Offsetting the greenhouse gas footprint of hydropower with floating solar photovoltaics

Hydropower is typically considered a low-carbon energy source. Yet, because of greenhouse gas (GHG) emissions from their reservoirs, some hydropower facilities exhibit high GHG intensities (that is, emissions per unit of electricity generated). Here we assess the potential for offsetting GHG intensities by combining reservoir-based hydropower with floating solar photovoltaics (FPV), a burgeoning renewable energy technology. We find that technically feasible FPV–hydropower integrations could enable over 50% of the world’s GHG-intensive hydropower plants to achieve low-GHG energy benchmarks. These findings have implications for both project-level hydropower management and broader climate change mitigation strategies. Renewable energy from reservoir-based hydropower plants can have high GHG emissions. Integrating floating solar photovoltaics on hydropower reservoirs can help offset GHG emissions from a large proportion of hydropower facilities.