HYDRAULIC POWER: CHARACTERISTICS, HOW IT WORKS, ADVANTAGES, USES - ENVIRONMENT - 2025

The hydraulic power is the ability of water to produce work in the form of motion, light and heat based on their potential and kinetic energy. It is also considered a clean, high-performance renewable energy.

This energy is determined by the flow, the unevenness between points on the ground through which the water moves and the force of gravity. It has been used by humans since ancient times to perform different jobs.

Itaipú Dam (Brazil and Paraguay). Source: Angelo Leithold

One of the first uses of hydraulic energy was to power water mills that took advantage of the power of the current. In this way, by means of gears, millstones could be moved to thresh wheat.

At present its most relevant application is the generation of electrical energy through hydraulic power plants or hydroelectric plants. These plants basically consist of a dam and a system of turbines and alternators.

The water accumulates in the dam between two levels of the channel (geodesic unevenness), generating gravitational potential energy. Subsequently, the current of water (kinetic energy) activates turbines that transmit the energy to alternators to produce electrical energy.

Among the advantages of hydraulic energy is that it is renewable and non-polluting, unlike other energy sources. On the other hand, it is highly efficient with a yield ranging from 90 - 95%.

The environmental impact of hydroelectric plants is associated with the variation in temperature and physical alteration of the water course. Likewise, waste oils and fats are produced that are filtered from the machinery.

Its main disadvantage is the physical alteration that it causes due to the flooding of large areas of land and the natural flow and course of rivers is altered.

The largest hydroelectric power station in the world is The Three Gorges, located in China, on the Yangtze River. The other two in importance are those of Itaipú on the border between Brazil and Paraguay and the Simón Bolívar or Guri hydroelectric plant in Venezuela.

characteristics

The source of hydraulic energy is water and it is considered to be renewable energy as long as the water cycle is not altered. Likewise, it can produce work without generating solid waste or polluting gases and is therefore considered clean energy.

performance

Energy efficiency refers to the relationship between the amount of energy obtained in a process and the energy that was necessary to invest in it. In the case of hydraulic energy, a performance between 90 to 95% is achieved depending on the speed of the water and the turbine system used.

How does hydropower work?

Scheme of a hydroelectric power station. Source: User: Tomia

Transformation of solar energy into kinetic energy

The foundation of hydraulic energy is in solar energy, the topography of the land and the earth's gravity. In the water cycle solar energy causes evaporation and then the water condenses and precipitates on the earth.

As a result of uneven ground and the force of gravity, surface water currents occur on the earth's surface. In this way, solar energy is transformed into kinetic energy due to the movement of water by the combined action of unevenness and gravity.

Later the kinetic energy of water can be transformed into mechanical energy that is capable of doing work. For example, blades can be moved that transmit the movement to a gear system that can operate various devices.

The magnitude of the hydraulic energy is given by the unevenness between two given points of the riverbed and its flow. The greater the unevenness of the land, the greater the potential and kinetic energy of the water as well as its ability to generate work.

In this sense, potential energy is that which accumulates in a body of water and is related to its height relative to the ground. On the other hand, kinetic energy is that which water releases in its falling motion as a function of topography and gravity.

Production of electricity from hydropower (Hydroelectric)

The kinetic energy generated by falling water can be used to produce electrical energy. This is achieved by building dams where water accumulates and is held at different levels of height.

Thus, the potential energy of water is directly proportional to the difference in level between one point and another and when the water falls it is transformed into kinetic energy. Subsequently, the water passes through a system of rotating blades and generates rotating kinetic energy.

The rotational movement allows moving gear systems that can activate mechanical systems such as mills, wheels or alternators. In the particular case of hydroelectric power generation, the system requires a turbine system and an alternator to generate electricity.

Turbines

The turbine consists of a horizontal or vertical axis with a system of blades that rotate the axis by the force of the water.

There are three basic types of hydraulic turbines:

Pelton turbine

Pelton turbine. Source: Robertk9410

It is a high pressure impulse turbine with a horizontal axis that works without being totally submerged. The impeller has a series of concave blades (blades or teeth) that are driven by jets of water.

