The U.S. Energy Independence and Security Act of 2007 mandates the use, if produced, of 6.06 x 10(10) L of advanced biofuels by 2022. The objective of this study is to determine the ethanol price necessary for a biorefinery to breakeven when using switchgrass as the single feedstock to produce ethanol. A holistic model that encompasses acquisition of land use services, feedstock production, harvest, harvest machine investment, feedstock logistics (storage, transportation), biorefinery location and size, and biorefinery investment is constructed and used to determine breakeven ethanol price. The model was solved for each of three biomass to ethanol conversion rates (250, 334, and 417 L of ethanol Mg-1 of biomass) and each of three biorefinery investment cost estimates ($2, $4, and $6 x 10(8) for a biorefinery with annual capacity of 379 x 10(6) L). Breakeven ethanol prices ranged from $0.44 L-1 with a conversion rate of 417 L of ethanol Mg-1 and an investment cost of $2 x 10(8), to $0.72 L-1 with a conversion rate of 250 L Mg-1 and an investment cost of $6 x 10(8). Improving the efficiency of conversion from 250 to 334 L Mg-1 decreases the estimated breakeven cost by $0. 07 L-1. Improved conversion efficiency results in a reduction of the total quantity of feedstock required and in the cost to deliver feedstock. Most of the cost reduction follows from reductions in land required (rent), and biomass harvest, storage, and transportation costs. (c) 2012 Elsevier Ltd. All rights reserved.