When we speak of offshore wind we refer to the wind farms that are established in the sea, a park that aims to get electricity thanks to the force of the wind. It consists in taking advantage of the wind speed to obtain energy by placing the wind turbines in the sea, where the speed is more constant and productive. Specifically, it is the different atmospheric and temperature pressures that may be present in different areas of the sea that cause wind currents.

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Advantage.

One of the most striking aspects of wind energy is the frequency of the wind since in the high seas it usually increases by 40% and they are much more regular than on land. This implies that offshore wind energy is much more productive than onshore wind farms.

Another advantage of the wind farm at sea is that it is much easier to move wind turbines by boat than in trucks and trains due to the large dimensions of each of its parts (weather vanes) and weight.
In addition, among its advantages, we can also mention the lower landscape and visual impact produced by offshore wind farms (they must be at least 3 kilometers from the coast).
It is a renewable energy that produces electricity and energy thanks to the kinetic energy produced by the wind. In addition, it does not produce polluting residues that are then emitted into the atmosphere.

On the other hand, by placing wind turbines in the sea all problems are avoided so that the wind energy reaches these generators. These problems can be due to geographical accidents (hills, mountain range, etc) or to the effect of man (buildings, constructions that can obstruct the correct passage of the wind towards the wind turbines.

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Offshore wind farms also help in the conservation of bird species since they are not usually as dangerous for migratory birds as traditional terrestrial wind farms.
Finally, note that the surface of the sea is 3 times larger than the land on our planet. The space to build marine electric mills is immense, without the need to "invade" rural areas.

According to Greenpeace, and supported by many other associations, with this energy in Spain could generate 25,000 MW of power until 2030, thus avoiding an approximate emission of 25 million tons of CO2 per year.

The unit power of wind turbines in the sea is higher than that of turbines on land. While on land, due to limitations associated with orography and transport, unit powers have been consolidated in the vicinity of 3 MW for wind turbines, with a clear tendency to increase the rotor diameter for a better use of the sites; At sea, new developments of offshore wind farms are composed of unitary powers of more than 5 MW, with prototypes of up to 10 MW of power.

Disadvantages.

The great disadvantage of offshore wind farms is the construction costs, as it increases the difficulty, which can mean that costs are increased twice as much as what would be installed on the land in spite of having the same capacity.

Another disadvantage is that this type of renewable energy is still in progress, we could say that it has not yet matured and little by little new technological advances are known that can mean big changes in the facilities that will make them much more viable.

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It is not yet known for sure, but it is possible that the turbines and the noise of the processes to obtain wind energy cause changes in the ecosystems of the area. This can be good in the case of birds that avoid this type of construction but also have negative aspects, by causing the migration of aquatic species that lived in the area where the wind turbines have been installed.

Little by little, we have to start to trust even more in renewable energies so that both their study and their use can be strengthened.

The cost also increases due to the need to build a system of "wiring" under the seabed that is capable of carrying the energy provided by marine wind turbines to the coast.

Floating wind turbines.

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This system would facilitate the installation of mills beyond the coastline, and even beyond the sea zone visible from land, more than 50 km. Simply "letting them fall" in sufficiently deep waters remain stable and afloat. It is precisely the water pressure in the submerged counterweight that counteracts the force of the wind that is produced against the blades of the wind turbine, balancing the assembly to avoid the loss of efficiency in the conversion of wind power into electricity.

The installation of offshore turbines, in addition to hiding them in view, is more effective than on land since the roughness of the sea in general is lower than that of even flat terrain; This feature allows offshore wind turbines of lower height and / or greater efficiency to be installed in proportion to those installed on the mainland.

By the way, you could even do a two for one and take advantage of the strength of the waves or tides to generate electricity.

References.

• https://en.wikipedia.org/wiki/Floating_wind_turbine
• https://news.nationalgeographic.com/2017/10/wind-farm-renewable-energy-scotland-video-spd/
• http://gwec.net/global-figures/global-offshore/
• https://www.americangeosciences.org/critical-issues/faq/what-are-advantages-and-disadvantages-offshore-wind-farms
• Wind Energy Handbook, Ervin Bossányi.
• Energy Resources and Systems: Volume 2: Renewable Resources, Mark A. Prelas, Tushar K. Ghosh.