Title: Earth, water, wind, and sun, our energy alternatives
Description: Discusses energy sources that are possible substitutes for fossil fuels, including geothermal power, water power, wind and solar energy.
Subjects: Power resources, Fuentes de energía, Energiequelle, Sources d'énergie, Duurzame energie, Alternatieve technologie, Economische aspecten, Energiebronnen