Offshore wind turbines tested on land at Østerild Test Centre

Monday 09 Oct 17

In Denmark, we have 13 offshore wind farms placed all over the country

At the National Test Centre for Large Wind Turbines at Østerild, several offshore wind turbines are being tested on land. But why do we test offshore turbines on land? Get the answer here.

There are two types of wind turbines: onshore and offshore wind turbines. As the name suggests, onshore wind turbines are located on land, while offshore wind turbines are located at sea

At Østerild Test Centre, wind turbines measuring up to 250 metres from the ground to the topmost blade tip are being tested. Thus, the centre is currently the only place in the world where test can be made on giant wind turbines.

At our latitudes, the largest wind turbines are mainly located at sea, but the testing must take place on land for several reasons:

  • The producers must constantly be able to measure and adjust the prototypes, and to replace the long blades or other large wind turbine components with the help of large cranes.  Therefore, there must be room for cranes, trucks, and wind turbine components around the wind turbines. Each wind turbine requires a working area of up to 150 times 100 metres.
  • The wind conditions at sea are not suitable for testing wind turbines. It must be done on land with the proper turbulence and roughness in wind turbines’ wind field.

Why wind turbines on land?
It is windier at sea than on land. On average, it is estimated that an offshore wind turbine can produce approx. 30 per cent more energy than an equivalent onshore wind turbine. However, onshore wind turbines located in the best coastal areas have a production comparable with offshore wind turbines. Offshore wind speeds are more constant than onshore wind speeds, and there is less turbulence. Even though offshore wind turbines produce more energy, the pressure is less than on onshore wind turbines.

Why do we even install onshore wind turbines then? The reason is that the costs of installing offshore wind turbines are much higher than the costs of installing similar onshore wind turbines, among other things because the foundations must be able to withstand major impacts from waves and ice.  It is also much more difficult and hence more expensive servicing offshore wind turbines.