Greenlink Interconnector has signed a contract with Siemens Energy and Sumitomo Electric for high-voltage direct current (HVDC) converters and cable for its planned 500MW interconnector that will link the GB grid with grids in Northern Ireland and the Republic of Ireland.
Work is due to begin on the 190km electricity interconnector at the start of 2022.
Siemens Energy will be responsible for the overall system design and the construction of two converter stations located close to the Great Island transmission substation in County Wexford and the Pembroke transmission substation in Pembrokeshire. They will be linked via an HVDC XLPE (crosslinked polyethylene) cable system by Sumitomo.
James O’Reilly, CEO of Greenlink, commented: “We are delighted to have reached another significant milestone in the delivery of the Greenlink project with the signing of the contract with Siemens Energy and Sumitomo Electric. Greenlink is one of Europe’s most important energy infrastructure projects, contributing to energy security, regional investment, jobs and the cost-effective integration of low carbon energy, and we have chosen a consortium with exceptional experience, skill and standing in the energy and engineering sector for this major undertaking. We will be looking to maximise local supply chain benefits during the three-year construction period and we look forward to working with Siemens Energy and Sumitomo Electric towards successful
commissioning in 2024.”
Greenlink has been designated a “Project of Common Interest”.by the European Union.

GB actions required to keep Irish customers online
The importance of interconnectors in managing more volatile markets was illustrated by events on Thursday 9 September, when GB power flowed to the Single Energy Market (SEM) in Ireland/NI through existing interconnectors in emergency action to support customers there.
According to NGESO, in its weekly Operational Transparency Forum, the GB market had “tight but adequate margins” across that week. On Thursday “Ireland were in amber alert status and had requested flows from us to them. We had access to megawatts, albeit at high cost, and we were able to support them. Eirgrid bought approximately 3GWh of SO to SO trades throughout the day.
“These trades prevented disconnection of Irish consumers – that was the level of alert they were at. They would have been disconnecting their consumers.”
The actions taken by NGESO to support its counterpart raised initial estimates of GB system management costs to £39 million, compared to around £21 million on the second most expensive day of the week. NGESO said reconciliation would assign a significant proportion of those costs to the SEM. It said “In the coming days and weeks those will be cancelled out and the costs will come down” with about £12 million in costs assigned paid by the Ireland markets.