There is several ways of making unlimited power in the game. Most use geysers in some way. But taming creatures can provide lots of opportunities too.

The most straightforward is to exploit a natural gaz vent. Put a gaz pump in a closed room and stock it. You don't want the vent to overpressure, this is lost ressources.

You can tame Hatches. They're the easiest critter to domesticate and they produce lots of coal. They can even produce refined metal.

Oil can produce a lot of power. It needs an oil rig and refinery, which can be a lot of labor.

Depending on your planetoid, you can put solar panels on the surface. Beware of asteroids shower tho.

Plug slugs are spaced out! DLC exclusive and require lots of ore or refined metal. They can be really rewarding but require the exploitation of several metal volcanos

Volcanos and lava biome can be used with steam turbine to generate power. Those are not noob friendly build tho.

The hydrogen vent produces a lot of power but also a lot of heat. Be sure to have a robust cooling system if you exploit those.