Evaluation of the environmental impacts of ethanol production from sweet sorghum

• Construction of a life cycle assessment of three processing options for bio-ethanol production from sweet sorghum.
• Identification of a semi-centralized processing option that is environmentally competitive to corn ethanol production.
• Decentralized and semi-centralized options result in 54% and 43% reduction in GHG emissions compared to gasoline production.

Ethanol from biomass feedstocks has the potential to reduce greenhouse gas emissions for fuel production. This work calculates the potential environmental impact from the production of ethanol from sweet sorghum using several processing options. The following three processing options were evaluated: 1) a farm scale decentralized option where all steps except the dehydration are performed on the farm, 2) a semi-centralized process where distillation and dehydration are performed at a biofuel refinery, and 3) a centralized process where sorghum stem is transported to a facility where all processing is performed. Results show that a centralized process where sweet sorghum stem is transported to a processing facility to produce ethanol has significant negative environmental impacts when compared to corn ethanol and other processing options. The centralized option resulted in a 62% increase in GHG emissions and a 50% increase in non-renewable energy use compared to corn ethanol. When the decentralized and semi-centralized options were compared to corn ethanol production, GHG emissions were reduced by 39% and 25% respectively. Non-renewable energy use reductions were 27% in the decentralized process and a 15% reduction in the semi-centralized process.