HOW HYDROPOWER WORKS

Understanding the water cycle is important to understanding hydropower. In the water cycle -

· Solar energy heats water on the surface, causing it to evaporate.

· This water vapor condenses into clouds and falls back onto the surface as precipitation.

· The water flows through rivers back into the oceans, where it can evaporate and begin the cycle over again.

Mechanical energy is derived by directing, harnessing, or channeling moving water

The amount of available energy in moving water is determined by its flow or fall.Swiftly flowing water in a big river, like the Columbia River along the border between Oregon and Washington, carries a great deal of energy in its flow. So, too,with water descending rapidly from a very high point, like Niagara Falls in New York. In either instance, the water flows through a pipe, or penstock,then pushes against and turns blades in a turbine to spin a generator to produce electricity. In a run-of-the-river system, the force of the current applies the needed pressure, while in a storage system, water is accumulated in reservoirs created by dams, then released when the demand for electricity is high. Meanwhile, the reservoirs or lakes are used for boating and fishing, and often the rivers beyond the dams provide opportunities for whitewater rafting and kayaking. Hoover Dam, a hydroelectric facility completed in 1936 on the Colorado River between Arizona and Nevada, created Lake Mead, a 110-mile-long national recreational area that offers water sports and fishing in a desert setting.