World's first floating wind farm Hywind Scotland faces shutdown for 'heavy maintenance'

The 6MW turbines will be towed back to Wergeland on the west coast of Norway as part of a maintenance programme that is likely to take around four months and will disrupt power output from the project operating 24km off Peterhead since 2017. All units will be reconnected back on the Hywind Scotland site when the maintenance is complete, a spokesman for the Norwegian company confirmed.

Hywind Scotland is fully operational at present but tow-in operations will begin later in the year, taking advantage of the more benign weather periods in late spring and summer in the Northern Hemisphere.

While acknowledging that towing all the turbines to shore for maintenance after seven years of operation was not planned at the outset, the Equinor spokesman claimed such actions are not entirely unexpected.

“We will conduct a combination of exchanging some components, maintaining others and using the opportunity to do regular service as well. All of this is something we regularly do at our other offshore wind farms. What’s different here is that we will tow the turbines to shore,” he said.

He added that the need for heavy maintenance became apparent through “ordinary monitoring and inspections, in close collaboration with the manufacturer."

Siemens Gamesa was asked to provide clarification of the nature of the problems on Hywind Scotland’s turbines, but a spokesperson said the company would not expand on the information provided by Equinor.

'Game changer'

The project was conceived, from the outset, as playing a key role in de-risking commercial floating wind and paving the way for much larger projects.

Equinor and 25% project partner Masdar invested the equivalent of $194m in the project and celebrated achieving a 60-70% cost reduction, compared with the Hywind Demo project in Norway. By attaining higher average capacity factors than established fixed bottom UK offshore wind farms, the project helped prove the potential of floating.

“Most offshore wind farms require heavy maintenance of turbines from time to time so this was always something that could happen. Towing the turbines to shore is currently the most safe, efficient and proven method to carry out such heavy maintenance of floating turbines,” the spokesman stated.

“Hywind Scotland is a pilot project and serves as a learning platform for future floating offshore wind farms. For future floating wind farms Equinor will have initiatives in place to reduce heavy maintenance events and to do more on-site repair solutions,” the spokesperson said.

Insurability concerns

Floating wind ambitions have indeed mushroomed since Hywind Scotland came online, including a potential 19GW of capacity in the pipeline as a result of the UK’s Scotwind tender.

But the problems apparently surfacing on Hywind Scotland go to the heart of challenges facing the floating sector.

This is felt particularly when it comes to underwriting costs in the insurance sector.

Michael Bullock, director of consultancy firm Renewable Risk Advisers, underlined this point during a recent industry conference in Lisbon where participants discussed the knock-on risks from equipment failure in relation to issues such as the availability of vessels, access to ports and reconnection challenges.

In addition to policy deductibles, insurers usually limit their exposure through serial defect clauses in policy wordings and in renewal negotiations, posing a risk of residual exposure to the project itself, to the extent that protection is not provided by OEM warranties and despite existing cover provided by insurers, Bullock noted.

“The costs of an unscheduled maintenance campaign across multiple offshore units will invariably be considerable, in addition to the substantial loss of revenue arising from turbine downtime.”

Bullock added that project developers can mitigate the risks through scenario analysis and contingency planning, feeding into operation, maintenance and spare parts strategies, including pre-negotiated call-off agreements for suitable vessels.

Anchor handlers

As one of the world’s leading companies in the offshore production of oil and gas, Equinor is better positioned than many to get its hands on anchor handling tug supply (AHTS) vessels.

Equinor is no stranger to risks emerging in the offshore wind sector, and is among those developers that have stepped back from deals struck for US projects made uneconomic by a surge in supply chain and capital costs.

But recent moves, such as the cancellation of the deal for New York's fixed bottom 1.2GW Empire Wind 2 project were presaged by the decision, back in May 2023, to suspend the subsidy-free 1GW Trollvind floating wind project in Norway “based on several challenges facing the project, including technology availability, rising cost and a strained timetable to deliver on the original concept”.

This 11-turbine wind farm, which uses 8.6MW Siemens Gamesa turbines, is expected to cover over a third of the annual power needs of the five platforms at Equinor and Enova’s Snorre and Gullfaks offshore oil fields on the Norwegian continental shelf.

And when announcing the decision to drop Trollvind, Equinor reaffirmed its commitment to applying its knowledge and learnings to develop floating offshore wind power at Utsira Nord and outside Norway.

“Floating offshore wind has the potential be a key part of the solution in the energy transition, opening up new areas for energy supply,” the Equinor spokesman stated.

“Hywind Scotland it is conceptually performing very well and has for many years delivered record high capacity factors. It is operating within its design parameters and within expected loads.”

He added that the Hywind Scotland operation would give Equinor and its partners “valuable experience to further develop maintenance methods and improve operational efficiencies for maintenance of commercial scale floating offshore wind projects in the future.”

Learning opportunities

A sector-wide need for operational and maintenance experience or “learning opportunities” was also flagged by Victoria Toft, head of data at offshore wind intelligence company Aegir Insights, who noted that total installed floating wind capacity only passed the 200MW mark in 2023.

She noted that concerns about operational requirements and the implication of repairs of large components raise serious questions for floating wind.

Some technology providers, such as Aker Solutions and Encomara, have come out with new products and solutions aiming, among other things, to facilitate the efficient connecting and re-connecting process with floating turbines.

But a silver bullet solution to the problem of serial defects or failures in large components has not yet emerged, Toft reckons

“Units in need of larger repairs or major component exchange often need to go far to find suitable ports, due to dimensions of the foundations,” she added.

In the case of Hywind Scotland, Wergeland was identified as the closest yard that was suitable for the heavy maintenance purposes, the Equinor spokesperson said.