CARBON SEQUESTRATION IN COAL SEAMS IN JAPAN AND BIOGEOCHEMICAL CARBON CYCLE IN TERTIARY SEDIMENTARY BASINS

摘要

A new research and development project "CO_2 sequestration in coal seams" began in Japan in 2002 to develop new type of "coal mines" for CO_2-enhanced coal gas recovery. Coal seams are promising for CO_2 storage and as sources of hydrocarbon gas. Researches are being devoted to a deeper understanding of CO_2-coal interaction, to monitoring of CO_2 behavior in coal seams, to prospecting of untapped deep coal seams, etc. Supercritical CO_2-enhanced coal seam gas recovery (ECGR) and in situ fire-free microbial gasification of coal can produce sufficient amounts of methane for the CO_2 emission-free closed-circuit power plant and new type of "coal mines" without underground works, even in gas-poor coalfields. Underground biogeochemical carbon recycling makes zero-emission closed-circuit power and heat generation possible, while coal seams and saline aquifers are capacious enough to accommodate large volume of CO_2 from fossil fuel and refuse-derived fuel (RDF). Tertiary sedimentary basins are suitable as CO_2 stores, hydrocarbon gas reservoirs and possibly CO_2-CH_4 converters. Subsurface biogeochemical carbon recycling can realize greenhouse gas control with restoration of energy resources.