Dams have an issue with methane emissions (a potent greenhouse gas)[1]. If I remember right, the type of dam also matters, and there are numerous problems with

Dams have an issue with methane emissions (a potent greenhouse gas)[1]. If I remember right, the type of dam also matters, and there are numerous problems with megadams in particular. [1]http://www.scientificamerican.com/article/methane-emissions-may-swell-from-behind-dams/ http://www.scientificamerican.com/article/methane-emissions-...