Reducing the Environmental Footprint of Corn Ethanol Production
This study explores the adoption of technologies that reduce the energy and environmental footprint of the corn ethanol production pathway at both the corn production stage and during the conversion to ethanol at the dry grind biorefinery. This is a follow-up effort to a similar study which benchmarked the industry’s performance in 2008. The study shows that at the biorefinery level modern energy and processing technologies such as sophisticated heat integration, combined heat and power technologies, variable frequency drives, advanced grinding technologies, various combinations of front and back end oil separation, and innovative ethanol and DDG recovery have further reduced the energy footprint of the corn ethanol production process.
Our work includes an assessment of over 50% of operating dry grind corn ethanol plants. On average, 2012 dry grind plants produce ethanol at higher yields with lower energy inputs than 2008 corn ethanol. Furthermore, significantly more corn oil is separated at the plants now which combined with the higher ethanol yields results in a slight reduction in DDG production and a negligible increase in electricity consumption.
The study also looks at new technologies that have recently been adopted and further increase the efficiency during the corn production phase of the corn ethanol pathway. For example, over the last several years higher corn yields have also increased the amount of corn stover and additional plant material produced by modern hybrids. As a result, growers have started to remove corn stover for use as animal feed in nearby feedlot operations. Consequently, acres producing corn for ethanol and DDG animal feed now also produce a second animal feed at the front end of the process in the form of stover feed. Other efficiency improvements during the corn production phase include more accurate and targeted delivery of chemicals and agricultural inputs, as well as corn hybrids that contain enzymes resulting in reduced processing energy and increased ethanol yields at the biorefinery level.
Steffen Mueller, PhD.