On 29 December 2025, the 750 MW MaresConnect interconnector between Ireland and Wales was included in the EU’s second list of Projects of Common/Mutual Interest (PCI/PMI), granting it priority energy infrastructure status with benefits such as accelerated permitting under the TEN‑E Regulation and eligibility to apply for Connecting Europe Facility funding for up to 50% of eligible development costs.
The same GEOxyz MMO Report records that geotechnical sampling for MaresConnect in Irish offshore areas, also aboard Geo Ocean VI, took place from 6 to 10 August 2025, completing the geotechnical phase.
GeoXYZ’s Ireland Offshore MMO Report for the MaresConnect Marine Survey (Geo Ocean VI) states that the offshore geophysical survey in Irish waters was carried out between 15 and 30 July 2025 and that the geotechnical survey phase took place between 6 and 10 August 2025. This report confirms that the geotechnical sampling operations along the MaresConnect subsea cable route in Irish waters started on 6 August 2025.
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MaresConnect is a proposed 750 MW HVDC interconnector project linking the Irish and Great Britain transmission systems. The scheme comprises two converter stations (one sited close to an EirGrid substation in the Greater Dublin area and one adjacent to National Grid’s Bodelwyddan substation in De...
Owners
Mares Connect, Ireland–Wales interconnector, Project #349 (TYNDP), NESO TEC PRO-000978
The GEOxyz Ireland Offshore MMO Report for MaresConnect states that offshore geophysical survey operations aboard Geo Ocean VI in Irish waters were conducted between 15 and 30 July 2025, marking completion of the geophysical phase.
During the July–August 2025 offshore survey campaign for MaresConnect, GeoXYZ was also scheduled to begin environmental sampling along the proposed subsea cable route in Irish waters in conjunction with geophysical investigations, using the Geo Ocean VI to collect data needed for environmental assessments.
According to the GEOxyz Ireland Offshore MMO Report for MaresConnect, offshore geophysical survey operations aboard the vessel Geo Ocean VI in Irish waters were carried out between 15 and 30 July 2025.
The CRU opened a public consultation on its Initial Project Assessment of the MaresConnect interconnector on 2 May 2025, inviting stakeholder responses through 11 July 2025.
Geophysical survey works for the MaresConnect subsea cable route commenced on 28 March 2025, with GEOxyz vessels Ros Áine and Geo Ocean VI conducting multibeam echosounder, side-scan sonar, magnetometer and sub-bottom profiler surveys along the route within 12 nautical miles of Ireland's east coast.
By late 2024, MaresConnect Limited had not yet submitted key planning and marine licence applications for its converter stations and onshore/offshore cable works; available sources up to early 2026 describe the project as progressing through surveys and regulatory assessments without mentioning lodged planning applications.
On 12 November 2024, Ofgem announced its minded‑to decision to award Cap & Floor regulation to the 750 MW MaresConnect interconnector as part of the Initial Project Assessment of its third Cap & Floor application window, effectively approving the project’s regulated revenue regime in Great Britain. Industry reports the same day described Ofgem as having approved five new undersea energy connectors including MaresConnect, confirming it as one of the interconnectors that will provide additional cross‑border capacity for GB.
On 23 August 2024, the Irish authorities issued a Foreshore Licence (FS007635) to MaresConnect Limited, granting consent for marine site investigation surveys for the MaresConnect electricity interconnector from approximately 50 metres landward of the high-water mark to the 12 nautical mile limit off the County Dublin coast, providing a legal basis for nearshore survey activities.
On 20 June 2024, MaresConnect Limited submitted a Maritime Usage Licence application (MUL240008) supported by environmental assessments to the Irish maritime regulator, seeking permission to undertake offshore site investigation and survey works for the MaresConnect interconnector from the 12 nautical mile limit out to Ireland’s Exclusive Economic Zone, including geophysical, geotechnical, ecological and metocean surveys along the prospective subsea cable route.
By 20 June 2024, MaresConnect Ltd was completing feasibility studies for the 750 MW HVDC MaresConnect interconnector between Great Britain and the Republic of Ireland, with the project in its planning stage and requiring further environmental and technical assessments and site investigations to inform the final interconnector design and subsequent development permissions in Ireland and Wales.
MaresConnect Limited initiated a non-statutory public consultation in autumn 2023, issuing an information brochure in November 2023 to inform communities and stakeholders in Ireland and Wales about the proposed 750 MW MaresConnect interconnector, its routing, landfall and converter station options, and to invite feedback as project design and environmental and technical assessments progressed.
The Irish Department of Climate, Energy and the Environment ran a formal public consultation from 13 July to 13 August 2023 on MaresConnect Limited’s Foreshore Licence application FS007635 for marine investigative survey works for the MaresConnect interconnector, with application documents available for public inspection and written submissions invited by post or email.
MaresConnect Limited submitted a Foreshore Licence application (FS007635) to the Irish authorities on 3 March 2023, seeking consent for marine investigative survey works for the MaresConnect electricity interconnector, including surveys extending 50 metres landward of the high-water mark along the coast between Portmarnock and Skerries in County Dublin.
In June 2022, Ofgem granted MaresConnect Limited an interconnector licence for the 750 MW MaresConnect project, formally authorising the company to develop and operate a new subsea and underground electricity interconnector between Dublin in Ireland and Bodelwyddan in Wales and recognising the project’s importance for additional GB–Ireland interconnection capacity.
On 11 May 2022, Foresight Group Holdings Limited, through its energy transition fund Foresight Energy Infrastructure Partners (FEIP), acquired a significant majority stake in the MaresConnect interconnector project, with Etchea Energy Nominees Limited retaining the remaining shareholding, providing new capital to progress development towards financial close and construction.
MaresConnect, a proposed 750 MW electricity interconnector linking the power systems of Ireland and Great Britain, was recognised as a project in ENTSO‑E’s Ten-Year Network Development Plan 2022 (TYNDP 2022), listed as Project #349, underscoring its strategic role in European energy infrastructure and renewable integration goals.
By 29 April 2022, project company MaresConnect Limited had submitted an application to UK energy regulator Ofgem for an interconnector licence, seeking authorisation to participate in the operation of the proposed 750 MW subsea and underground MaresConnect electricity interconnector linking Ireland and Great Britain.
In 2018, MaresConnect Limited secured and entered into a 750 MW grid connection agreement with National Grid for a connection at the Bodelwyddan 400 kV substation in Denbighshire, North Wales. This agreement formally confirms the availability of a UK grid connection point for the MaresConnect interconnector and is repeatedly referenced in later developer and project materials as an existing connection agreement supporting the planned 750 MW link between Ireland and Great Britain.
MaresConnect Limited applied for Cap & Floor revenue regulation in Great Britain under Ofgem’s third Cap & Floor application window, with Ofgem subsequently assessing the project’s benefits as part of that window ahead of an initial decision expected in early 2024. The project had earlier indicated its intention to seek Cap & Floor support in the UK and to participate in Ofgem’s third window once it opened in summer 2022.
MaresConnect Limited was established as a project-specific company and subsidiary of Mares Interconnector Holdings Limited, an Irish limited company funded by private capital, to develop, construct and operate the 750 MW MaresConnect subsea and underground electricity interconnector between Ireland and Great Britain.
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