East-West Interconnector

Overview and Purpose

The East-West Interconnector is a high-voltage direct current (HVDC) submarine and subsoil power cable that connects the electricity grids of Ireland and Great Britain. Commissioned in 2012, this 500 MW capacity link spans 261 km, with 186 km running beneath the Irish Sea and 75 km underground. It connects Rush North Beach in County Dublin, Ireland, to Barkby Beach in Prestatyn, Wales.

Developed by EirGrid, the Irish national grid operator, and later transferred to its subsidiary EirGrid Interconnector Limited (EIL), the project aims to increase competition, enhance security of supply, and better utilize wind energy capacity. The interconnector allows Irish suppliers to access the British mainland market and British suppliers to enter the Irish market without significant initial capital expenditure, reducing barriers to entry.

Technical Specifications

The East-West Interconnector uses ±200 kV HVDC Light technology, making it the first HVDC Light transmission system to employ ±200 kV cables. ABB provided the cables and converter stations for the project. The interconnector's construction began in 2010 and was completed in 2012, with the official inauguration taking place on September 20, 2012, in Batterstown, County Meath.

Technical features of the East-West Interconnector include its ability to transmit enough energy to power 300,000 homes. It also offers ancillary services such as frequency response, reactive power, and black start capability. The advanced HVDC Light technology used in the interconnector requires minimal maintenance and is expected to have a 40-year lifespan.

Financing and Support

Financing for the project came from multiple sources, including a €300 million loan from the European Investment Bank, capital investments from commercial banks, EirGrid equity, and a €110 million grant from the European Commission. The European Union classified the UK-Irish Interconnector as a priority project under its Trans-European Networks initiative.

Operational Aspects

The interconnector operates bidirectionally, allowing electricity to flow in either direction between the Single Electricity Market (SEM) of Ireland and the British Electricity Trading and Transmission Arrangements (BETTA) market. This capability provides benefits such as improved security of supply, increased competitiveness, and support for renewable energy growth in both countries.

Challenges and Maintenance

The interconnector has faced some operational challenges. In September 2016, a fault occurred during annual maintenance at the converter station in County Meath, leading to limited export capacity to the UK until June 2017. In March 2022, following a planned three-week shutdown, the interconnector operated at below 1% capacity for an extended period.

EirGrid has a long-term service agreement with NKT for inspection surveys and remediation work on the East-West Interconnector. This agreement ensures the cable is maintained in optimal condition and can withstand extreme conditions for safe operations.

Role in Renewable Energy

The East-West Interconnector plays a crucial role in Ireland's renewable energy goals, supporting the country's target to generate 40% of its electricity from renewable sources. By connecting to the UK national grid, it also allows Ireland to access power from across Europe via interconnectors between Britain and the continent.