
Federal reservoirs could help meet the country’s solar energy needs, and the potential is “surprisingly large” according to a new study published in Solar Energy.
Evan Rosenlieb and Marie Rivers, geospatial scientists at the U.S. Department of Energy National Renewable Energy Laboratory (NREL), and Aaron Levine, a senior legal and regulatory analyst at NREL, quantified for the first time how much energy could be generated from floating solar panel projects installed on federally owned or regulated reservoirs.
The potential is “surprisingly large.”
Reservoirs could host enough floating solar panels to generate up to 1,476 terawatt hours, or enough energy to power approximately 100 million homes a year.
“That’s a technical potential,” Rosenlieb said, meaning the maximum amount of energy that could be generated if each reservoir held as many floating solar panels as possible. “We know we’re not going to be able to develop all of this. But even if you could develop 10% of what we identified, that would go a long way.”
Levine and Rosenlieb said they have yet to consider how human and wildlife activities might impact floating solar energy development on specific reservoirs, but they plan to address this limitation in future work.
Floating solar panels, also known as floating PV, can generate electricity without competing for limited land. They also shade and cool bodies of water, which can help prevent evaporation and conserve valuable water supplies.
“But we haven’t seen any large-scale installations, like at a large reservoir,” Levine said. “In the United States, we don’t have a single project over 10 megawatts.”
Previous studies have tried to quantify how much energy the country could generate from floating solar panels. But Levine and Rosenlieb claim to be the first to consider which water sources have the right conditions to support these kinds of power plants.
In some reservoirs, shipping traffic causes wakes that could damage the mooring lines or impact the floating infrastructure. Others get too cold, are too shallow, or have sloping bottoms that are too steep to secure solar panels in place.
However, some hydropower reservoirs could be ideal locations for floating solar power plants, the study found. A hybrid energy system that relies on both solar energy and hydropower could provide more reliable and resilient energy to the power grid. If, for example, a drought depletes a hydropower facility’s reservoir, solar panels could generate energy while the facility pauses to allow the water to replenish.
Additionally, to build new pumped storage hydropower projects, some developers create entirely new bodies of water. These new reservoirs are disconnected from naturally flowing rivers, and no human or animal depends on them for recreation, habitat, or food (yet).
In the future, the researchers plan to review which locations are close to transmission lines or electricity demand, how much development might cost at specific sites, whether a site should be avoided to protect the local environment, and how developers can navigate state and federal regulations. The team would also like to evaluate even more potential locations, including other, smaller reservoirs, estuaries, and even ocean sites.
The research was funded by the Solar Energy Technologies Office and the Water Power Technologies Office in DOE’s Office of Energy Efficiency and Renewable Energy (EERE).
Read the full study here.