A nine-partner Japanese consortium has commenced work on a 30MW+ floating wind farm, situated approximately 25km off the coast of Akita Prefecture. The consortium, working under the banner of ‘The Southern Akita Floating Offshore Demonstration Project Aimed at Overseas Expansion via Cost Reductions’, will install two floating wind turbines, each rated more than 15MW, in depths of approximately 400m.
The project has been selected as Phase 2 of the Green Innovation Fund’s ‘Cost Reductions for Offshore Wind Power Generation’ initiative. The Green Innovation Fund was established by Japanese R&D agency New Energy and Industrial Technology Development Organization (NEDO), to financially support companies working towards carbon neutrality by 2050.
The consortium is being led by Marubeni Offshore Wind Development Corporation, with other partners including: Japan Marine United Corporation (JMU); Tokohu Electric Power Co; Akita Floating Offshore Wind; TOA Corporation; Tokyo Seiko Rope; Kanden Plant Corporation; JFE Engineering Corporation; and Nakanihon Air Service Co. The project will run until March 2031, with the demonstrative Akita wind farm scheduled to commence operations in autumn 2029.
As part of Phase 1 of the Green Innovation Fund, which ran between 2021-2023, JMU researched and developed a semisubmersible floating superstructure, designed to reduce typical superstructure fabrication and installation costs. JMU will now conduct further R&D, focusing on areas related to installation and operations.
For example, one area will involve establishing a method by which joining can be conducted while the turbine components are at sea, to “enable enhanced mass production of floating substructures”, JMU says, adding: “As wind turbine generators [WTGs] become larger, floating substructures also become larger…the options for construction facilities which enable [construction of the] whole floater in one piece are very limited.” JMU envisages assembling the floating substructures, supplied as modular “split-building blocks”, in the field.
“JMU’s floating substructure design is simple and can be easily fabricated by yards that deal with steel structures, such as ship and bridges,” the company continues. “Through building alliances with those yards, JMU will establish [an] optimal construction [methodology] by gathering hull blocks, fabricated concurrently in separate yards, to one place and joining [them] at sea.”
The project aims to establish a method whereby joining can be conducted while the turbine components are at sea
JMU also notes that WTG installation procedures are sensitive to severe weather conditions, running the risk of project downtime. The group’s R&D efforts will then analyse ways in which to improve the availability of offshore support vessels, including crew transfer vessels (CTVs).
The project will also push for the creation and standardisation of “high-precision structural analysis methods for large floating substructures”, JMU says. “As WTGs become larger, the natural frequency of the floating substructure and the WTG tend to interfere with each other. Conventional design methods are not sufficient to fully analyse the effects of wind loads to avoid [this] interference. JMU will establish highly accurate structural analysis methods to optimise the reliability and cost of floating substructures.”
The company adds that it will develop a system of “taut/semi-taut hybrid mooring” to realise a more cost-effective means of procurement and installation, and will also utilise digital twin technology to model considerations such as the asset’s power output over time, as well as its overall lifespan. “It is important to predict failures in advance…since it is not easy to access floating offshore wind turbines located far offshore [on a daily basis]”, JMU comments.
