Conversion of Carbon Dioxide and Hydrogen into Methane in Bench-Scale Microcosms and Packed Column Reactors

Escalating energy demands, rising costs, and increasing awareness of the environmental impacts of current energy sources have created an immediate need for sustainable, alternative energy resources and innovative fuel technologies. It is believed that a potential carbon-neutral fuel source can be generated through the microbial production of methane gas by methanogenic archaea. Carbon dioxide captured from the atmosphere and renewable production of hydrogen can be used to support these microorganisms for the large-scale production of methane. Bench-scale investigations involving 160 mL serum bottle batch experiments and two 11L packed-column reactors were conducted to evaluate the feasibility and efficiency of microbial conversion of carbon dioxide and hydrogen to methane. The biogeochemical conditions within the microcosms and reactors were monitored and adjusted in order optimize microbial activity and methane production rates. Parameters such as type of solid support media, hydrogen and carbon dioxide partial pressures, soil/non-soil environments, and reactor circulation rate were experimentally varied in order to determine their effect on microbial methane production. Microbial activity was evaluated based on hydrogen and carbon dioxide consumption, methane production, conversion rates and efficiency, organic acid aqueous concentrations, and reaction mass balance. Rapid and efficient methane production observed in the reactors and microcoms indicated that methanogenic archaea can be supported in optimized environments for the sustained production of methan