A hydroelectric power station is a set of water power engineering works with a series of suitable machines. The objective of a hydroelectric power station is to obtain electricity from the potential energy of moving water.
These types of power plants take advantage of the potential energy of water to generate electrical energy.
The energy produced by hydroelectric plants is renewable. Thanks to the water cycle, this resource can be endlessly reused for the same purpose without undergoing a purification process. however, it depends on the annual volume of total entries.
Hydroelectric plants can activate their production in a few minutes with the immediate opening of the gate valves. Then, the water is released, and water turbines start producing electricity. This feature provides the ability to cover sudden spikes in electrical demand that may occur quickly.
In the United States, there are about 80,000 dams. The largest hydropower plant in terms of installed capacity is The Three Gorges Dam in China.
How Does a Hydroelectric Power Plant Work?
A modern hydroelectric power plant comprises a reservoir, a dam, gates, turbines, and generators.
The tank stores the "fuel" and allows operators to control the amount of water fed to the turbines. It also serves as a settling reservoir.
Water Inlet
The water from the basin is transported to the turbines through an inlet (gate dam) and a forced conduit. An inlet filter system further cleans the water. The filter must ensure that it is relatively free of suspended solids that could damage the turbine blades.
The hydroelectric systems work together to open and close the gate valves. This action allows the flow of water to flow downstream of the basin. These systems are the regulator, the brakes, the gate controls, etc.
Water Turbine
The water wheel of the past has been turned into a modern turbine. Unlike the shape of the blade, the three main types of water turbines are Francis, Kaplan, and Pelton. They are named after their inventors.
Regardless of the type of design, the turbine transforms the water power into mechanical energy.
Electric Generator
The water turbine is connected through the shaft to an electric generator's rotor that converts mechanical energy into electric power.
For maximum efficiency, the turbines are tailor-made for each hydroelectric plant.
What Are the Types of Hydroelectric Plants?
We can divide hydroelectric plants into three broad groups depending on the height of the fall. Each type uses a specific water turbine design to maximize performance.
In low voltage pressure installations, the height of falling water is less than 25 m.
In Medium voltage installations, the height of falling water is between 25 and 100 m. It is the most common hydropower plant.
High voltage installations where the height of falling water is more significant than 100 m.
What Are the Pumped-storage Stations?
Pumped storage plants are conventional hydroelectric power plants. They fill their storage basin with water when there is an excess of electricity production.
The power plant then purchases electricity at a price below its average price. At this point, it changes its shape and pumps water into its storage tanks. When consumption exceeds the supply, the plant sells the electricity produced at a higher price than its average cost.
These types of plants use two reservoirs located at different heights. When there is demand, the plant generates electricity like a conventional plant. The falling water from the upper pool drives the turbines and is stored in the lower reservoir.
When the demand is low, water is pumped back from the lower reservoir to the upper one.
Characteristics of a Hydroelectric Plant
The main characteristics that determine the production capacity of a hydroelectric plant are:
The power that depends on the difference in level between the top and the bottom of the dam.
The maximum water flows that the plant is capable of passing through the water turbines.
The characteristics of electric turbines and generators.
The energy that the plant is capable of guaranteeing in a given time (generally one year).
There are four water turbines used to transform mechanical energy into electricity:
Pelton turbine
Kaplan turbine
Turgo turbine
Francis turbine
What Are the Pros of Hydropower Plants?
The benefits of electricity generation through hydroelectric plants compared to other alternatives are:
1. Low Economic Cost
The main advantage of hydropower is that there are no fuel costs. The cost of running a hydroelectric plant is almost immune to increases in fossil fuel costs.
Fuel is not necessary and does not need to be imported.
The overall labor cost is low as the plants are automated and are understaffed during operation.
This kind of power station can be set with relatively low construction costs. It provides a useful income source to offset base operating costs.
2. Environmental Benefits
This way of generating energy does not emit greenhouse gases.
Being renewable energy, it does not consume fossil fuels. Therefore, it does not emit greenhouse gases with carbon dioxide, among others.
3. Other Types of Activities: Sports, and Tourism
The reservoirs located in the plant sometimes offer facilities for water sports, becoming tourist attractions in themselves.
The multiple uses of dams for installed irrigation can support relatively constant cultivation establishment with the water's reach.
What Are the Cons of Hydroelectric Power Plants?
1. Maintenance
A problem related to hydroelectric plants is the pile of sediment in the upper reservoir. This problem inevitably appears over time.
To avoid this problem, they must dredge the pileup sediments off and on.
2. Environmental Issues
The presence of a dam implies certain complications at the environmental level:
Hydroelectric dams block the transport of solids from rivers (sand and gravel).
The water leaving the plant is free of sediment. It upsets the balance between solid supply and erosive activity in downstream waters. Due to the reduced or no solid contribution, there is the phenomenon of coastal erosion.
Building dams and larges flooding areas mean a landscape change.
It implies the destruction of natural habitats.
Many of these problems do not occur in "MINI-HYDRO" systems. In many cases, Mini-hydros do not require the construction of dams.
