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Feature Article

Determining high output, cost-effective feedstocks for carbohydrate and lignocellulosic conversion is a key step in achieving successful commercial supply of bioproducts, particularly biofuels. A number of crops show great potential as biorenewable feedstocks and the development of these species for commercially viable supply of biomass is becoming increasingly important for the future of the biorenewables industry.

Switchgrass (Panicum virgatum) is one such feedstock and has been widely studied as a potential lignocellulosic bioenergy crop in the United States for over twenty years. This work was sponsored mainly by the US Department of Energy, through Oak Ridge National Laboratory, and I was one of the subcontractors on this project at Auburn University in Alabama. Switchgrass occurs naturally east of the Rocky Mountains from the Gulf of Mexico all the way into Canada. It has many attractive features for energy production, such as establishment from seed (which facilitates rapid expansion compared to vegetative establishment), the ability to be harvested with existing farm equipment, relatively quick field drying and impressive yields without the need for high fertilizer applications. In addition, most researchers who have tried switchgrass for production of liquid fuels, heat and/or electricity rate it highly as a feedstock. President Bush referred to switchgrass specifically in his 31 January 2006 State of the Union address, as a potential feedstock for production of cellulosic ethanol. The result was a flood of enquiries about the outlook for this crop.

The technologies to convert material like switchgrass into liquid fuels are still in the fledgling stage, and this remains a barrier to its widespread establishment. Furthermore, in the absence of such a market, seed supply is limited. There is certainly nowhere near enough seed available to plant the millions of acres needed to contribute meaningfully to the plan announced by President Bush in his 2007 State of the Union address: to reduce gasoline consumption in the US by 20% within 10 years. Therefore, while switchgrass is an attractive energy crop, it is not an immediate option, but offers considerable opportunity in the mid- to long-term future (5-10 years or more).

Further research and development is needed to ensure that feedstock crops, such as switchgrass, are cost-effective and are able to meet the biomass supply demands that a commercially viable biorenewables industry will impose. At this critical stage in development of the biorenewables industry, the dissemination of accurate scientific information on promising feedstocks is of great importance.

David Bransby

David Bransby is Professor at the Department of Agronomy and soils at the Auburn University College of Agriculture, USA and was appointed Fellow of the American Society of Agronomy in 1998.

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