Seaqualize tool helps floating ships to install wind turbines in deep water

Seaqualize is developing the Delta600p. This active heave compensation tool dampens the movement of a load hanging in the hook of a heaving ship. As a result, wind turbine installation can be performed by floating ships instead of jack-ups and is less restricted by weather conditions and water depth.

The company is to receive an investment of 350,000 euros from investment fund UNIIQ and Rabobank for further development of the tool. The funding will enable the company to prepare the tool for the first practical tests. Seaqualize is thus building the world’s first active heave compensator for 600mT that can be flexibly suspended in a crane hook.

Using floating ships for deeper water

In order to make wind energy profitable, there is a continuous effort to increase the capacity of a wind turbine. Whereas in 1990 a wind turbine was about 50 metres high and supplied 0.5 MW, in 2020 a wind turbine will measure 175 metres on average and supply about 10 MW. For wind turbines of this size, it makes sense to move from land to sea to build wind farms.

Nowadays, this is happening more and more often and further from the coast, in ever deeper water. This brings challenges, as large and heavy wind turbine components must be installed in all types of weather. The heaving (going up and down) of the ship is an important factor in this respect, which significantly limits the number of days in which installation can be carried out. In addition, this also affects the safety of the installation as a whole, where many people still have to perform actions on site.

At the moment, installation is usually carried out from a jack-up, a special ship that can stabilise itself above sea level by means of extendable legs. There are limitations to these jack-ups, because they can only be made stable in certain soils and to a maximum water depth. The places where you can then go are not sufficient for all sustainable energy ambitions. Therefore, the market is looking for ways to also use floating ships for this work.

Also read: Construction kicks off for Jan De Nul’s new 5000-tonne crane vessel

Control over crane load

The Delta600 is attached to the crane’s hook. By using adapted spring technology in a smart way, the tool is able to neutralise movement with minimal use of energy. In this way, a delicate load from a floating ship can be lowered onto a platform very carefully and in a controlled manner, for example, or picked up from a supply ship.

This control over the load can increase the number of days in which installation can be carried out by 20 to 50%. This saves time when constructing a wind farm and therefore money for the contractor and other parties in the chain. This additional load control is an important step towards the safe floating installation of wind turbines.

Watch a video of the system’s black load test below. The embodiment was pressurised to 110 per cent safe working load (SWL) for DNV surveying purposes. This was done in two positions: fully extended and retracted. The movement you see in the video is exactly how the tool behaves when it is actually compensating heave in the crane hook of an offshore heavy lift vessel.

Author: Mariska Buitendijk

Mariska Buitendijk is one of SWZ|Maritime's journalists as well as the magazine's copy editor.