Ithaca, new York
July 5, 2005
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; 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. Further, its
production and use contribute to air, water and soil pollution
and global warming," Pimentel says. 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," says Pimentel. "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. |