Van Oord and Ecowende have signed a contract for the design, construction and installation of tree reefs and oyster hubs at Ecowende’s Hollandse Kust West wind farm (HKW, site VI) in the North Sea.
According to Van Oord, this is the first time tree reefs will be implemented on such a large scale in the North Sea, enhancing the biodiversity in natural way.
Tree reefs are circular, biodegradable reef structures made from discarded fruit trees, which are relatively sturdy and stable. The trees will be collected from the Dutch fruit cultivation sector and are usually cleared as soon as they start producing less fruit.
The tree reef concept was developed by the Royal Netherlands Institute for Sea Research (NIOZ), whose pilot in the Wadden Sea showed that the complex structure of fruit trees can offer marine life a highly valuable habitat.
A large North Sea tree reef is expected to create habitats for even more benthic and fish species, enhancing local biodiversity.
Van Oord and Ecowende will also collaborate on constructing oyster hubs at the wind farm.
This ecological innovation was developed in collaboration with Waardenburg Ecology. The hubs consist of adult oysters of varying sizes placed on designated cable crossings to serve as a source of oyster larvae.
The wind farm will function as a connection site, stimulating larval distribution to otherwise isolated locations and facilitating the colonisation of new areas. Van Oord has already installed oyster hubs successfully at multiple offshore wind farms, such as Borssele 1 and 2 and Luchterduinen.
“As a partner of Ecowende, Van Oord is excited to bring innovative solutions such as Tree Reefs and Oyster Hubs to the Hollandse Kust West wind farm. This marks a significant step in our commitment to not only delivering sustainable offshore infrastructure but also enhancing biodiversity in the North Sea,” said Karen Vennik, Commercial Director for ƶijϻ Energy and Ocean Health at Van Oord.
Van Oord plans to install the tree reefs in 2026 on four cable crossings in the Ecowende wind farm, with approximately 1,000 trees forming the reefs. They are expected to biodegrade underwater within 10 to 20 years, gradually being replaced by natural reef-building species.
The Oyster Hubs will be installed in 2026 or 2027 on three cable crossings.
Ecowende’s partner Waardenburg Ecology will measure and monitor the effects of these two innovations.
The Ecowende wind farm (Hollandse Kust West Lot VI) will be located about 53 kilometres off the Dutch coast, near IJmuiden.
The wind farm will have an operational capacity of 760 MW, making 3% of the current Dutch electricity demand greener.
Ecowende plans to have the wind farm fully operational and commissioned by late 2026.