Mod Info:Solar is great and all, but if you want your factory to function during the night, you need enough accumulators that you could put Elon Musk and his Tesla gigafactories to shame. Nuclear power solves that option, but good luck finding and mining enough uranium until the very late game, especially if you play with tiered ores. And it, if you have the mods for it, can turn your factory into a radioactive wasteland. Boilers and steam is easier and more reliable, but does not scale that well, and pollutes enough that your factory looks more like 1900s London than the pristine land it once was.
Enter geothermal power. Tap into the hot rock deep underground, and use that to boil easy-to-obtain water into steam, without burning anything. Granted, it has one hell of a startup cost - each well will set you back a significant amount of resources, not to mention the heat exchangers and steam engines or turbines. And it requires power to continue operation; rely on it exclusively, and the first significant brownout might become a death spiral to total blackout. And of course you have to find such an upwelling of hot water first.
But it costs nothing consumable except for water, and pollutes very little. And a sufficient-size plant can easily eclipse even a handful of reactors.
Has integration with AlienBiomes if present: Geothermal upwellings only occur in volcanic biomes, but are plentiful throughout.
Screenshots/Video:A sample geothermal plant (30-60MW capacity):
Another plant, this one designed to come online as a backup: