Offshore wind energy is currently one of the fastest growing renewable energy sectors. In 2022 alone, new wind farms with a capacity of approximately 9 GW were launched around the world, thanks to which the global potential of offshore installations increased to over 64 GW.
Today, nearly 20 countries have their offshore windmills. Apart from China and Europe, projects are being developed in Japan, Taiwan, Vietnam, South Korea and the USA. Other countries also have ambitious plans in this regard, including India, Brazil, Colombia, Australia, New Zealand, Canada and the Philippines. In total, there are almost 15,000 wind turbines operating on approximately 300 offshore farms. Soon, such installations will also be built in the Polish part of the Baltic Sea.
It all started in 1991, when 11 turbines of the world's first offshore wind farm, Vindeby in Denmark, started operating. The investment had less than 5 MW of total installed capacity, which allowed to meet the annual energy needs of only about 2,200 households. A lot has changed since then. Today's offshore windmills have 30 times more power and are higher than the Palace of Culture and Science in Warsaw.
| Vindeby wind farm from 1991 | The largest modern offshore farms | |
| Power of a single turbine | 0,45 MW | 15 MW |
| Rotor diameter | 37,5 meters | 236 meters |
| Tower height | 54 meters | 280 metres |
| Power utilization factor | 22% | More then 60% |
| Average annual production | 9.61 GWh | 80 GWh |
Specialists have no doubt that the future belongs to offshore. The main argument for this is the constantly increasing demand for electricity. In the European Union alone, the demand for it will more than double by 2050 - from the current 3,000. TWh up to 6.8 thousand TWh. Wind energy will play a key role in this transformation. Today, wind accounts for only 16 percent. Europe's energy mix, but by 2050 this percentage is expected to increase to 50%.
This technological revolution will be supported by the increasing efficiency of offshore wind farms, but also by increasingly lower investment costs. Since 2012, they have fallen by 63 percent in Europe. This means that the expenditure on new offshore installations is in most cases lower than the costs of newly built coal and gas power plants. Moreover, the resources of offshore wind energy are almost unlimited. A 2019 report by the International Energy Agency found that offshore wind had the potential to generate more than 420,000 TWh per year. This is 18 times more than the current global demand for electricity!
What do offshore wind farms look like?
An offshore farm is a complex organism consisting of many elements. The most important of them include: a set of wind turbines of various numbers located in a given water area, power and telecommunications networks and power stations.
Wind turbines are placed at sea according to a specific pattern, creating an orderly grid. It includes, among others: distance between windmills. It must be not less than seven or eight times the diameter of the rotor. This is when production is most effective.
Construction of a windmill
A typical, single wind installation includes:
- foundation,
- tower,
- gondola with rotor and generator.
Element parameters:
- Weight – over 2,000 thousand tone
- Length – over 100 m
A foundation is a structure located below the surface of the water. It can be made using several technologies, depending on the distance from the shore and the depth of the sea, as well as the geological structure of the seabed.
The most popular solution in the world is monopile foundations. They consist of steel cylinders directly driven to a depth of up to 50 meters into the seabed. This structure is characterized by relatively low costs and ease of use in areas where the water is quite shallow (usually 20-30 meters deep).
Element parameters:
- Weight – over 1,000 tons
- Length – over 200 m
The tower is a structural element of a wind power plant on which the rotor, gondola and generator are mounted. Its size (height and diameter) depends on, among others: on the turbine model and wind conditions. The diameter of the tower is larger at the base and can reach 20 meters, while near the gondola it reaches 4 meters. Towers are most often made of steel or concrete. They are mounted using a connector (transition element) on the foundation.
Weight approx. 600 tons with:
- rotor – blade length – approx. 110 m, weight approx. 20 tons,
- generator.
A key structural element of a wind power plant responsible for converting kinetic energy into electrical energy. The mechanism is very simple. Under the influence of a gust of wind, the windmill blades begin to move, and the kinetic energy is transferred to the rotation of the rotor. Then, through the shaft, it goes to the generator, which turns it into electricity.
