Document Type

Dissertation - Open Access

Award Date

1986

Degree Name

Doctor of Philosophy (PhD)

Department

Plant Science

First Advisor

Carl A. Westby

Abstract

Fodder beets yield two to three times more fuel ethanol per hectare than corn. This increased productivity should reduce feedstock costs and, consequently, ethanol production costs. The major factor that has limited use of this crop is the lack of a proven technology to process fodder beets -- economically and energy efficiently -- to fuel ethanol on a commercial scale. Research reported herein rectifies this situation by examining the technical and economic feasibility of community scale fuel ethanol production from fodder beets using two novel, continuous fermentation systems solid-phase fermentation and diffusion fermentation. Laboratory scale, batch fermentation trials were first conducted to determine optimum levels for important fermentation parameters. For the solid-phase fermentation process, these included grinding beets with a 1.27-1.91 cm hammermill screen, using a 5% (v/v) yeast inoculum, and maintaining a pulp pH of 3.0-3.5 to prevent contamination. For diffusion fermentation these parameters included using 1.91-2.54 cm beet cubes, and 0.25% potassium meta bisulfite, or 0.20% sodium meta bisulfite, or pH 2.0-2.2 to prevent bacterial contamination. Utilizing this information, the commercial scale continuous fermenters [sic] were operated using optimum levels of each parameter. Material and energy balances, and costs were determined from the resulting operational data. The energy balance (energy output/energy input) for each novel process was 3.0, which compares favorably with ethanol production from corn (2.26). Production costs for the solid-phase process ($0.492/L ethanol) were similar to ethanol produced from corn ($0.497/L), however the diffusion process was more costly ($0.529/L). In each process, beers or pulps containing 8-10% (v/v) ethanol were produced. Since ethanol production costs from fodder beets were equal to or higher than those for corn, it is likely that corn will remain the feedstock of choice for fuel ethanol production -- at least under present conditions. Before fodder beets can become a primary ethanol fuel feedstock, production costs must be lowered below those of corn. Only then will investors assume the increased risk of processing a new crop using a recently developed fermentation system. Future research on fodder beet production and processing hold the potential for achieving such cost reductions.

Library of Congress Subject Headings

Alcohol as fuel
Alcohol fuel industry
Beets

Format

application/pdf

Publisher

South Dakota State University

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