In 2002, the Japanese Ministry of Economy, Trade, and Industry began a 6-yr project on carbon dioxide (CO₂) sequestration in coal seams entitled Japan CO₂ Geosequestration in Coal Seams Project (JCOP), a component of the Carbon Dioxide Sequestration and Effective Use Program. The goal of JCOP is to develop a series of processes that can (1) extract the CO₂ discharged from thermal power plants and other large-scale emitters, (2) fix it in a stable state within coal seams, and in the process (3) recover methane (CH₄) as a clean energy source. The project involves fundamental research into CO₂ adsorption on coal, CO₂ monitoring methods that ensure the safety of the sequestration process, and micropilot tests.

From analyses of JCOP results obtained to date, several outcomes can be highlighted. (1) A total of 461 t of CO₂ was injected at an average rate of 3.0 tons/day. (2) Carbon dioxide breakthrough has not yet been observed. (3) An enhanced coalbed methane effect was observed. (4) Coal-seam permeability changed dynamically because of coal-matrix swelling or shrinkage. (5) Nitrogen (N₂) injection was effective in recovering the lost injectivity associated with coal swelling. (6) A history-matched model was constructed for the micropilot tests based on coal properties determined in situ or with laboratory measurements. (7) No signs of CO₂ leakage have been observed so far.