Enhancing biofuel production by ultrasonics

Abstract

This work evaluated the use of high-powered ultrasonics to enhance biofuel production in terms of efficiency and costs. A wide range of feed stocks, including switch grass, corn stover, and soft wood, were studied. The effect of ultrasonic pretreatment on the removal of lignin for hydrolysis of starches and cellulose to fermentable sugars was studied. It was found that many of the pretreatments were very successful in enhancing lignin removal. For example, time of dissolution of lingo-cellulosic biomass in ionic liquids was reduced from hours to minutes accompanied by a significant decrease in energy consumption compared to mechanical stirring. In addition, it was found that hydrolysis of corn starch could be greatly accelerated utilizing ultrasonics. Economic models showed that the technology, once implemented, would have a payback period of less than one year. The work also focused on biodiesel production. It was seen that ultrasonics accelerated the transesterification process so that soy bean oil could be converted to biodiesel in less than a minute, compared to 45 min using traditional methods. It was shown that yeast grown from glycerin, a co-product of biodiesel production, could be extracted and simultaneously converted to biodiesel with ultrasonics in less than a minute, compared to traditional techniques that require multiple processes and relatively long cycle times (+1 h).