Floating solar power: evaluate trade-offs

[...]for some projects, so much methane - a potent greenhouse gas - is released from decaying submerged plant matter that they can emit as much carbon per unit energy as do fossil-fuel power plants10. For some of those sites, putting solar panels over just 2% ofthe reservoir's surface could double the electricity production, thereby halving the carbon intensity - which is an important metric in climate policy (see Supplementary information). Covering 10% of the world's hydropower reservoirs with floating solar panels would install nearly 4,000 GW of solar capacity9 - equivalent to the electricity-generation capacity of all fossil-fuel plants in operation worldwide. Wind turbines, for example, have harmed birds and bats, and their installation offshore can create noise pollution for marine life, interfere with whale migrations and pose complications for commercial fisheries.