New method makes long horizontal drilling possible

In a pilot, a long horizontal tunnel was created using the E-Power-Pipe drilling method at a depth of approximately 2m for part of the Tilburg Noord-Best route in the Netherlands. The project involves placing the 150kV aboveground connection underground.

The E-Power-Pipe method, developed by Herrenknecht, makes it possible to drill a distance of around 2km in one go, and at a shallower depth than the usual 5 to 25m. The new method’s shallow depth means the cable is much easier to approach and any repairs can be carried out more quickly. As a result, the security of electricity supply is considerably higher and maintenance costs lower. In addition, TenneT says, the E-Power-Pipe causes less disruption to the surroundings.

“In recent years we have been working with the market to find alternatives to the existing construction methods for a high-voltage connection,” says Hans van Tol, project manager at TenneT. “One of the results is this method, which enables us to drill horizontally in one go for up to 5km in the future. This causes less inconvenience for local residents and routes/tracks may be shorter. Thanks to this method, we put far less strain on nature and the landscape, and the work can also be done faster than with open excavation, for example.”

The new method provides promise for future work. “At least 3,000km 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: city, people and vulnerable nature,” says TenneT innovation manager Bas Swinkels. “The rapid undergrounding of existing and new connections using this new method can be a good solution and has potential for the future.”

TenneT worked with the contractor Heijmans and the cable supplier Prysmian to study various drilling techniques over long distances. The study ultimately led to a system design for underground drilling, with associated cable and the E-Power-Pipe drilling method.