MaresConnect is a 750 MW electricity interconnection project linking the Irish and GB electricity transmission networks, enabling electricity to be transported in both directions between Ireland and Wales. Once completed, estimated electricity flows over the interconnector would be equivalent to power 570,000 homes.

MaresConnect will consist of submarine and underground HVDC power cables linking two converter stations, one in Wales and one in Ireland.

The selection of the connection point in Ireland is subject to an ongoing engineering review looking at existing and future EirGrid substation locations in the Greater Dublin Area. The existing substation locations include the Maynooth, Woodlands and Belcamp substations. Underground HVAC cables will be used to link the MaresConnect converter station to the EirGrid substation. The converter station in Wales will be built close to the National Grid substation at Bodelwyddan, where an extension is planned to facilitate the MaresConnect connection as well as other connectees. The MaresConnect converter station will be connected to the Bodelwyddan substation via underground HVAC cables.

MaresConnect will foster the integration of further, substantial renewable energy sources to support the Irish and UK governments’ 2030 green energy targets and achieve their Net Zero goals. Further interconnection between the two nations will increase security of supply. Interconnection creates downward pressure on wholesale energy prices, leading to savings for energy consumers.

The project is expected to result in approximately €860 million of private capital investment in Ireland and Wales and will create long-term jobs in construction and operations. In addition, the project has the potential to bring further benefits with the inclusion of a high-speed direct fibre optic communications link between Ireland and Great Britain.

The Irish and GB energy markets face many challenges related to outdated infrastructure, a rapidly changing generation mix and the need to fight climate change. Addressing these challenges will require a significant shift to renewable energy, supported by an improved transmission network that can distribute energy from source to demand centres while ensuring security of supply.

MaresConnect’s aim is to be part of this transformation by delivering an additional 750 MW of cross-border transmission capacity between the Irish and GB electricity transmission networks, providing infrastructure to support energy security and downward pressure on consumer energy prices, thereby assisting the transition to a low carbon energy future.

A recent study* conducted by independent risk management and assurance expert, DNV to support Ireland’s National Policy on electricity interconnection found that additional interconnection by 2030 would reduce curtailment by 2.2TWh which would be a circa 20% reduction in curtailment for the SEM.

* Impacts of increased electricity interconnection on achievement of Ireland’s 2030 and post-2030 climate and energy objectives – p. 56 (§ 6.3.4)

MaresConnect is being developed by Foresight Group’s energy transition fund, Foresight Energy Infrastructure Partners (FEIP), and Etchea Energy Nominees Limited (EENL). The development activities are carried out by MaresConnect Limited (MCL), which is a special purpose vehicle incorporated in Ireland.

FEIP was launched in January 2020 by Foresight Group. FEIP is a fully discretionary investment fund with a broad mandate covering renewable energy generation assets, transmission and distribution assets and renewable energy assets.

Foresight, the investment manager of FEIP, is a sustainability-focused infrastructure and private equity investment manager listed on the Main Market of the London Stock Exchange. Founded in 1984, the Foresight Group has a long-standing focus on environmental, social and governance (ESG) and sustainability-focused strategies.

EENL is owned by the management team. Based in London and Dublin, Etchea Energy is a leading company in the development of projects in the energy sector.

MaresConnect Interconnector is privately financed by Foresight Energy Infrastructure Partners (FEIP) and Etchea Energy Nominees Limited (EENL).

MaresConnect’s objective is to complete the development phase of the project in 2026, followed by a three-year construction period and commencement of operations in 2029.

The interconnector consists of two high voltage direct current (HVDC) power cables and a fibre optic cable which runs approximately 190 km under the Irish Sea and 55 km underground, linking the two converter stations.

HVDC is more efficient at transporting electricity over long distances, especially underwater. The cables have lower current losses than comparable AC cables and negligible heating effects, making them suitable for burial both on land and in the sea bed. Therefore, there will be no cables overhead between the two converter stations. Another advantage of HVDC cables is the relatively small footprint required to lay them underground. HVDC technology offers the added benefit of being able to successfully connect two networks even if they are out of phase as is the case of the Irish and GB networks. In converter stations, the direct current (DC) in the HVDC cables is converted to alternating current (AC) so that it can be connected to the substation and used in the national transmission and distribution networks. A fibre optic cable provides communication between converter stations for system monitoring, control and security.

In Wales, MaresConnect will connect to a proposed extension to the Bodelwyddan 400kV substation in Denbighshire. In Ireland, it will connect to an existing sub-station in the Greater Dublin Area.

The cable landfalls will be determined following extensive technical and environmental studies as well as consultations with local planning authorities and the respective grid operators and local communities.

The preferred subsea cable route will be identified after separate technical surveys and  environmental studies and consultation with stakeholders.

