if Quaise Energy is successful, I think they'll have beat them to the punch as building a geothermal plant on land and just reusing existing gas turbine will make this much cheaper. realengineering channel did a video.

Lots of things can hinder hit, but adding underwater to any mix increases complications dramatically. (Speaking from marine experience.)

They did say that it would be cheaper to do geothermal on land, though that depends on whether that is (easily) available in the first place. Land-based geothermal struggles with issues such as geothermal-induced earthquakes, IDK if this going to be any better under water.

I really want geothermal energy to succeed, it seems like a great, reliable energy source that isn't dependent on foreign countries (e.g. solar is very China-dependent), but it carries real risks. Then again, the pacific rim region is prone to earthquakes anyway, so they'll need to earthquake-proof their buildings with or without geothermal power.

Why wouldn't you consider it green?