The first hydroelectric power facility when into operation in 1882 on the Fox River In the state of Wisconsin.
Hydro electricity is the cheapest form of energy. The initial costs are in building the dam and power plant—the actual power source—water and its force of flow, are free. This results in a lower price per kilowatt hour.
Operating costs of hydroelectric plants are low—very few employees are required to do the work necessary to keep the plant in operation.
Construction costs of new dams are low in comparison to other types of power generating facilities.
China generates the most hydroelectric power on the planet, although hydro is a popular method of electric power in nearly every region on earth.
The massive “Three River Gorge” dam in China began filling its reservoir in 2003 but did not become fully operational until 2009. This dam is considered one of the largest in the world. It is 1.4 miles wide and 607 feet high.
Three Gorges is expected to generate enough power in 5-8 years to completely cover its construction costs which were approximately 22 BILLION U.S. dollars.
Hydroelectricity is the largest “renewable” source of electric power in the United States because the water that generates it is the result of annual snow melt and rainfall. It is also one of the “greenest” options, although the dams do have an environmental impact on existing freshwater habitats.
The typical hydroelectric facility is a three component system; an electrical plant where the electricity is channeled controlled and redirected a dam which constricts the flow or a river or stream by opening or constricting water passing through it and the turbines which spin the generator which produces the actual electrical current.
The biggest hydro electric plant/damn is Grand Coulee Dam in Washington State on the Columbia River. The power generated by this plant provides more 70% of Washington’s electrical needs.
Hydroelectricity is a very flexible source of energy. Dam engineers can control the flow of water in the turbines quickly in response to fluctuating demands for power.
Hydroelectric power is the most cost effective source of electricity for power hungry industrial applications like the production of aluminum.
Hydro electric dams not only provide power, the reservoirs that are formed behind the dams are often used as recreational areas and become popular tourist attractions themselves. Lake Havasu is the reservoir of the Parker Dam on the Colorado River between California and Arizona. This reservoir provides aquatic recreational opportunities in what would otherwise be a desert. Lake Havasu has between 3-5 million visitors annually.
Hydroelectric dams are an important part of flood control in the areas they serve.
Power generating hydro electrical facilities are not always huge structures. There are four recognized sizes:
- Large: Hydro power stations that generate between a few hundred megawatts to more than 10 gigawatts are considered large facilities.
- Small: Small hydro is defined as having a generating capacity of up to 10 megawatts, but may be as much as 25 or 30 in some countries. These facilities generally serve a small community or single industrial plant.
- Micro-facilities produce more than 5 kilowatts but not over 100 kW. These plants provide for the electrical needs of small communities or isolated homes.
- Pico— these hydro sources produce less than 5 kilowatt hours—enough to power a few light bulbs or a TV for a few hours a day in a single household.
Not all hydroelectric facilities are above ground! Underground stations take advantage of height differences between two waterways such as waterfalls and lakes. A tunnel is constructed underground which directs water from the higher reservoir to a generating hall built near the lowest point of the water tunnel. A horizontal “tailrace” then directs water onward to the lower waterway outlet.
In addition to dams and underground stations there are other unique types of hydro electrical power generation
- Tidal sources use the rise and fall of tides in the ocean. These predictable daily cycles in areas that are capable of permitting construction of reservoirs can become a method of generating power in peak demand periods. Other tidal types of power generation harness water’s kinetic energy (power potential from movement).
- Run-of-the-river hydro makes use of rivers that have small or nonexistent reservoir capacities. These plants rely on the natural and seasonably changeable flow of a river. Power is generated in the moment or is allowed to bypass the dam power potential untapped.
Pumped storage facilities move water between two reservoirs at different elevations to generate power during peak demand times. In times of low demand, water is pumped to the higher reservoir; when demand rises the water is then released to flow back to the lower reservoir through a turbine.