Continuous cellulose-to-glucose process

Abstract

A continuous cellulose-to-glucose process has been developed by W. Brenner at New York University as part of an EPA project for conversion of solid wastes to fuels; the technology could help improve the economics of fermentation of wood, paper, and agricultural and municipal wastes to ethanol for gasohol. A 1 ton/day demonstration plant has been built and is operating on sawdust and pulped newspaper. It uses a twin-screw extruder of the type used in plastics processing to slurry the cram-fed cellulosic feed. Dilute sulfuric acid is added near the outlet of the extruder to hydrolyze the cellulose, which is heated by steam to 450/sup 0/F, to glucose in up to 60% yield; the low residence time minimizes acid-catalyzed degradation. Energy consumption is 1600 Btu/lb cellulose, but this could be reduced by insulating the extruder barrel and quenching the reaction mixture in a heat exchanger. According to C. Rogers (EPA), this technology could produce ethanol by fermentation for $0.85-$1.00/gal, of which $0.60/gal would be for cellulose hydrolysis at mobile plants in the field, with the glucose syrup transported to local fermentation plants. V. R. Srinivasan (La. State Univ.) is studying continuous fermentation of the glucose syrup to methane.