Composite maps are the final product of combining all suitability maps into one map for the Mt. Simon/Eau Claire storage complex and one map for the St. Peter/Maquoketa storage complex.
Mt. Simon Sandstone Storage Complex
The Mt. Simon Sandstone Composite Play Map integrates subsurface, surface, and societal CRS maps to delineate a broad suitable to most suitable fairway across much of Illinois, particularly in the southern two-thirds of the state. Subsurface suitability decreases northward, primarily due to declining formation-water salinity and, secondarily, reduced depth; additional reductions occur in southwestern Illinois where the Mt. Simon thins or is absent due to non-deposition or erosion, and in southeastern and southernmost Illinois adjacent to known faults. Within the otherwise favorable fairway, localized areas of lower suitability are associated with a high density of legacy wellbores penetrating the confining unit or the presence of saline springs. Surface constraints reduce suitability in wetlands, karst terrains, and mined areas, while societal considerations indicate generally favorable conditions statewide, with reduced suitability over the Mahomet Aquifer Sole Source Aquifer (where carbon capture and storage siting is restricted under Illinois Public Act 104-0119) and areas of uncertainty within city limits where additional public-acceptance information is needed.
St. Peter Sandstone Storage Complex
The St. Peter Sandstone Composite Play Map integrates subsurface, surface, and societal constraint and risk screening to delineate a suitable to most suitable fairway across much of Illinois, primarily within the southern half of the state. Subsurface suitability decreases northward, primarily due to declining formation-water salinity and decreasing depth, with additional reductions in southeastern and southernmost Illinois adjacent to known faults. As a result, the favorable fairway is narrower than that observed for the Mt. Simon Sandstone, and within this fairway, localized areas of lower suitability are associated with a high density of legacy wellbores that penetrate the confining unit or with the presence of saline springs. Surface constraints reduce suitability in wetlands, karst terrains, and mined areas, while societal considerations indicate generally favorable conditions statewide, with reduced suitability over the Mahomet Aquifer Sole Source Aquifer (where carbon capture and storage siting is restricted under Illinois Public Act 104-0119) and areas of uncertainty within city limits where additional public-acceptance information is needed.