Gearbox, generator, blade and other component exchanges on floating wind farms built around Fred Olsen 1848’s next-generation Brunel design could be carried out at sea in “less than half the time” of towing units into port for repair, according to calculations by the company for a new crane-barge solution unveiled today (Tuesday).
The Brunel Maintenance Solution is based on a barge fitted with both jacking system and a state-of-art crane that attaches itself to the eponymous innovative steel floating foundation, removing the need for complicated dynamic lifts during replacement operations, while creating a working space for component lay-down.
“The solution will significantly reduce the time for maintenance operations,” said Fred Olsen 1848 CEO Sofie Olsen Jebsen.
“The alternative for floating offshore wind and standard in the industry is towing the foundations to shore. Even compared with a very optimistic and optimised tow-to-shore calculation, the Brunel Maintenance Solution would reduce the time per replacement by more than a half.”
The maintenance solution forms part of a “holistic” approach to floating wind power being developed by Fred Olsen 1848, launched in 2021 by Norwegian maritime industrial giant Fred Olsen to fast-track a range of inventive offshore renewable energy technologies to market, as first revealed in Recharge.
The geometry of the Brunel floating foundation, a triangular tubular steel hull with twin towers supporting the turbine, provides for a water depth clearance of some 10 meters above the pontoons and a large open area inside the base that means a jack-up barge can be pulled in by ocean-going tugs, and then mobilised for lifting operations.
“The barge will jack down and affix to the top of the pontoons. This allows for fast mobilisation and enables Brunel to remain in operational draft,” noted Jebsen, adding the Brunel Maintenance Solution design requires no modifications to tower or turbine.
“Our holistic approach is based on our belief that in addition to attending to excellence on all technical parameters, floating wind foundations have to be designed with integrated solutions to assembly, manufacturing, transportation and O&M [operations and maintenance. The O&M phase of the floating wind projects represents a significant part of the total cost.”
Jebsen highlighted the “decades of experience” Fred Olsen companies, “especially from [wind turbine installation outfit] Fred Olsen Windcarrier and Global Wind Service, which has led to the creation of the solution”.
She added: “A floating foundation will never succeed unless it comes with a strong integrated solution that keeps the complexity and cost down for the O&M phase of projects. This solution is an important step both in our development of Brunel and for the realisation of floating wind farms on a commercial scale.”
Last autumn, Fred Olsen 1848 signed up Dutch contractor Huisman to work on a novel concept that uses a lightweight telescopic crane fitted using a “quick connection” interface ring mounted atop the to the ‘open’ pontoon of a generic semisub floating foundation.
The Brunel – named after the British engineering giant – is a low-draft semisubmersible platform engineered around mass-producible steel tubulars, such as are used for monopile foundations, which can be manufactured at a large number of existing factories and transported piecemeal to coastal yards for assembly into platforms that are then towed-out to site for installation.
The Brunel platform is designed for a one-a-week build-rate. A first unit is expected to be in the water by 2027.
With ‘Takt time’ – the rate of per-unit production – central to the floating wind sector’s drive to screw down its levellised cost of energy to match the €50/MWh ($53/MWh) at which conventional bottom-fixed offshore wind plants are producing in Europe.
