Underwater Compressed Gas Energy Storage (UWCGES): Current Status, Challenges, and Future Perspectives

Abstract

Underwater compressed air energy storage was developed from its terrestrial counterpart. It has also evolved to underwater compressed natural gas and hydrogen energy storage in recent years. UWCGES is a promising energy storage technology for the marine environment and subsequently of recent significant interest attention. However, it is still immature. In this study, the latest progress in both academic and industrial fields is summarized. Additionally, challenges facing this emerging technology are analyzed. The pros and cons of UWCGES are provided and are differentiated from the terrestrial variant. Technical, economic, environmental, and policy challenges are examined. In particular, the critical issues for developing artificial large and ultra-large underwater gas storage accumulators and effective underwater gas transportation are comprehensively analyzed. Finally, the demand for marine energy storage technology is briefly summarized, and the potential application scenarios and application modes of underwater compressed gas energy storage technology are prospected. This study aims to highlight the current state of the UWCGES sector and provide some guidance and reference for theoretical research and industrial development.

Isothermal Deep Ocean Compressed Air Energy Storage: An Affordable Solution for Seasonal Energy Storage

“…For this reason, we considered the possibility of expanding the potential for CAES by proposing the construction of cheap compressed air storage tanks in the deep sea. Seymour proposed the first basic rigid Underwater Compressed Gas Energy Storage (UWCAES) system in 1997 [24][25][26], which consisted of a small tank or a long pipe with ballast boxes in the deep sea. The primary differences between UWCAES and IDO-CAES is that IDO-CAES uses isothermal compression, which increases energy storage efficiency, and instead of using ballast bins, the pipelines are filled with sand, which is cheaper.…”

Compressed Air Seesaw Energy Storage - a Solution for Long-Term Electricity Storage

“…Seymour suggested in 1997 the first simple rigid Underwater Compressed Gas Energy Storage (UWCAES) solution, which consisted of a long pipe or a small tank with ballast bins [18][19][20]. The main disadvantage of this system is that only one of the tanks is pressurized, while the other one is the atmosphere.…”

“…A review of marine renewable energy storage solutions is described in [21]. A review of Underwater Compressed Air Energy Storage is presented in [18,22]. There have been few attempts to construct commercial-scale underwater compressed air storage devices.…”

“…There is little doubt that isothermal compression and expansion may considerably enhance round-trip energy efficiency. Most research for improving heat transmission and attaining isothermal processes is based on the liquid piston idea, which is accompanied by liquid spray, wire mesh, porous media and water-gas two-phase foam [18]. Based on quasi-steady-state theoretical analyses and low-speed trials, a very high exergy compression efficiency in the 85-95 % range was attained [42,43].…”

“…However, when considering the transient operation of the system and the off-design operation of hydraulic facilities, the performance degenerates. There is currently a scarcity of research that take into account actual different operational circumstances [18]. With an 81 % round trip efficiency, the AirBattery is an industrial isothermal CAES device that stores air by isothermally displacing it with water [44][45][46][47].…”