chapter  5
28 Pages

Plant Resources for Bio-energy and Chemical Feedstock Uses

Growing fresh plant biomass represents a source of carbon for energy and feedstock production that is an alternative to the use of deposits of ancient plant biomass (fossil fuels). Rather than return CO2 to the atmosphere as we do when we burn fossil fuels we have the potential to recycle carbon, fixing it in growing the plant and returning it to the atmosphere when the biomass is consumed. Biofuels may be produced in a more carbon neutral process, avoiding the addition of greenhouse gases to the atmosphere and the associated risk of global warming. For example, life-cycle assessment of ethanol production from switchgrass has produced an estimate of a 94 per cent reduction in greenhouse gas emissions compared with conventional fuel from oil (Schmer et al, 2008). Despite this potential the current first-generation technologies for biofuel production (based upon conversion of non-structural carbohydrates (sugars and starch) to ethanol or plant oils to biodiesel) have been assessed as often having minimal advantages, and may in fact have a net negative impact when all social, environmental and economic factors are considered (Charles et al, 2007). The efficiency of these first-generation processes is being rapidly improved. However, current substantial investments in improvement of technologies for biofuel production (US Department of Energy, 2008) are essential to achieving the promised potential of plants to deliver significant reductions in greenhouse gas emissions.