Installing tidal power turbines in Dutch eastern Scheldt

Working with Tocardo Tidal Turbines, a producer of tidal and free-flow water turbines, Mammoet carried out the transportation and installation work for this renewable energy project at the Easter Scheldt storm surge barrier (Oosterscheldekering). The project, known as OTP2, comprised five tidal turbines in a steel structure with a total weight of 500 tons.

The project raised a number of installation challenges for the teams involved. As this is a flood defense barrier it was not possible to drill into its columns. So Mammoet worked with Huisman Engineering on a way to precisely secure the structure in place using a pull-rod clamped onto each column. To complete this solution a coupling jaw was placed on each column to guide the TPP into place. This approach allowed a safe, swift and efficient installation.

The TPP’s steel construction was engineered and built by Huisman. On 17 September the 50-meter long and 21-meter wide structure was transported by Mammoet, mounted on 24 axle lines of self-propelled modular transporters on two coupled barges via water from their fabrication point at Schiedam to Neeltje Jans for installation. At Neeltje Jans, the steel unit was maneuvered into place ready for installation. With just one and a half hours of installation time available, as the teams raced against the tide and currents, it was essential to have everything prepared to install the structure between two pillars of the barrier as soon as the current allowed.

It was not possible to use conventional anchors due to concerns about damage to the seabed. The double barge also needed to be moored at a safe distance of about 30-meters from the surge barrier due to strong currents. Mammoet designed a special mooring system for this project using the remaining anchor points from the original installation of the storm surge barrier 30 years ago. With extra buoys in place to ensure the anchor lines would not touch the seabed, the preparations were complete.

The installation was successfully executed on 24 September. In the one-and-a-half-hour time span available Mammoet carefully maneuvered the double barge from its anchor points toward the barrier using winches, secured its position and hung the TPP on the pull-rods. The partner companies are now able to complete the necessary work for the TPP to be fully operational and commence generating their first tidal energy.