Discusses solar, wind, biofuel, hydro, and geothermal energy sources. Everyone is looking for ways to expand our sources of renewable energy-- but which system is best? What is "renewable" energy, and what are the pros and cons of each source? Sneideman and Twamley introduce you to solar, wind, biofuel, hydro, and geothermal energy. They also provide hands-on activities and links to online primary sources.