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Re: E-M:/ Get ready for coal-fired ethanol plants

Enviro-Mich message from Rane Curl <ranecurl@engin.umich.edu>

On Thu, 2 Mar 2006, Alexander J. Sagady wrote:

1) Is there likely to be any net energy savings from using ethanol for a percentage of transportation fuel, given the energy expended in mining and transporting coal, and growing and transporting corn and other feedstocks?

There are conflicting studies out there, although USDA & DOE appear to give their blessings on the validity of net energy production.

Even then, the positive energy excess is only about 20% of the fossil energy put into manufacturing the ethanol. If the process is fueled from the ethanol produced (to stop further emission of fossil CO2), the net energy yield is very much smaller than that from fossil fuels, and hence very much greater in cost.

2) Is there likely to be any net environmental improvement from using ethanol, given the tradeoffs between reductions in pollution from vehicles and increased pollution from ethanol plants and further up the fuel manufacturing chain?

That is a complex question because ethanol changes the mix of hazardous air pollutants emitted by vehicles....if memory serves me correctly it is more aldehydes with ethanol and less 1,3-butadiene & benzene.... ....kind of exchanging one set of carcinogens for a weaker set of carcinogens, but the weaker carcinogens are also know pulmonary irritants/toxicants (formaldehyde and acetaldehyde).

The big environmental improvement is in eliminating the generation of more fossil carbon CO2 (as noted above).

--Rane L Curl

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