Geological Suitability for Underground Energy Storage in Morocco: Salt Formations, Porous Media, and Abandoned Mines

Abstract

This study provides a national-scale assessment of Morocco's geological suitability for underground energy storage in salt formations, porous reservoirs, and abandoned mines. It develops a comparative spatial decision framework adapted to Morocco's geological diversity, integrating geological, lithological, structural, hydrogeological, environmental, socio-economic, and infrastructure-related criteria. The workflow combines a geospatial database with a multi-criteria decision approach, in which indicators such as depth, thickness, porosity, permeability, caprock conditions, fault proximity, seismic risk, protected areas, and distance to energy infrastructure were standardized, weighted, and spatially combined to classify storage suitability. The weighting procedure was supported by the analytic hierarchy process, with consistency verification and sensitivity analysis used to improve methodological transparency. The results indicate that salt-bearing sectors located near Casablanca and Agadir, especially those located near major industrial and renewable-energy corridors, represent favorable targets for compressed-air, natural-gas, and hydrogen storage because of their low permeability, sealing capacity, and pressure resistance. Porous reservoirs mainly represented by Paleozoic to Neogene formations show promising but more site-dependent potential, particularly where reservoir quality and caprock integrity are favorable. Abandoned mines are identified as locally attractive options for thermal-energy storage and underground pumped-hydro storage, although their feasibility depends strongly on rock-mass stability, hydrogeological conditions, and previous mining disturbances. The resulting suitability maps reveal clear spatial differences between the three storage options and can support the identification of priority areas for detailed investigation and future energy-storage development in Morocco.