Hydroelectric power plant converts the potential energy of a watercourse, be it natural or engineered, into a green electricity supply. Hydroelectricity refers to electricity produced when the power present in the flowing water is tapped upon. It is also known as hydroelectric power or hydroelectric energy. This type of energy emanates from the movement of water by a wheel or another mechanism for the performance of various tasks. For instance, running water powered up the Greek mill which grinded wheat into flour.
Working Principle of Hydroelectric Power Plant
In general, the scheme of a power plant involves damming a river to create a reservoir.
Canals, adduction channels, diversion tunnels, penstocks, and water rotation work with mechanical energy generation in rotating electric generators. The turbines generate mechanical energy by turning with the aid of the water. This water is sent through the discharge channel back to the watercourse.
A rotating alternator transforms the mechanical power acquired from a turbine into electrical energy. The electricity thus obtained must be transformed to be transmitted over great distances through a transformer which reduces the current intensity and increases voltage before being supplied in transmission lines.
The energy then hits a second transformer on arrival at its point of use, before being deployed, which increases the current intensity but decreases the voltage to render it appropriate for industrial, commercial, or domestic purposes.
Also Read: 5 Major Advantages and Disadvantages of Hydroelectric Energy
Types of Hydropower Plants
There are three types of hydropower facilities. They are impoundment, diversion, and pumped storage. Some of these dams are associated with hydroelectric plants, while others are not.
1. Impoundment
An impoundment facility is the most popular type of hydropower plant. A dam is used to form an artificial storage area, where the river water in a reservoir is held until it becomes necessary. The turbine is activated by rotations of water which in turn leads to the production of electrical power. It can release the water to cater to changing electricity demands or other purposes, such as flood control, recreation, and fish passage among other environmental and water quality needs.
2. Diversion
Sometimes when this happens a small section of the river is diverted into a canal or penstock to take advantage of the gradual falls in a riverbed to generate electricity known as a diversion also referred to in hydrology as run-of-river. Penstocks are closed conduits that carry a controlled amount of water to open the appropriate gate, valve, or turbine. However, not all diversions might need a dam.
3. Pumped Storage
There is another kind of hydropower known as pumped storage hydropower or PSH which operates just like a gigantic battery. A PSH facility can help in storing electricity produced by other power sources like solar, wind, and nuclear for future use. These storage plants pump water from a low-lying dam to a high-lying one, thereby storing up energy.
In case there is less demand for electricity, a PSH facility is used to store energy. The water is pumped from a lower to an upper reservoir. The water is stored in an upper reservoir and released back to the lower reservoir during times of high electrical demands turning a turbine that generates the electricity.
Also See: What is Water Turbine?
Hydroelectric Power Plant Sizes
Power plants can be classified as big ones supplying numerous consumers with electricity, and medium and small ones produced by personal users for their use or for selling to utilities.
- Large Hydropower: However, there is no single definition of large hydro projects; in this context, DOE refers to those over 30 megawatts (MW).
- Small Hydropower: The Department of Energy (DOE) defines a small plant as between 100 KW and 10 MW.
- Micro Hydropower: A micro hydropower plant has a specification of about 100 Kilowatts. Small-scale or micro-hydroelectric power systems can generate sufficient power for a residence, farm, ranch, or village.
Also Read: What is Conventional Hydroelectric Plant?