DOE develops cheaper, more efficient pre-treatment for biomass

Source: Katherine Ling, E&E reporter • Posted: Monday, May 13, 2013

A salty, enzyme-free bath may be the key to cost-competitive advanced biofuels.

Researchers at the Energy Department’s Joint BioEnergy Institute (JBEI) have developed an ionic liquid pre-treatment for cellulosic biomass that does not require the usual expensive enzymes and uses less water, the agency announced today.

The new technique breaks down the fiber or lignocellulosic biomass in plants into two liquid streams that make recovery easier. One stream is a sugar-rich water phase that is recovered and fermented into cleaner alternatives to gasoline, diesel and jet fuels; the other stream creates lignin-rich ionic liquid that can be recycled, DOE said.

The key to this new pre-treatment is the addition of an acid catalyst — sodium hydroxide — instead of the expensive enzymes that have been previously relied upon, according to Blake Simmons, a chemical engineer who heads JBEI’s Deconstruction Division and is the leader of this research.

“The combination makes it easy to extract fermentable sugars that have been liberated from biomass and also easy to recover the ionic liquid for recycling,” Simmons said in a statement. “By eliminating the need for enzymes and decreasing the water consumption requirements of more traditional ionic liquid pretreatments we should be able to reduce the costs of sugar production from lignocellulose.”

Ionic liquids are liquid salts at room temperature and have been an environmentally friendly alternative for volatile organic solvents in other industries. They have had limited use so far in biofuels because of their high costs, although they have shown great promise for use in blended feedstocks for advanced biofuels (Greenwire, Feb. 5).

A paper describing the JBEI team’s research has been published in the journal Biotechnology for Biofuels. The team’s next step will be to scale the process up to 100 liters at the Advanced Biofuels Process Demonstration Unit at Lawrence Berkeley National Laboratory.

JBEI is one of three bioenergy research centers established by DOE’s Office of Science in 2007 that support multidisciplinary, multi-institutional research teams pursuing the fundamental scientific breakthroughs needed to make production of cellulosic biofuels, or biofuels from nonfood plant fiber, cost-effective on a national scale.

The institute is led by Berkeley Lab and includes the Sandia National Laboratories, the University of California at Berkeley and Davis, the Carnegie Institution for Science, and the Lawrence Livermore National Laboratory.