This paper analyzes the abatement costs associated with greenhouse gas reductions achievable by co-firing corn stover with coal at 71 coal-fired, utility-scale power plants in the Midwestern USA. The cost per metric ton of abated CO₂-equivalents is estimated using facility-specific supply functions for corn stover assuming best carbon management practices, county-level corn production data, a life cycle inventory tool for calculating biomass feedstock emissions, and simplified cost models for coal and co-fired capital and operating costs. Abatement costs vary substantially across the power plants modeled: mean costs were $123.71 per metric ton CO₂-eq at a 5% co-firing rate, $64.43 for 10% co-firing, and $49.20 for 20% co-firing, with coefficients of variation of 26%, 38%, and 48%, respectively. Lower abatement costs are primarily associated with high co-firing rates and high estimated unit costs for coal. The local corn yield and collection radius do not appear to have a substantial impact on estimated abatement costs. This advances our understanding of the abatement costs associated with co-firing biomass and coal, and the drivers of variability in abatement costs, by modeling feasible production scenarios using actual power plant and corn production data instead of idealized scenarios.