Advanced enzymes lower production costs

By Luke Geiver | April 15, 2010
Several major enzyme providers recently announced improvements in their advanced enzymes for cellulosic ethanol production. The newest versions of these enzymes are creating higher production yields at a reduced cost, easing concerns that cellulose-based biofuels cost too much for too little.

Enzyme giant Novozymes Inc. released its newest version, the Cellic CTec2, in February. The CTec2 (when combined with the HTec2), reduces enzyme costs per gallon of ethanol to 50 cents, according to the company. Essentially a cocktail mix made up of earlier enzymes, the CTec2 can be used on various feedstock types including corn cobs and stalks, wheat straw, sugarcane bagasse and wood chips. "We have had a very positive response," said Cynthia Bryant, marketing manager for the global fuels division of Novozymes. "Before CTec2, enzymes, and specifically the cost to use them in a cellulosic ethanol process, were a key concern that needed to be addressed." The positive response, according to Bryant, is directly related to the enzymes' ability to improve performance 1.8 times over the previous enzyme. "Now, with CTec2, enzymes have become a tool because of the benefits the enzymes provide to the process, such as significantly lower enzyme use cost and process flexibility." After 10 years working with research partners such as Greenfield Ethanol Inc., Inbicon, Lignol Energy Corp., Poet LLC and ICM Inc., the enzyme is now being used, but Bryant said their efforts are not done. "CTec2 is just the beinning. Our cellulosic ethanol research and development effort is the largest Novozymes has ever undergone. With over 150 people dedicated to developing solutions for the industry, we will continue to develop solutions that provide further improvements."

In the same month, competing enzyme developer, Genencor, introduced Accellerase Duet, an extension of the earlier Accellerase 1500 enzyme. The Duet version will reduce biofuel enzyme dosing three-fold using a whole-broth formulation which provides nutrients for the fermentative organisms. "Inbicon has successfully trialed Accellerase in our demonstration biorefinery in Kalundborg, Denmark, and sees promise in using Duet now that it has been launched," said Niels Henriksen, CEO of Inbicon.

A subsidiary of Dupont Danisco, Genencor uses proprietary protein engineering methods to identify enzyme variants, according to Francis Stalder of Genencor. The approach allows for improved performance in the critical parameters of high-efficiency, low-protein loading, and a tolerance to real-world process conditions said Stalder. The Duet enzyme is currently being used at the Vonore, Tenn., cellulosic ethanol plant to convert corn cobs and eventually switchgrass.

For wheat-based ethanol producers, the release of Verenium's newest enzyme means improvements to fuel production costs as well. Verenium's new enzyme, Xylathin, breaks down the compound, xylan, that's found in grains such as wheat, rye and barley, significantly reducing mash viscosity. The enzyme also allows producers to reduce grain water retention and most notably, enzyme dosage. "Xylathin is effective over a wide temperature and pH range allowing producers greater operational flexibility and significant reductions in processing costs," according to Janet Roemer, executive vice president of Verenium.

Outside the recent enzyme developments, ZeaChem Inc. has developed a commercial grade bio-based acetic acid. The pure, glacial acid will be used in the production of ethyl acetate at a proposed 250,000 gallon-per-year facility in Boardman, Ore. Created through a broth in the front end fermentation process, an acid/hydrogen reaction process will eventually be put to use in the cellulosic ethanol process at the Boardman plant. "ZeaChem's biggest fermentation hurdles are now behind us and we have significantly de-risked future integrated operations," said Jim Imbler, president and CEO. The Boardman plant will come online in 2010 with the help of a $25 million U.S. DOE grant ZeaChem received in December.