Different Sources of Hydroelectricity
Hydroelectric energy is received mainly from the water energy of the rivers. Hydroelectric power stations are usually built on rivers. The power of the water current acts upon the turbines setting a generator in motion. The generator produces electric energy. Hydroelectricity can also be received from the power of the rising tide. But this way of producing hydroelectric energy is more complicated and expensive.
Earlier water energy was transformed directly into mechanical work. People used hydro power for milling and sawing. It also helped to supply fields with water. Beside that rivers are used for such purposes as transporting timber from forests to industrial centres. At present hydroelectric energy is the principal form of useful energy received from running water.
The amount of water produced by running water depends on the volume and velocity of water. As a rule, hydroelectric power station is built on a steep slope or at the waterfall to use the water energy potential accumulated by water as a result of the level difference. In some areas dams are built to regulate the flow of water and to produce hydroelectricity.
Functioning of hydroelectric power stations does not involve the air pollution by carbonic acid gas. The latest generation of turbines gives up to 90 percent of energy outcome. There is much water in the world and in a way we can rely on it. But it is not that all regions are equally supplied with powerful water flows. And building a new dam is always connected with large sums of money and irretrievable changes in the landscape.
One more problem is that of dam sedimentation. Soil and other substances washed down by the river form silt behind the dam and it stops functioning in a proper way. That is why can say that in spite of all its advantages hydroelectricity cannot replace such sources of energy as gas and oil altogether, but it is still of great use for the mankind.