According to an analysis by researchers at the US Department of Energy’s National Renewable Energy Laboratory (NREL), hybrid systems consisting of floating solar panels and hydroelectric power plants could have the technical potential to produce a significant portion of the electricity generated worldwide every year.
The researchers estimate that adding floating solar panels to bodies of water that are already home to hydropower plants could generate up to 7.6 terawatts of potential electricity per year, or about 10,600 terawatt hours of potential annual generation, from solar PV systems alone. These figures do not include the amount generated from hydropower.
For comparison: According to the International Energy Agency, final global electricity consumption in 2018, the last year for which statistics are available, was just over 22,300 terawatt hours.
“That’s really optimistic,” said Nathan Lee, a researcher with the NREL Integrated Decision Support Group and lead author of a new paper published in Renewable Energy magazine. “This does not represent what might be economically feasible or what the markets might actually support. Rather, it is an upper limit on realizable resources that takes into account the constraints of the water body and the performance of the generation system.”
The article “Hybrid floating solar photovoltaic hydropower systems: Benefits and global assessment of technical potential” was co-authored by NREL colleagues Ursula Grunwald, Evan Rosenlieb, Heather Mirletz, Alexandra Aznar, Robert Spencer and Sadie Cox.
Floating photovoltaics (PV) is still an emerging technology in the US, but its use has caught on overseas where there is less space for floor-mounted systems. Previous NREL work estimated that installing floating solar panels on man-made US reservoirs could generate about 10 percent of the country’s annual electricity production.
So far only a small floating solar / hydropower hybrid system has been installed, and that in Portugal.
NREL estimates that 379,068 fresh hydropower storage facilities around the world could host combined floating PV sites with existing hydropower plants. Additional location data is required prior to any implementation as some reservoirs may be dry during parts of the year or otherwise unsuitable for hosting floating PV.
Potential advantages result from coupling floating PV with hydropower. For example, a hybrid system would reduce transmission costs by connecting it to a common substation. In addition, the two technologies can balance each other out. The greatest potential for solar energy is in the dry season, while in hydropower the rainy season is the best opportunity. In one scenario, this means that hybrid system operators could use pumped storage hydropower to store excess solar energy.
The research was funded from NREL’s Laboratory Directed Research and Development Program.
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