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All about hydropower plants

Harnessing kinetic energy

What is a hydroelectric or hydropower plant?

Also known as a hydroelectric power plant, it is an infrastructure whose main purpose is to capture and exploit the kinetic energy contained in the natural flow of water.

These plants are strategically located along rivers and streams, where the powerful force of moving water becomes a fundamental resource for electricity production.

Hydropower plants generate a renewable energy source that contributes to sustainability and the reduction of Greenhouse Gas Emissions (GHG). In addition to mitigating the adverse effects of climate change, they are highly efficient and versatile, adapting to different scales of power generation, from microgeneration to large-scale projects, supplying entire regions with clean electricity.

How hydropower plants work

Hydropower plants employ a number of key components and an ingeniously designed process that efficiently harnesses the hydrological cycle.

Water catchment. A strategic location is chosen on a river or reservoir where a large amount of moving water can be captured. This is done by means of a dam or weir that controls the flow of water.

Water conveyance. The water is directed through a pipeline or conduction channel that guides the water to the hydropower plant.

Turbine activation. The water reaches hydraulic turbines through the pipeline, which are activated by the water flow.

Power generation. The turbines are connected to electric generators called alternators, which cause electricity to be produced when the water turns the hydraulic turbines.

Current transformation. The electricity generated in alternators is initially an alternating current (AC). This usually has a low voltage, so a transformer is used to increase its voltage and make it suitable for long-distance transmission.

Transmission and distribution. The electricity generated is transmitted over high-voltage transmission lines to the points where it is needed. Often, an electrical substation is used to reduce the voltage before distributing it to consumers.

Control and regulation. Hydropower plants are equipped with control and regulation systems that monitor and adjust water flow and electricity generation to maintain a constant and stable supply of energy.

Energy storage. Some hydropower plants have the ability to store water in a reservoir. This makes it possible to regulate water flow and electricity generation according to demand, which makes them a flexible energy source.

How a hydropower plant works

Hydropower is clean and returns water to its original course, but do you know how it works and what types of power plants exist?

In this video we show you everything you need to know about hydropower plants. Check it out.

Types of hydropower plants

There are different types of hydropower plants depending on factors such as the availability of water resources, the scale of power generation required, and geographical conditions.

Run-of-river hydropower plants

They harness the constant flow of water from rivers or streams, without using reservoirs. The water is diverted through a channel and directed through a pipe to a turbine that generates electricity. They are especially efficient and suitable for areas with constant flows of water.

Hydropower plants with a reservoir

Water is stored in reservoirs and the flow to the turbines is regulated. They can be large scale (traditional hydropower plants), or smaller in size. Reservoirs offer flexibility to adjust electricity production according to demand.

Pumped-storage hydropower plants

They are essential for storing energy. In periods of low demand they pump water from a lower reservoir to an upper reservoir using electricity. If it is high, water is released from the upper reservoir by hydraulic turbines. An example is the pumped-storage hydropower plant in Aguayo, Cantabria.

Bypass or channel hydropower plants

Instead of blocking the river with a dam, these plants divert part of the water flow through a channel to the turbines, allowing the river to continue its course. This minimizes environmental impact, although it reduces water storage capacity.

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Parts of a hydroelectric power plant

Although the configuration and size of a hydroelectric power plant can vary depending on the type of location, the main parts are:

Dam or weir. Structures that block the flow of water from a river or stream, creating a reservoir. Depending on their design, they are gravity, arch or buttresses.
Resevoir. A large resere of water created by the dam. It stores the liquid and regulate its flow towards the turbines.
Piping and ducts. The water from the reservoir is transported through pipes or ducts, which direct the current to the hydraulic turbines.
Turbines. The moving water reaches the turbines, which using their rotating movement, take advantage of the kinetic energy of the current to generate mechanical energy.
Generators or alternators. Hydro turbines are connected to generators or alternators that convert mechanical energy into electricity.
Engine house or room. The turbines, generators, and other equipment are housed in these buildings where plant operation is controlled and monitored.
Transformer. Transformers are responsible for increasing the voltage of the electricity generated, to facilitate its long-distance transmission.
Transmission lines. The electricity is then transmitted through high voltage lines, from the power plant to the consumption and distribution points.
Electrical substation. In some cases, an electrical substation is used to reduce the voltage before it is distributed for consumption.
Control and regulation systems. Hydroelectric power plants are equipped with control and regulation systems that monitor and adjust water flow as well as electricity generation to maintain a constant energy supply.

Benefits of hydraulic power plants

There are different types of hydroelectric power plants, depending on factors such as the availability of water resources, necessary generation scale, and geographical conditions.

circuito cerrado de energía eléctrica dinámica

Renewable energy source

Hydroelectric power plants use the water cycle, a renewable and environmentally friendly energy source. They do not emit polluting gases, which contributes to reducing the carbon footprint.

electricidad estática entre el pelo y un cepillo

Flood control

Dams can help control floods by regulating water flow to rivers and streams, being an important component in power plant safety.

energía electromagnética por medio de imanes

Energy storage

Power plants with reservoirs can store water, allowing them to adjust hydraulic energy production on demand. This makes them very useful for managing the intermittency of other renewable sources.

Grid stability

These power plants provide grid stability by supplying constant and adjustable hydraulic power, reducing the risks of blackouts and voltage fluctuations.

Long useful life

Hydroelectric power plants tend to have a long lifespan, allowing for long-term power generation with profitable initial investments.

Energy efficiency

They are highly efficient at converting kinetic energy into electricity, making them a safe energy source.

Supplying homes with hydraulic energy

At Repsol, we carry out outstanding work in the field of hydraulic energy, managing 3 hydroelectric groups comprising a total of 12 power plants located in the north of Spain, in regions such as Asturias, Cantabria, and Castilla y León.

With an installed capacity of 697 megawatts (MW), these power plants can supply diverse populations, from small communities to larger cities, guaranteeing a secure and sustainable energy supply in the northern Spain. To measure this capacity, 697 MW is equivalent to the annual consumption of all homes in Madrid.

These power plants represent Repsol's firm commitment to generation of clean energy and innovation in the renewable energy sector, contributing significantly to energy sustainability and the reduction of emissions in Spain.