Hydroelectricity is the generation of electricity from the force of moving water. Water that is either flowing, or falling under the influence of gravity, can be used to turn turbines that power electricity production by a generator.
Hydroelectric power comes in many different forms and is used with many different types of water source. Turbines can be set up to take advantage of flowing water in a river, the controlled flow of water as it passes through a dam, or the movement of waves and tides in the sea. Hydroelectricity can also be produced from falling water, for example at a waterfall.
Hydroelectricity is the modern form of hydropower. Waterwheels and mills have traditionally been used to grind flower and to power machinery, but today it is more commonly used to generate electricity. Hydroelectric production often occurs on a grand scale, with large hydroelectric power plants and turbines built into huge dams. However, it is also possible to use hydroelectricity for domestic production, on a small scale, if there is a suitable source of moving water nearby.
Hydroelectric power is the most commonly used form of renewable energy. Globally, about 20 percent of electricity production is through hydroelectricity. Hydroelectric power makes up 88 percent of all renewable electricity production. Paraguay produces all of its electricity through hydroelectric power, but it only uses 10 percent of the hydroelectricity that it produces, exporting the rest to Argentina and Brazil. Norway is also heavily reliant on hydroelectricity, which produces about 99 percent of its electricity. Other countries that generate most of their internally produced power from hydroelectricity are Canada, Venezuela and Switzerland. China is the largest producer of hydroelectricity, although it forms a smaller proportion of total energy production.
Most hydroelectricity is currently produced from dammed water flowing through turbines, but there are also some hydroelectric power plants that use flowing rivers to create electricity. Run of the river hydroelectric plants do not have the capacity to store large amounts of water like plants that are built into dams. Rivers can also be used to generate power without using any form of storage. Tidal power stations can make use of the predictable movements of the tides to generate power at known times. This can be helpful for the scheduling of power production from different sources. Production from pumped storage hydroelectric systems can also be scheduled, and used to store energy until it is required.
Hydroelectricity can be used in order to store electricity that has been produced through more intermittent kinds of renewable power. Unlike solar and wind power, hydroelectric power can be produced at any time. Its production can therefore be manipulated according to current demand. It is also possible to store the energy that is generated by another form of power and then to release it through hydroelectric production. Water can be pumped up to a lake or storage tank using the power generated by a traditional power plant or from renewable sources of energy. When demand rises and the power needs to be released, the water can be allowed to flow out of the storage tank, usually through a tunnel. As the water flows or falls away, it generates electricity by turning hydroelectric turbines.
Most of the cost and the energy required to create a hydroelectric power plant is used during the initial construction phase. The costs and the amount of work and materials that are needed vary a great deal, according to the type of hydroelectric production that is being used. Once the system has been set up, no fuel is required and electricity production is very cheap.
Hydroelectricity is a clean source of power since no pollution is produced. When reservoirs are created, they can provide hydroelectric power, but they also serve other functions such as the supply of water for human consumption and irrigation, flood control and recreation. Reservoirs do require the flooding of large areas of land, however, which means that ecosystems and communities are destroyed. The flow of water downstream of the reservoir will be changed, and if the flow is reduced too much it can result in serious environmental problems and drought.
Although hydroelectricity is the most widely used form of renewable energy, there are a number of other sources of renewable power. PennEnergy.org is a good place to learn about these types of power.