The construction of offshore wind farms is important in making energy generation more sustainable. GBM Works is conducting a pilot on Maasvlakte together with partners this spring, using a new method for sustainable and cost-efficient installation of monopile foundations for wind turbines.
GBM Works, founded by Ben Arntz as spin-off of TU Delft, developed the vibro drill method in which the foundation piles for wind turbines (monopiles) are inserted in the sea bed via vibration elements on the base of the pile. In contrast to pile driving, the force isn’t applied to the top of the pile; the weight of the pile itself is used to insert the pile. GBM Works has requested a patent for the method.
Maasvlakte as test site
Initial small-scale trials with the method took place on Maasvlakte in 2017. More and increasingly larger equipment was used in subsequent trials. At the end of 2018, GBM Works vibrated a 16-tonne sheet into the sea bed. ‘Maasvlakte is an interesting test site because the sand bed is the same as the sea bed,’ stated Civil Engineer Govert Meijer, who coaches GMB Works. As industry and knowledge partners, SIF, Van Oord, TU Delft, Deltares and the Port of Rotterdam Authority have joined forces to facilitate the further development of the vibro drill method and to provide financial support for pilots.
Low-noise, faster, cheaper
The vibro drilling of monopiles is interesting both economically and ecologically, explained Joris van Rossem, Test and Logistics Engineer at GBM Works: ‘Hammering a monopile makes a lot of noise, which is harmful to the ecosystem. Our method is low-noise, which means that we do not need to erect any expensive soundproofing screens around the monopiles. We also get the pile into the ground faster than when using the classical hammer method. As the vibration elements are already fitted to the pile during installation, we can work faster and are less dependent on weather conditions. Vibrations at the base also cause less fatigue damage: damage as a result of material fatigue. This means that it may be possible to use lighter monopiles in the future.’ It is expected that all these advantages will save millions of euros when installing foundations for wind turbines, which will ultimately result in a lower cost price for wind energy.
Pilot on the water
GBM Works will start a fourth pilot on Maasvlakte in May/June 2019. Instead of a sheet, for the first time a real, relatively small monopile will be vibrated into the ground. Not on land, as in previous pilots, but in the sea bed. The partners are currently seeking the most suitable location for the pilot. Meijer: ‘We are investigating the possibility of conducting the pilot from an offshore platform on flat sea bed area.’ Van Rossem: ‘We aim to conduct penetration tests for four weeks and will use these to further test our method’s reliability and speed. We’ll also be re-measuring noise levels, examining how firmly the piles sit, and checking their bearing capacity.
‘The development of offshore wind farms is an important link in the energy transition’
— Twan Romeijn, Business Manager Breakbulk and Offshore Industry, Havenbedrijf Rotterdam
A boost for the area and sector
‘The development of offshore wind farms is an important link in the energy transition,’ stated Twan Romeijn, Business Business Manager Breakbulk and Offshore Industry at the Port of Rotterdam Authority. ‘As Port Authority we are investing heavily in the offshore industry. We’re realising offshore activities on Maasvlakte to enable offshore companies to collaborate and develop their activities. In this context we’re also making land available at this site to enable innovative start-ups to conduct trials. While doing this we will, of course, safeguard the continuity and safety of other activities in the area. The development of GBM Works is promising, which is also apparent from the fact that various industry partners have become involved. This broad collaboration is a great boost for the area and sector.’
GBM Works aims to market the vibro drill method from 2021.