East Lansing, Michigan – A new process, developed and patented by researchers at Michigan State University, may cut the cost of making biofuels from cellulose. The process pre-treats corn crop waste, or stover, before conversion into ethanol, eliminating the need to add extra nutrients.
The AFEX (ammonia fibre expansion) pretreatment process was developed by Bruce Dale, professor of chemical engineering and materials science. It uses ammonia to make the breakdown of cellulose and hemicellulose in plants 75 per cent more efficient than when conventional enzymes are used alone. Plant cellulose must be broken down into fermentable sugars before they can be turned into biofuel.
“It’s always been assumed that agricultural residues such as corn stover didn’t have enough nutrients to support fermentation,” Dale said. “We have shown this isn’t so.”
The research also shows that chemical compounds created when the stover goes through the AFEX process can improve the overall fermentation process, contrary to conventional theories that the compounds are detrimental and should be removed. The research has been published in the current issue of the Proceedings of the National Academy of Sciences.
Cellulosic material pretreated with the AFEX process can be fermented into ethanol without additional processing. “Washing, detoxifying and adding nutrients back into the pretreated cellulose are three separate steps,” Dale said. “Each step is expensive and adds to the cost of the biofuel. Breaking down cellulose into fermentable sugars cost effectively has been a major issue in slowing cellulosic ethanol production. Using AFEX as the pretreatment process can dramatically reduce the cost of making biofuels from cellulose.”
The researchers said the next step could be a pilot plant, and that they are working to make the new technology adaptable to several companies that are interested in opening cellulosic ethanol plants in Michigan.