The overall objective of the study is to identify cost effective materials to produce novel fermentation feedstocks. Usually the most "cost effective" raw material for any project will be very site specific. Therefore, the study results are presented as a global overview offering directives for other work, as well as establishing methodology for comparing composition and cost of various selected raw materials. Areas identified for future research and development may be carried further in specific EU funded fermentation projects.
Sugar beet produces high sugar and biomass yields in EU conditions but at high prices related to the quota system which allows excellent and guaranteed returns to growers and processors. However, if grown on surplus land for energy, beet production, harvest and supply options could provide biomass (beet and tops) at attractive prices. There is also the potential for optimising sugar processing system to reduce the overall costs of production and supply sugar/molasses enriched pulp as a "wet" raw material for fermentation as well as animal feed.
The present high market price of grain precludes it as a competitive fermentation raw material. However, whole crop cereals and cereal straws (particularly oilseed rape straw which has high hemicellulose content and limited alternative uses) are potential biomass raw materials. There are also significant opportunities to use cereal processing residues as raw materials.
The expanding maize starch industry in Eastern European states may also be a burgeoning market for fermentation techniques developed in the EU for cost effective ethanol production based on hemicellulose rich stover and process by-products. Costs of production in these countries, based on large estates and low fixed costs and overheads, could be extremely attractive for "bio-fuel" production. Non traditional energy crops are still under development in the EU, but there is either limited or no commercial production. However, estimates of costs of production and high "fermentable sugar contents" within these crops, particularly sweet sorghum, suggest that delivered costs would be low.
The project is part of the overall activities of a concerted action, supported under the AIR programme, which aimed to bring together information on alternative fermentation feedstocks. In part, the interest was derived from previous work, supported partially by the ECLAIR programme (AGRE-0063), using a thermophilic bacteria to produce ethanol. The organism studied can use both 6-carbon sugars, (such as glucose) and 5 carbon sugars (such as xylose) which can be obtained from the hemicellulose fraction of agricultural residues or from novel energy crops. Hence, the study extends beyond the conventional use of sucrose and starch. However, by-products or alternative methods of obtaining lower cost fermentation feedstocks from the sugar and starch industries are also considered.
The study was completed in phases. Phase 1 (1996) developed an overview of available raw material sources and outline methodology for data evaluation. Phase 2 evaluated selected raw materials in greater detail to indicate specific industrial sources, costs and relevant research, development and demonstration projects. Phase 3 of the project developed an outline spreadsheet computer model to compare specific raw materials and their sensitivity to key cost features.
It was found that biomass resources are available as traditional and non traditional field and forestry crops, crop and forestry field residues, processing by products and municipal solid wastes. Municipal solid wastes were not considered further. For other materials, chemical compositions were summarised with sugars classified on the basis of the carbohydrate source and ease of hydrolysis.
An analysis of the cost of delivered sugars from typical raw materials was completed. Initial conclusions were that:
- to be cost effective, all sugars, particularly those derived from hemicelluloses, must be available for fermentation
- in the short to medium term, residues of agro processing operations were the least cost option, particularly where there were either limited markets for the residues as animal feeds or where the costs of drying and storage of such materials were prohibitive - in the longer term, however, the production of high yielding energy crops, rich in hemicellulose and fibre such as sweet sorghum, provides the best potential for low cost supply of significant levels of sugar for the fermentation industry.
- research on key elements of the production supply chains for these materials should be developed in association with hydrolysis and fermentation units to determine the real process costs.
Examples of each of these raw materials were studied in greater detail to identify specific commercial sources and to suggest areas for future funding of RD&D programmes by the EC. Raw materials included in this part of the study were:
- Sugar beet and sugar processing by products
- Starch crops (wheat and maize) and starch process by products
- Sweet sorghum, Miscanthus and short rotation coppice as non traditional energy crops
Whole crop, field crop residues and processing residues were incorporated within each raw material type.
Funding SchemeCON - Coordination of research actions
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