The hydraulic energy (also called water power or hydropower) is obtained thanks to the kinetic energy and the potential energy of water currents (such as waterfalls or rivers) and tides. For example: hydroelectric plants, water mills, marine energy.
The Kinetic energy It is the energy that any body possesses thanks to its movement. For example, if we put a pencil against a piece of paper and hold it still, the pencil does not transmit any energy to the paper (no kinetic energy).
On the other hand, if we hit the paper with the tip of the pencil, that is, we move it at high speed, the pencil breaks the paper thanks to its kinetic energy. For this reason, hydraulic energy does not come from lakes or lagoons, but from moving bodies of waterlike rivers and seas.
The potential energy it is the one that is in an object due to its relative position within a system. For example, an apple on a tree has the potential energy of its fall, that is, the potential energy is greater if the apple is located higher.
Using the potential energy of water means using the difference in height between where the water comes from and where it will fall. The force with which it falls thanks to the acceleration of gravity is converted into kinetic energy.
Advantages of hydraulic power
- Renewable energy. That is to say that it will not be depleted by its use, thanks to the water cycle. Even if a huge amount of water leaves a reservoir and passes through the hydroelectric plant, that water will return to the reservoir thanks to the water cycle, which will cause the water to evaporate and fall back as rain.
- High performance. Unlike other renewable energies (such as solar energy), little space is needed to obtain large amounts of energy.
- Does not produce toxic emissions. Like those produced by other energy sources such as fossil fuels.
- cheap. Its operation is independent of oil prices. Although the construction of a hydroelectric plant can be very expensive, its useful life can exceed 100 years.
Disadvantages of hydraulic power
- Although there are forms of hydraulic energy that do not affect the environment, most are hydroelectric plants, which form reservoirs, that is, the flooding of large areas of land around what was previously a river. This has a profound environmental impact, forcing the relocation of numerous species and dramatically changing the landscape.
- The ecosystem is also modified downstream because the water that comes out of the dams has no sediment, which causes faster erosion of the riverbanks. In addition, the flow of the river is drastically modified in a short time.
Examples of hydraulic power
- hydroelectric plants
They convert the water energy in electrical energy. They use the potential energy of a large body of water (the reservoir or artificial lake) due to its unevenness with a riverbed. The water is dropped through a turbine, in which its potential energy is converted into kinetic energy (motion) and the turbine converts it into electrical energy.
The first hydroelectric plant It was built in 1879 in Niagara Falls. Currently, this is the cheapest form of energy, due to the little maintenance that the installations require and the amount of energy that is obtained daily.
- Watermills
They use the kinetic energy of a water course. It is called windmill because in its first uses it was used to grind grains. The water moves the blades of a wheel that is located slightly submerged in the water course. Through a set of gears, the movement of the wheel in turn moves a pair of circular stones called millstones that press the grains, turning them into flour.
Currently the water wheels They can also be used to obtain electricity through a transformer, in a similar way to the operation of turbines in hydroelectric plants.
However, the amount of energy obtained It is much lower since the water moves at a higher speed due to the fact that the natural unevenness of the rivers is much less than that used in hydroelectric plants. The first waterwheels were built in ancient Greece, in the third century BC.
- marine energy
It is a specific form of utilization of water energy. It is classified in:
- energy of ocean currents. Ocean currents are surface movements of the waters of the oceans. They are produced by multiple factors, such as terrestrial rotation and winds. To take advantage of the kinetic energy of the currents, rotors are used.
- osmotic energy. Sea water is salty, that is, it has a concentration of salts. The rivers, on the other hand, do not have salt. The difference in salt concentration between rivers and seas produces pressure-retarded osmosis, when the two types of water are separated by a membrane. The pressure difference on the two sides of the membrane can be used in a turbine.
- sea thermal energy (sea thermal). The difference in temperature between deeper (colder) and surface (warmer) ocean waters allow a thermal device to move to generate electricity.
other types of energy
| Potential energy | Mechanical energy |
| Hydroelectric power | Internal energy |
| Electric power | Thermal energy |
| Chemical energy | Solar energy |
| Wind power | Nuclear energy |
| Kinetic energy | sound energy |
| Caloric energy | Geothermal energy |
| Hydraulic energy | |