People have harnessed the formidable power of moving water for millennia, but they have only used it to generate electricity since the late nineteenth century. Since that time, it has become an important alternative energy source to fossil fuels. In fact, more electricity is produced by waterpower than by any other renewable energy source in the United States. This book offers an in-depth look at the turbines used to generate hydroelectricity. It explains which locations are best for generating hydroelectricity and explores the cultural and environmental concerns raised by the building of dams. The focus is on hydroelectric plants, but this book also discusses pumped hydro storage, tidal power, and wave energy.