An optimization framework to identify key management strategies for improving biorefinery performance: A case study of winter barley production

Authors: KAR, SAURAJYOTI - Drexel University; RIAZI, BAHAR - Drexel University; GURIAN, PATRICK - Drexel University; SPATARI, SABRINA - Drexel University; Adler, Paul; PARTON, WILLIAM - Colorado State University

Submitted to: Biofuels, Bioproducts, & Biorefining (Biofpr)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/29/2020
Publication Date: 9/15/2020
Citation: Kar, S., Riazi, B., Gurian, P.L., Spatari, S., Adler, P.R., Parton, W.J. 2020. An optimization framework to identify key management strategies for improving biorefinery performance: A case study of winter barley production. Biofuels, Bioproducts, & Biorefining (Biofpr). 14:1296–1312. https://doi.org/10.1002/bbb.2141.
DOI: https://doi.org/10.1002/bbb.2141

Interpretive Summary: Carbon credits and costs associated with biofuel production are important for industry viability, but complex to balance tradeoffs; we developed a framework to optimize this decision-making process. We found that adoption of nitrogen management practices was a win-win, reducing both production costs and greenhouse gas emissions, with choice of co-products being the most important factor in meeting the 50% advanced fuel target for reduction of greenhouse gas emissions. Adoption of this framework would help biorefineries to identify crop management strategies, location of production fields, and biorefinery design to reduce production costs while increasing the carbon credits from the biofuel produced.

Technical Abstract: Selecting locations and practices for energy crops requires planning the economics and assessing the carbon intensity of the fuel. This study develops a framework for selecting near-optimal cropland sites that minimize the cost to produce a targeted quantity of an energy crop annually, considering soil properties, fertilizer management, and Spatio-temporal trends in crop yield and soil emissions. The biogeochemical model, DayCent, simulates site-level crop yield, and soil emissions. As a case study, this framework is applied to a 2.08×108 liters year-1 capacity barley-to-ethanol biorefinery located in central Virginia, that selects winter fallow cropland site in the MidAtlantic region of the USA. The framework implements carbon crediting as per California’s Low Carbon Fuel Standard. Our analysis shows that the biorefinery’s strategy on co-product significantly influences its life cycle carbon intensity ranging from 0.74 gCO2e MJ-1 to 59 gCO2e MJ-1 on average. Coastal counties in Delaware shows low soil emission and high yield, but higher transportation distances increase the life cycle carbon intensity of these distant croplands. When co-products are used, the least intensive nitrogen fertilizer management with fertilizer applications in spring is identified as the cost-optimized choice for the biorefinery – also economically favored option by growers, suggesting that detailed monitoring of these practices might not be needed to assure the adoption of low emission cultivation practices. However, the framework might demonstrate different results for other biofuel-crop scenarios or different geographic locations. The presented framework can assess the performance of a biorefinery prospectively and improve investors’ confidence in the biofuel industry.