Cellulase Cost-Reduction Contracts

The Biomass Program's model process design (PDF 5.1 MB) for a large-scale lignocellulosic biomass-to-ethanol production plant is based on enzymatic, rather than thermochemical hydrolysis, of cellulose Download Adobe Reader. One main reason for this choice is that there is more opportunity for cost reduction for enzyme-based technology (although its cost is higher to start with) than with already relatively well-developed thermochemically-based processes. The most important opportunity for cost reduction is the effective cost of using the cellulase enzymes. Current commercial production of enzymes generally (for example in detergents) and for cellulase enzymes specifically (for example for "stone-washing" jeans) is relatively both small in scale (compared to the market size that would be needed to support a large-scale cellulosic ethanol industry) and recent (most industrial enzyme technology is only a few decades old). As such, cellulases are currently considered specialty products, and ten-tofifty-fold decreases in the effective cost of the enzymes are needed and believed to be achievable by reducing enzyme production costs and improving enzyme performance. In combination with other targeted improvements in sugar platform technology (reducing cellulase costs is just one of many Program targets — albeit a key one), achieving this level of cellulase cost reduction would enable enzyme-based processing to surpass thermochemical cellulose hydrolysis processing economics and would make producing ethanol or sugar from lignocellulosic biomass competitive with producing it from starch.

The Biomass Program therefore placed separate, parallel contracts in 2000 with the world's two largest industrial enzyme manufacturers, Genencor International and Novozymes, with the goal of reducing cellulase costs for commodity biomass conversion applications. As of early 2004, both companies have already reported over ten-fold decreases to an effective cost of below $0.50 per gallon of ethanol produced. Continuing work is expected to further reduce cellulase costs to about $0.10 per gallon of ethanol or less — the cost target established by the Biomass Program for this key element of sugar platform technology development.