The history and use of hydropower are closely linked to the impressive water reserve that the Earth has. More than 70% of the blue planet is covered by this precious resource, but the journey to make it a reliable source of energy is far from being fun!

Hydroelectric energy from the driving force of rivers and waterfalls is now one of the main sources of green energy. With the evolution of technology, numerous revolutionary plants and installations have made it possible to take advantage of the power of water to better exploit its potential.

Origin, history, operation, different forms... SirEnergies offers you an immersion in the exciting world of hydraulic energy!

What is the origin of hydraulic power?

Like wind energy and biomass, Hydraulic power is the result of a double action: that of the force of the Moon's gravity and that of the Sun. We don't necessarily expect it, right?! To be more specific, we can say that the origin of hydroelectric energy is linked to the Water cycle.

Under the impulse of the Sun and the wind, ocean water evaporates and forms clouds. The water vapor is then condensed by the lowering of temperatures, and is then transformed into precipitation (rain and snow).

Rainfall feeds the Earth's porous layers, leading to the formation of groundwater. They also flow into rivers, lakes, and lagoons, which in turn flow into the oceans. The force of attraction of the Moon and that of the Sun finally produce tides whose force is exploited: this is the origin of Hydraulic power !

The first machine created to use tidal energy was The paddle wheel. It has given way to watermills since ancient times to pump water, operate hammer hammers or mill grain. The pre-industrial era was then the scene of numerous techniques based on hydraulic force, but the first hydroelectric power plant arrived in the 19th century. Its objective? Transforming the power of water into electrical energy!

When was hydraulic power invented?

Hydraulic power was invented In 1869 in Grenoble by the French engineer Aristide Bergès. The device originally used was used to turn shredders using the hydraulic force of a 200 m waterfall. “White coal” thus laid the foundations of a real revolution that led to the first electric power plant in 1878.

Created by William George Armstrong, this 7 kW machine was used to power the Cragside estate in England. Other power plants were created later to light parks, small towns and castles.

The development of electrochemistry and industry led researchers to develop the first electrical transformers. Starting from 1889. Hydroelectricity then took off with the manufacture of the first hydraulic power plants of more than 1 MW. However, it was not until the end of the First World War and the extension of the electrical network to benefit from more powerful hydraulic power plants.

In France, the expansion of electricity in the 1920s marked the beginning of a frantic race towards the development of hydroelectricity. The production of this renewable energy was then multiplied by eight with the advent of the first hydraulic dams.

How does hydraulic power work?

While hydroelectric power is considered to be a major ally in the race for the development of renewables, this is largely thanks to its mode of operation. In principle, it remains the same regardless of the device used.

To produce hydroelectric energy, we exploit the Height difference between two points in the same watercourse. It can also be two levels of a dam. In fact, the water flow speed accelerates sufficiently to activate the adjacent production device.

The device consists of a dam erected to retain a large quantity of water. The latter crosses a water intake at a high speed. The result is a transformation of hydraulic power into kinetic energy. The turbine of the hydroelectric power plant then takes care of converting kinetic energy into mechanical energy.

The hydraulic power plant is equipped with a generator used to transform mechanical energy into electricity. All that remains is to modulate the electrical voltage to adapt it to the domestic network.

The water used finally leaves the dam and continues its normal course, without any alteration. The quantity of energy produced thus depends on three factors:

• hydraulic pressure,
• the volume of water,
• the flow speed.

Water pressure, for its part, depends on the height difference between the location of the turbine and the watercourse. In other words, the greater the difference in altitude between these two points, the more energy is generated!

What are the different forms of hydraulic power?

Despite its numerous advantages, hydroelectricity remains dependent on one element: water. To get around the problem, it was necessary to design and create several types of hydraulic power plants. We invite you to discover the main devices used.

Power station along the river

Far from the poetic image to which its name refers, Power station along the river is a device designed to allow blue gold to pass from the dam to the power plant as it flows. Here, the flow is very high, even if the fall of the water does not exceed 30 m.

The run-of-river power plant makes it possible to produce electricity continuously. In France, the hydroelectric park includes around 90% of run-of-river power plants for a total power of nearly 8,500 MW.

