SBIR-STTR Award

Enchi Corp. aims to develop consolidated bioprocessing (CBP) for conversion of cellulosic biomass into fuels and chemicals at low cost and without added enzymes or thermo chemical pretreatment. This SBIR project targets the application of CBP with the shortest path to commercial deployment in the US: conversion of corn stover to ethanol co-located at an operating corn ethanol plant. The overall objective of Phase I is to provide proof-of-concept for continuous cascade fermentation as a means to achieve a > 2-fold reduction in reaction time to achieve high conversion - directly impacting the cost of fermenters the largest contributor to capital costs. Technical analysis presented herein shows that: 1) Cascade continuous processing offers several- fold shorter CBP reaction times compared to batch or single-stage continuous processing - a benefit specific to CBP and not applicable to processes with added cellulase; 2) A single continuous bioreactor brought to steady-state and subsequently operated in batch mode by turning off the feed exhibits the same qualitative behavior and similar quantitative behavior as cascade continuous fermentation and is thus a valid and practical system for demonstrating the merits of continuous cascade processing. Using economic models developed in consultation with POET we project robust investment returns at a production capacity and cost an order of magnitude smaller than the demonstration cellulosic ethanol plants built over the last decade. The proposed work plan involves determining the maximum solids loading at which fractional carbohydrate solubilization is undiminshed in continuous culture obtaining solubilization vs. time curves for the above-described operating strategy comparison to fermentations performed in batch mode and techno economic analysis. Realization of Phase I objectives will validate cascade continuous fermentation as a means to substantially accelerate conversion of corn stover via CBP resulting in lower capital costs and higher investment returns. Improved technology for low-cost conversion of corn stover to ethanol would lead to increased revenue and job creation for both corn farmers and fuel producers and would represent an important step toward realizing the long-anticipated vision of expanded use of cellulosic feedstocks in the bioeconomy and in rural America.