Also a possibility to look at would be geothermal power that would work off magma. Or a steam powered machine where you drop water into boiler that is on top of magma so that it liquefies and rises up to the top to turn a turbine and make electric power. Since the introduction of steam geysers and water geysers i feel like all these are ideas to implement. The way to balance the Hydroelectric plant is if it produces contaminated water which would then have to be sifted out of the water with a purifier. The steam would take either building it someplace hot where it could break or by making it require coal to use. It could produce polluted oxygen or something from the coal and the water evaporation. The Geothermal power would require intense heat which would require finding a magma chamber which the dupes have to enter to build and maintain it. could produce co2 or anything the devs would want. But in order for the dupes to survive in the chamber they have to have heat shielded clothing on.