[H-SC06] CCUS (Carbon Dioxide Capture, Utilization, and Storage) for Climate Mitigation

[HSC06-P09] Suggestion of the deep sea-bed CO₂ sequestration to suppress ocean acidification

*Takaomi Tobase¹ (1.Electric Power Development Co., Ltd.)

Keywords:neutralization reaction , CO2 sequestration , ocean acidification, bicarbonate ion

As a method of CCS, CO₂ ocean sequestration has been ever studied along with CO₂ underground storage. However, a problem of ocean acidification has the CO₂ ocean sequestration pointed out, and only the underground storage is accepted with the London protocol (2006 revision). On the other hand, the potential of the CO₂ ocean sequestration is extremely high in the peripheral sea area of Japan. Therefore we suggest a method of the deep sea-bed CO2 sequestration to suppress ocean acidification. This method supplies both carbonation material (alkalis such as the abolished concrete or limestone) and CO₂ on the sea bed where is deeper than water depth 3,500m. Suppress ocean acidification on by neutralization reaction.
About this matter, we performed elementary indoor experiment. The experiment put a cement hardening body in a container with the water (pure water and seawater) which CO2 dissolved and performed ingredient analysis and pH measurement of the water. As a result, the calcium carbonate ingredient of the cement hardening body decreased, and calcium ions in the water increased. The result of the pH measurement of the water which dissolved CO2 was before put a cement hardening body, and pH was 4-5. And pH became the neutrality to 6-7 on the seventh day. These results show the thing that a neutralization reaction occurs in the water. It is thought that the CO2 changes to a bicarbonate ion existing in the neutrality domain.