The life cycle greenhouse gas emission benefits from alternative uses of biofuel coproducts

Abstract

Coproducts from bioenergy processing have potential as alternative products in the market, thereby reducing greenhouse gas (GHG) emissions. Thus far, the environmental benefits from coproduct use have been overlooked in most studies because of the lack of knowledge on their effective use and the limited commercialization. The objective of this study is to investigate the energy and GHG emissions savings by using biofuel coproducts. The effects of coproduct use on the overall life cycle GHG emissions performance of biofuels were evaluated. Dry distiller grains in the wheat to ethanol pathway, and crude glycerine and canola meal from biodiesel, are assumed to replace animal feed, fossil fuel, fertilizer, synthetic glycerine. A system expansion approach was implemented to estimate GHG emissions savings. The results show that the overall life cycle GHG emissions from the wheat to ethanol pathway can be reduced by 2–34% when dry distiller grains displace fertilizer, fossil fuel, or animal feed. In the canola to biodiesel pathway, GHG emissions can be reduced by 5–26% and 8–41% when canola meal replaces animal feed and crude glycerine replaces synthetic glycerine. The study highlights the potential role of the coproducts from biofuel production in additional GHG emissions reduction over the life cycle.