Vattenfall has commissioned a group of entrepreneurs from Wieringerwerf in the Netherlands to produce 140 so-called ‘monopile covers’ for the Hollandse Kust Zuid offshore wind farm.
It is a new, circular product made of composite to seal the foundation piles for offshore wind turbines. The first 40 covers will be delivered in August, and another 100 the following year.
Over the next 2 years, Vattenfall will build 140 wind turbines just off the Dutch coast. This summer will see the installation of all foundations at sea. The foundation piles include electrical systems, work platforms and ladders for employees.
The top section features an entry where the pole of the turbine will eventually be placed. This entry must be tightly sealed during construction, and at the same time be easily and safely accessible for employees to carry out maintenance. Previously, steel or aluminium was used for sealing. However, the disadvantage of these materials is that they are not sustainable, because they require a lot of energy to produce and are scrapped after a construction project.
Vattenfall challenged its suppliers to come up with a sustainable, safe alternative.
“Think of it as a reusable composite hat,” Leo Theuws, director of Theuws Polyester, explains. “The cover we have developed consists of a number of composite panels that fit together like pie wedges. It features an access door and technical details for, among other things, cable entry etc. The panels are translucent, so that employees can work in daylight. During the construction of the wind farm, there is still no electricity available, and bringing extra batteries for lighting is a costly operation at sea. By inserting or removing panels, we can make the ‘hat’ bigger or smaller. When the construction of the wind farm is complete, we will take back the panels. These will then be reused in subsequent projects. The product is therefore completely circular and cost-effective.”
Prototype convinced Vattenfall
“A year ago, Vattenfall’s interest led to the foundation of CCM, Composite Cover Manufacturing, a consortium of four companies,” partner Wil Dinnessen, managing director at CCM, explains. “Theuws is responsible for the production and assembly of the monopile covers. CMM will provide all services on site and will take back all panels after construction to reuse them for other projects. Together with two other parties, we have built a prototype, partly financed from the ERDF programme ‘Kansen voor West en provincie Noord-Holland’ (Opportunities for West and the Noord-Holland region). Last summer we transferred a mock-up to the Maasvlakte. Here there is a test foundation at the terminal of Sif Netherlands, the supplier of the foundations. Using this foundation, we can simulate everything that happens at sea. Following optimisation, our prototype turned out to function excellently.”
The first to recognise the possibilities of this innovation was Piet Goverse, programme manager of the project ‘Valorisatie Hightech Sector Composieten NH’ (Valorisation High Tech Sector Composites Noord-Holland region). Development company NHN is the lead party for the EFRO project, in which twelve high-tech composite companies from the province of North Holland and six knowledge institutions work together.
“Piet brought us together to investigate whether a business case could be finalised,” says Wil Dinnessen, business partner of Leo Theuws. Wil is convinced that without a composite cluster, the project would not have existed in this form. “The cluster is the backbone of the collaboration, development and financing. Piet Goverse has also been a significant factor in the success. He was more or less the driving force, connector and lubricating oil of this project.”
The cluster has already noticed significant international interest, including from the UK and Taiwan.