Hot topic at FEW: cellulose
As a precursor to the official start of the 2008 FEW, attendees had the option of attending the Ethanol 101 Seminar. Approximately 200 people attended the daylong event and heard from a wide variety of speakers. The most popular presentation of the day was delivered just after lunch by Mark Holtzapple, a professor at Texas A&M University. His presentation, titled "Carboxylate Platform: The MixAlco Process," might have seemed a bit advanced for an audience presumed to be new to the industry, but the long line for questions after he left the stage proved that people were interested in hearing more about the process. It consists of forming a large pile of biomass, pretreating it with a combination of lime and air to remove the lignins, and then utilizing a carboxylate method to produce fuel. The fuel produced in this case is a biobased gasoline, rather than ethanol.
According to Holtzapple, research on the process began in 1991. He said some of its advantages as opposed to other cellulosic conversion methods include the ability to use wet feedstocks that are composed of any material, including biomass, sewage sludge and municipal solid waste (MSW). The MixAlco process doesn't require the use of genetically modified organisms and is an energy-efficient process.
A semiworks plant is currently under construction in Bryan, Texas, and should be operational in September, according to Holtzapple. The plant will be capable of producing 300 to 400 gallons of gasoline per day. He estimated that once the process is commercially realized, a city with a population of 800,000 can produce enough MSW and sewage to fuel a plant that produces 45 MMgy of fuel at a capital cost of 81 cents per gallon.
During a workshop session titled "Alternative Feedstocks," Jonathan Mielenz, biomass program manager for the Oak Ridge National Laboratory, presented the possibility of soybean hulls as a cellulosic ethanol feedstock. He has been experimenting with this product in the laboratory and has come to the conclusion that soybean hulls can be used as a viable feedstock to not only produce ethanol but also to still be used as a high-protein animal feed.
Mielenz used a simultaneous saccharification and fermentation process in his experiments and discovered that pretreatment doesn't make a difference in production levels, thereby potentially saving the producer 18 percent in production costs. Mielenz assured session attendees that the fermentation portion of production is simple, and the end result is both ethanol and a high-protein, low-lignin animal feed. He has determined that by utilizing his method-if soybean hulls were put into production as a feedstock nationwide-the United States could produce an additional 300 MMgy of ethanol and 1.4 million tons of animal feed.