Liquid fuels production from biomass. Progress report No. 5, July 1-September 30, 1978

Abstract

The current program to convert biomass into liquid hydrocarbon fuels is an extension of the previous program to ferment marine algae to acetic acid. In that study, it was found that marine algae could be converted to higher aliphatic organic acids and that these acids could be readily removed from the fermentation both by membrane or liquid-liquid extraction. It was then proposed to convert these higher organic acids to aliphatic hydrocarbons via Kolbe Electrolysis, which may be used as a diesel fuel. The specific goals for the current program are: (1) Establish conditions under which substrates other than marine algae may be converted in good yield to organic acids. The primary task in this regard is methane suppression. (2) Modify the current 300 liter fixed packed bed batch fermenter to operate in a continuous mode. (3) Change from membrane extraction of organic acids to liquid-liquid extraction. (4) Optimize the energy balance of the electrolytic oxidation process. The primary task in this regard is to reduce the working potential required for the electrolysis while maintaining an adequate current density. (5) Scale the entire process up to match the output of the 300 liter fermenter. The accomplishments in this program are onmore » schedule. Substantial progress has been made on the problem of methane suppression through the use of sulfide addition and the identification of bromoethane-sulfonic acid as a specific inhibitor of methanogenesis. A conceptual design of a continuously fed fixed packed bed fermenter is presented. Experimental results show that the electrolysis of organic acids produced by fermentation to liquid hydrocarbon fuels already have a favorable energy balance of 6/1 based on the applied potential and over 10/1 based on the working potential.« less