Sugar crops as a source of fuels. Volume II. Processing and conversion research. Final report

After a summary of the principal findings with respect to both the agricultural research reported in Volume I and processing and conversion research reported in the present volume, detailed discussions are presented on the following topics: processing of sugar crops for the manufacture of fermentable sugars, conversion of fermentable sugars into ethanol considered from both a technical and economic viewpoint, research and development implications of the technical and economic results. Appendices provide detailed equipment lists, materials and energy balances, and costs for the manufacture of ethanol from sugarcane and from molasses, using state-of-the-art technology. Ethanol from sugarcane or sweet sorghum is unlikely to be available in large quantities for less than $1.00 per gallon because improvements in sugar crop production and processing are needed to hold the raw material costs for ethanol to $0.70 per gallon. When reasonable provisions are made for fermentation, distillation and return on investments, the target of $1.00 per gallon appears appropriate. There are opportunities to manufacture liquid motor fuels other than ethanol from sugar crop juice and/or associated lignocellulosic fractions. Typical alternatives are 2,3-butanediol, ketones derived from short-chain fatty acids, and microbial oils.