Tuesday, May 3, 2011: 3:30 PM
Willow A-B, 2nd fl (Sheraton Seattle)
The production cost, both at present and in the future (2020), of lignocellulose-based ethanol was compared to corn ethanol to determine economic competitiveness and whether existing cost projections are realistic. A techno-economic model was used to estimate the current production cost for a base-case, 50 ML yr-1 softwood facility, and cost reduction test cases targeting feedstock switching, scaling, enzymes, and co-products. The progress ratio, the rate at which production cost is reduced for every doubling of cumulative production, was found to be feasible for lignocellulosic ethanol to be competitive with corn ethanol by 2020 (volumes mandated by 2007 EISA). However, cost reductions must occur across all production components. With ethanol as the sole product, lignocellulosic feedstock, whether softwood, hardwood, or crop residues, is competitive with, but not substantially less than, corn for first generation ethanol. Cellulase enzyme cost projections by industry and government were deemed to be aggressive and cellulase cost would need to be significantly lower than that of amylase enzymes on a protein unit basis. Opportunities for capital cost reduction relative to first generation are related to the pretreatment-hydrolysis operational strategies, including severity of pretreatment and hydrolysis residence times. Instead of maximizing ethanol yield, operators can benefit from maximizing the hydrolysis rate with shorter residence times and using residues for co-products including heat and power. Increasing facility scale up to 1 BL yr-1 output substantially reduces per unit capital costs, but not to a level competitive with average (150 ML yr-1) corn ethanol facilities.