BioMatNet Item: Commercial Success of ECLAIR Programme - AGRE-0063: High temperature ethanol fermentation of lignocellulose waste

Commercial Success of ECLAIR Programme
AGRE-0063: High temperature ethanol fermentation of lignocellulose waste

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Biological Conversion : Biotechnology : FAIR-CT98-4822 Commercial Success of the ECLAIR Programme : Liquid Biofuels and Biogas : Process Engineering : Straw : Wood (Lignocellulose)

This Item is taken from a report produced by CPL Scientific on the Commercial Success of ECLAIR Programme 1999 under contract FAIR-CT98-4822. The Project Summary, Links to Individual Project Reports and Preface and Overview are available in separate items.

AGRE-0063: High temperature ethanol fermentation of lignocellulose waste

Science Background

Ethanol derived from agricultural raw materials (bioethanol) can be used as a fuel additive, as anhydrous ethanol or following conversion to ETBE (ethyl tertiary butyl ether), as a blending compound or as a fuel for spark ignition engines. Within the EU, raw material (sugar, starch) prices prevent economic production by conventional yeast-based fermentation of hexose sugars (glucose, fructose). Use of lower cost feedstocks, such as agricultural and forest residues, is limited due to costs of obtaining fermentable sugars by enzyme hydrolysis and problems of inhibitors and yields if acid hydrolysis is used. Furthermore, ordinary baker's yeast will not ferment the pentose (5C) sugars such as xylose. Most organisms that will ferment 5C sugars are inhibited by low concentrations of alcohol. However, use of thermophilic organisms facilitates removal of the ethanol as fermentation proceeds.

Objectives

The objectives were to develop a laboratory scale pilot plant to test a novel continuous fermentation process based on the thermophilic bacteria, Bacillus stearothermophilus that was capable of using the pentose sugars derived from low-cost agricultural wastes. Specific objectives were to improve the strain of bacteria used reducing the amount of organic acids formed as by-products, to demonstrate the two stages of the process (a growth stage and a fermentation stage), to develop a complete 'closed' system, to determine yields on xylose (5C sugar) as model substrate and to test various feedstocks (hydrolysates) derived from wood, straw and sugar beet residues. The results would be used to estimate the performance and economics of an integrated system.

Significant changes and results since end of ECLAIR

This ECLAIR project led to the formation of a UK-based SME, AGROL Ltd, set up with venture capital with the coordinator as one of the directors. The main objective of AGROL is to commercialize the thermophilic fermentation process. In 1998 an improved strain was obtained by genetic engineering, that had properties similar to those obtained by mutation during the ECLAIR project. A small (4 tonne per annum ethanol) pilot plant has been constructed, coming on-line in early 1999.

Results

At the end of the project

The ability of the organism to produce ethanol from both model substrate and hydrolysates of agricultural residues was established. Yield and other data suggested that this process could produce ethanol at a price below that derived from petrochemical sources. However, the use of conventional chemical mutation and selection failed to produce a stable strain, although the potential for such improvement was established, setting targets for a subsequent gene deletion programme using genetic engineering. The problems with the strains hampered reactor development. However, good results were obtained in 'open' reactors enabling the concept of a two-stage aerobic (growth)/anaerobic (fermentation) closed membrane reactor system with vacuum removal of the ethanol to be designed, modelled and used in the economic assessment.

Current position

The establishment of Agrol and availability of venture capital has enabled genetic engineering techniques to be applied to strain improvement, reactor design and setting up of a pilot plant.

Impact

Commercial

The project resulted in the establishment of a new biotechnology company, formed with the coordinator as one of the directors, with the specific objective of commercializing the process funded under ECLAIR, as well as exploiting other aspects of thermophilic organisms and heat-stable enzymes.

Associated

AGROL coordinated the concerted action AIR-CT94-1990: Novel fermentation feedstocks that established a network throughout Europe to investigate availability and cost of alternative agricultural materials and process options, as well as construct a database and economic models covering such feedstocks.

Contacts

Author