Economics of biomass gasification/combustion at fuel ethanol plants

Dry-grind ethanol plants have the potential to reduce their operating costs and improve their net energy balances by using biomass as the source of process heat and electricity. We modeled various technology bundles of equipment, fuels, and operating activities that are capable of supplying energy and satisfying emissions requirements for dry-grind ethanol plants of 190 and 380 million L (50 and 100 million gal) per year capacity using corn stover, distillers dried grains with solubles (DDGS), or a mixture of corn stover and syrup (the solubles portion of DDGS). Results showed favorable rates of return on investment for biomass alternatives compared to conventional plants using natural gas and purchased electricity over a range of conditions. The mixture of corn stover and syrup provided the highest rates of return in general. Factors favoring biomass included a higher premium for low carbon footprint ethanol, higher natural gas prices, lower DDGS prices, lower ethanol prices, and higher corn prices.