Living Green: The Missing Manual

Water Power

As mentioned on Hydro power for homes, moving water is another clean and renewable energy source whose history goes back to ancient times. Villages and towns sprang up next to rivers because they provided water, transportation, and energy to power mills.

Hydropower remains an important source of energy. According to the U.S. Department of Energy, American hydroelectric plants can generate enough electricity to supply 28 million households with power—that's enough to save about 500 million barrels of oil. Hydropower accounts for more than 70% of the electricity generated from renewable sources in the U.S. Other countries do even better: Brazil, Canada, Norway, and Venezuela all get most of their electricity from water.

In a hydroelectric plant, water gets diverted from a river, flows through a pipe (called a penstock), and turns the blades of a turbine as it flows back to the river. The turbine spins a generator, which produces the electricity. There are two kinds of hydroelectric plants:

• Dams. As you know, dams store water by blocking a river and creating a reservoir. The stored water drives a water turbine and powers a generator to create electricity. When demand for energy is high, the dam can let more water through to generate more electricity.

  

• Run-of-the-river systems. This kind of plant takes advantage of water that's flowing from higher to lower ground. Instead of storing ...