Submitted to: Trade Journal Publication
Publication Type: Trade Journal
Publication Acceptance Date: 5/24/2007
Publication Date: 6/22/2007
Citation: Adler, P.R. 2007. Biofuels and the Greenhouse Gas Factor. Solar Today 21:26,54. Interpretive Summary: An interpretive summary is not required.
Technical Abstract: Biofuels have been scrutinized for their potential to be used as a fuel substitute to offset a portion of the greenhouse gas (GHG) emissions produced by fossil fuel combustion. But quantifying that offset is complex. Bioenergy crops offset their greenhouse-gas contributions in three key ways: by removing carbon dioxide from the air and storing it in crop roots and soil as organic carbon; by producing coproducts like protein for animal feed, which saves on energy to make feed by other means; and by displacement, whereby replacing a fossil fuel with a biobased one "recycles" rather than adds more carbon dioxide to the atmosphere. Compared with the life cycle of gasoline and diesel, ethanol and biodiesel from corn-soybean rotations, which included 50 percent stover harvest, reduced GHG emissions by about 40 percent. This reduction was about two times greater than using ethanol produced from corn grain alone. However, using switchgrass and hybrid poplar would produce nearly a three-fold greater reduction in GHG emissions compared to corn-soybean rotations.