What is it about?

An indicative economic appraisal of a biorefinery investment has been undertaken for the case of an archetypal, full-scale process plant based on bioethanol production from wheat straw: a cellulosic co-product or ‘waste’ stream. A ‘life-cycle’, or ‘through-life’, biofuel chain was examined from the supply of wheat straw, through biochemical conversion processing, and distribution of product to fuel terminals for use in the transport network. The process technology investigated was dilute acid pre-treatment and enzymatic hydrolysis. Discounted cash flow (DCF) investment appraisal formed the key evaluation methodology, and the results were found to depend on the discount rate and lifespan of the biorefinery. Analysis of suitable UK locations, refinery scale or size, and logistics established potential low cost areas with good access to wheat straw.

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Why is it important?

An indicative economic evaluation of an archetypal, full-scale biorefinery for processing wheat straw into bioethanol has been undertaken across the life-cycle or through-life fuel chain. The process technology investigated was dilute acid pre-treatment and enzymatic hydrolysis. DCF investment appraisal found that feedstock costs were a primary component of the overall price; representing 37% of the total. There is scope to reduce the estimated 'minimum ethanol selling price' (MESP) further, especially the cost of feedstock and for producing the enzymes employed within the enzymatic hydrolysis process. Key additional financial factors identified were the discount rate, and overall investment depreciation as dictated by the biorefinery lifespan. The largest risk was found to be associated with the availability of the wheat straw. In addition, the operation of the biorefinery needs to be as close to the maximum capacity as possible in order to mitigate against compounding reductions associated with low throughput or yield.

Perspectives

The UK Research and Innovation (UKRI) is a non-departmental public body currently responsible for funding research and knowledge exchange at UK universities and via the national innovation agency. Its Biotechnology and Biological Sciences Research Council (BBSRC) established a BBSRC Sustainable Bioenergy Centre (BSBEC) – actually a research network - that in turn supported a project on the generation of bioethanol from the lignocellulosic biomass, including excess straw, spent grains and waste generated from food production. The present contribution has formed part of that project, and is a companion to other studies on straw use and availability in England, the development of fermentation techniques for lignocellulosic residues to produce bioethanol, the environmental impact of biofuels, and the thermodynamic performance of bioethanol production from wheat straw (a cellulosic co-product or ‘waste’ stream). DCF investment appraisals of this type enable industrialists and policy makers to determine the implications of bioethanol production from wheat straw within a low carbon future.

Professor Emeritus Geoffrey P Hammond
University of Bath

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This page is a summary of: Bioethanol processing from wheat straw: investment appraisal of a full-scale UK biofuel refinery, Biofuels, October 2022, Taylor & Francis,
DOI: 10.1080/17597269.2022.2132722.
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