Hydropower is the energy that comes from moving water. Water runs downhill in a path of least resistance due to the gravitational pull of the earth. This constant supply is replenished by the continuous solar evaporation of water from our oceans and lakes and the inevitable return to earth in the form of snow and rain. From the moment it touches ground water trickles, creeps, flows and rushes downhill and downstream eventually finding its way back to the sea. The suns energy is therefore in the flowing water.
Turbines are the mode of energy collection. As water flows through a turbine the kinetic energy of flowing water is converted to mechanical energy which can be used to grind grain, drive a sawmill, pump water and produce electricity. There are several types of turbines used to capture this kinetic energy. Run-of-the-river turbines are submerged in a stream or river and are rotated by the waters flow. The spinning turbine turns a magnet through coils of wire generating a current of electricity. These turbines do not need a dam and have low environmental impact.
The more commonly used hydropower system collects the energy from falling water. A dam is used to capture water. The captured water is released down a pipe with a turbine positioned at the bottom. The vertical distance of the falling water determines how much energy can be captured. The larger the drop the more energy harnessed. The turbine is then used to collect the kinetic energy. Some rivers have the potential to have several of these dams and hydropower stations. The Columbia River which flows through Washington and Oregon supports seven of theses stations.9
Rivers currently contribute over 12 percent of the U.S. electrical supply. Over the past 100 years dams and hydropower plants have been used in the U.S. Because of this long history of development most of the highly marketable river sources have been developed. However there is still room for expansion of hydropower while opportunities exist in the development of small hydropower plants which can supply local electrical needs. This has recently been seen in a renovated plant at Cornell University. This hydropower system provides 5 percent of the electrical needs for the university and generates $250,000 worth of electrical sales to the local utility companies.
Waterpower represents a clean source of electricity. The cost of a power station is relatively low once the station is built. The energy is relatively free once the equipment costs needed to harness it have been paid back. Reservoirs of water offer recreational benefits like boating and fishing, or can be used as companions to solar and wind power.
However, hydropower has environmental impacts. Dams flood large areas covering much more area than solar facilities producing the same amount of energy. Ecosystems have been disrupted by turning narrow stretches of moving water into a wide still pond or lake, disrupting long established plant and animal communities. Local, state and federal regulations cause difficulties in the production of a new power station. These productions require patience, close work with local citizens and environmental groups and constant interactions with government agencies.9
