MECHANICAL ENERGY STORAGE SYSTEMS: COMPRESSED AIR AND UNDERGROUND PUMPED HYDRO.

Compressed air and underground pumped hydro storage are near-term load-leveling and peak-shaving technologies that are being considered by electric utilities. Assessments of the technical and economic feasibility of these storage systems have concluded that no major technical barriers for their implementation exist and that the systems are economically competitive with conventional peaker and intermediate-load plants. This paper reviews and compares the characteristics of these two energy storage systems, evaluates their potential impacts, and presents recent research results with particular emphasis on air storage technology. In addition, advanced concepts and technical areas in which further work would be beneficial are discussed.