ガスハイドレートを利用した海底下二酸化炭素貯留の経済性評価

抄録

A new concept for CO₂ geological sequestration is proposed as one of promising countermeasures against the global warming. For general geological sequestration technologies, there are still some issues we need to tackle, such as the shortage of possible sites to sequestrate, environmental risks due to leakage, and costs. In order to solve these problems, we propose a system to sequestrate a large amount of CO₂ in the form of gas hydrate under the seafloor safely. In this system, we capture a mixture of CO₂ and N₂ from the flue gas exhausted from 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. Besides, by using the CO₂ + N₂ 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 CO₂ and the cost of this system. From the results, the amount of CO₂ 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 CO₂ aquifer storage.