Already registered? LOGIN.

Feature Article

European countries such as the UK grow several million tonnes of wheat surplus to food requirements every harvest. This surplus starch looks an attractive feedstock, but the recent sharp hike in grain prices has ignited the "food vs fuel" debate. Wheat straw for cellulosic ethanol or bioenergy might be preferred, especially if valuable specialty chemicals could be extracted first.

The BioResources Group of the Society of Chemical Industry (SCI) recently held a conference focusing on wheat as a feedstock.

Wheat for biofuels

Ensus will use one million tonnes of wheat feedstock to manufacture 400 million litres/year of bioethanol from early 2009. Technical director John Pinkney explained that bioethanol from wheat can have a much better net energy output than other biofuels. A high protein animal feed co-product will offer an alternative to soybean meal. This will improve the economics and help stave off expansion of the Brazilian soybean crop on to virgin agricultural land at the expense of natural carbon sinks.

Ensus believe wheat yields must to continue to rise if feedstock requirements are to avoid disrupting the food supply. Prof. Peter Shewry (Rothamsted) and Dr John Foulkes (University of Nottingham) discussed progress in understanding the genomics and physiology of wheat yield. In Europe, plant breeders have been increasing the yield potential of new wheat varieties by about one tonne/ha each decade. Prof. Andy Greenland (NIAB) pointed out the importance of cooperation between physiologists, agronomists and breeders in defining targets for crop improvement. More efficient use of nitrogen fertilizer is also important. This would increase the net energy gain from growing wheat.

Although little of agribusiness giant Syngenta's research involves wheat directly, Dr Bruce Link described some current work on biofuels. Tropical sugar beet is a drought tolerant new bioethanol feedstock being developed in India as an alternative to sugar cane. For maize, Syngenta are developing more heat stable and pH tolerant alpha amylase enzymes which will cut the cost of biothanol production from grain. In the longer term, maize hybrids expressing multiple cellulase enzymes will be commercialised to facilitate the production of cellulosic ethanol.

Bioenergy and high value bioproducts

More than 100 million tonnes of wheat straw in EU 25 are surplus to annual needs for animal feed and bedding. Dr Angela Karp (Rothamsted) noted that wheat straw's low density and low yield make it less attractive as a bioenergy feedstock than woody perennials such as miscanthus and willow. These both produce high yields of biomass with low fertilizer inputs. However, they are expensive to establish and difficult to remove when returning land to arable cropping. Although the area of woody biomass crops has been increasing, this will undoubtedly be checked by the current high cereal prices.

Dr Fabien Deswarte (University of York) described how supercritical CO2 technology has been used to extract a variety of waxes including alkanes, fatty acids, sterols and polycosanols from wheat straw. Some of these are particularly good for lipstick - over her lifetime, the average woman apparently uses 3 kg of lipstick! Dewaxed straw itself has a number of advantages. Calorific value for burning is higher; it is more suitable for pulp and paper because contamination from ‘pitch' is reduced; and better ‘bondability' means strawboards can be made using cheap, water-based resins.

Biopolymers are now made from polylactic acid and 1,3-propandiol and plants manufacturing platform chemicals such as ethylene are being built. However, Dr Adrian Higson & Dr John Williams (NNFCC) noted that the current price volatility of oil and crop commodities makes economic forecasting difficult.

Prof. Jim Dunwell (University of Reading) discussed the science, regulation and commercialisation of GM crop plants for pharmaceutical production. GM maize and rice are already producing commercial drugs for Prodigene and Ventria, respectively, and the US biopharma market value could reach $2 billion by 2012. However, strict containment of biopharma crops is critical and as a key food crop wheat is very unlikely to be used in ‘biopharming'.

Way forward?

UK Research Councils have an alternative energy programme, but there has been little interest in biofuels compared to wind and wave power noted Dr Alf Game (BBSRC). The main policy drivers continue to be EU directives on biofuels. There is, however, the Integrated Biorefining Technologies Initiative – a partnership between UK industry and government to define the R&D and demonstration needs of biorefineries. Wheat is the most widely grown, highest yielding and often the most profitable crop for arable farmers in NW Europe. Whether wheat is a sustainable way forward for bio-feedstocks is a complex question with answers rooted in what bioscience can deliver, economics and public perception. 

 "Wheat for Biofuels, Bioenergy and High Value Bioproducts" was organised by SCI BioResources Group and held at Syngenta's Jealott's Hill International Research Centre, Bracknell, UK on 29 April 2008.

 
Related links

Read More...

• Interview with Bruce E. Dale
• New Generation Biofuels announces collaboration agreement with Burmeister and Wain Energy A/S
• Power to the people

• transgenic crop   
• wheat straw  
• wheat  
• bioethanol  
• bioproducts