The Integrated Monopile Installer

‘We transformed a threat into an opportunity’

IHC IQIP’s Integrated Monopile Installer has the wind firmly in its sails. Six offshore wind projects have already been executed successfully and over 350 monopiles have been installed. On every project it has added value throughout the complete process, thus enabling the installation of even extra-large monopiles. IQIP’s Technical Account Manager Henk van Vessem takes us on a trip down memory lane from the development of what was initially a noise mitigation system (NMS), leading up to the creation of IQIP’s award-winning Integrated Monopile Installer.

Development
The genesis of the first Integrated Monopile Installer, came in 2007 as a result of the strict regulations in place for all German offshore wind projects. “Germany usually sets the precedent when it comes to technical reform and their noise thresholds are the strictest in the world,” says Van Vessem. “We risked losing business if we didn’t find a way to meet the new requirements. The restrictions increased the cost price for the offshore wind industry, and we wanted to bring back the levelised cost of energy (LCOE). Noise mitigation actually became a side effect.” 

IQIP (formerly known as IHC Hydrohammer) took the lead and, together with TNO, carried out research to determine the most efficient mitigations method for underwater noise in an offshore environment. The results were then used to determine the design and method statement for the NMS to be used for the installation of a monopile offshore. “Testing prototypes in a basin is completely different to testing in open water,” adds Van Vessem. “We had to assess the NMS in an offshore environment to work out its actual efficiency.” 

Offshore testing
In cooperation with the Delft University of Technology, an extensive test setup was made to facilitate the research. It was Van Oord that provided the perfect opportunity to test the prototype NMS during the installation of two monopile foundations. Both monopiles, with a diameter of 3.35m each, were installed with a Hydrohammer S-800 at a water depth of 25m. The prototype used for the project, was especially designed by IQIP to meet the specific parameters of the installation. “The results confirmed that we had reached the “Technology Readiness Level 8” (TRL8) stage,” says Van Vessem with a smile. “The NMS proved to comply with the German legislation regarding underwater noise during pile driving.” It was time to officially put the first NMS on the market.

Deployment
The first commercial deployment of the NMS took place in the summer of 2012 on the Riffgat offshore wind farm. This was carried out by IQIP’s customer Seaway Heavy Lifting. In total 30 monopiles had to be installed. They were first preinstalled with a vibratory hammer and, after installation of the NMS, driven to their target depth with a Hydrohammer S-1800. During installation of five of these monopiles, measurements were taken to check the underwater noise levels. The test results showed a significant noise reduction and complied with German regulations. All 30 monopiles were installed without any significant issues. 

Proven technology
The knowledge and experience gained during every subsequent project has been transferred into the next generation of equipment. “Contractors use more than just a Hydrohammer during installation,” continues Van Vessem. “These individual tools take up a great deal of deck space, manpower, handling time and costs. By combining multiple functionalities in one piece of equipment, we could speed up the installation process, increase flexibility, eliminate risk and reduce costs.” This is how the Integrated Monopile Installer came to life.

The NMS underwent a positive shift from being seen as a ‘burden’, into a fully integrated installation tool that increases productivity. “It was no longer just about noise mitigation,” explains Van Vessem. “With the Integrated Monopile Installer, we transformed a threat into an opportunity.” 
Designed to conform to DNV guidelines, and with continuous improvements added every day, it remains the only reliable proven technology for noise mitigation during pile-driving operations.