Researchers from the University of Stavanger in Norway propose that the ocean depths hold potential for a novel form of subsea energy storage, offering a solution to manage excess power generated by renewable sources.
In a recent publication in the Journal of Energy Storage, the researchers introduce the concept of Subsea Pumped Hydro Storage as a viable means to transform seabeds into extensive utility-scale energy storage facilities.
As global efforts intensify towards achieving net-zero emissions, the proliferation of wind and solar farms presents a challenge in balancing the intermittent nature of renewable energy sources with supply and demand. Recognizing this challenge, the researchers underscore the significance of energy storage in providing stored energy during periods of low supply and accommodating surplus energy during periods of low demand.
While on-land pumped hydro remains the predominant form of energy storage, it is constrained by geographical limitations, requiring mountainous terrain and ample freshwater sources. In contrast, subsea pumped hydro systems offer the potential to overcome these constraints, utilizing the expansive seabed and enabling co-location with deepwater offshore renewables.
The mechanism of subsea pumped hydro involves deploying large rigid tanks on the seafloor. During times of surplus or inexpensive green power, water is pumped out of these tanks, creating a pressure differential that stores potential energy. When energy is required, water rushes back into the tanks, driving turbines to generate electricity.
In their study, the researchers conducted a comprehensive assessment of potential seabed locations for deploying such systems. They also evaluated turbine options, identifying Pelton turbines, commonly used in hydro-power systems, as having high theoretical efficiency.
While similar in principle to compressed air energy storage, which has also been proposed for underwater applications, subsea pumped hydro offers distinct advantages, utilizing water rather than air to spin turbines.
The researchers suggest that deploying subsea pumped hydro systems near offshore energy hubs, particularly in regions like the North Sea, could mitigate curtailment issues during periods of excess power generation. They emphasize the importance of additional revenue streams for operators to incentivize further offshore wind development, especially in the context of recent project cancellations.
As the global pursuit of innovative energy storage solutions continues, the researchers advocate for subsea pumped hydro as a promising technology with significant potential impact.