Testing is at the heart of the offshore wind success story, the basis of cost reduction, investor confidence and job creation, but faces stiff challenges
Testing offshore wind turbines and components is not just about making sure new technology works. Doing so has helped drive down the cost of energy from offshore wind to the point at which the industry is going global. It has helped OEMs, led to new manufacturing opportunities and created jobs, and laid the groundwork for massive projects that are the cornerstone of efforts to decarbonise the economy.
But as turbines continue to grow in size, as ambitious targets are set for the UK offshore wind sector, and as attention turns to floating wind, there are challenges ahead for test centres, as ORE Catapult director test facilities Tony Quinn, tells Offshore Wind Journal.
“Scaling up presents challenges in terms of materials, manufacturing and reliability,” Mr Quinn says. “The purpose of the testing we do at ORE Catapult is to identify potential challenges at an early stage and eliminate problems that would only become apparent at a later date. That means OEMs can take corrective action early.
“At the ORE Catapult, we don’t just test components. We test complete systems and replicate the loads that turbines will be subject to over their lifetime. Certification is an important part of the process, but the ability to simulate the lifetime of something intended to operate in a harsh environment for 25 years gives you a whole lot more value.
“Testing gives you confidence in technology, and confidence in technology paves the way for investment decisions like the ones we’ve seen recently in the UK sector of the North Sea.” Ultimately, he says, that also leads to manufacturing and job creation, economic activity and decarbonisation.
The last decade has seen test centres like the ORE Catapult play an incredibly important role in the UK offshore wind success story. But Mr Quinn says recognition is growing that scale is becoming an issue for testing establishments. For the next few years he expects full-scale demonstration to continue to be the preferred mode of testing, but such is the pace of the development that keeping up is increasingly difficult.
“We need test centres that can match the fast pace of growth in the size of turbines, but it takes time to develop and build new, larger facilities that can handle them, and it is tremendously expensive,” Mr Quinn says. And there is a risk, he believes, that testing could become a bottleneck to bringing new technology to market.
“There are very few facilities in Europe or anywhere else that are able to test a 15-MW turbine, and by the end of the decade we could be looking at 20-MW turbines,” he tells OWJ. “Computer simulation and digitalisation can help – and we urgently need to further develop the ability to use computer simulation to predict how materials will behave – but we will continue to need to test to validate computer models.”
As highlighted recently by OWJ, the ORE Catapult is hoping to build a new facility, the Energy Central Offshore Wind Demonstrator project, where leading equipment manufacturers can test innovations at component level. The turbines tested at the facility would be up to 300 m in height and in the 20-MW range.
Mr Quinn believes this kind of facility has what he calls “gravitational pull” that can attract inward investment, creating opportunities for local companies and for the development of intellectual property. “A facility like that is a way of testing new technology, but it’s also a means of technology development, and it provides a route to market for next-generation technology that will continue to drive down the cost of offshore wind,” he says.
He agrees that floating wind is also a challenge for testing facilities. “With floating wind, a turbine has to be capable of operating in a much more dynamic environment. The same is true of subsea cables. Cables have been tested for electrical integrity for years but we now need to test their ability to withstand the effects of currents, waves and tides,” he says.
Whether bottom-fixed or floating wind, says Mr Quinn, ambitious targets for offshore wind will also place incredible pressure on the industry and on manufacturing. “The Prime Minister has talked about 40 GW by 2030, and the Committee on Climate Change has talked about 75 GW in the long term,” he says. “Demand for green hydrogen from offshore wind could drive targets even higher, but if we are going to get anywhere near those targets we need to quickly find ways to industrialise blade manufacturing, and the only way to do so is to test new ways of working.”
And where will the money for new test facilities come from? Some of it has to come from industry, from OEMs, Mr Quinn believes, but there is also a clear rationale behind government funding.
“Ultimately,” he says, “it is in any country’s interest to create jobs, export opportunities and help reach net zero. The UK’s standing as a world leader in offshore wind has never been higher,” he concludes, “but we need to invest in testing to maintain our relevance as offshore wind goes global”.
Fraunhofer IWES managing director Prof Dr-Ing Andreas Reuter leads another long-established test centre and shares many of Mr Quinn’s views about the challenges facing testing. He highlighted some of the investments the German centre is making in new facilities and some of the challenges involved in testing ever-larger blades.
“Not long ago, a 60-65-m blade seemed big, but we already have a 107-m blade and 120-m blades are on the horizon. The rate of growth in blade length is a big challenge. It can take 4-5 years to develop and build a new facility to test them, by which time the technology has already moved on,” he told OWJ.
“In the long-term, I don’t think it’s really possible to continue like this and we have to question the value of one-time tests on each prototype of a new blade.
“Testing prototypes is essential of course, but it involves testing one blade in one way, in a very proscribed set of circumstances. It’s a compromise, and of limited value. ”
In future, he says, greater use needs to be made of digitalisation and of digital blade testing. Doing so, with reference to real-world blades, it will be possible to simulate much longer-term effects on blades and test them in a much wide range of environmental conditions.
In the near-term Fraunhofer IWES is investing €30M in its dynamic nacelle testing laboratory, a full-scale test stand for nacelles. The upgraded facility will see converter and generator systems for multi-megawatt turbines tested for electrical grid compatibility. “It is something that is very hard to do with a prototype,” Professor Reuter explained.
To meet the challenges of ever-larger blades, a new blade testing facility capable of handling 120-m blades is under construction and should enter operation by the end of 2021.
In keeping with Germany’s focus on green hydrogen and on using offshore wind to produce green hydrogen, €20M is being invested as part of the Green Hydrogen for Bremerhaven pilot project. This will see Fraunhofer IWES build an electrolysis test field. Among the objectives are to test the electrical characteristics of electrolysers operating on fluctuating electrical supply from renewables and develop control and monitoring systems to stabilise the grid when hydrogen is being produced.