Prospect of Geological Sequestration of CO₂ for Greenhouse Gas Mitigation and Natural Gas Recovery

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The annual 70 million tons' CO₂ injection separated from flue gas of fossil fueled power plants into aquifer may reduce Japan's artificial carbon dioxide emission as much as 6% with annual cost of 420 billion yens that match 1, 200 yens/c carbon tax. Geological sequestration of CO₂ is a technically and economically feasible option for mitigation of greenhouse gas emission.
Carbon dioxide injection under gas-hydrate-filled layers or under permafrost layers can realize the greenhouse gas mitigation and recovery of unused natural gas. Autogenous sealing of CO₂ in deep and cool aquifers assures virtually complete and practically unlimited subsurface containment of CO₂.
Chemoautotrophs fix carbon dioxide in deep aquifers even without sun light. Methanogens can convert CO₂ into methane in deep anoxic aquifers. Biogenetic restoration of subsurface hydrocarbon deposits is expected in CO₂injected aquifers after tens or hundreds of years. Microbiological recycling of CO₂ in aquifers is an attractive future technology for energy-short countries such as Japan. Important key for underground CO₂ recycling is hydrogen supplies owing to microbial decomposition of organic matter and from geochemical water-rock interaction in deep rock formations.