Don’t forget hydro =/= green. Its ecological impact is significant and it’s producing greenhouse gases.

How does hydro produce greenhouse gases?

Is it because of the massive amount of concrete needed or because of something else?

Massive amount of concrete, fossil fuels used to rapidly cool the concrete, methane released in the areas that get drowned during the process. Not to mention all of the best dam sites in the US were tapped in the 30s and 40s. That well is dry in terms of net new power.

Interesting. Did not know about that !

One more question, by fuels used to cool the concrete, I'm thinking you are referring to powering the pumps that circulate the cool water in the tubes inside the concrete slabs, right? Or is it cooled differently?

Yes, you seem to have it. I believe they also have to supercool the water before running it through the cooling pipes.