Hydro power is facing a deepening dry spell
renewable energy has been going through a dry patch.
Generation from solar farms roughly tripled between 2018 and 2023, while the output of wind turbines almost doubled. That provided enough extra clean energy to power Japan and Russia, put together. Meanwhile, the hydroelectric dams that generate about one-seventh of the world’s electricity stood still: The additional 52 terawatt-hours in 2023 was only enough to fuel Greece.
That’s not overly surprising. Hydro’s problems resemble those of the other veteran form of clean power, nuclear. Unlike wind and solar, it’s been an established technology for decades, so much of its growth potential has already been exploited. Like nuclear, it’s dependent on the building of costly and time-consuming projects to move forward, and shows little sign of reducing its (already low) costs. Compounding the problems, a two-year drought connected to the La Niña climate cycle during 2022 and 2023 caused a collapse of generation in China, home to about a third of the world’s hydro dams.
It would be nice to dismiss this as a temporary setback. When drought conditions recede, generation should surge back to prior levels — something we appear to be seeing in China now, where wetter weather has been filling reservoirs and drove coal to an estimated record-low 53% share of generation in May. A recent study of 610 US hydropower projects shows there may be more long-lasting issues.
The productivity of a power plant can be measured by its capacity factor — the number of kilowatt-hours it
