Early in the 21st century, two facts are becoming impossible to ignore: oil is only going to get more expensive, and global warming traceable to our use of fossil fuels will impact civilization in ways that we're only beginning to grasp. Stepping in to fight these massive problems are the rapidly evolving technologies that harness renewable energy. MODERN MARVELS shows how air, water, earth, and fire are transformed into clean, reliable sources of energy. This incisive hour takes an in-depth look at the most proven and reliable sources: solar, wind, geothermal, biofuels, and tidal power. From the experimental to the tried-and-true, renewable energy sources are overflowing with potential... just waiting to be exploited on a massive scale. And unlike fossil fuels, they'll always be there.