Life Cycle Assessment (LCA) of transportation fuels from biomass resources is a cradle to grave evaluation of energy and environmental issues associated with producing, collecting, and transporting the biomass, converting the biomass into transportation fuels, and distributing and using the transportation fuel in motor vehicles. Biomass transportation fuel LCAs frequently include an assessment of the petroleum derived product that they will displace (e.g., gasoline, diesel), as a means to compare the two products.
An integrated biorefinery is a facility in which bioenergy and bioproducts are produced from both lignocellulose (e.g., corn stover, switchgrass) and starch (corn grain) biomass resources. Operations within a biorefinery are synergistic. The production of ethanol from corn grain, corn stover, and switchgrass produces byproducts such as distillers’ dried grains and solubles (DDGS) from the conversion of corn grain to ethanol and electricity and steam from the conversion of corn stover and switchgrass to ethanol and must be accounted for in an LCA.
Corn and switchgrass production practices and location, and the quantities of corn stover that can be removed for bioenergy use are important considerations as they significantly affect the environmental impacts.
A recent LCA of integrated biorefinery scenarios (corn grain-corn stover; corn grain-switchgrass; corn grain only for comparison) found that both biorefinery scenarios provided increased benefits relative to gasoline and the stand-alone corn grain facility with respect to crude oil use, non-renewable energy use, and greenhouse gas emissions. Relative to gasoline and the corn grain facility, ethanol production in the biorefineries increased production of compounds involved in acidification and photochemical smog formation.