(384a) Life Cycle Assessment of Pyrolysis Oil and Bio-Char From Corn Stover

Currently, there is research interest at the federal level through the Energy Independence and Security Act (EISA) to develop advanced biofuels that can serve as “drop-in” replacements for petroleum products that can utilize existing refining and distribution networks. Research in this area aims to both decarbonize and address energy security issues related to liquid fuel demand.  Biofuels are renewable, low carbon fuels that are derived from biomass converted through different thermo-chemical or bio-chemical processes. Among the possible conversion processes, fast pyrolysis, the rapid thermal decomposition in the absence of oxygen, is considered to be an effective technology by which biomass, can be converted to valuable pyrolysis oil (bio-oil), biochar and gaseous products. Bio-oil and bio-char can each be used as a fuel and the gas can be recycled back into the process. In particular, bio-oils are attractive because of their high energy density and convenience in usage, storage and transport. Bio-char, rich in carbon, is resistant to degradation and can be either used as a source of energy for the process or as a soil amendment to enhance the sustainability of biomass harvesting and a means of carbon sequestration. The latter strategy will allow more residues to be removed from land by providing soil organic carbon (SOC) while benefiting from carbon storage.  This study investigates the life cycle (LC) greenhouse gas (GHG) emissions and cost of different scenarios of pyrolysis of corn stover to bio-oil. A LC model is developed using data from literature, prior work (Spatari et al., 2010, Pourhashem et al.2010), and SimaPro life cycle inventory data to characterize the corn stover feedstock; and an Aspen Plus chemical process design developed by the United States Department of Agriculture (USDA) on the pyrolysis of the corn stover feedstock to bio-oil in a 200 ton/day scale facility. We study the cost effectiveness of the options for producing bio-oil as a final product or upgrading it to a drop-in transportation fuel; and the two options of utilizing the biochar byproduct i.e., as a source of energy or using it as a soil amendment and a means of sequestering carbon. The GHG emissions of the bio-oil and drop-in fuel produced are compared to low-grade heating fuel oils and gasoline, respectively. Results from this research show how different input parameters along the feedstock-fuel pathway affect the economics and net carbon intensity of different biorefinery products.