British engineers have found an ingenious new use for sheep’s wool, developing biodegradable ropes that could help remove plastic from commercial seaweed farming.
Researchers at Queen’s University Belfast have spent the past two years investigating whether pure wool can replace the synthetic ropes and twine commonly used to cultivate seaweed at sea.
The project began with trials at Queen’s experimental seaweed farm on Strangford Lough in Northern Ireland and has now progressed to industrial-scale trials in Norway, with further work taking place in Iceland.
The researchers have been using wool from Whiteface Dartmoor sheep to produce biodegradable ropes on which seaweed can be grown.
It offers a potentially simple solution to a problem facing the rapidly developing seaweed farming industry.
Commercial seaweed is commonly cultivated on synthetic ropes suspended in the water. Although these can be reused, repeated use causes wear and can release microplastic fibres into the marine environment. Ropes can also break and be lost at sea, while those reaching the end of their useful lives may be incinerated or sent to landfill.
The wool alternative is designed to avoid those problems.
Once the seaweed has been harvested, the biodegradable wool rope and any remaining seaweed material can be processed together into fertiliser, potentially creating a circular system without the need to dispose of synthetic rope.
The British-led project has now demonstrated that the idea can work beyond small laboratory and experimental trials.
Working with UK wool-products manufacturer The Provenance Company and Norwegian producer Arctic Seaweed, the Queen’s team has successfully cultivated three commercially important types of seaweed on longlines made from 100 per cent wool.
Industrial-scale trials have taken place at Arctic Seaweed’s Trettosen farm near Bergen in Norway.
Researchers successfully grew sugar kelp, winged kelp and sea lettuce on the wool lines, which the team says represents an industry first at this scale.
Dr Pamela Walsh, from Queen’s School of Mechanical and Aerospace Engineering, said it had been rewarding to see the idea progress from a small proof-of-concept experiment at Strangford Lough to industrial-scale trials overseas.
Initial research was supported by the Engineering and Physical Sciences Research Council’s Impact Acceleration Account, with further support from Innovate UK helping the researchers develop more advanced marine ropes and move towards larger-scale testing.
The work could also offer an interesting new market for British wool.
Wool prices have been depressed for years, leaving some farmers receiving relatively little for their fleeces compared with the cost of shearing their sheep.
The wool being used in the seaweed project comes from Whiteface Dartmoor sheep, while The Provenance Company manufactures the wool products in Britain.
Company founder Kim Stead said the project demonstrated the potential for natural materials to help tackle environmental problems and described the successful commercial testing as an exciting development for farmers, British wool and British manufacturing.
There is still research to be done.
A peer-reviewed study published this year by researchers involved in the project found that untreated pure wool successfully supported kelp growth during both nursery and open-water cultivation.
The performance of the wool varied according to its thickness and the conditions of the trials, but researchers concluded that it represented a promising route towards reducing plastic pollution from seaweed aquaculture.
With the project now moving from experimental waters in Northern Ireland to commercial-scale trials overseas, a material Britain has produced for centuries could find itself with a decidedly modern new purpose.
From Dartmoor sheep to the waters of Norway, British wool could one day be helping to grow food and other marine products while keeping plastic out of the sea.
