The marine environment is in decline, with only 19% of England’s estuaries and 45% of coastal waters achieving good ecological status, alongside significant losses of habitats such as oyster reefs, seagrass beds and horse mussel beds. As National Grid expands its offshore electricity transmission network, understanding and mitigating the impacts of subsea cable infrastructure on marine ecosystems is increasingly important.
To address this, National Grid proposes a one-year feasibility study to assess whether restoring horse mussel beds could provide a viable nature-based solution to compensate for impacts associated with offshore cable routes. As a promising but unproven approach in the UK, the project will evaluate practical and scalable restoration methods that support biodiversity recovery, meet environmental obligations and align with emerging marine policy. The study aims to enable sustainable offshore network expansion while enhancing marine ecosystem resilience.
Benefits
The restoration of horse mussel beds represents a promising, yet currently unproven solution that has not previously been implemented in the UK. This project therefore offers a significant opportunity for innovation and industry learning, with the potential to establish a viable compensation measure for future offshore projects such as EGL4 and ASTI. As these restoration approaches have not been trialled at scale, they would be pioneering for National Grid and could set a precedent for wider adoption. There is already emerging interest from other Transmission Owners (e.g. SSEN), as well as offshore developers such as wind farm operators, given the applicability of horse mussel restoration across UK and Scottish waters.
This project responds directly to increasing regulatory and environmental pressures to avoid biodiversity loss, comply with evolving marine policies, and deliver effective compensation for impacts on protected marine areas. By developing scalable and reliable restoration approaches, the project will provide a robust evidence base to support confident implementation. It will also contribute to UK-wide marine restoration and biodiversity enhancement efforts, aligning with National Grid’s B4.8 commitment to deliver measurable environmental improvements across offshore projects. Over a longer period, the development of successful restoration techniques could reduce consenting delays, compliance costs, regulatory risk and help develop offshore infrastructure more efficiently.
In addition, determining the feasibility of large-scale hatchery production could unlock wider socio-economic benefits, including the creation of skilled employment opportunities in coastal communities affected by offshore infrastructure development. The outputs generated through this study will inform the development of long-term onshore aquaculture facilities and offshore marine recovery zones funded through our Offshore portfolio. This aligns with National Grid’s B2.1 commitment to promote social mobility by fostering new skills and employment opportunities within local communities.
Building on these strategic advantages, the following summarises the key measurable benefits the project is expected to deliver:
Deliver a validated feasibility assessment within 12 months, providing actionable evidence on the use of horse mussel restoration as a scalable compensation measure for offshore cable impacts.
Create a transferable innovation pathway for the sector, positioning National Grid (together with other UK TOs/DNOs) as a leader in marine restoration while enabling adoption by other Transmission Owners and offshore developers across UK and Scottish waters.
Leave a positive environmental and societal legacy by demonstrating how offshore infrastructure can actively contribute to ecosystem recovery and long-term marine resilience.
Unlock socio-economic value in coastal communities by assessing hatchery feasibility, supporting skills development, and enabling future job creation aligned with RIIO‑T3 B2.1 commitments.
Deliver long-term consumer and system value by identifying cost-effective, scalable restoration solutions that reduce environmental risk, improve project efficiency, and align with NIA objectives for net benefit.
