David Pimentel1,3 and Tad W. Patzek2 Received and accepted 30 January 2005
Energy outputs from ethanol produced using corn, switchgrass, and wood biomass were each less than the respective fossil energy inputs. The same was true for producing biodiesel using soybeans and sunflower, however, the energy cost for producing soybean biodiesel was only slightly negative compared with ethanol production.
Findings in terms of energy outputs compared with the energy inputs were: • Ethanol production using corn grain required 29% more fossil energy than the ethanol fuel produced. • Ethanol production using switchgrass required 50% more fossil energy than the ethanol fuel produced. • Ethanol production using wood biomass required 57% more fossil energy than the ethanol fuel produced. • Biodiesel production using soybean required 27% more fossil energy than the biodiesel fuel produced (Note, the energy yield from soy oil per hectare is far lower than the ethanol yield from corn). • Biodiesel production using sunflower required 118% more fossil energy than the biodiesel fuel produced.
The energy required to produce ethanol from grain is substantial. That is true.
But ethanol is not the only useful by-product obtained from grain. Take into consideration the high protein corn mash that makes excellent livestock feed and other food by products. The energy required for producing ethanol is significantly less because ethanol is not a stand alone product and the rest of the process is not waste material. The same goes for soybeans. The study assumes there is only one usable by-product of ethanol and soy diesel production, which is not the case. Significant amounts of the energy used in processing would have been used anyhow to process the grain even if ethanol was not figured into the process.
And the assumption of the study is that only fossil fuel is used solely as the processing energy. Supplementing the fossil fuel with biomass plant waste like corn stalks and wood chips reduces the fossil energy considerably.
Every solution has it's imperfections, including oil.