The Borssele Wind Farm Site V, part of a new sustainable energy zone, consists of two turbines and is now fully operational. The two wind turbines play an important role in demonstrating innovations for the offshore wind market. The consortium was given a unique opportunity to jointly test and demonstrate advanced novel technologies in the field of wind energy.
For developers of commercial offshore wind farms, the potential benefits of large innovations are often diminished by the perceived risk of these innovations. Erik de Boer, Managing Partner Investri Offshore: “Therefore, Borssele V presents an important and unique opportunity to display commercial and technical proof of concept of novel, innovative wind energy solutions in offshore conditions, while simultaneously contributing to the decrease of Levelized Cost of Energy (LCoE) of offshore wind energy.” The innovations tested under operational circumstances are now proving themselves in offshore practice and therefore present a more manageable risk to investors.
The Borssele Wind Farm Site V
This site has been designated as an innovation site within the Borssele Wind Farm Zone. However, it is not only a test site; Borssele V will also provide sustainable electricity to 25,000 households. Vandebron, a Dutch energy company, will be the off-taker of the produced energy of Borssele V.
The following innovations are demonstrated at Borssele V:
1. Slip Joint
The Slip Joint is an alternative connection between a monopile and a turbine. The connection is based on friction, without having to use grout or bolts. Installation takes place simply by sliding the wind turbine’s foundation elements over the monopile. It works the same way as two upside-down paper cups stacked on top of each other and provides a fast, simple and safe installation solution combined with reduced maintenance requirements.
2. Oval cable entry hole
A Cable Protection System (CPS) is used to protect electrical cables when pulled in the wind turbine through entry holes in the foundation. Optimisation of both the entry hole dimensions (by the implementation of an oval design instead of the traditional round holes) and the Cable Protection System, reduces stress concentration in the monopile wall resulting in reduced steel usage in the section of the foundation.
3. Eco-friendly Scour protection
Offshore wind farms in the North Sea can make an increasingly large contribution to biodiversity targets, restoring ecosystem functions and improving ecosystem services. In that respect, innovation site Borssele V is a great example: it offers the opportunity to gather knowledge about best practices in the development of oyster reefs.
The seabed surrounding the two Borssele V wind turbines is fitted with eco-friendly Scour protection. Oysters are placed on the protective layer of rock on the seabed to stimulate biodiversity and to provide a natural habitat for aquatic wildlife. In addition, the team wants to gather knowledge on the life stage in which the European flat oyster can best be introduced on scour protection. When do we have the best results? When we place oyster seed, juvenile and adult oysters or a combination of all?
With the Eco Scour research program and the placement of eight new offshore reef structures, the research team hopes to increase their understanding of the large-scale development of oyster reefs in the North Sea.
4. Thermally Sprayed Aluminium (TSA)
Currently, most metal structures used in the offshore wind industry are protected against corrosion using a conventional paint system and therefore have a lifespan of 25 years. Thermal Sprayed Aluminium (TSA) is a novel coating technology. It can be applied to a metallic surface in a similar way as paint while the characteristics are much more durable and thus ensure a design lifespan of more than 35 years. To reduce the cost price of this technology, an automated and controlled system to faster apply TSA on monopiles is successfully developed for Borssele V.
5. ICCP optimisation
The Impressed Current Cathodic Protection (ICCP) systems are manufactured and installed as a long-term solution to corrosion problems. Internal corrosion of a foundation can significantly reduce the structural lifetime if not properly mitigated. ICCP is an effective way to achieve proper mitigation of a foundation. ICCP systems work by supplying a controlled direct current to the underwater surface. This current, monitored continuously by zinc reference electrodes, is automatically adjusted by the system itself to prevent corrosion. The ICCP system guarantees the correct degree of protection/mitigation, as the system adapts rapidly to the conditions present and continues to offer optimal protection.
Borssele V provides the opportunity to prove in daily practice that these innovations meet the requested user standards. The consortium Two Towers consists of Investri Offshore, Green Giraffe and Van Oord. Borssele V has proven that, with all its innovations, it is at the same level of safety as a regular offshore wind farm. Therefore, it is expected that the demonstrated innovations will set a new standard for future foundation designs.