The company has worked alongside Northern Offshore Services (N-O-S) and MHO-Co to develop the innovative vessels which will take around four hours to travel to site, from their base at the port of Grimsby, on the east coast of the UK.
The Hornsea Two CTV’s will also carry Z-Bridge’s newly developed motion compensated transfer system, called Bring-to-Work.
This unique transfer system will be installed as an additional feature for technicians to access the Hornsea Two transition pieces (TPs) directly from the CTV.
Jan Stilling, Lead Marine Specialist for Ørsted said: “The new CTV’s have incorporated large battery capacity that makes it possible to stay offshore overnight in hybrid mode meaning they’re not burning fuel for up to eight hours while the vessels keep their positions without anchoring or mooring to a buoy.
He continued: “The new gangways will work as additional support for the extra access required during construction on site.”
N-O-S will take delivery of their 39-meter “Energizer” in Spring 2021 and MHO-Co are due to deliver their two 35-meter CTV’s in Summer 2021.
The batteries installed on all three vessels can be recharged either by power surplus, the onboard generator or via a recharging buoy system that will be tested during the construction face of the wind farm.
Both designs have been created in preparation for implementing fuel-cell technology once suitable storage for the fuel types such as hydrogen or methanol has been developed for use onboard.
David Kristensson, Group CEO of Northern Offshore Services said: “I am grateful that N-O-S has been awarded the contract for supplying our CTV services to Ørsted during the construction of Hornsea Two. Energizer, the first CTV in our E-Class series, represents years of research and development and will provide the best possible performance during the most difficult sea conditions. In addition, I am very excited about our new hybrid solutions that will reduce both the fuel consumption as well as the emissions at sea. The Hornsea Two project represents the perfect start for our new vessel series.”
In a world first, MHO-Co’s vessels feature both a diesel mechanical and a diesel electric Inboard Performance System (IPS) driveline setup in both hulls. The diesel electrical drivelines can also be powered from the large onboard researchable battery pack during night-time and slow steaming.
Mik Henriksen, Group CEO of MHO-Co said: “We at MHO-Co are very happy with the award of contracts to supply four CTV’s for the construction of Hornsea Two, with two already set to work, the MHO Asgard and the MHO Apollo are the next step towards carbon neutral operation. As with our previous CTV’s we have worked with Ørsted to design superior sea keeping to support windfarms further offshore, with a high level of comfort for the technicians. These new boats will also be used to take next step technologies like hydrogen fuel cells, methanol and new types of batteries to market. MHO-Co has also been involved in the development of new ways to access turbines, such as the Z-Bridge.”
Bastiaan Spruit, General Manager at Z-Bridge said: “We are extremely proud that we have been contracted to support Ørsted’s ambition to reduce the CO2 footprint and increase safety during transfer of technicians by CTV’s . The Bring-to-Work is a fully motion compensated offshore access system. It will allow teams of four technicians to transfer in a trolley direct from the CTV to the TP platform. By eliminating stepping to the boat landing and climbing ladders this will improving safety. We see that this will also significantly reduce the required visit time per TP, lowering fuel consumption and improving operational efficiency. The Bring-to-Work system is the first offshore access system installed on a CTV that is able to transfer people direct to the TP platform elevation.”
Scheduled for completion in 2022, Hornsea Two will become the world’s largest offshore wind farm, with a capacity to generate 1.4GW of clean energy, enough to power 1.3 million homes in the UK.