Academic Study Discredits Ethanol, Biodiesel
July 15, 2005 |
July 15, 2005 |
"There is just no energy benefit to using plant biomass for liquid fuel,"
- David Pimentel, professor of ecology and agriculture at Cornell
Ithaca, New York [RenewableEnergyAccess.com] We regularly report on biofuels -- from industrial ethanol facilities to home-brewed biodiesel -- because they're a big slice of the renewable energy pie. A new study from Cornell University and University of California-Berkeley directly challenges that, saying that turning plants such as corn, soybeans and sunflowers into fuel uses much more energy than the resulting ethanol or biodiesel generates.
"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; and 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 produced, and sunflower plants requires 118 percent more
fossil energy than the fuel produced.
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.
"The United State desperately needs a liquid fuel replacement for oil in the
near future," says Pimentel, "but producing ethanol or biodiesel from plant
biomass is going down the wrong road, because you use more energy to produce
these fuels than you get out from the combustion of these products."
Although Pimentel advocates the use of burning biomass to produce thermal energy
(to heat homes, for example), he deplores the use of biomass for liquid fuel.
"The government spends more than $3 billion a year to subsidize ethanol
production when it does not provide a net energy balance or gain, is not a
renewable energy source or an economical fuel," Pimentel said. "Further, its
production and use contribute to air, water and soil pollution and global
warming."
He points out that the vast majority of the subsidies do not go to farmers but
to large ethanol-producing corporations.
"Ethanol production in the United States does not benefit the nation's energy
security, its agriculture, economy or the environment," Pimentel said. "Ethanol
production requires large fossil energy input, and therefore, it is contributing
to oil and natural gas imports and U.S. deficits."
He says the country should instead focus its efforts on producing electrical
energy from photovoltaic cells, wind power and burning biomass and producing
fuel from hydrogen conversion.
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