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Environmental, economic, and energetic benefits/costs of biofuels [#64]
There is a paper in the Proceedings of National Academy of Sciences of the US on the topic of the environmental, economic, and energetic costs and benefits of biodiesel and ethanol biofuels. PNAS, July 25, 2006, vol. 103(30).

The summary of the paper is as follows:
Negative environmental consequences of fossil fuels and concerns
about petroleum supplies have spurred the search for renewable
transportation biofuels. To be a viable alternative, a biofuel should
provide a net energy gain, have environmental benefits, be economically
competitive, and be producible in large quantities without
reducing food supplies. We use these criteria to evaluate,
through life-cycle accounting, ethanol from corn grain and biodiesel
from soybeans. Ethanol yields 25% more energy than the
energy invested in its production, whereas biodiesel yields 93%
more. Compared with ethanol, biodiesel releases just 1.0%, 8.3%,
and 13% of the agricultural nitrogen, phosphorus, and pesticide
pollutants, respectively, per net energy gain. Relative to the fossil
fuels they displace, greenhouse gas emissions are reduced 12% by
the production and combustion of ethanol and 41% by biodiesel.
Biodiesel also releases less air pollutants per net energy gain than
ethanol. These advantages of biodiesel over ethanol come from
lower agricultural inputs and more efficient conversion of feedstocks
to fuel. Neither biofuel can replace much petroleum without
impacting food supplies. Even dedicating all U.S. corn and soybean
production to biofuels would meet only 12% of gasoline demand
and 6% of diesel demand. Until recent increases in petroleum
prices, high production costs made biofuels unprofitable without
subsidies. Biodiesel provides sufficient environmental advantages
to merit subsidy. Transportation biofuels such as synfuel hydrocarbons
or cellulosic ethanol, if produced from low-input biomass
grown on agriculturally marginal land or from waste biomass,
could provide much greater supplies and environmental benefits
than food-based biofuels.
posted on 2007-02-16 14:09 UTC by Mr Gerard Alleng, Center for Energy and Environmental Policy
 

  • United Nations
  • United Nations Environment Programme