of a mold-based process for cellulosic ethanol production. (Earlier post.)
The ultrasonics research is supported by an $80,519 grant from Iowa State's share of the Grow Iowa Values Fund, the state’s economic development fund.
Grewell said the researchers’ next step will be to quantify the amount of ethanol produced when corn slurry is treated with ultrasonics. Then the process will be tested at a larger, pilot scale.