Getting Pumped Up
Interest in Pumped Storage Hydropower Grows in Many Countries
Grid operators are taking a closer look at pumped storage hydropower to balance growing intermittent renewable generation, according to an EPRI review of the technology. Compared to newer, battery-based energy storage technologies, electric utilities are more familiar with pumped storage hydropower and its operational and maintenance requirements. Global capacity is projected to nearly double from 147 gigawatts in 2015 to 284 gigawatts in 2025.
First deployed in North America in 1929, this mature technology accounts for more than 90% of the world’s grid-scale storage capacity. During off-peak demand when power is the least expensive, the facility consumes electricity to pump water from a lower reservoir into an upper reservoir. During peak demand, water released by the upper reservoir flows through a hydroelectric turbine to generate electricity.
As more intermittent solar and wind generation is installed, bulk-scale storage capacity becomes more valuable, helping grid operators to smooth generation and shape energy profiles. According to the EPRI study, the trend is driving many countries to investigate the technical and economic feasibility of pumped storage hydropower projects. In Hawaii, Kauai Island Utility Cooperative is reviewing projects with existing reservoirs that would use solar energy to pump the water into the upper reservoir.
Recent advances include variable-speed turbines that enable efficient operations at a range of speeds to accommodate intermittent generation. Siting on abandoned mines and using underground reservoirs instead of damming rivers can reduce construction costs and minimize adverse environmental impacts. EPRI is investigating these and other advances as well as the technology’s value through more flexible operations.