Previously, I asked "why won't ethanol just go away", lamenting what a stupid program ethanol is and how much subsidy money is poured down that drain, not to mention the effect it seems to have on the Iowa primary every 4 years. Yet another study has shown that ethanol consumes more energy to make than it actually produces.
Turning plants such as corn, soybeans and sunflowers into fuel uses much more
energy than the resulting ethanol or biodiesel generates, according to a new
Cornell University and University of California-Berkeley study.
"There is just no energy benefit to using plant biomass for liquid fuel,"
says David Pimentel, professor of ecology and agriculture at Cornell. "These
strategies are not sustainable."
Pimentel and Tad W. Patzek, professor of civil and environmental engineering
at Berkeley, conducted a detailed analysis of the energy input-yield ratios of
producing ethanol from corn, switch grass and wood biomass as well as for
producing biodiesel from soybean and sunflower plants. Their report is published
in Natural Resources Research (Vol. 14:1, 65-76).
In terms of energy output compared with energy input for ethanol production,
the study found that:
- corn requires 29 percent more fossil energy than the fuel produced;
- switch grass requires 45 percent more fossil energy than the fuel produced;
- wood biomass requires 57 percent more fossil energy than the fuel produced.
In terms of energy output compared with the energy input for biodiesel
production, the study found that:
- soybean plants requires 27 percent more fossil energy than the fuel
- sunflower plants requires 118 percent more fossil energy than the fuel
In assessing inputs, the researchers considered such factors as the energy
used in producing the crop (including production of pesticides and fertilizer,
running farm machinery and irrigating, grinding and transporting the crop) and
in fermenting/distilling the ethanol from the water mix. Although additional
costs are incurred, such as federal and state subsidies that are passed on to
consumers and the costs associated with environmental pollution or degradation,
these figures were not included in the analysis.