Alternative power plants and fuels
Experimental technologies could provide clean energy, aside from intermittent solar and wind energy and their inherent energy storage.
A Few Details
Nuclear Generation IV or nuclear Fusion could soon fuel power plants to mass-produce electricity, even liquid hydrogen.
Clean coal, i.e., burning coal and capturing+storing CO2, is only experimental. It could be added on existing coal plants.
Biofuels may improve enough to become mass produced without infringing on food production or reforestation efforts.
Wave, tide, geothermal and other energies could be used in power plants aside from existing dams and other plants that already exist.