PRELIMINARY ASSESSMENT OF UNDERGROUND RESERVOIRS FOR COMPRESSED AIR ENERGY STORAGE IN PORTUGAL

Abstract

Compressed Air Energy Storage (CAES) is a technology that can store tens to hundreds of MW of power capacity. In a CAES plant ambient air is compressed and stored in a geological reservoir and, later, when electricity is required, the pressurized air is heated and expanded in a turbine, driving a generator for power production. This paper presents a preliminary assessment of underground geological reservoirs for deploying large scale CAES in Portugal. Under the scope of the Portuguese contribution to the EU funded project ESTMAP – Energy Storage Mapping and Planning -, public access geological information was collected, compiled in a database and spatially referenced in a GIS environment. The GIS and database were then cross-checked with the criteria for selecting CAES reservoirs and with existing or forecasted spatial, environmental and social constraints to define those reservoirs worth studying at the local scale. Several target study areas and prospective reservoirs were identified, mostly related to salt domes, but potential was also identified in onshore saline aquifers and in post-hercynian and alpine igneous rocks.