New Floating Solar + Hydro Combo Could Meet Nearly Half of Global Power Demand

Combining solar power with hydroelectricity in floating reservoirs could meet nearly 50% of global electricity demand, says a new study being described as “potentially market-making.”

The U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) estimates that as much as 7.6 terawatts of power (or 10,600 terawatt-hours of annual generation) could be produced by installing solar atop some 379,000 of the world’s existing hydro reservoirs, writes Recharge News.

Noting that this calculation does not even include the output from the hydro plants themselves, Recharge says such a surge in generation would go a long way—in fact, nearly half of the way—to fulfilling the world’s electricity needs, which the International Energy Agency pegged at just over 22,300 terawatt-hours in 2018.

While celebrating such “optimistic” findings, lead author Nathan Lee, integrated decision support group researcher for NREL, also urged caution, noting that 7.6 TW “does not represent what could be economically feasible or what the markets could actually support.” Rather, he said, “it is an upper-bound estimate of feasible resources that considers waterbody constraints and generation system performance.”

Hard numbers aside, notes Recharge, “coupling floating solar and hydropower is seen having a strong rationale for a number of reasons, including that a hybrid system could have lower transmission costs by linking two seasonally-aligned power sources to a common substation.” The two technologies could act to support and balance each other during their respective high and low production seasons.

“The greatest potential for solar power is during dry seasons, while for hydropower rainy seasons present the best opportunity,” said Lee. “Under one scenario, that means operators of a hybrid system could use pumped storage hydropower to store excess solar generation.”

Even without being coupled to hydro, floating solar “has been hailed for its huge potential in the next wave of the energy transition, with the ability to capitalize on unused water surfaces to produce renewable power in countries where land may be scarce,” writes Recharge.

Citing the technical advisory group DNV GL, Recharge adds that “human-made inland waters alone have the potential to support up to four terawatts of new power capacity globally.”

Case in point: installers in the Netherlands are hard at work on the world’s biggest floating solar power system to date on the surface of a drinking water reservoir located in the storm-battered northern tip of the country. Consisting of a network of 73,500 panels interlaid across 15 purpose-built sun-tracking island platforms, the installation is a response to increasing resistance to large, land-based solar and wind systems—resistance rooted partly in concerns for how these systems disrupt the region’s role as a key rest stop for migratory birds.

A World Economic Forum report on the new system added that the Netherlands’ accelerating embrace of floating solar owes to the country’s particular vulnerability to rising seas.

The Netherlands is also pioneering floating solar out on the high seas, with Recharge reporting earlier this year how a critical pilot project survived the “bomb cyclone” of Storm Ciara, which packed wind of up to 115 kilometres per hour and waves over five metres high.