How new tech is pushing the boundaries in offshore wind

Offshore wind turbine blades demonstrate engineering at its most extreme.
For twenty years – the lifespan of a typical turbine – they’re expected to be able to spin up to 300mph, 24 hours a day, 365 days a year.

They’re also super-lightweight, but must withstand some of the harshest weather conditions the world has to offer.

“Just because blades don't have moving parts doesn't mean they don't need maintenance,”

Andrew Bellamy of consultancy 8.2 Aarufield told a Scottish Renewables member event this week.

Andrew is one of a growing number of people who are sharing knowledge and best practice on how to ensure offshore turbines blades are maintained throughout their lifespans.

While the world of offshore wind O&M has focussed more on gearboxes than external components until now, he thinks that is changing.

Erosion of the blade – and at 300mph, it’s easy to understand how rain and salty air make that happen – has, he says, become “the Achilles heel” of the sector:

“Quite simply it’s now in the top five maintenance considerations of offshore wind farms."

Detecting blade erosion early is key.

Companies like 3M are working on thin-film sensors which could be embedded in the surface of the blade.

They’d report erosion electronically, before it becomes critical.
Maintaining offshore turbines – the focus of the Edinburgh event, which was sponsored by Fred. Olsen Windcarrier – is a real challenge.

Natural Power’s Jeff Bryan argued strongly for finding the right balance of corrective and preventative maintenance.

If you act only at the moment of failure you risk facing long downtimes and expensive repairs.

Monitor, plan ahead and pick your moment, and the outcomes change.

Failing turbines can be adjusted, protected from bad weather and then repaired fully in better conditions.

Lost revenue from downtime, Jeff said, can be £10,000/day+ for 7MW offshore machines, making failures costly.

That’s particularly true when you learn that unscheduled repairs can account for 75% of total offshore wind turbine maintenance costs.

As the size of offshore wind projects grows, so does their distance from shore and the water depth in which they must operate.

The difficult gets even harder.

Fred. Olsen Windcarrier’s General Manager UK David Matthews introduced the Scottish Renewables event with a video showing the company’s solution.
An offshore O&M base, serviced by helicopters and a fleet of ships, would allow technicians to live within the wind farm for weeks at a time.

Maintenance could be carried out as soon as the weather allowed, reducing downtime.

Helicopters could survey blades at a fraction of the cost of a deployment from shore.
And – in the most innovative high-tech scenario – drones could drop parts and tools, wrapped in waterproof packaging, onto turbines during the night, leaving technicians free to come and go.

As offshore wind matures, innovations like these could well become reality.

And with larger machines sited in more powerful conditions further offshore, new technology like this presents an opportunity to reduce the levelised cost of energy over the coming years.

Blog by Lindsay Roberts, Senior Policy Manager, Scottish Renewables.