Issue Date: June 18, 2007
Steve Griffin's letter on ethanol as fuel was interesting (C&EN, April 23, page 4). Clearly he is right about energy return on energy invested (EROEI). The energy must come from somewhere, but I think that he may be missing a few points.
I know nothing about Brazil or its ethanol industry, but from my experience in South Africa, I would guess that they use bagasse (sugarcane stalks) as distillation fuel, in which case the energy "costs" nothing, and their figures are probably correct.
As far as ethanol from corn is concerned, is this isolated by distillation? The answer may be to extract ethanol from the fermentation liquor with methylene chloride. It has to be distilled eventually, but because the aqueous liquor does not have to be heated, much less energy is required and methylene chloride is easily recovered.
David A. H. Taylor
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