Conversion of distiller’s grains to renewable fuels and high value protein: Integrated techno-economic and life cycle assessment

Distiller’s grains are a byproduct of corn ethanol production and provide an opportunity for increasing the economic viability and sustainability of the overall grain-to-fuels process. Typically, these grains are dried and sold as a ruminant feed adjunct. This study considers utilization of the residuals in a novel supplementary fermentation process to produce two products, enriched protein and fusel alcohols. The value-added proposition and environmental impact of this second fermentation step for distiller’s grains are evaluated by considering three different processing scenarios. Techno-economic results show the minimum protein selling price, assuming fusel alcohol products are valued at $0.79 per liter gasoline equivalent, ranges between $1.65–$2.48 kg protein–1 for the different cases. Environmental impacts of the systems were evaluated through life cycle assessment. Results show a baseline emission results of 17 g CO2-eq (MJ fuel)−1 for the fuel product and 10.3 kg CO2-eq kg protein–1 for the protei...