A LCA of corn and switchgrass bioenergy feedstocks using data from a long-term study

Authors: Ramirez, Salvador; Schmer, Marty; Mitchell, Robert - Rob; Jin, Virginia

Submitted to: National Agricultural Aviation Association Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 6/14/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: One way to determine the sustainability of a product, such as aviation fuel, is to conduct a life cycle assessment of the product. A life cycle assessment evaluates the environmental effects of the entire life cycle of a product i.e., the extraction of raw materials, the manufacturing of the product, its distribution and use, and its recycling or final disposal. A life cycle assessment of corn and switchgrass–feedstocks that could eventually be made into sustainable aviation fuel–was conducted to determine how sustainable these feedstocks are. Data from a long-term USDA field experiment that compared corn and switchgrass was used in the life cycle assessment to minimize the amount of estimated factors. For example, the amount of greenhouse gas emissions from the long-term experiment were used in the life cycle assessment as opposed to using programs that estimate potential GHG emissions. The life cycle results suggest that both corn and switchgrass are sustainable based on the GHG emissions, but that switchgrass is considerably more sustainable.

Technical Abstract: Diverse aviation fuel production pathways will be needed to meet the growing demand of sustainable aviation fuels. A burgeoning fuel production pathway for sustainable aviation fuels is the cultivation of sustainable bioenergy feedstocks, such as corn (Zea mays L.) and switchgrass (Panicum virgatum L.), in the United States Midwest. The sustainability of these feedstocks depends on agricultural management, as well as matching bioenergy crops to landscape capabilities. A life cycle assessment was conducted using long-term data from one of the oldest bioenergy-specific field experiments in North America. This long-term field trial called 9804 was established in 1998 in eastern Nebraska and compared the productivity and sustainability of corn and switchgrass bioenergy systems under different harvest strategies and nitrogen (N) fertilizer rates on marginally productive cropland. Crop yields, soil nitrous oxide emissions, and changes in soil organic carbon stocks from 9804 were used in the LCA to account for direct impacts of management while the EcoInvent inventory (v. 3.10) was used to model upstream, indirect, and overall impacts of sustainable aviation fuel production. Using measured data from long-term studies in LCA will more accurately capture the overall environmental impacts for the aviation sector.