Economic viability of consolidated bioprocessing utilizing multiple biomass substrates for commercial-scale cellulosic bioethanol production

The depletion of fossil fuel resources requires a greater emphasis on the development of renewable energy technologies. Ethanol produced via biochemical means is a renewable liquid fuel option that shows great promise. In this paper, the large scale production of ethanol via a method of converting lignocellulosic material without the need for enzyme hydrolysis, termed consolidated bioprocessing (CBP), is analyzed and compared to traditional separate hydrolysis and fermentation (SHF) methods to determine the profitability of biochemical ethanol production. Optimal process topologies for both the CBP and SHF technologies are selected from superstructures considering multiple biomass feeds, chosen from those available across the United States, and multiple prospective pretreatment technologies. Steam cogeneration is also considered to produce the necessary hot utilities as well as electricity as a salable byproduct. Results show the optimal consolidated bioprocessing plant produces about 66 million gallons of ethanol to be sold at a breakeven price of $1.31 per gallon ($0.35 per liter) from a pure sugarcane bagasse feed and sodium hydroxide pretreatment method in addition to 67 MW of electricity per year. These results compare favorably to SHF production methods, showing a 20% decrease in the minimum ethanol selling price (MESP) and 197.5% increase in electricity generation despite a 13.3% drop in ethanol production. A long term economic evaluation is performed to determine an attractively profitable selling price for the ethanol produced. Additional analysis is done on the effect of a mixed biomass feed on process profitability and impact on biomass harvesting radius.