On the Earth there is ca. 1.4 billion km3 of water. It is an enormous amount which is a potential source of energy. Water is called “white coal” because its energy gives electricity and does not pollute natural environment.
Water constantly moves in global hydrologic cycle. In this cycle water is evaporating, forming clouds and precipitating. The water is either absorbed into the soil or transferred to surface runoff. The water from rain and melting snow reaches rivers, lakes, reservoirs, and finally seas and oceans. The water evaporates back to the atmosphere and the cycle begins again. The energy of this water cycle can be used for electricity production. The force of moving water can be extremely powerful while the gravity drives the water, moving it from high to low ground.
Hydropower is energy that comes from water in motion. Hydropower is produced by converting the kinetic energy of moving water to mechanical energy in a turbine. Turbines and generators convert the energy into electricity. The electricity is then fed into the electrical grid and used by energy consumers.
Generally, the turbine is a type of water wheel that is connected to a generator. Water passes through the blades of a turbine installed on a shaft. The water strikes and turns the blades of a turbine. It pushes the blades and they spin converting kinetic energy of water into mechanical energy. The shaft spins with the rotating blades and turns a rotor in an electric generator. Inside the generator there are large electromagnets attached to the rotor that is located within a coil of copper wires called the stator. As the generator rotor spins the magnets a flow of electrons is created in the coils of the stator. A/C current is produced. The electrical current is then passed through transformer system and sent across transmissions lines.
There are several types of turbines. The most common type of turbine is the Francis Turbine.
Why use water as energy source?
Hydropower is a constant and reliable energy source with relatively low operating costs. It is independent from prices of uranium, oil or other types of fuel. It does not depend on import of any resource from abroad.
Hydropower facilities have a long life span, much longer than other sources of power, and can operate for many years after they are built. For example design life expectancy of nuclear power stations is ca. 40 years. At present, there are several hydropower stations in the world which have been operating longer than one century.
Impoundment hydropower creates reservoirs that offer a variety of recreational opportunities. They can be used for water sports and leisure. Moreover, this type of hydropower can be used for irrigation purposes. Many dams are used to control flooding and regulate water supply.
Hydropower does not pollute the air or produce greenhouse gases. It is a clean method of energy generation.
What are potential obstacles?
Hydropower can be impacted by drought. When the water level is too low, hydropower stations cannot operate properly and they generate less energy.
Although impoundment hydropower has several advantages it may also have negative impact on natural environment. Sometimes it is necessary to flood large areas, and this is connected with possible relocations and changes in natural environment. Moreover, it can cause changes in the geology.
Hydropower facilities may have negative impact on biological structure of rivers.