Sustainable and low-cost installation of monopile-foundations for future very large wind turbines

Within 5 years, the GROW research project SIMOX (Sustainable Installation of XXL Monopiles) aims to have innovative technologies for the installation of large wind turbines commercially available. By testing multiple techniques, SIMOX will develop new and necessary technical and environmental knowledge. Such techniques must enable the installation and decommissioning of XXL monopiles for very large offshore wind turbines in a sustainable, cost-effective, societally and environmentally acceptable manner. At the beginning of February, the Netherlands Enterprise Agency (RVO) decided to support this project. The participating companies are investing 2 million euro in this project and the government is contributing 4 million euro.

Current installation methods for monopiles face major barriers for future large monopiles. The dominant method used now to drive monopiles into the seabed is the hydraulic impact piling (hammering). The major disadvantages of the impact driving method are the generation of underwater noise that can be harmful to marine fauna and inapplicability of the method to piles extraction at the end of their service time.

Alternative installation technologies are being researched, developed, and tested at various Technology Readiness Levels (TRLs). However, none of these technologies has reached a TRL that makes it a preferred/ready solution for the installation of future XXL monopiles (with a diameter bigger than 7,5 and up to 11 meter that weigh from 1000 to 2400 tonnes) under a broad range of soil conditions. With a better understanding of their performance and a validation of the underlying models, the development of these technologies can be enabled, which should ensure that offshore wind remains one of the lowest-cost, electricity generation options.

Research of multiple alternative technologies in one project

This unique project will study and test various alternative technologies and aims to bring the required knowledge for these options at the same level. The techniques that are included are:

• Conventional vibratory driving, e.g. vibratory driving with a purely vertical excitation; an enhancement of this technology by means of introducing fluidisation of the internal soil column in the pile will also be tested.
• Gentle Driving of Piles: a concept which is an emerging technology that combines a vertical vibratory excitation with a high-frequency torsional shaking.
• Blue Piling, a modification to the conventional impact driving which reduces noise, will be included in the modelling of driveability and noise prediction, based on data generated outside of SIMOX.

Key topics of research are driveability, environmental and ecological aspects (with a focus on underwater noise during pile driving), and bearing capacity of the soil. Finally, the implications for decommissioning at the end of the monopile service life will be assessed.

The three-year SIMOX project is part of the GROW program and is led by the team of Prof. Andrei Metrikine of the Delft University of Technology. Deltares and TNO will also take active part in research and test campaign. The offshore contractors Van Oord, Boskalis and Seaway7 will lead the on- and nearshore tests, supported by DOT (Delft Offshore Turbine), whereas equipment manufacturers Sif, IHC IQIP, CAPE Holland and GBM Works will provide the monopiles and installation technologies. Operational aspects will be monitored and assessed by Shell, RWE and Siemens Gamesa Renewable Energy. Finally, the project will involve environmental and regional economic stakeholders in an early stage.

David de Jager, director of GROW: “SIMOX is unique in its comprehensive approach to understand and assess multiple technologies under similar, controlled conditions. Tests with scaled monopiles will be performed in laboratories, at two onshore sites and at a nearshore site. This is also a good example of how the GROW consortium wants to (co)operate: a joint effort to tackle a challenge that is relevant for the offshore wind industry as a whole.”

 About SIMOX and GROW

The Sustainable Installation of XXL Monopiles research project (SIMOX) is a Joint Industry Project and supported by funds from the MOOI scheme. The subsidy scheme, which is covered by the TKI Wind op Zee, part of the Topsector Energy, is managed by the Dutch Ministry of Economic Affairs and Climate. Project partners are Boskalis, Delft Offshore Turbine, Deltares, Royal IHC, RWE, Seaway7, Sif Netherlands, Shell, TNO, TU Delft and Van Oord (all part of the GROW consortium), and CAPE Holland, GBM Works and Siemens Gamesa Renewable Energy. SIMOX is a GROW project. GROW is a joint research program that initiates research and accelerates innovations in offshore wind (www.grow-offshorewind.nl).