Techno-Economic Analysis of Different Forage Sorghum Varieties for Bioethanol Production

Forage sorghum could be a promising feedstock for biofuels or bioproducts productions due to natural drought-tolerant and a high carbohydrate content. This paper identifies five different forage sorghum varieties, including wild type, brown-midrib (BMR), non BMR, photoperiod sensitive (PS), and photoperiod insensitive, and quantifies their economic feasibilities for bioethanol production. The techno-economic model integrates biomass sorghum supply system and the downstream high gravity ionic liquid-based biomass deconstruction and bioconversion processes. The baseline minimum selling prices of ethanol (MESP) result in as low as $0.99/L $3.74/gal) for non-PS sorghum variety and as much as $1.21/L ($4.59/gal) for PS sorghum. If the lignin fraction of biomass is sold as a byproduct instead of the onsite energy generation considered for the baseline scenario, the minimum selling price of the PS-based bioethanol could be reduced to $1.01/L ($3.83/gal). Regardless of the lignin utilization scenarios, biomass feedstock price is found to be the single most influential input parameter to the MESP. Overall, bioenergy sorghum with a high biomass yield and carbohydrates content along with the lignin valorization result in a competitive price of bioethanol relative to gasoline.