Hydroelectricity and Hydropower Plant

Hydroelectricity

Hydroelectricity is the form of energy produced with the help of the flow of water. Both moving and stagnant water contains energy. While moving water contains kinetic energy, stagnant water contains potential energy. When both of them are added, enormous amounts of energy can be created. In addition, hydroelectricity is a form of renewable energy source. It means very less pollution is generated while making this energy.

Presently, hydropower contributes nearly 20% of the world's electricity generation methods and more than 65% of renewable energy sources.

Hydroelectricity generating methods

Hydroelectricity is generated by the potential energy stored in water. The water is stored in a dam or barrage and released from a certain height over a turbine that generates electricity. The power generation quantity depends upon the volume of water released and the difference between the turbine and source outflow.

There are three predominantly used methods for the generation of hydroelectricity that are discussed as under:

1. Impoundment hydropower plants
This is the most common type of hydroelectric power plant. In an impoundment hydropower plant, a big dam is used to store the water in a reservoir. The dam is constructed near the river, where the height of the water can be controlled. The water is released from the height and is allowed to fall on a turbine. The turbine rotates when the water falls from a big height. A generator is connected to the turbine that generates electricity. After the generation of electricity, it is transferred to other places with the help of power grids.
We can generate electricity anytime as per our need. The water stored in dams is released to control floods, fish passage, recreation, and meet other water or environmental needs.

2. Diversion hydropower plants
A diversion hydropower plant is also referred to as a 'run of the river' power plant. In this, a channel is created through a canal or a penstock. The channel is made so that it can utilize the natural fall of the river bed. This natural fall helps in producing energy from the fall. A penstock is a closed conduit that helps transfer the water to the hydropower plant, perpendicular to the direction of the natural flow of water. It is constructed by cutting a piece of channel. Gates, valves and turbines regulate the water in a diversion hydropower plant.

3. Pumped storage hydropower plants
The most power generating hydropower plant is the pumped-storage hydropower plant. It is sometimes referred to as a giant battery. This power plant not only produces electricity but can also store energy. And not only water, but it can also store energy from other sources like solar, wind and nuclear. The energy made from other sources is used to pump the water from a lower elevation to a higher elevation to fall, producing electricity.
When the electricity demand is low, the energy produced from other sources stores water from a lower elevation to higher elevations. And when energy demand is high, the water is released from a higher elevation to lower elevation over the turbines to create energy.

Sizes of hydropower plants

The size of a hydropower plant depends upon the water holding capacity, the amount of energy it needs to produce and the area where the plant needs to be built. Therefore, hydropower plants are both large and small in size. While large plants are used to produce energy, the smaller plants (known as micro or macro plants) are operated by bigger units to meet their energy needs or sell the power utilities. The different types of hydropower plants according to their sizes are:

1. Large hydropower plant – The sizes of large hydropower plants vary from place to place. A hydropower plant is said to be large if it can store more than 30 megawatts of energy.
2. Small hydropower plant – A hydropower plant is small if it generates power between 100 kilowatts to 10 megawatts.
3. Micro hydropower plant – Micropower plant is said to have a capacity less than or equal to 100 kilowatts. This category of hydropower plants can produce energy for a single home, farm, village or ranch.

Advantages of hydroelectricity

1. Hydroelectricity is a low-cost power generation method that produces high-value power.
2. Hydropower is the most flexible source of energy production. The energy production starts instantaneously and takes about a minute to catch the speed.
3. Hydropower generation methods produce very low carbon dioxide.
4. Water is a major by-product that is released by many industries. We can use that water to generate power if channelized properly.
5. Saltwater is present around us in abundance. We can use the water to generate a large amount of energy instead of using coal and petroleum.