Heavy lifting and transport specialist Mammoet has completed the marshalling of 116 XL monopile foundations for the Nordseecluster A and Thor offshore wind farms, the company said on Tuesday.
The operations, carried out at Buss Terminal Eemshaven in the Netherlands, supported joint offshore wind developments by RWE (51%) and Norges Bank Investment Management (49%). Together, the Nordseecluster (A & B) and Thor projects are planned to reach a combined capacity of up to 2.6 gigawatts (GW).
Mammoet was contracted by Buss Ports in 2023 to manage the phased load-in, temporary storage, and load-out of monopiles of varying specifications. Each foundation weighed around 1,500 tonnes, with lengths ranging from 85 metres for Nordseecluster A to approximately 100 metres for Thor.
The company said a key focus of the year-long project was logistical efficiency, particularly in reducing the number of transcontinental sea voyages required to transport the components from China.
“By overcoming the tidal constraints and the limited ground-bearing capacity of the quay, it made it possible for up to 10 monopiles to be delivered at a time instead of eight or nine,” Mammoet said in a statement. “Over the duration of this year-long project, several trips from China were spared as a result. With each voyage taking around 60 days of sailing, the time and cost savings were significant.”
The load-ins involved transporting the monopiles using Mammoet’s self-propelled modular transporters (SPMTs) equipped with saddles developed by Buss. Due to limited quay bearing strength and changing tidal conditions, Mammoet used an extended linkspan ramp and retained sea grillages during offloading to expedite disembarkation.
The monopiles were unloaded from vessels using a roll-on/roll-off (RoRo) method in a transverse orientation, an approach that enabled more units per voyage and required the structures to be offloaded ‘sideways’. Once onshore, the monopiles were moved to a temporary storage area and later repositioned for final load-out using onboard vessel cranes.
Preliminary engineering began in September 2023, including a feasibility assessment using Mammoet’s XXL monopile transport system. The company worked closely with Buss to integrate their respective systems for safe handling of the large components.
The operation forms part of broader infrastructure preparations for the Nordseecluster and Thor projects, which are among several large-scale offshore wind developments planned in Germany and Denmark to support Europe’s renewable energy targets.
