25 November 2022

Tidal energy or how to generate electricity with the movement of the tides

Have you ever heard of tidal energy? Today we are going to tell you everything about this great unknown among renewable energy sources.

URLREPLACE

Enlace copiado

Turbinas mareomotrices funcionando con la corriente del mar.

Everyone has now heard of renewable energies, but very few of us know what tidal energy is. The most surprising thing is that, despite not being widely known, this type of energy has been in use since the 1960s.

Tidal energy - also known as ocean energy - is a clean and renewable energy source that harnesses tidal movements. This was used in the past to operate grain mills in Europe. But now it is being used to generate electricity in a responsible way.

The first tidal power plant was opened in France in the 1970s in the estuary of the river Rance. This plant had the highest production of this type of energy in the world until 2012. The Sihwa Lake power plant in South Korea has now taken over top spot. However, Britain is the leading country in this field, because of its great potential, producing half of all the tidal energy generated in Europe.

Spain has the Magallanes Project at Redondela in Galicia. This is a platform floating on the sea that is connected by a mast to a gondola. Hydro turbines then take advantage of tidal currents to convert them into electricity. There is also a plant in Gipuzkoa using the power of the sea to generate electricity. However, this is not tidal energy, as the electricity is generated from the waves themselves, rather than the tides.

This is the main difference between tidal and wave energy. These are not the only marine renewable energy technologies. There are also technologies such as floating photovoltaic, and floating and fixed wind technologies.

Marine renewable energy technologies.

Marine renewable energy technologies

Floating photovoltaic
Wave energy
Tidal energy
Floating wind
Fixed wind

Source: European Commission

Accessible version

Of these, wave energy is the most similar to tidal energy. But, while wave energy is generated from the movement of waves, which occur on the surface of the sea, tidal energy is due to the movement of the tides, regular movements of enormous masses of water caused by the gravitational forces of the sun and moon.

How does tidal energy work?

Tidal power plants can transform tidal movement into electricity through the principles of kinetic and potential energy. These underwater facilities must meet some very specific geographical conditions for this. In general, they need to be located in estuaries or bays where there is a difference of at least 5 metres between the highest and lowest sea levels.

These power plants have turbines and alternators that generate electricity from the rotation of their blades and through the circulation of the water. There are currently three types of power plants for producing tidal energy:

Tidal stream generator

Tidal stream generators harness the kinetic energy of moving water in a similar way to turbines.

Tidal stream generator

Tidal stream generators harness the kinetic energy of moving water in a similar way to turbines.

Tidal stream generator

Tidal stream generators harness the kinetic energy of moving water in a similar way to turbines.

Tidal barrages

Tidal barrages exploit the potential energy in the rise and fall of tides.

Tidal barrages

Tidal barrages exploit the potential energy in the rise and fall of tides.

Tidal barrages

Tidal barrages exploit the potential energy in the rise and fall of tides.

Dynamic tidal power

Dynamic tidal power (also known as DTP) is a mixture of the previous two.

Dynamic tidal power

Dynamic tidal power (also known as DTP) is a mixture of the previous two.

Dynamic tidal power

Dynamic tidal power (also known as DTP) is a mixture of the previous two.

The advantages of tidal power, like other renewable sources, are that it is clean, practically inexhaustible and environmentally friendly, as no harmful gases are emitted. These facilities also have very long useful lives. Some - such as the one in the estuary of the river Rance we mentioned earlier - were built half a century ago and are still operating perfectly. A final advantage is that - unlike renewable sources such as wind - the tides are highly predictable, which is really useful for estimating the power each plant can produce.