Ultrasound Enhances Biomass Conversion into Biofuels

A study at the Iowa State University has found that ultrasound enhances the chemical reactions necessary to convert biomass feedstock into biofuels.

A team of engineers at ISU has shown that the use of ultrasonics in the pretreatment of a wide variety of feedstocks could increase the efficiency of separating lignin from the biomass so that sugar dissolution could occur in minutes rather than the hours required for traditional pretreatments. Lignin is the tough polymer that binds the complex polysaccharides together in plant cell walls. Lignin prevents access to enzymes that are destined to degrade the polysaccharides, and thus represents an important barrier in the fermentation process that turns simple sugars into biofuel.

The research team has also shown that when corn feedstock is treated with ultrasound rather than cooked with jet steam at extreme temperature, the sonically ground corn particles provided more surface area for enzymatic action, resulting in fermentation yields comparable to output from conventional jet steaming. This finding offers an opportunity to reduce the cost of biofuel production, based on the team's economic analysis.

The study also found the potential of ultrasound to accelerate transesterification, the main chemical reaction for converting oil to biodiesel. The researchers at one point discovered that ultrasound converted soybean oil into biodiesel in less than a minute, rather than the 45 minutes it normally takes. This is said to be faster and a less complicated method than traditional techniques requiring multiple steps and relatively long cycle times.