PROVIDENCE – For the better part of two months now, four of the five wind turbines at America’s first offshore wind farm haven’t been spinning.
Ørsted, the Danish offshore wind developer, shut down the turbines off Block Island in June for routine maintenance but also to carry out inspections after problems arose in Europe with the same model of turbine manufactured by General Electric.
Workers at the Merkur wind farm in the German North Sea found signs of stress fatigue on the support structures of the “helihoist” platforms on some of the project’s GE Haliade turbines. Power generation at the 396-megawatt array was temporarily halted to come up with a solution to the problem, but the wind farm has since come back online.
In June, Ørsted said it had put the five-year-old Block Island Wind Farm “on pause as a precautionary safety measure” to see if similar problems had arisen with the platforms at the top of the turbines that equipment and workers can be lowered onto from helicopters.
“We are working closely with the supplier on a solution that will allow us to safely restart generation as soon as possible,” Mikkel Mæhlisen, head of North America operations at Ørsted, said in an email at the time.
Ørsted said this week that workers from GE found “stress lines” in the Haliade turbines but that a risk assessment found that they are structurally sound. Repairs and maintenance are expected to be completed in the coming weeks.
When the 6-megawatt turbines were installed in 2016, they were considered state of the art. But the industry has advanced quickly in a short time, and developers are now investing in turbines of twice the power capacity and more. Vineyard Wind, the first large offshore wind project to win federal approval, plans to use GE’s latest Haliade model, which has a 13-megawatt capacity, for its wind farm in the waters between Block Island and Martha’s Vineyard.
‘How can they make any money when the turbines are never running?’
The standstill at the Block Island Wind Farm hasn’t gone unnoticed by islanders and fishermen who frequent the waters around the turbines. Richard Hittinger, first vice president of the Rhode Island Saltwater Anglers Association, said that for much of the summer he’s seen either one turbine turning or none.
He recently saw crews cleaning stains off the turbines and doing work on the blade tips.
“Guys on my boat have been commenting all summer ‘How can they make any money when the turbines are never running?’” he said in an email.
Ørsted said the cleaning witnessed by Hittinger is part of the regular maintenance of the turbines.
The company said that summer is the best time for such work. That’s because the winds aren’t as strong or as steady in the warmer months, so it’s easier and safer for crews. It also means that Ørsted isn’t losing as much money as it would if the wind farm had to halt operations in the winter, when generation typically goes up.
Compounded by ongoing problems with underwater cable
But the timing of the problem isn’t so good for the wind farm, because it comes amid ongoing difficulties with the underwater electric cable that takes power from the 30-megawatt project across Block Island Sound to the mainland electric grid.
While there have been no problems with the cable’s landing point on the mainland, in Narragansett, where a horizontal directional drill was used to bury it in a deep trench, it’s been a different story on Block Island, where a jet plow was employed at lower cost.
Because the shoreline off the island proved to be rockier than expected, the cable was buried at shallower depths than planned. Waves soon started uncovering portions of it, and the problem grew worse over time.
Last year, in response to complaints from Block Island beachgoers and concerns from state coastal regulators, both Ørsted and National Grid decided to rebury the affected portions.
Although Ørsted was able to complete its share of the work without a hitch, National Grid had to suspend its part after discovering sand, mud and other material blocking a conduit pipe it installed under the seabed.
Will turbine repairs affect electric bills or power supply?
Work is set to resume in the fall, but it’s unclear how the difficulties will affect the $31-million cost of the replacement project and whether Rhode Island electric ratepayers will be on the hook if there’s an increase.
The surcharge that National Grid customers already pay for the cable has been the source of recent controversy. The chairman of the state Public Utilities Commission has excoriated the company for a fee that he has described as wildly inflated and unjustified. National Grid is in the midst of determining a new rate structure.
Despite the continuing issues, the cable is still in full operation, so Block Island’s power supply hasn’t been interrupted by the temporary shutdown of the wind farm.
And in another piece of good news, Rhode Island ratepayers aren’t on the hook for the repairs to the wind turbines. Unlike National Grid, Ørsted, as stipulated by the long-term power sale contract approved by state regulators, cannot pass on any unforeseen costs to electric customers.
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