We are primarily tasked with providing power transmission services, system services and facilitating the energy market. Our core tasks follow from our appointment as grid operator under the Dutch 'Elektriciteitswet' (E-wet) and the German 'Energiewirtschaftsgesetz' (EnWG).
The necessary energy transition brings us many challenges. For TenneT this means, for example, expanding and reinforcing its grid in order to maintain high security of supply. At least 3,000 kilometres of (underground) cable must be laid in Germany and the Netherlands in the next 10 years. We want to carry out this work with as little impact as possible on the environment: people and (vulnerable) nature.
Undergrounding of cables by means of drilling can be a good solution. This is currently only possible over a limited length. Together with our contractors, we want to develop the techniques further and investigate in the Netherlands which maximum horizontal drilling lengths are possible in order to realise connections faster and with less inconvenience to the surroundings. The aim is to further develop our construction techniques for underground cable routes to minimise the impact on people and the environment.
Open excavations like this cause a lot of inconvenience. With horizontal drilling, this is prevented as much as possible.
Together with various market parties, we have successfully worked on possible solutions in recent years. Together with cable supplier Prysmian and contractor Heijmans, various techniques have been studied that should make horizontal drilling possible up to a maximum of 5 kilometres in one go. The major advantage is that the use of these techniques causes less inconvenience to local residents and routes are often shorter. Not only can the work be done more quickly than open excavation, it also places less burden on nature and the landscape. Permit procedures are also expected to be shorter.
The study of various drilling techniques shows that there is no "holy grail" in the field of innovative drilling methods for long distances: The various aspects of each situation, such as the environment and the soil , as well as the diameter of the cable, must be considered in order to apply the most optimal drilling technique. And also consider aspects such as accessibility of the cable in the event of failure, the diameter of the cable (and therefore the size of the reels), the transport of cables and conduits and the manufacture of conduits on site.
In 2021 TenneT will start testing the E-Power-Pipe method developed by Herrenknecht for the first time. This method makes it possible to drill a distance of 2 kilometres in one go. A length that counts as a prelude to the desired 5 kilometres. The main advantage of this technique over other drilling techniques is the repair time. This is due to the shallow location of the cable of two to three metres below ground level, in contrast to cables that are now often 5 to even 25 metres deep (depending on their length). Because of its shallow location, the cable is much easier to approach and can be repaired within two weeks. As a result, the potential maintenance costs are significantly lower. The pilot of this technique will be used in the project Tilburg Noord - Best.
Watch the animation by Herrenknecht
Watch the animation on the website of Herrenknecht if you are curious how this works. The implementation of the pilot project in Tilburg Noord-Best is expected to start in October 2021. This will be the first time in the Netherlands that such a length will be drilled underground, using this technique.