Abstract
We propose a new system to sequestrate a large amount of CO_2 in the form of gas hydrate under the seafloor safely. In this system, we capture a mixture of CO_2 and N_2 from the flue gas of a coal-fired power plant and inject the mixture into marine sediments, where pressure is high enough and temperature is low enough to form hydrates. By using the mixture gas, we can reduce the cost and avoid the blockage by the hydrates in marine sediments. In this work, we assessed the potential amount of sequestrated CO_2 and the cost of this system. From the results, the amount of CO_2 that can be sequestrated offshore Japan by this system was estimated to be twice and the sequestration cost was reduced by 15%, compared with those of CO_2 aquifer storage.
