@sapphire @lain @cjd @mithrandir @shmibs

They are, but they have just one problem - they use *massive* amounts of land, require a very specific geology and nobody wants them anywhere close.

When I say "massive" I mean surface power density of 0.14 W/m2 of land used, as compared to 240 W/m2 for nuclear power for example.

So if a nuclear power plant occupies a hectare for some power output, you will need 1714 hectares for equivalent hydro plant.