Installation Method to Benefit Offshore Wind

HMC Tests Rotor Nacelle Assembly Innovation

By Malcolm Ramsay

New installation methods for offshore wind turbines promise to expand the areas where projects can be developed, accelerating demand for breakbulk transport and larger vessels.

The latest advance for the sector is the launch of a new Rotor Nacelle Assembly, or RNA, installation method, tested by Dutch specialist Heerema Marine Contractors. The firm performed a demonstration project in the North Sea last month to collect vital operational data and based on positive results predicts the method will stimulate new demand.

"This method allows Heerema to unlock areas that are unfavorable for jack-up vessels, such as the Baltic Sea,” Sarah Killoh of Heerema told Breakbulk, noting that the system is already planned for deployment and will be used next year near the German island of RĂ¼gen in the federal state of Mecklenburg-Western Pomerania.

Larger Cargoes

Developed in partnership with DOT and the Delft University of Technology (TU Delft) the RNA demonstration project involved a raft of new technologies, aimed at easing the installation of large components and reducing time and costs.

Heerema’s CEO Koos-Jan van Brouwershaven said that testing of the RNA installation method offshore was "a significant step forward” in the firm’s “ambition to deliver the solutions clients need for the next generation of offshore wind turbine generators. This project is another example of proving our methods offshore that have been developed in our Simulation Center.”

Developed over the course of two years, the RNA project was meticulously planned at the company’s onshore Simulation Center located at Heerema’s headquarters in Leiden, and aims to reduce relative motion between the vessel’s crane and the geostatic foundation of the offshore structure.

This added control over positioning will allow operators to handle bigger loads with greater precision and builds on a guided root end positioning tool, known as the GREPT, developed specifically for the project by Heerema. This blade assembly tool enables offshore handling and installation of blades safely and efficiently and also enables larger blade sizes.

This is expected to greatly improve the economics of installation for larger rotor sizes, accelerating a shift towards larger blades and adding pressure for breakbulk operators to upgrade vessels to meet requirements.

Future of Offshore Wind Farms

Alongside testing of the RNA system, the partners also implemented new motion tracking sensors, to record more than 15 million samples that will be fed back to the simulation center to further improve future designs.

Calling wind energy “the leading edge of a current environmental revolution,” David Domingos, a researcher on the project from Delft Center for Systems and Control, noted that this form of “pioneering offshore installation, gives the chance to gather unique data, important to shape the future of offshore wind farms.”

Killoh of Heerema said the RNA system will be used aboard Heerema’s second-largest vessel, Thialf, for the Arcadis Ost 1 project next year. Based in the Baltic Sea this project Is being developed on behalf of client Parkwind and is already being carefully modelled at the company’s Simulation Center. 

Increased Scope

In total, HMC forecasts that the offshore wind industry will produce 228 gigawatts by 2030, with demand accelerating the need for larger and larger offshore wind turbines with new projects “being planned for installation in remote locations and deeper water depths.”

The latest project pushing these boundaries is the Hornsea Two project, which will take the mantle of world's largest offshore windfarm from its namesake Hornsea One, when it comes fully online in 2022, delivering 1.3 gigawatts of capacity. The latest stage in this giant project saw breakbulk specialist Jumbo transport and handle the largest number of monopiles and transition pieces ever shipped in a single contract.

The firm utilized its K-3000 class heavy-lift vessel Fairmaster for the project, transporting 141 monopiles and 131 transition pieces to the Netherlands from Rostock, Germany and Aalborg, Denmark. Cargo was transported in three different loading configurations allowing for re-configuration depending on need.

“We converted the Fairmaster into a kind of ‘Swiss Army knife’ that provided an unrivalled heavy lift vessel intake of large diameter monopiles and transition pieces,” said Boudewijn van der Garden, commercial manager at Jumbo.

The firm used inlays in the saddles to accommodate different diameters of monopiles with the resulting clearances sometimes 50 centimeters or less. The firm also installed project-specific lifting lugs onto the Fairmaster’s deck hatches to optimise operations.

"This engineered flexible solution made it an extremely efficient vessel for the project and is one of the things we’re most proud of – it helped us conclude the project scope within just 37 voyages in a period of just under 12 months,” explained Maarten De Gruyter, project manager for Jumbo.

As the scope and scale of new projects such as this grows a new era for deepwater wind development promised to reshape breakbulk activity, as it opens up a raft of new possibilities for sites and creates pressure for infrastructure beyond the current hubs.

Last month, the world’s largest floating offshore wind farm, Kincardine Offshore Windfarm Ltd., or KOWL, became operational with 50-megawatt capacity and the next generation of floating windfarms look set to dwarf this output, signalling a rapid shift to deep water scenarios.

”The Kincardine project shows how boundaries of offshore wind technology are constantly being pushed forward,” said Nils de Baar, president, Vestas Central and Northern Europe. ”We stand ready for the next phase of commercial scale floating offshore wind.”

Earlier this year, developer Hecate Independent Power announced plans for a massive offshore wind project off the coast of Iceland that would feature 10 gigawatts of fixed and floating wind turbines, connected to the UK by thousands of klilometers of high-capacity submarine power transmission cables a project that would require far-reaching breakbulk activity