"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.

Source: Cornell University