Moving past batteries: the renewed case for pumped hydro storage

June 2025

The debate between pumped hydro and batteries has gained renewed momentum in recent years. For a long time, the focus in energy storage discussions was primarily on batteries—such as lithium-ion technology used in homes, electric vehicles, and large-scale grid applications. These batteries have been celebrated for their rapid response and modularity, making them ideal for short-term regulation and frequency control.

However, a shift is now underway. Industry experts and commentators highlight pumped hydro storage as an essential complement to battery solutions. Unlike chemical batteries, pumped hydro can provide sizable, long-duration storage, filling critical gaps in the energy system.

An article in Ny Teknik pointed out that the power industry often favours flexible consumption from consumers over investing heavily in physical storage infrastructure.

Moreover, the existing grid's fee structure has historically tended to disadvantage pumped hydro, making it less attractive economically. Recognizing these challenges, some advocates have called for policy reforms—proposals aimed at incentivizing large-scale energy storage projects, particularly pumped hydro storage plants capable of storing energy over days or even weeks. Experts agree that batteries are currently most effective in short-term applications.

Typically, lithium-ion batteries handle regulation and frequency balancing for one to two hours—adequate for immediate balancing but insufficient for covering sustained day-night fluctuations. While the expansion of longer-term battery storage is progressing, the pace remains sluggish due to cost, scale, and technical limitations.

Recent studies, such as Fortum’s ongoing pumped hydro projects, suggest reservoirs could experience a renaissance in Sweden. These facilities can bridge the gaps that batteries, with their limited capacity, cannot fill. With suitable site availability, they could serve as large-scale, reliable repositories of renewable energy, especially during periods of low wind or sunshine. Despite this promising outlook, public awareness remains relatively limited.

The general populace tends to be familiar with batteries—thanks in part to Tesla's Powerwall and widespread consumer adoption—but knowledge about pumped hydro as an energy storage solution is comparatively scarce.

Many do not recognize the historic role and potential of water reservoirs in balancing the grid. In the broader public debate, a “return” of hydropower as an energy storage option is beginning to emerge.

Media coverage tends to originate from trade journals or local outlets near planned or existing projects, rather than from mainstream news sources. A comparative perspective— “beyond batteries”—can offer a fresh angle in this discussion. Although experts acknowledge pumped hydro’s clear advantages—such as its scalability, longevity, and cost-effectiveness—this approach remains less prevalent in wider discourse. Elevating awareness about pumped hydro’s potential could help diversify strategies for a cleaner, more resilient energy grid.