Climate Resilience: Modeling the Impacts of Yield Variability on Switchgrass Supply Chains
Open Access
- Author:
- Stauffer, Haley
- Graduate Program:
- Biorenewable Systems (MS)
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- June 25, 2021
- Committee Members:
- Paul Heinemann, Program Head/Chair
Tom L. Richard, Thesis Advisor/Co-Advisor
Erin Webb, Committee Member
Saurabh Bansal, Committee Member
Christine Costello, Committee Member - Keywords:
- Bioenergy
Biomass
Biomass Supply Chains
Resilience
Climate Change
Switchgrass
Iowa
Drought Tolerant
Varieties
Dry Matter Loss
Biomass Storage
Harvest
Transportation
Biomass Economics
Logistics
Feedstock
Feedstock Handling
Simulation
Modeling
Discrete Event Simulation
Biogeochemical Modeling
DayCent
ExtendSim - Abstract:
- The successful integration of advanced lignocellulosic biofuels in the United States (U.S.) is largely dependent on identifying and addressing uncertainty and risk along the feedstock supply chain. Uncertainties in the biofuel industry are due to numerous factors, such as weather, natural disasters, and market demand/price disruptions. These factors affect crop yield taken off the field and yield stability, generating financial downstream consequences. Few studies have quantified uncertainty of supply risk in the switchgrass biomass supply chain for the biorefinery stakeholder. This thesis attempts to address this gap by measuring the economic impacts on a standardized biomass supply chain (BSC) from a genetically improved drought-tolerant switchgrass phenotype compared to a base case variety applied in a five (5) county region in southern Iowa (IA). The steps modeled in the supply chain included harvesting, storage, and transportation to a biorefinery using the ExtendSim Pro discrete event simulation tool. Simulated field-level annual yield values were collected from the daily time-step biogeochemical model, DayCent. DayCent inputs included 35 years of historical weather data from 1979-2013 using the Northeast Regional Reanalysis (NARR), and soil properties from the Soil Survey Geographic Database (SSUGRO). The counties in IA with the greatest potential for switchgrass production were identified using the Department of Energy’s (DOE) 2016 Billion Ton Report yield density screening tool with the price of switchgrass at $80/dry ton. Results from the IA case study show that in simulations from low yielding, bad weather years, the drought tolerant switchgrass variety was higher yielding than the base case variety and required less land, resulting in a potentially smaller economic burden on the supply chain compared to the excess land needed to satisfy the biorefinery in the base-case scenarios, however, this was not a significant economic impact in good weather years. The conclusions gathered from these integrated models will enable informed decision making on a least cost structure of the U.S. switchgrass BSC in times of yield variability.