There is a really big environmental impact to building new dams, they completely change the local environment of an area and have much further reach than most people realise.
So it means that creating new dams as a way to generate hydroelectric power is not as easy and green as people might think and can have bad consequences as well as generating clean power.
But there are a lot of dams all over the world of all kinds of shapes and sizes, some really quite old by now and some that are much more modern, that are literally just dams and do not have any power generating purpose.
I was wondering what the effect would be if those dams were retrofitted with hydropower generators. How much extra clean energy would that produce worldwide, is is possible and affordable,, and would it have any bad consequences?