Using crops as a source of bio-energy for transportation would make much more efficient use of land, and slash greenhouse emissions, if directed towards generating electricity rather than liquid biofuel, a study has found.
The study by US researchers at Stanford University and the University of California found that converting biomass to ‘bio-electricity’ rather than ethanol offers 80 per cent more green energy per unit of land used.
The study team of Eliott Campbell, David Lobell and Chris Field found that an acre of switchgrass could produce enough battery power to drive a small electric SUV for 14,000 miles. The same acre of crop would only produce enough ethanol to power a similar vehicle with an internal combustion engine for 9000 miles.
When comparing the emissions savings over the full life-cycle of the energy alternatives, that is, their production and consumption, the bio-electricity produced twice as many greenhouse emissions savings over fossil-fuel use than did the biofuel.
The findings are significant amid worldwide efforts to replace carbon-intensive fossil fuels and the internal combustion engine with low or zero-emissions alternatives. While biofuels are presented as one fuel alternative - generating no net increase in atmospheric carbon over their life-cycle – significant sustainability issues have arisen over their production. Fuel crops compete for land with food crops, which threatens higher food prices and further clearing of forest land.
“Bio-electricity outperforms ethanol across a range of feedstocks, conversion technologies, and vehicle classes,” the authors say. They cautioned that the study did not compare bioelectricity and ethanol on the basis of other important factors such as water use, emissions of other air pollutants or economic viability.
GreenBiz 11.5.09
More:
“Greater Transportation Energy and GHG Offsets from Bioelectricity Than Ethanol” Science magazine