Hydroelectric power isn't quite as clean as many believe though. >We estimate that GHG emissions from reservoir water surfaces account for 0.8 (0.5–1.2) Pg CO2

Hydroelectric power isn't quite as clean as many believe though. >We estimate that GHG emissions from reservoir water surfaces account for 0.8 (0.5–1.2) Pg CO2 equivalents per year, with the majority of this forcing due to CH4. https://academic.oup.com/bioscience/article/66/11/949/2754271 https://academic.oup.com/bioscience/article/66/11/949/275427... That's between 2% and 3% of our global greenhouse gas emissions. About three quarters of greenhouse gas emissions come from energy production and about 15% of all energy production is hydro power if I recall correctly. It's much better than fossil fuels, but not quite clean.