Hydroelectric power or hydroelectricity is nothing but using water to generate electricity. Hydroelectricity is widely produced and is one of the most common electricity generating methods. It is also the most popular renewable energy source. It is estimated that hydroelectric power accounts for 19% of world electricity production and makes up 63% of the total electricity produced from renewable sources.
Hydroelectric power is generated using the potential and kinetic energy of water. Water is stored by building dams at select sites of water bodies. Therefore, dams store the potential energy of water. To generate electricity, the potential energy is converted to kinetic energy when the water in the dam passes from a great height, over turbines connected to a generator. The amount of electricity produced will depend on the volume of water involved and the height from which it flows.
A typical hydroelectric power plant comprises of a dam, supply pipes called penstocks, turbines (powerhouse), generator or electrical substation, and a reservoir. The penstocks are used to increase the height of water flow over the turbines while the reservoir collects the water to feed to the dam. Some hydroelectric plants do not use reservoirs. Instead, a river is diverted from its natural course so that water can flow over the turbines. This type of plant is called a run-of-river plant.
The main reason why hydroelectricity is popular is its cost effectiveness. Hydroelectric plants require less infrastructure costs than other electricity generating sources like nuclear energy and coal. The cost of producing electricity from water works out to around 25 cents per kWh (kilowatt hour). Another factor contributing to cost savings is that a hydroelectric plant can remain operational for 50 to 100 years.
As electricity production only requires a steady supply of water, hydroelectric power is a renewable resource and is virtually inexhaustible. Running a hydroelectric power plant does not require any additional non-renewable fuel sources, which minimizes the production of greenhouse gases like carbon dioxide.
The major drawback of constructing a hydroelectric power plant is the damage to the local ecosystem. Building dams changes the natural course of a river, thereby affecting the aquatic populations in the river. It also alters the levels of gases like oxygen and carbon dioxide and minerals in the river, which impacts the local flora and fauna. Run-of-the-river hydroelectric plants have the least impact on the environment as they do not affect the eco-system.