As renewable generation expands across the country, states must come up with new ways to integrate all that clean power into their existing grid. In doing so, they must account for the unique characteristics of their infrastructure and geography.
No state is more unique in that regard than Alaska. Recognizing these characteristics, a recent study by the U.S. Department of Energy (DOE) identifies one resource in particular that could help the state meet its future energy storage needs: pumped storage hydropower.
Pumped storage hydropower (PSH) is a type of hydroelectric energy storage. It acts like a battery that can be charged and discharged as needed. It consists of two water reservoirs at different elevations. Power is generated as water moves down from the higher reservoir through a turbine as it passes into the lower reservoir. The water is later pumped from the lower reservoir back into the upper reservoir where it is stored until another discharge is needed. When clean energy from renewable power, like solar or wind, is used to power the pumps, the system is entirely fossil-fuel free.
Published in July 2023 by the DOE’s Argonne National Laboratory, the study looks at the potential of PSH to help Alaska meet its future energy storage needs. The study, “The Prospects for Pumped Storage Hydropower in Alaska,” confirms that numerous locations in Alaska are suitable for the development of PSH projects. Regarding larger, grid-scale projects, the study identifies the potential for more than 1,800 closed-loop systems in Alaska, with a total energy storage capacity of about 4 terawatt-hours.
Many locations were also identified as suitable for smaller-scale PSH systems. However, suitability is very site-specific, with such factors as available renewable resources and existing infrastructure, like reservoirs, transmission access and construction road access, influencing the overall potential of a site.
The study conducted further analysis on small, remote sites and concluded that PSH projects with 10-hour energy storage are likely to be more economical than those with larger reservoirs providing 10 days of energy storage. It also finds that in these remote locations, lithium-ion batteries may still be a more economically viable energy storage option.