(139e) Integrated Electro-Microbial Conversion of CO2 to Higher Alcohols

One of the major challenges in using electrical energy is the efficiency in its storage. Current methods, such as chemical batteries, hydraulic pumping, and water splitting, suffer from low energy density or incompatibility with current transportation infrastructure. We report a method to store electrical energy as chemical energy in higher alcohols, which can be used as liquid transportation fuels. We genetically engineered a lithoautotrophic microorganism, Ralstonia eutropha H16, to produce isobutanol and 3-methyl-1-butanol in an electro-bioreactor using CO₂ as the sole carbon source and electricity as the sole energy input. The process integrates electrochemical formate production and biological CO₂ fixation and higher alcohol synthesis, opening the possibility of electricity-driven bioconversion of CO₂ to commercial chemicals. Man-made photovoltaic device is relatively efficient in converting sunlight to electricity. The biological photosystems, on the other hand, are limited by the intrinsic design and biomaterials available, for which no near-term improvements are in sight. Thus, this process also provides a way to increase photosynthetic efficiency by coupling man-made photoelectric generation device with biological CO₂ fixation and fuel production capability.