A Techno-Economic Analysis of Ethanol Production from Torrefied and Alkaline Pretreated Wheat Straw

Torrefaction is economically viable for bioethanol production if the supply chain benefits outweigh the yield loss. To evaluate this trade-off, technoeconomic models were developed for two ethanol production pathways from wheat straw: one using raw and alkaline-pretreated biomass (R-AP) and the other using torrefied and alkaline-pretreated biomass (T-AP). These models accounted for biomass transportation from the farm gate to the biorefinery gate. Additionally, decentralized commercial torrefaction facilities near the farms were simulated to estimate the production cost of torrefied biomass. For the scenarios modeled, the cost of torrefied biomass is 49% higher per dry Mg than the cost of raw wheat straw. Under base-case conditions, Net Present Value (NPV) of the T-AP biorefinery is ~ 37% lower than that of the R-AP system. Feedstock cost is the most sensitive factor for both systems. For the R-AP system, storage loss and transportation costs ranked second and third in importance, while for the T-AP system, NaOH and boiler costs are the second and third most influential variables. Torrefied biomass becomes more profitable than raw biomass when electricity prices exceed $0.14/kWh or when the average roundtrip distance to the biorefinery is ≥ 188 km from the biomass procurement area. Furthermore, the profitability of the T-AP system can be improved by increasing the alkaline concentration during pretreatment. These findings indicate that torrefaction can be advantageous under specific scenarios, and that the comprehensive models developed here—integrating thermochemical and biochemical processes with transportation and storage—serves as an effective tool for identifying cost-effective configurations, representing a key novelty of this work.