Subsea Long-Duration Energy Storage for Integration with Offshore Wind Farms

Long-duration energy storage systems are becoming a vital means for decarbonizing the global economy. However, with floating wind farms being commissioned farther offshore, the need to co-locate energy storage with the energy harnessing units is becoming more essential. This paper presents a transient thermal analysis of the charging process of a subsea open-cycle hydro-pneumatic energy storage system. The proposed system is designed for integration with floating wind turbines in deep water sites. Situating the system subsea presents unique opportunities for integration with offshore wind plants through the exploitation of well-known subsea pipeline technology and the surrounding seawater environment, which acts as a natural heat sink/source. The results obtained from numerical modeling in Python© Version 3.7.4 present the variation in various operating parameters with time. The outcomes reveal that the proposed system is able to achieve a work ratio and an energy storage capacity ratio of up to 0.80 and 0.95, respectively. Furthermore, the proposed open-cycle system is predicted to boost the energy storage density by a factor ranging between 2.00 and 8.10 when compared to the energy storage density of conventional closed-cycle units. Namely, the energy storage density of the long-duration energy storage can reach up to 16.20 kWh/m3 when operated in an open-cycle configuration.