Modelling of the potential of floating photovoltaics for mitigating climate change impacts on reservoirs

Deployment of floating photovoltaics (FPVs) on water reservoirs is accelerating, and their lifetimes are expected to extend far into the 21 st century. One of their potential co-benefits is mitigation of climate change-induced impacts on water quality. However, there has been little investigation of this possibility. We used MyLake, a 1D (vertical) numerical model, to simulate water quality impacts in a UK reservoir of different FPV coverages under four future climate scenarios and a present-day baseline case. We tested hypotheses that increased FPV coverage would offset climate-induced reservoir warming, stratification duration lengthening, phytoplankton biomass increases and taxonomic dominance changes. FPV coverage's ability to offset climate warming varied between the four climate scenarios, and seasonally within them. It was able to fully offset changes in stratification duration and to entirely prevent thermal stratification in all four future scenarios. Climate-induced increases in phytoplankton biomass and taxonomic dominance patterns were also entirely offset if sufficient FPV coverage was applied in all future scenarios. According to these results, FPV coverage will be able to compensate partially or fully for thermal and phytoplanktic changes in reservoirs under future climates. However, the amount of coverage required varies seasonally and depends on future climate trajectories.