The more jets of water hitting the turbine, the more power it will generate. This type of turbine is used for waterfalls from 25 to 200 meters high and reaches an efficiency of up to 90%.

Francis turbine

Francis turbine. Source: The original uploader was Stahlkocher at German Wikipedia.

It is a medium pressure reaction turbine with a vertical axis and works completely submerged in water. The impeller is made up of blades that are driven by the water led through a distributor.

It can be used in waterfalls from 20 to 200 meters high and reaches an efficiency of 90%. This is the type of turbine most frequently used in large hydroelectric plants in the world.

Kaplan turbine

Kaplan turbine. Source: TheRunnerUp

It is a variant of the Francis turbine and, like this one, has a vertical axis, but the impeller is made up of a series of adjustable blades. It is of high pressure reaction and works totally submerged in water.

The Kaplan turbine is used in waterfalls from 5 to 20 meters high and its efficiency can reach up to 95%.

Alternator

The alternator is a device that has the ability to transform mechanical energy into electrical energy through electromagnetic induction. Thus, magnetic poles (inductor) are rotated within a coil with alternating poles of conductive material (for example copper wound in soft iron).

Its operation is based on the fact that a conductor subjected for a certain time to a variable magnetic field, generates an electrical voltage.

Advantage

Hydraulic power is widely used because it has many positive aspects. Among these we can highlight:

It is economical

Although in the case of hydroelectric plants the initial investment is high, in general terms in the long term it is cheap energy. This is due to its stability and low maintenance cost.

In addition, the economic compensation provided by reservoirs with possibilities for aquaculture, water sports and tourism must be added.

It is renewable

As it is based on the water cycle, it is a renewable and continuous source of energy. This implies that it does not run out in time unlike the energy from fossil fuels.

However, its continuity depends on the water cycle not being altered in a given region or globally.

High performance

Hydraulic energy is considered very efficient and with a high performance that is between 90 to 95%.

It is not polluting

This type of energy uses a natural source such as water and also does not produce waste or polluting gases. Therefore, its impact on the environment is low and it is considered a form of clean energy.

Presence of reservoirs

In the cases in which reservoirs are built for the use of hydroelectric energy, these present a series of additional benefits:

- They allow to regulate the flow of the river and avoid floods.

- They represent a reservoir of water for human consumption, irrigation and industrial use.

- They can be used as recreation areas and for the practice of water sports.

Disadvantages

Dependence on rainfall

A limitation of hydroelectric power generation is its dependence on the rainfall regime. Therefore, in particularly dry years the water supply can drastically decrease and the reservoir level is lowered.

When the water flow is reduced, the generation of electrical energy is lower. In such a way that in regions that are highly dependent on hydroelectric energy supply problems can occur.

Alteration of the natural course of the river

The construction of a dam in a river alters its natural course, its flood regime, dwindling (decrease in flow) and the sediment dragging process. Therefore, changes occur in the biology of plants and animals that are aquatic or located in the vicinity of the body of water.

On the other hand, the retention of sediments in the dam alters the formation of deltas at the mouth of the rivers and alters the soil conditions.

Danger of dam breaking

Due to the large volume of water stored in some hydroelectric dams, a breach of the retaining wall or nearby slopes can cause serious accidents. For example, during the year 1963 the slope of the Vajont dam (now disused) in Italy occurred, causing 2,000 deaths.

Applications

Ferris wheels and water pumps

The rotation of a wheel driven by the kinetic energy of the water allows water to be drawn from a shallow well or channel into an elevated channel or reservoir. Likewise, the mechanical energy generated by the wheel can drive a hydraulic pump.

The simplest model consists of a wheel with blades with bowls that collect the water at the same time as they are driven by the current. Then, in their rotation, they drop the water into a tank or channel.

Mills

For more than 2000 years, the Greeks and Romans used hydraulic energy to move mills to grind cereals. The spinning of the wheel driven by the stream of water activates gears that turn the millstone.

Forges

Another ancient application of hydraulic power-based workability is its use to activate the forge bellows in blacksmithing and metallurgy work.

