Wind Energy
January 8, 2021


In the Norwegian North Sea, the energy company Equinor is building the largest floating offshore wind farm: Hywind Tampen is also a pilot project for offshore wind power industry, using concrete SPAR buoys. This technology is based on post-tensioning to ensure optimal resistance and durability of the structure.

Installed west of the city of Bergen, the 88 MW floating wind project is designed to supply electrical power to the nearby oil and gas platforms.
With 11 turbines, it will be the world’s largest floating offshore wind farm and a pilot project for the offshore wind power industry using concrete SPAR buoys. This technology is adapted to deep waters and allows to place the wind turbines far from the coast, where the wind is faster and steadier.
The use of concrete and the optimized construction process, with almost no maintenance, have allowed SPAR buoy foundations for offshore wind turbines to emerge as an efficient solution for deep water sites.

Vertical post-tensioning tendons for the Hywind Tampen project

VSL is contributing to this world-first: the company is responsible for the post-tensioning works of the semi-submersible concrete structures, consisting of tendons with up to 85m in length, installed offshore with no access along the cables.

In a harsh environment where the wind towers are subject to extreme loads imposed by the wind and the ocean (waves, currents, drifting ice blocks…), post-tensioned concrete offers optimal resistance and durability.

An optimized construction process

To speed up the installation on site, the post-tensioning tendons will be fully prefabricated by VSL and delivered to site ready for installation. With no access along the vertical tendons, all the post-tensioning operations will be done from the top of the concrete hulls including grouting in a single operation without intermediate steps.

The works should be completed during the autumn 2022.

Mathieu Guilé, Civil Works Business Development Manager
Josep Fabra, Business Development Manager for Wind Energy