Lake power plant

Lake power plants are large-scale hydroelectric devices. With their huge storage capacity, you can find them in the high mountains, in places that are suitable for falls of 30 m.

The main defect of Lake power plants ? The flow rate of water. Their functioning is based on the retention of a hydraulic dam, hence the term “reservoir lake”. Water from snowmelt and rivers is stored seasonally in a reservoir large enough to regulate electricity production over more than 400 hours!

Small hydroelectric power plants (PCH)

With an operation very similar to that of a run-of-river power plant, small hydroelectric power plants (PCH) have a power of less than 10 MW. They work without reservoirs: the device used here is used to create a difference in altitude to generate Hydraulic power.

The exploitation of PCHs of less than 4.5 MW is carried out under the authorization regime. The installation therefore belongs to a private owner who uses it for sale or self-consumption of electricity. Power plants with a capacity greater than 4.5 MW are state-owned. Their exploitation is governed by the concession regime (entrusted by the Public Authority to an operator).

Pumped energy transfer stations (STEP)

The mention of this acronym makes one think of the famous “step by step” formula... Rightly so! In fact, the pumped energy transfer stations (STEP) produce hydroelectric power on the same principle. They also have the particularity of being reversible.

WWTPs use the height difference between their turbine and the waterfall to create electrical energy. In periods of low consumption, they use electricity from the associated network to start the operation of a pump. The latter causes water to rise from the lower basin to the upper basin, in order to perpetuate the transformation cycle.

Tidal power plants

THEtidal power plant is a hydroelectric power plant used to exploit tidal energy. In other words, it uses sea level fluctuations to create electricity. Its installation requires sites such as bays or estuaries in which the tide amplitudes are high.

The operation of a tidal power plant is the same as that of a conventional power plant. It is enough to establish a dam across the operating site to form a storage basin. In short, nothing very complicated. However, the particularity of this installation lies in the principle of the communicating vessels that it uses. Two cycles are then possible depending on the level of water available: the simple and the double effect.

The tidal turbines

THEtidal turbine is a propeller equipped with a hydraulic turbine, which transforms the driving force of river or marine currents into mechanical energy. It differs fundamentally from the wind turbine, as it is very easy to predict marine currents, unlike winds and their intensity.

Tidal turbines can produce up to 1 MW of electricity per year. To do this, the device must be in contact with an average current of 2.5 m/s. Its interception surface must, for its part, be approximately 300 m.

Wave farms

La Wave farm is a set of devices anchored in the same place. The exploitation site is often located near the coast or on the high seas to better capture wave energy.

The various known and tested states of progress concern:

• articulated floating chain,
• Vertical oscillating column,
• submerged oscillating wall,
• Immersion pressure plant,
• Water column.

For the International Energy Agency (IEA), global marine power is equivalent to 90,000 terawatt hours (TWh). Wave farms are therefore an effective way to exploit this inexhaustible source.

Hydraulics in a few figures

To better understand hydropower and its importance, we looked at numbers. The statistics in France and the rest of the world speak for themselves!

Hydraulics in France

The French hydraulic park is characterized by an installed capacity of 25,718 MW. It corresponds to 42% of the renewable electrical power installed in our country. France has more than 2,300 hydroelectric power plants. In addition, four regions produce more than 90% of production. It is about:

• Auvergne-Rhône-Alpes,
• The Grand Est region,
• Occitanie,
• Provence-Alpes-Côte d'Azur.

The Palme d'Or goes to Auvergne-Rhône-Alpes with more than 45% of national production.

Hydraulics in the world

Hydraulic power represents approximately 16% of electricity production global. It ranks third among the most used energy sources, but in first place when it comes to renewable energy.

Asia produces 27% of the world's hydroelectricity production. China is the main producer, followed by Brazil, Canada and the United States.

In conclusion, the history of hydraulic power is that of a perpetual quest to put the power of water at the service of modernity. From the invention of Aristide Bergès in the 19th century to the present day, hydroelectric power plants have seen major advances. However, it is legitimate to ask whether hydroelectric power is the most ecological source of energy...