Bringing the Ocean to Society
29 Aug 2019
Introducing Ifremer's synthetic fibers
EurOcean Co-Founder and Member creates new mooring materials for wind turbines.

How to moor future wind turbines at sea? Compared to chains, synthetic materials offer features and benefits sought by operators. At Ifremer’s headquarters in Brest,  France, researchers tested the resistance over time of these ropes that we would like to be able to immerse for ten or twenty years.

Conventional materials limit maintenance and impose equipment replacement operations. The stakes are high for operators who imagine future fields of floating wind turbines moored to the bottom. There is no question of using heavy chains, cumbersome and complicated to deploy in view of the quantities to be implemented on the largest fields under study. Synthetic materials, such as nylon, offer a credible alternative, already used on some oil rigs.

"In recent years, a submerged rope only lasted a year or two in the water," summarizes Peter Davies from Ifremer. "It would lose a lot of his qualities and gave up quickly in case of repeated friction. We worked the braiding and the architecture of these ropes with a Belgian company, as well as the coatings. We have significantly improved our knowledge of the strength and longevity of this type of fibber."

To limit the wear, the processes of elongation and the aging of these lines subjected to repeated and numerous efforts. The flexibility of synthetic fibers also helps to absorb shocks, reducing jolts that can ultimately weaken the machines and have a real impact on their performance. Finding the right fiber for the right use, at a lower cost. "The ideal would be to use a biobased fiber but it is currently difficult to increase their sustainability," said the scientist.

In order to limit the use of fibers from petrochemicals, which is more aligned with the field of renewable energies, there is a great temptation to use components that are less harmful to the ocean. But for the moment, only products derived from hydrocarbons meet the demanding specifications of these machines that will have to stand in time, withstand storms and millions of tension cycles generated by waves and wind.

Use ecological fibers, recyclable at will but need to replace them more often or rely on nylon with proven resistance but still from the oil chain? For project developers, the cost of implementation and the desire for longevity on giant fields requiring anchor kilometres easily dictated their choice.

The work carried out in Ifremer's laboratory at Plouzané is progressing rapidly. "With the modifications made to the fibers tested in the laboratory, we are able to guarantee the effectiveness of a synthetic rope subjected to friction and repeated efforts over several years underwater. So many advances that will one day benefit mooring, towing and, why not, boaters who will also free themselves from their chains.

Original news article by Le Télégramme available here (in French).