In this review, the status quo of social acceptance of CCS is discussed in relation with international efforts to establish understanding on CCS. The author analyzed suspended 43 CCS project cases out of total 133 cases, and identified major impacting factors: economic reasons, legislative reasons, political reasons and social protests were 50%, 25%, 10% and 12% respectively. All of these impacting factors are within the range of social acceptance considerations, and could be solved by stakeholder engagement efforts. The author reviewed ISO/TC265 CCS standards which encourages to establish preferable social acceptance on CCS project by way of stakeholder engagement process and risk communication process. The author summarized recommendations from CCS stakeholder engagement process. Then, the author surveyed reports on public perceptions on CCS and CCS outreach works. Finally, the author researched literally succeeded and failed cases in of social acceptance gaining among communities in vicinity of CCS site and discussed the issue.

A project of CO₂ injection in the Ishikari coal basin (Yubari-shi, Hokkaido, Japan) since 2002 has shown that injection of CO₂ into coal seams affected their permeability. Adsorption of CO₂ caused swelling of the coal matrix and lowered the permeability of coal seams, probably because of closure of cleats and pores in the coal seams. However, a temporary recovery of permeability was observed after subsequent injection of N₂, suggesting that some amount of adsorbed CO₂ was replaced by N₂ and the closure of cleats and pores were mitigated. However, the changes of mechanical properties of coal in the process are not yet fully understood. In this study, we injected CO₂ and N₂ into coal specimens recovered from the Ishikari coal basin and observed the changes of coal strength under hydrostatic pressure and temperatures typical of a coal basin. We conducted triaxial compressive strength tests on the coal specimens to clarify the effects of CO₂ and N₂ on the mechanical properties. Our results are summarized below.

1) We verified that swelling and shrinkage of the coal were associated with adsorption and desorption, respectively, of CO₂.

2) The triaxial compressive strength tests showed that injection of CO₂ caused decreases of peak strength and Young's modulus.

3) Both coal strength and Young's modulus recovered when previously injected CO₂ was replaced by N₂.