Onshore, the underground cable routes and converter stations sites will also be identified following consultations and technical and environmental assessments.

The interconnector cables will be undersea or underground over its entire length between the converter stations in Ireland and Wales. The offshore cables will be buried in the seabed or laid on the seabed with protection if burial is not practicable, using special vessels equipped with tools for laying cables.

The cables could either come ashore via trenching or a Horizontal Directional Drill (HDD). The method of installation selected will depend on the results of consultation and technical and environmental surveys. The selected method will be clearly described in planning documentation to ensure that the local community and permitting authority is fully informed on the proposed methodology to be used when reviewing the application documentation.

The exact cable routes in Ireland and Wales will be determined following consultation and the completion of studies. Local road networks can be used for the installation of cable routes and will be fully assessed and considered during the design phase.

All the onshore cables will be buried underground.

All cables between the two converter stations will be underground and once installed there will be no permanent visual impact from the cables (e.g. any vegetation clearance required during construction will be temporary and will be restored). The converter station could cover an area of up to 4 hectares (265 m x 150 m). We will carry out a visual impact assessment and create visualizations based on views agreed with the local planning authority to ensure that impacts are minimised. Such impacts will be carefully considered and appropriate mitigation measures such as landscaping and building improvements will be implemented.

HVDC cables emit low Electromagnetic Fields (EMF) which are consistent with World Health Organisation guidelines and do not pose a health risk. The planning application will include an EMF assessment which will ensure the safe design of the interconnector and will be available for scrutiny.

The HVDC cables we use emit lower electromagnetic fields (EMF) than HVAC cables and both technologies comply with World Health Organization guidelines. MaresConnect will engage expert consultants and is committed to conducting EMF assessments to provide further confidence where necessary.

All cabling is routed underground or under the seabed (or sheltered on the seabed where this is not possible). The power cables are housed in protective armoured sheathing and buried on land with a protective sleeve and warning tape. Marking posts are placed at ground level at regular intervals in exiting land boundaries.

Our environmental and technical investigations include noise and vibration assessment. Most of the expected noise and vibration impacts will occur during the construction of the converter stations and cable laying and will therefore be transient and in isolated locations. However, we will ensure that this is kept to a minimum. During operation of the converter station there will be noise from some of the electrical and mechanical components. All operational noise will be assessed within the Environmental Impact Assessments and the development will be designed to ensure that any noise generated is factored into the final converter station design to ensure that residents do not witness a loss of amenity due to noise or vibrations. We support the placement of noise related planning conditions on the development to provide additional comfort to residents.

Our aim is to deliver positive outcomes to local wildlife and the surrounding environment. We are working closely with independent experts on a series of environmental and technical studies, the results of which will help us shape the project ensuring it is environmentally considerate and to minimize its impact. We will conduct comprehensive Environmental Impact Assessments, allowing detailed review by stakeholders. Our surveys and assessments will be submitted as part our planning application for public review and will also be reviewed by Natural Resources Wales and the National Parks and Wildlife Service in Ireland.

We fully appreciate the beauty of North Wales and Dublin beaches and their value to local residents, visitors and wildlife. We are aware that some may have concerns about possible damage during construction. For this reason, we will consult with local communities, independent experts and stakeholders, including Natural Resources Wales and the National Parks and Wildlife Service in Ireland, to carefully design the project supported by a range of environmental and technical studies.

To ensure minimal environmental impact, our current plan involves deploying cables between the landfalls and the sea by drilling under the beaches, a technique known as Horizontal Direct Drilling (HDD).

We will evaluate the potential impacts of MaresConnect on designated and non-designated local archaeology and cultural heritage.

To mitigate potential impacts, we will consider the anticipated impacts of the proposed scheme and aim to avoid negative consequences. Where possible, mitigation measures will be designed to provide benefits such as preserving the visual ambiance of historic assets.

We strive to avoid undisturbed archaeological remains and to preserve them in situ. If that proves unfeasible, we recommend archiving for preservation.

Installation will be carried out in accordance with best practice and will ensure that the final road surface meets the standards set by the relevant road authority.

During the development of the project, we will consult extensively with a range of legal advisers, NGOs and local, provincial and national government agencies.

Numerous environmental and financial benefits will be provided by MaresConnect.

  • Energy security – Strengthen the security of electricity supply
  • Savings – Reducing wholesale energy prices
  • Net Zero – Mainstreaming green energy in Wales/UK and Ireland
  • Jobs – Job creation in construction and in operation and maintenance
  • Electricity Transmission – Equivalent to 570,000 households
  • Investment – ​​€860m of private capital investment benefiting Ireland and Wales

We will be holding a number of local community consultations and opportunities for interested members of the public to have their say. Details will be made available well in advance, including via our website.

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