(239b) Challenge of Feedstock Flexibility

Catchlight Energy LLC is a 50:50 joint venture of Chevron and Weyerhaeuser formed to convert forest-based lignocellulosic biomass into economical, sustainable liquid transportation fuels. A bioconversion approach is targeted to result in an early commercial success in the southeastern United States. Catchlight Energy's strategy in the bioconversion pathway is to form non-exclusive partnerships with technology providers who have development plans consistent with this goal.

Economical feedstock supply will be a challenge for large scale biorefineries. Catchlight Energy is exploring ways to increase biomass density on Weyerhaeuser timberland. Potential biorefinery feedstocks include intercrops grown between timber tree rows, such as switchgrass, and residuals, such as harvest residues and understory cleanings. Each feedstock offers different benefits and problems. Switchgrass is easier to convert to ethanol through enzymatic hydrolysis than woody material, but poses new logistical challenges. An estimate of the mass and sugar loss from allowing switchgrass to lie unharvested over winter is presented. Moisture stability was investigated but found not to be problematic up to 90% humidity. The seasonality of herbaceous crops such as switchgrass suggests that a competitive biorefinery will need to be capable of using all available feedstocks. Thus, while softwoods are less amenable to enzymatic hydrolysis, improvements in the bioconversion of this feedstock will yield cost reduction benefits to the industry.