Biological production of ethanol from CO₂ produced by a fossil-fueled power plant

Carbon dioxide, as the end product of fossil fuel combustion, is responsible for the global warming. To decrease emissions of CO₂, a new method that directly converts CO₂ into ethanol is proposed here, and hydrogen is demonstrated to be the most suitable electron donor. The bacteria, Clostridium ljungdahlii and Moorella sp. HUC22-1, are anaerobic microorganisms which may be used to facilitate the conversion. An ethanol production facility located adjacent a fossil fuel electric power plant was simulated in SuperPro Designer. For C. ljungdahli, the production cost of ethanol was estimated at $0.83/gal, which compares quite favorably to a current ethanol selling price of $3.43/gal. For Moorella, the ethanol production cost was much higher than for C. ljungdahli. However the latter bacterium also produced significant quantities of acetate, which is sellable. For neither scenario were economic credits taken for reduced carbon dioxide emissions. Based on the preliminary economics provided by the simulations, further research is warranted into electricity-ethanol co-generation.