When it comes to sustainable energy supply, hydroelectric power plants are playing an increasingly important role. They use the mechanical energy of flowing or falling water to generate electricity. But: How does a hydroelectric power plant actually work?
Hydroelectric power plants have a long tradition in Germany. They are one of the oldest methods of generating renewable energy. In fact, people are already using the power of water for more than 5,000 years. In the past, water pressure in rivers used to drive millstones.
Today, hydropower covers more than 16 percent of the world’s electricity needs. There are 7,300 hydroelectric power plants in Germany. Together they have an installed capacity of around 5,600 megawatts. Most of the hydroelectric power plants are in Bavaria and Baden-Württemberg. They make up around 80 percent of all German hydropower plants.
How does a hydroelectric power plant work?
Hydroelectric power plants generate electricity using water. The energy of flowing water – also known as fluid mechanical energy – drives turbines. This creates rotational energy. Generators ultimately generate electrical power from them.
The efficiency of hydroelectric power plants is up to 85 percent, which is significantly higher than that of other types of power plants. There are four common types: air hydroelectric power plants, water storage power plants, pumped storage power plants and tidal power plants.
This is how run-of-river and storage power plants generate electricity
Run-of-river power plants use the natural flow of a river. The amount of electricity generated depends on the water mass and the head, which is why rivers are often dammed by weirs in order to increase the height difference and increase efficiency.
Because: the bigger the difference, the higher the efficiency. The turbine is powered by a continuous flow of water, allowing for constant electricity production. The generator transforms the energy from the rotation into electricity.
At a Storage power plant A dam or dam stores large amounts of water. This creates reservoirs to store water. Additional water from surrounding rivers often flows into the collecting basins via tunnels. If necessary, the water can be led through pipes to the lower-lying machine house. There it hits a turbine at high pressure and drives a generator.
This is how pumped storage plants and tidal power plants work
Pumped storage power plants use excess energy to pump water from a lower to an upper basin. This stores potential energy. If there is a need for energy, the water is returned to the lower basin. It drives turbines that generate electricity. This form of hydroelectric power plant acts as an energy storage device and stabilizes the power grid. It can also supply large amounts of electricity if required.
Tidal power plants generate electricity using the ebb and flow of the tide. The currents set turbines in motion and drive generators. At low tide the turbines turn in one direction, at high tide they turn in the other.
The disadvantage: Tidal power plants are dependent on currents and therefore cannot continuously generate electricity. A dam is typically part of the construction. The turbines are installed there. However, this design only works with a tidal range of around five meters. The difference in height between low tide and high tide must therefore be correspondingly large.
Alternatively, there are also ocean current power plants. Similar to wind power plants, they have rotors that are located below the surface of the water. The water current sets them in motion and drives the generators to produce electricity. A large tidal range is not necessary.
Hydroelectric power plants in Germany
In 2020, around 3.3 percent of the gross electricity generated in Germany was generated with the help of hydroelectric power plants. For comparison: wind energy supplied 24 percent in the same period. Hydropower therefore plays a rather minor role in Germany.
How much electricity is produced in a year also depends on precipitation. In recent years the value has fluctuated between 19 and 29 terawatt hours. That’s enough for 800,000 to 1.2 million households in this country.
However, hydroelectric power plants also have some disadvantages: On the one hand, the construction of dams and the diversion of rivers can have a significant impact on nature. Fish and other aquatic creatures are particularly affected.
In addition, the construction of the systems is expensive and time-consuming. Large projects in particular require significant investments. Hydroelectric power plants ultimately always depend on natural water sources. Dry periods or changing weather conditions can affect electricity production.
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The article How does a hydroelectric power plant actually work? by Beatrice Bode first appeared on BASIC thinking. Follow us too Facebook, Twitter and Instagram.
As a Tech Industry expert, I can explain that a hydroelectric power plant works by harnessing the power of flowing water to generate electricity. The basic principle is to use the energy of moving water to turn a turbine, which then spins a generator to produce electricity.
The process begins with water being collected in a reservoir or dam, where it is stored until needed. When the water is released, it flows through large pipes called penstocks, which direct the water towards the turbine. The force of the flowing water causes the turbine to spin, converting the kinetic energy of the water into mechanical energy.
The turbine is connected to a generator, which contains coils of wire that are rotated within a magnetic field. This movement of the wire within the magnetic field induces an electric current, which is then transmitted through power lines to be used as electricity.
Overall, hydroelectric power plants are a clean and renewable energy source that can provide a reliable source of electricity. They are also flexible in their ability to adjust output based on demand, making them a valuable asset in the transition to a more sustainable energy future.
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