The foundation of a wind turbine
The foundation for the wind turbine is built as a steel structure on four piles – a robust solution when an earthquake shakes the subsurface.

Offshore jacket design

Offshore wind turbines must withstand typhoons and earthquakes in Taiwan

Many new offshore wind farms are soon to be constructed in Taiwan and at these latitudes the turbine foundations must be able to withstand severe earthquakes and yearly typhoons.

When an earthquake shakes Taiwan, the seabed transforms into something resembling quicksand. The island state is located in a typhoon belt and has regular visits from violent wind forces. To build offshore wind turbines, which can withstand this kind of natural phenomena, is rand new in the field of offshore wind and requires special constructions, which ensures that the turbines stand firm – even when a layer of up to twenty metres of seabed is “liquid” and typhoons shake the turbines.

One of the solutions is called a jacket and it is a foundation built like a grid construction of steel resting on four piles. In relation to a foundation with only one pile – a monopile – a jacket is much more robust in relation to the size of foundation at greater depths and specific types of subsurface. A jacket is also used in Europe, for example, in very deep water.

Taiwan is the front runner in offshore wind turbines

Not only is there speed in the wind in the Taiwan Strait. New powerful winds are also blowing in the development of Taiwan’s energy sector. The island state’s nuclear power plants are to be replaced with, among other things, wind energy, and as the front runner in Asia, Taiwan is developing many wind farms. In one of the parks, NIRAS’ jacket design foundations will form the foundation piles for initially two offshore wind turbines.

NIRAS is behind the so-called detailed design – in other words, a design so detailed that it can be used to manufacture structures at the supplier. There is a comprehensive analysis of wave and current conditions prior to the detail design, as well as designing models of the seabed. If all goes according to plan, the blades on the new offshore wind turbines will rotate and supply power to Taiwan at the end of 2018.