Hydraulic fracture

In mining and oil, the kinetic energy of water is used to erode rock, fracture it and facilitate the extraction of various minerals. For this, gigantic pressurized water cannons are used that hit the substrate until it erodes it.

This is a destructive technique for the soil and highly polluting the waterways.

Fracking

A very controversial technique that is gaining momentum in the oil industry is fracking. It consists of increasing the porosity of the bedrock containing oil and gas in order to facilitate its removal.

This is achieved by injecting large amounts of water and sand at high pressures together with a series of chemical additives. The technique has been questioned for its high water consumption, polluting soils and waters and causing geological changes.

Hydroelectric plants

The most common modern use is to run electric power generating plants, so-called hydroelectric plants or hydroelectric plants.

Examples of hydropower plants

The Three Gorges

Three Gorges Dam (China). Source: Le Grand PortageDerivative work: Rehman

The Three Gorges Hydroelectric Power Plant is located in China's Hubei Province on the course of the Yangtze River. Construction of this dam began in 1994 and was completed in 2010, reaching a flooded area of ​​1,045 km² and an installed capacity of 22,500 MW (megawatts).

The plant includes 34 Francis turbines (32 of 700 MW and two of 50 MW) with an annual electrical energy production of 80.8 GWh. It is the largest hydroelectric plant in the world in terms of structure and installed power.

The Three Gorges Dam has managed to control the periodic flooding of the river that came to cause serious damage to the population. It also guarantees the electricity supply of the region.

However, its construction had some negative consequences such as the displacement of around 2 million people. In addition, it contributed to the extinction of the critically endangered Chinese river dolphin (Lipotes vexillifer).

Itaipu

Itaipu Dam. Source: Herr stahlhoefer

The Itaipú hydroelectric plant is located on the border between Brazil and Paraguay on the course of the Paraná River. Its construction began in 1970 and ended in three stages in 1984, 1991 and 2003.

The dam's flooded area is 1,350 km² and has an installed capacity of 14,000 MW. The plant includes 20 Francis turbines of 700 MW each and has an annual electrical energy production of 94.7 GWh.

Itaipu is considered the largest hydroelectric plant in the world in terms of energy production. It contributes 16% of the electrical energy consumed in Brazil and 76% in Paraguay.

Regarding its negative impacts, this dam affected the ecology of the islands and the delta of the Paraná River.

Simon Bolivar (Guri)

Simón Bolívar hydroelectric plant (Gurí, Venezuela). Source: Warairarepano & Guaicaipuro

The Simón Bolívar hydroelectric plant, also known as the Guri dam, is located in Venezuela on the course of the Caroní River. Construction of the dam began in 1957, a first stage was completed in 1978, and was completed in 1986.

The Guri dam has a flooded area of ​​4,250 km² and an installed capacity of 10,200 MW. Its plant includes 21 Francis turbines (10 of 730 MW, 4 of 180 MW, 3 of 400 MW, 3 of 225 MW and one of 340 MW)

Annual production is 46 GWh and it is considered the third largest hydroelectric plant in the world in terms of structure and installed power. The hydroelectric plant provides 80% of the electrical energy that Venezuela consumes and part of it is sold to Brazil.

During the construction of this hydroelectric plant, large areas of ecosystems in Venezuelan Guiana were flooded, a region with high biodiversity.

Today, due to the deep economic crisis in Venezuela, the production capacity of this plant has been significantly reduced.

References

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2.- Raabe J (1985). Hydro power. The design, use, and function of hydromechanical, hydraulic and electrical equipment. Germany: N. p.

3.- Sandoval Erazo, Washington. (2018). Chapter 6: Basic Concepts of Hydroelectric Plants.https: //www.researchgate.net/publication/326560960_Capitulo_6_Conceptos_Basicos_de_Centrales_Hidroelectricas

4.- Stickler CM, Coe MT, Costa MH, Nepstad DC, McGrath DG, Dias HO and Rodrigues BS-Soares-BS LCP (2013). Dependence of hydropower energy generation on forests in the Amazon Basin at local and regional scales. Proceedings of the National Academy of Sciences, 110 (23), 9601–9606.

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