Sustainable Transportation Energy Pathways (STEPS)
Available online at https://doi.org/10.1016/j.jclepro.2017.05.059
Alexiades, Anthy, Alissa Kendall, Kiara S. Winans, Stephen R. Kaffka (2018) Sugar Beet Ethanol (Beta vulgaris L.): A Promising Low-Carbon Pathway for Ethanol Production in California. Journal of Cleaner Production 172, 3907 - 3917
This study examines sugar beet (Beta vulgaris L.) as a potential low carbon intensity (CI) fuel feedstock, assuming sugar beet production in California and simulating a facility that exemplifies opportunities for biofuel producers to reduce greenhouse gas emissions, improve fossil-fuel efficiency, and minimize waste. The strategies explored in this study—utilizing byproducts and agricultural residues for renewable process energy and recycling water and nutrients—are not unique to sugar beet-ethanol. As such, the results from this study could be applied to different biofuel pathways to improve greenhouse gas performance.
Sugar beets grown in California have unique potential as a biofuel feedstock. Although a mature agricultural product with well-developed supply chains, sugar beet production in California has contracted over recent decades as market demand for sugar production fell. As a consequence, despite their advantages for use in rotation, growers have turned to other crops and a new market for sugar beet products, such as ethanol, is needed before they are again widely planted.
California’s Low Carbon Fuel Standard (LCFS) is a fuel-neutral performance standard and one of the first regulations requiring the use of life cycle assessment to evaluate CI for specific fuel pathways. The average CI of ethanol used in California in 2015 is approximately 20% lower than California gasoline blendstock, as assessed under the LCFS. CI results in this study are designed to be comparable with the analyses performed under the LCFS. The CI of sugar beet ethanol determined in this study, 28.5 g CO2e/MJEtOH, excluding indirect land use change (ILUC) emissions, is 44% lower than the 2015 average CI of ethanol (adjusted to exclude ILUC), and 71% lower than gasoline used in California. Commercial production of this modeled pathway could help achieve the greenhouse gas reduction targets of the LCFS as well as the Advanced Biofuel target set by the federal Renewable Fuels Standard.
Keywords: Life cycle assessment; Biofuel; Low Carbon Fuel Standard; anaerobic digestion