Heerema Marine Contractors has developed a new method for offshore floating wind installations that is said to eliminate the need for wet-tows and marshalling yards.
Using the Floating to Floating installation method, floaters can be constructed on land before being dry-towed on a transport vessel to the location, Heerema said.
After arrival, they are installed using Heerema’s floating installation frame to lift the floaters from the vessel. After that, they are installed on location.
Heerema’s floating installation frame submerges the floaters down by weight, removing the need for high-tech ballasting or tensioning systems and reducing installation duration, the company said.
The bottom foundation work can be executed in parallel by optimizing the capabilities of Heerema’s semi-submersible crane vessels.
”We want to show an alternative solution for installing offshore floating wind, especially targeting some of the bottlenecks for scaling up. We strongly believe that by opening up to new ways of working and collaboration floating wind can reach the potential the industry is looking for,” Jeroen van Oosten, Business Unit Director Wind at Heerema Marine Contractors, said.
Heerema said that it approached the development of the Floating to Floating installation method by tackling the challenges of reducing the Levelized Cost of Energy (LCoE) in offshore floating wind, improving schedule robustness and duration, and removing bottlenecks in the supply chain.
The company said that the installation method was developed to deliver solutions to industry challenges, such as efficient use of resources like steel and port infrastructure, offshore logistics and maintenance, and reaching the required scale and rate of installation.
Currently, there are various proposed methods that involve assembling floating foundations in port before wet-towing to the field. This presents logistical challenges, as well as there being pressure on the number of suitable harbors, Heerema said.
The volume and weight of floating foundations are reduced by removing the need for wet-towing. Also, the floater is lifted directly from the transportation asset in the field, which means both the floater and wind turbine generator can be optimized for in-place conditions only.
A low-tech floater design is possible by integrating installation requirements such as ballasting provisions into reusable installation tooling, removing the requirement to build these functionalities into each floater, according to the Dutch company.
By efficiently using space onboard transport vessels to deliver multiple floaters directly from the fabrication yard to the offshore wind site, transport and marshalling costs are said to be significantly reduced.
And by removing the need for in-port assembly of the floater and the wind turbine, there is less space and draught required in the port and reduced quayside capacity, which helps avoid one-off mega-investments in port areas, Heerema said.
Eliminating ”time-consuming and highly weather-sensitive wet tows and mooring connections”, leads to higher throughput on floating wind projects, Heerema said.
The floating to floating installation method means floater and wind turbine campaigns can be decoupled, reducing supply-chain pressure, and resulting in a more efficient process.
The crane-supported floating to floating installation method is said to be built on proven technologies from the oil and gas floating platform industry. It allows the saving of tons of steel per floater and will reduce overall project CAPEX, according to Heerema.
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