Related projects

Gentle Driving of Piles 1.2 (GDP1.2) 

JUNE 2021 - SEPTEMBER 2023 

This project is complementary to the GDP1.0 project (TEHE117100). The GDP1.2 project is an important step towards the final goal of the whole GDP projects chain which aims at creating a commercial GDP product. Even though GDP1.0 tests were concluded to be very successful, there are a number of questions that should be answered before starting the design, manufacturing, and certification of the full-scale GDP shaker for offshore applications. The questions that will be answered in the framework of the GDP1.2 project are (i) is the GDP technique as effective in clay as it has been demonstrated to be in the sand?; (ii) can the power consumption of the GDP shaker be significantly reduced by independent variation of the amplitude and frequency of the shaker?; (iii) can the choice of the optimal frequencies and amplitudes of the GDP shaker be automated so as to become self-tuning? The aim of the GDP 1.2 project is to answer these questions in order to get a step closer to the final product. 

Sustainable Installation of XXL Monopiles (SIMOX) 

JUNE 2021 - MARCH 2024 

Monopiles are by far the most commonly used foundations for offshore wind turbines in the North Sea and it is expected to remain so in the future. Monopiles are straightforward to fabricate, relatively inexpensive to manufacture, use less space on transport vessels, and are reliable. The dominant method used now to drive monopiles into the seabed is hydraulic impact piling (hammering). The big disadvantage of the impact-driving method is the generation of underwater noise that can be detrimental to fauna and the method is not suitable for extracting piles again at the end of the lifetime. 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 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 for the North Sea.

Gentle Driving of Piles 2.0 (GDP2.0) 

October 2023 - October 2026 

For the commercial application of a GDP shaker, it was necessary to make several adjustments to the original design. The principles on which the first prototype was built did not yet allow it to be scaled up to commercial size due to issues with fatigue and high energy consumption. There was also no proper control of the amplitude-frequency characteristic available yet. In this project we will therefore design, engineer, procure, construct and test an improved large-scale prototype of the GDP shaker that would be able to install monopiles of up to 4 m in diameter.

The new design of the large-scale GDP shaker will solve the problems by integrating new methods and principles. Instead of two eccentric motors, the shaker will be based on a series of smaller synchronised units. Each unit can independently deliver low-frequency vertical vibration or high-frequency torsion.

A new gripping system for the shaker will also be developed, which is essential for an efficient transfer of the torsional vibrations from the shaker to the monopile. The new GDP shaker will be tested in an onshore/nearshore test campaign by installing and removing a monopile with a diameter of 4 meters.

Grants

NWO Take-off phase 1: Vibratory extraction of monopiles from the seabed with minimal effect on coastal structures 

MARCH 2022 - DECEMBER 2022 

We offer a method and a device for the removal of old monopiles that have been used to support offshore wind turbines from the seabed. This is a major part of the decommissioning operation. Currently, the monopiles are normally cut below the sea surface or below the seabed, so that the residual part of the pile remains in the soil. This method is not environmentally friendly; nor does it comply with the circular economy goals. Therefore, new methods of monopile extraction are being developed. The most promising among those are the extraction by means of pressurizing the air in the inner part of the monopile and the vibratory extraction. Our patented method belongs in the second class. The current vibratory extraction technology relies on the vibratory devices that excite vertical vibrations at the frequency of about 20 Hz thereby enabling an easy pull-out of the monopile. While this technology is efficient, it may be suboptimal when the extraction is needed near the dams and other coastal structures that can be sensitive to a relatively high level of soil vibrations that are excited by the conventional hammers. The extraction technology offered within this project will utilize the GDP (Gentle Pile Driving) vibratory hammer that is being developed and tested within the GDP and SIMOX projects funded by RVO. The GDP technique consists of a simultaneous vertical (about 20 Hz, low intensity) and torsional (high frequency, low amplitude) excitation. The superb efficiency as well as low noise and vibration emission of this technology have been demonstrated within the GDP project for monopiles of 76 cm in diameter and about 10 m in length. The innovative patented feature of this hammer is the introduction of the torsional high-frequency and low-amplitude vibration as a main pile extraction mechanism. The fact that torsional vibrations cannot propagate in the water eliminates the issue of noise emissions protecting the well-being of the marine species as well as the operators. In the soil, the vibration propagation is also reduced drastically as already tested in the course of the GDP project, protecting the neighboring structures from harmful undesired vibrations. The vertical low-intensity vibrations are used only as a mechanism that makes pile extraction easier when needed. Actually, in the case that the specification of a project allows, the vertical vibrations are switched off or used restrictively. 

NWO Faculty of Impact: VibroTwist: a game-changing pile driving and removal technology 

JUNE 2022 - JUNE 2024

Vibrotwist is a spin-off company to commercialize a new pile driving and removal technique invented at TU Delft, in which TU Delft will be a shareholder. As an installation device for the monopiles of offshore wind parks, which has a marginal environmental impact compared to conventional techniques, it helps the Energy Transition. It also contributes to the Circular Economy by allowing the extraction of the whole body of monopiles during the decommissioning. This grant is a great opportunity for the future company CEO to develop and excel in entrepreneurial skills in order to make VibroTwist a success.