A race has begun and is currently being led by Asian and European countries, although Uruguay is also taking the lead in advancing in the fight against climate change by installing offshore wind farms that will generate clean and cheap energy.
By Antonio D'Eramo
There are several factors that come together in the development of wind farms built on offshore platforms. It will suffice to point out some main considerations such as the irruption of the climatic emergency for which many nations have decided to put faith, decisively, in renewable energies.
This means a change in trend that will make it possible to exploit, on a larger scale, the natural and inexhaustible resources of planet Earth, such as the wind and the sea, reducing those traditional energy sources related to the production of carbon and gases that cause the greenhouse effect and end up harming and altering ecosystems.
Observing the sea, engineers can only imagine, and then design and build, huge windmills that companies in the energy sector don´t hesitate to present to society.
The impact of the size of windmills ‘blades is less than on land and, according to estimates, by the year 2035, 25% of wind turbines will be built on seawater and by that time in future, the current energy production will be tripled and costs will be reduced by up to 65%.
An example of this, is the mill designed by the Chinese company Ming Yang Smart-Energy that developed the largest offshore wind power generator known today. Each of the three blades that will form part of this prototype will be 118 meters long. The new model will generate 45% more energy than the previous prototype from the same company, which would increase the capacity to supply electricity to more than 20,000 homes for 25 years, which represents its useful life.
In Europe, meanwhile, Germany is one of the countries that is working best with the new methodology. Since the beginning of 2008, the European country has planned to build 30 huge offshore wind farms by the year 2030.
Another major consideration for working with windmills is to avoid dependency on foreign oil and gas. Germany's dependence on fossil fuel imports from the Caucasus and Russia is a compelling geopolitical reason for adopting this innovative technology.
The construction of these gigantic facilities that will change the appearance of many seas is full of challenges. Perhaps the example of the German project is sufficient to understand how this structure can be assembled without being destroyed by the sea.
Since 2010 there has been a technique that keeps the towers of the windmills standing in the middle of the North Sea. To move them away, as much as possible, from the coasts where they usually cause visual and noise pollution, the high seas “floating towers” technique has been designed.
Speaking to DW, Professor Finn Gunnar Nielsen, from the Norwegian company Statoil-Hydro, presented the original idea of floating windmills. Nielsen is an engineer for offshore platforms for oil and gas extraction, an expert in operations with heavy material on the high seas where the atmospheric conditions and the violence and depth of the waters in the North Sea are exhausting.
“The tower that supports the windmill floats on the water in a vertical position. The tower resembles a thin bottle about 100 meters long submerged in water and which gets thinner as it comes out of the water. Other than that, these windmills are just like any other, with a rotor and huge blades,” Nielsen explained.
The tower that supports the mill is filled with heavy material below sea level, while above it is filled with air that serves as an engine. The expert gave an example for a non-professional to understand, “the principle is comparable to a round cup that dances on a saucer but doesn´t fall because its own momentum always keeps it standing, even though it wobbles. By keeping the center of gravity very low and the center of buoyancy very high, a combination is achieved that results in stability.”
For this reason, the mills that have the tower´s point of gravity located very close to the base while the center of impulse is located about 300 feet above generate technical characteristics that make the tower practically impossible to knock down, even when the waves are very intense.
The mill designed by the Chinese company Ming Yang Smart-Energy has spectacular measures. In total, the tower, added to the blades, reach a height of 793 feet that will allow the generator to reach up to 90 GWh of electricity, a remarkable figure for wind power generation.