GROW side-event at the WindDays - Foundation Innovation presentations

Gentle Driving of Piles

Maxim Segeren (TU Delft)

The installation of offshore monopiles has become more challenging with the increase of the diameters of the piles. The goal of this project is to make the pile installation process as efficient as possible by means of testing a novel pile vibrator exciting two different modes of motion of the monopiles. We call the proposed method “Gentle Pile Driving” (GPD) for its envisaged capability to reduce the driving loads and the emitted, harmful for the environment, installation noise. A large experimental campaign which takes place this summer at the Maasvlakte II, where scaled monopiles will be installed using various installation methods, including the GDP method. The GDP project is the first GROW project and is coordinated by Delft University of Technology (TU Delft). Our project partners are Deltares, TNO, Innogy, Shell, Eneco, Van Oord, Boskalis, Seaway Heavy Lifting, DOT, SIF, IHC and Cape Holland.

The Slip Joint connection

Reinder Jorritsma (DOT BV) and Sander Suur (Van Oord)

The connection between a monopile and the tower of the wind turbine has caused some headaches in the past and the Slip Joint is the logical next step in the evolution of this interface. It works and looks like two paper cups upside down stacked on top of each other. The connection is based on friction, where the weight ensures a firm and stable connection. Installation is done by simply sliding the wind turbine over the monopile without the use of grout or bolts. This simple mechanism allows for cost reduction in material, equipment & personnel as well as allowing for a shorter installation time.

project 1: Slip Joint Offshore Research project (SJOR) 
As part of the SJOR project a slip-joint connection was deployed offshore for the first time in September 2018. Installation was done in less than an hour and operation of the windturbine started within 24 hours. The data required for a Design Method Certification is successfully gathered and decommissioning is planned for August this year.

project 2: Borssele V innovation site
Borssele V has been designated as an innovation site, situated within site III of the Borssele Wind Farm Zone. Several innovations are to be implemented in this 19MW wind farm. One of them being the slip joint connection that will be used to connect the monopile and transition piece. 

​​​​​​​Sustainable monopile decommissioning

Ahmed Elkadi (Deltares / TU Delft)

Currently, offshore monopiles are removed by cutting them off several metres below the seabed, which leaves behind tonnes of steel buried in the seabed. The Hydraulic Pile Extraction Scale Tests (HyPE-ST) project aims at developing innovative and smart technology to remove the entire monopile in order to make it possible to recycle the steel. The research will take place in the Deltares’ Water-Soil Flume facility in Delft, the Netherlands. Scaled monopiles will be tested on the possible use of water-pressure to fully retrieve them from the seabed. The tests will take place in different soil conditions such as sands with varying densities, clay, and layered soils. The project is scheduled to be concluded by the end of 2019. The HyPE-ST project is part of the GROW program and a joint industry initiative of innogy, Deltares, DOT BV, IHC IQIP, Jan De Nul Group and ECN part of TNO. The project has also received financial support from the Topsector Energy of the the Dutch Ministry of Economic Affairs and Climate.