A significant milestone in the development of Ireland’s offshore wind resources was reached earlier this month with the commencement by EirGrid of marine and coastal surveys off the south coast.
The surveys will enable progress on EirGrid’s Powering Up Offshore – South Coast project, which aims to deliver the grid transmission infrastructure needed to connect 900MW of offshore wind generation, enough to power one million homes, to onshore grid connection points along Ireland’s south coast.
The project will involve new offshore transmission cables connecting two new offshore substations to landfall locations, new onshore substations, connections between landfalls and the new onshore substations by underground cables and connections to the existing electricity transmission network by either underground cables or overhead lines.
“The offshore transmission infrastructure is really important,” says EirGrid chief technology, transformation and offshore officer Liam Ryan. “It comprises the substations and cables and other infrastructure needed to connect offshore wind farms to the grid.”
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The project will support phase two of the Government framework for the development of offshore wind energy infrastructure. In phase one, Ireland’s first offshore wind auction secured 3GW of power from three wind farm projects off the east coast and one off the west coast. The developers of those projects will also develop the offshore grid infrastructure to connect the wind turbines to the onshore electricity grid.
Phase two will be developed in an area known as the South Coast – Designated Maritime Area Plan (SC-DMAP). The SC-DMAP includes four proposed areas for future offshore wind development. The current project involves the first area for development, known as Tonn Nua. This phase differs from phase one in that EirGrid and not the developers will be responsible for the development of the offshore grid infrastructure.
“We received a Maritime Usage Licence from Mara, the Maritime Area Regulatory Authority, on July 7th,” says Ryan. “This enables us to carry out the marine surveys, which will allow us to understand the environment for laying cables and constructing the offshore substations. The licence award was a key milestone for us.”
Geo-data specialist Fugro was awarded the marine survey contract under EirGrid’s Offshore Marine Survey Framework. “Fugro will perform comprehensive geophysical, geotechnical, environmental and metocean surveys as well as intertidal non-intrusive landfall investigations involving geophysical and environmental surveys,” says Ryan.
“The surveys will be carried out across an area of 306 square kilometres and the substation platforms will be located between 12.2 and 12.4km offshore. These surveys are key for assessing seabed conditions, soil properties, and environmental impacts across the landfall, intertidal, nearshore, and offshore zones related to cable corridors for the project.”
Surveying activity is scheduled to continue until September this year. It will resume in July 2026 and continue for three months.
Some of the landfall surveys are on private lands, but some are also scheduled on public beaches at potential landfall locations, Ryan explains. The beaches where non-intrusive surveys will take place are Ballycroneen and Ballycrenane in Co Cork and Carnivan, Long Gap and Blackhall Beach in Co Wexford. “EirGrid are engaging with local communities, landowners and local authorities in relation to these works,” he adds.
“The insights gained as a result of this work will play a key role in informing plans for the installation of the transmission infrastructure for offshore wind energy and will guide how EirGrid progresses the project in a way that is best for our marine ecosystem and local communities.”
Community engagement is critically important, according to Ryan. “We will engage with local communities, fishers and other stakeholders throughout the project. This is the first time that Ireland has really started to look at offshore wind and we are trying to make it a really positive experience for all parts of society. We will make sure that all voices are heard, as we have done in the past with other projects.”
The survey data will enable EirGrid to identify suitable locations for the new offshore substations and cable routes. “Nothing has been decided at this stage,” says Ryan. “We are still looking at options at this point in time. In essence, this work is about giving certainty to the developers that the transmission network is going to be there for them to connect offshore wind farms to the onshore grid. That’s critically important.”
There will also be other benefits. “The surveys will help us to identify other challenges, and we will be able to share some of that data with the developers. We have already seen in phase one that there is a willingness to share data and learnings on the part of developers. It’s about everyone involved putting on the green jersey to collectively deliver for Ireland Inc.”
The next steps following the completion of the surveys in 2026 will mean a decision is made on where to put the offshore substations and cables. “We will then go for planning permission,” says Ryan. “All going well after that, we hope to go to procurement and construction and have the infrastructure energised by the early 2030s.”
