Pilot project tests more sustainable alternative to scour protection

Offshore wind developer RWE has initiated a pilot project that will test the effectiveness and environmental credentials of a sustainable alternative to conventional rock-based scour protection for the foundations of offshore wind turbines.

Working with UK-based ARC Marine, which specialises in nature-inclusive solutions to marine construction, RWE is testing a new form of ‘eco-engineered’ scour protection based on the use of the British company’s reef cubes.   

The developer hopes the reef cubes will function as effectively as conventional scour protection, protecting the foundations of offshore wind turbines on the Rampion offshore windfarm off the south coast of the UK, enhancing marine biodiversity at the same time. ARC Marine is to provide more than 75,000 reef cubes for the project, using low-carbon, recycled materials to manufacture them.

ARC stands for ‘Accelerating Reef Creation,’ a principle brought to life through the design of the reef cube, which the British company has been developing since 2015. With a unique 3D textured finish, the design of reef cubes is customisable, based on deployment location, target species and sea state. The diameter of passageways built into the cubes can also be tailored to suit specific species requirements.

Another advantage of the reef cube concept is that manufacturing can be localised, close to deployment sites, which minimises their CO2 footprint, particularly when compared with conventional rock-based solutions. The company says a reef cube can reduce CO2 levels by 50-100 kg per tonne compared with conventional solutions and they provide a 91% carbon saving compared with the use of ordinary Portland cement.

Designed and produced by ARC Marine using its proprietary ‘Marine-crete’ construction process, reef cubes do not contain plastic. They are certified for a 99-year lifespan, an application for certification for a 1,000-year lifespan is being progressed, and they can be deployed using standard industry side dump or fall-pipe vessels to the base of a foundation for an offshore wind turbine.  

RWE describes the Rampion pilot as a ‘flagship project’ that can demonstrate and evaluate the potential of ‘nature inclusive design’ (NID) solutions to effectively meet engineering and biodiversity requirements in the offshore wind market.

The Reef Enhancement for Scour Protection (RESP) pilot project at the Rampion windfarm is a first-of-its-kind initiative and is cofunded by Innovate UK. Over the past 18 months, the project has achieved several important milestones, marking significant progress in the application of reef cubes as a scour protection solution. Recent months have seen the team working on the project complete hydrodynamic stability testing of a reef cube scour pad at HR Wallingford’s physical modelling facilities in England. The partners have also undertaken ecological baseline surveys, secured a marine licence for the full-scale deployment of the reef cubes at Rampion, and have placed all contracts for deployment. In addition, a scaleable manufacturing process has been developed using locally sourced, low-carbon, recycled materials.

The reef cubes for the project will be a mix of 15-cm and 35-cm cubes, all engineered with rough surfaces and built-in ‘shelter spaces’ that promote the settlement and protection of marine species found in the area around the Rampion windfarm, such as the European seabass, common starfish and brown crab. Data and insights gathered during the RESP pilot will help to assess the potential benefits of using NID to increase biodiversity in future offshore developments while addressing a critical engineering issue.  

“Deriving multiple benefits in this way delivers increased value and could lead to setting new practices for biodiversity integration across the renewables industry,” says RWE, which has set a target of achieving a net positive impact on biodiversity for new assets by 2030.

RWE Offshore Wind chief executive Sven Utermöhlen says the RESP “reflects RWE’s commitment to pioneering nature-positive solutions that support the resilience of offshore wind assets and the biodiversity of marine ecosystems.” Mr Utermöhlen says the company is proud to partner with ARC Marine to advance what he described as “this innovative solution, which offers a practical and scaleable approach to sustainable offshore development.” 

ARC Marine founder and chief executive Tom Birbeck says, “This pilot is the world’s first full-scale deployment of nature-inclusive designed reef cubes as an alternative to imported rock scour protection. This kind of solution can create valuable new habitats while still addressing engineering needs. We are thrilled to see RESP move from concept to reality alongside RWE and see reef creation being actively explored during offshore energy construction.”