Subsurface water is a pretty common thing for earth-like planets. Why did you decide no water for subsurface Nauvis?

This was intentional to push the player towards the new geothermal power plant as an underground power source bootstrap, and then to push the player toward using the multi-level pipes. Barreling water + mult-level-belting + un-barrelling water is another option but still locked behind subterranean tech like multi-level pipes.

Huh. I guess I haven't gotten to the geothermal plant yet. I used the Stirling generator mod.

It should unlock when you get the mining drill equipment. If you can reach the underground it's supposed to be available. Do you know if you might have another mod that also introduces a geothermal power plant? There may be a naming conflict that is causing it not to be available until later.

It does. I didn't even notice. I've mae one and I don't understand how it works. It's just blinking red lightning bolt.

Do you have it connected to a power pole? And/or are you in the editor with time paused?

It should “just work” and give you a small amount of free power (on a large footprint).

Yes, I'm on a power pole. It does work, giving power but still has the lightning bolt. Very weird.

I believe that happens when there is not enough power being generated for the whole grid. There is a tiny energy buffer in each plant and if that runs out it will show that symbol

Ah thanks.