A FACTORIAL DESIGN ANALYSIS OF A BIOMASS TO ETHANOL-PRODUCTION SYSTEM

A least cost, dynamic programming solution was derived by an algorithm for ethanol production from woody biomass. Conversion of the feedstoc k was based on an enzymatic hydrolysis/fermentation process. The final cost of ethanol from this system, prior to any sensitivity analysis, was $0.45 L-1 A sensitivity analysis, using a factorial design, compar ed the relative impact of various model parameters on production costs . The factorial design analysis can be used as a guide for lowering fi nal product costs. Three factors were incorporated into the first fact orial design: the size of the manufacturing facility, storage retentio n, and the price of alternative feedstocks. Each of the main factors h ad an impact on the solution cost. Facility size had the largest effec t, representing 45.3% of total cost variability. Storage deterioration and the price of alternative feedstocks had lower effects of 17.4% an d 17.6%, respectively. The largest interaction effect, at 17.4%, illus trated that storage deterioration and facility size have a joint effec t on production costs. The second factorial design employed five facto rs. Ethanol yield from the woody feedstock accounted for 44.0% of the total variability in final product cost. Harvesting equipment capabili ty placed a 36.8% effect on the final product cost. The third largest effect, at 8.7%, was plantation yield. Although plantation yields are of key importance to feedstock prices, they had a lesser impact than t he other factors on the final product cost over an entire production p rocess. Storage retention and facility size had a reduced impact on to tal costs when considered in combination with other design factors. Ba sed on this study the focus for research and technological improvement s should be on conversion yields from wood, harvester equipment capabi lities, and plantation yields. (C) 1998 Elsevier Science Ltd. All righ ts reserved.