Hydraulic energy: what it is, how it works and its advantages

What is hydraulic energy?

Hydraulic energy is a type of energy that takes advantage of the movement of water. It is sometimes also called water energy and it enables us to obtain electricity by making use of kinetic energy and potential energy from currents and waterfalls.

It is clean and renewable energy that uses the force of streams, rivers and waterfalls. Normally when we think of hydraulic energy, what comes to mind are hydroelectric power stations on dams in reservoirs.

However, we should not forget that ancient civilisations, like the Romans and Chinese, already used water mills to take advantage of the power of water.

Nowadays, the most frequent use of hydraulic energy is to produce electricity. Just to give us an idea, hydraulic energy installations in Spain represent 17% of all electricity generated.

How does a hydroelectric power station work?

A hydroelectric power station basically works by using a turbine that rotates when it is driven by a current or a waterfall. The most efficient way to produce electricity in a hydroelectric power station is to build it at the base of a dam, in order to control the flow of water through the turbine in a stable way.

Operation of a hydroelectric power station step by step:

1. Accumulation of water: dams accumulate a large amount of water inside reservoirs. The water's energy at that time it is being stored is in the form of potential energy, a type of energy that depends on height.
2. Opening the sluice gate: the moment the water is allowed to flow and, by the action of gravity, the potential energy of water is transformed into kinetic energy.
3. Turbine movement: when water flows it transfers that kinetic energy, as a result of its movement, to the turbine in the hydroelectric power station causing it to rotate.
4. Generator action: the movement of the turbine activates the generator that is capable of transforming mechanical energy into electricity by the action of a magnetic field.
5. Voltage change in the transformer: after the production of electricity (usually alternating current) it is conducted to a transformer to increase the voltage. This is how the energy can be transported from the power station to the different supply points.
6. Connection to the electricity grid: once the electricity leaves the hydroelectric power station it is connected to the electricity grid to be transported and distributed to the different final consumers.

This process makes it possible to obtain electricity from hydraulic energy in an efficient, clean and sustainable way. This energy then becomes part of what we will use for all kinds of tasks, both private and professional.

Different types of hydroelectric power stations

There are many different types of power stations that harness hydraulic energy to produce electricity. They are usually classified either by their production capacity or by the source of water they use to produce electricity (by their location).

Power rating

They are classified into three types of power station according to the power they have and the amount of hydroelectric energy they are capable of accumulating:

• Micro-hydroelectric power plants: they are the smallest and reach a maximum of 1 MW.
• Mini-hydroelectric power plants: those that generate between 1MW and 10MW.
• High power hydroelectric power plants: all those plants that generate more than 10MW.

Classification by location

In this case, the classification of hydraulic power stations by location is related to the type of water source they use to produce electricity. There are essentially two types of power stations:

• Water's edge or flowing water power stations: they are located on the bank of a river to take advantage of flowing water to generate energy. They work continuously as they cannot store water like reservoir power stations do.
• Reservoir power stations: these are located in the lower part of a reservoir. They use the controlled flow of stored water that passes through the turbines to generate the electricity. They are the most frequent type of power stations because they can produce energy constantly throughout the year.

Other power stations of this type are less common and called regulation and reversible power stations. So-called regulation hydroelectric power stations are similar to water's edge power stations, but with a limited capacity to store part of the volume of water from the river and use it as an energy reserve.

Reversible or pumping power stations use part of the energy generated in the production of hydroelectric power to pump the water back into the reservoir. This is how the use of water when producing electricity is optimised.

Hydraulic energy in Spain

In Spain there are currently more than 1350 power stations that use hydraulic power to produce electricity. Of these 1350, approximately 1200 are mini-hydroelectric power plants.

With regard to the Autonomous Communities, Extremadura has the largest number of installations, 30% of the sector, followed by Castile-León and Andalusia.

Technological research continues to increase and improve the production of electricity from hydraulic energy and to increase electricity production.  Together with wind energy and solar energy they are expected to be one of the major ways of achieving the objectives for decarbonisation and sustainable energy production.

Advantages and disadvantages

Every source of energy, even hydraulic energy, has its advantages and disadvantages. Although when we talk about sustainable energy the pros far outweigh the cons, let's analyse the advantages and disadvantages of hydraulic energy.

Disadvantages of hydraulic energy

• High initial cost: the costs associated with the construction of the power stations and the reservoirs that feed them are high.
• Dependence on the climate: in times of drought or severe flooding of rivers, electricity production can be greatly affected, even to the point of having to shut the plants down.
• Changes in the environment: even though we are always trying to affect the environment less with the installation of mini and micro power stations, the reservoirs which are essential for the supply of water, affect the environment.

Advantages of hydraulic energy

• Cheap energy: once the construction costs for the power stations have been amortised, the electricity produced from hydraulic energy has a very economical cost.
• It enables planning: although it is a type of energy that is highly influenced by climatic effects, with correct hydraulic management plans can be made to obtain energy in the long-term.
• Clean and sustainable energy: hydraulic energy does not generate polluting waste, it uses a renewable energy source and greatly reduces CO2 emissions.
• Very safe: it can be said that hydroelectric power plants use water as their "fuel" to generate electricity, this makes them very safe compared to other types of power stations. 

Together we can progress to a new way of producing and consuming energy. Even now you can live your daily life using this type of clean, renewable and sustainable energies thanks to Endesa Única, more than a flat-rate electricity tariff and 100% sustainable.