Ireland is focused on achieving its climate and energy goals of becoming carbon neutral by mid-century with an interim target of 51 per cent emissions reduction by 2030 relative to 2018 emissions levels. It plans to achieve these targets through the Climate Action Plan 2023 (CAP2023) published in December 2022 under the Climate Action and Low Carbon Development (Amendment) Act 2021 to implement the economy-wide carbon budgets and sectoral emissions ceilings. Northern Ireland, which is part of the UK, also aims to achieve carbon neutrality by 2050. By 2030, both Ireland and Northern Ireland, whose electricity systems and markets are integrated (since 2007), aim to deliver up to 80 per cent renewable energy sources (RES) generation, an increase from their previous goal of 70 per cent. 

To its credit, Ireland has achieved significant strides in the sector. The integrated power system of Ireland and Northern Ireland, managed by the Irish transmission system operators (TSO) EirGrid and System Operator of Northern Ireland (SONI) (also a part of EirGrid Group), has been able to handle up to 75 per cent variable renewable generation (referred to as system non-synchronous penetration or SNSP) at any point in time since April 2022. This made it the first in the world to reach this level, overcoming major technical challenges associated with integrating electricity from wind farms, solar farms and interconnectors that link it with other countries. The plan is to take SNSP to 95 per cent by 2030 to achieve the country’s renewable ambition.  This requires RES capacity addition of over 22 GW, including 5.5 GW of onshore wind, 5 GW of offshore wind (OSW), 8.4 GW of solar and close to 3 GW of storage capacity by 2030. This ambition must be achieved while retaining the reliability, resilience and affordability of the electricity system. 

In this background, in July 2023, EirGrid and SONI, which operate the integrated Single Electricity Market (SEM) of the two countries, published the revised Shaping Our Electricity Future Roadmap Version 1.1’. This is an update of the plan first published in November 2021, outlining the network, market and operational changes required to deliver a power system with 80 per cent RES share by 2030. EirGrid Group plans to invest EUR3.4 billion across the island by 2030 including an additional EUR236 million under the latest plan.

Key drivers

The key driver for investments in the grid is the need for it to carry much more power from the upcoming new renewable capacity to the demand centres. By 2030, electricity demand is expected to increase substantially to 56 TWh across the island from about 40 TWh in 2021. This is due to the increasing use of electricity for transport and heating as well as demand from power-intensive users like pharmaceutical plants, high-tech manufacturing and data centres. 

On the supply side, huge amounts of wind and solar is proposed to be integrated into the grid. Particularly, the country plans to add 5 GW of OSW capacity by 2030 in addition to 2 GW for hydrogen production. This is being supported by the Department of Environment, Climate and Communications’ (DECC) Renewable Electricity Support Scheme (ORESS), the auctions for which are being conducted by EirGrid. In June 2023, EirGrid announced the final results for the first ORESS 1 auction selecting four OSW projects aggregating 3,074 MW (of the six qualified projects), which are capable of delivering 12 TWh electricity annually. The 1.3 GW Codling Wind Park is the biggest of the selected projects. The auction resulted in hugely competitive prices — an average of EUR86.05 per MWh, which is claimed to be one of the lowest prices paid by an emerging OSW market in the world. To compare, Ireland’s average wholesale electricity price over the past 12 months was over EUR200 per MWh. This marks phase one of the country’s OSW development. In April 2023, DECC published the phase two framework and policy to transition to the longer term enduring offshore regime. EirGrid will launch the first auction under this phase ORESS 2 by end-2023 with a focus on delivery of the 2030 OSW goal. Notably, EirGrid will build offshore transmission infrastructure for ORESS 2, including offshore substations and submarine cables connecting offshore substations to the onshore grid. Further, the latest policy proposes that future OSW projects will connect to offshore substations to be designed and built by EirGrid, which will be a first for the company. However, successful participants in any subsequent auctions (after ORESS 2) may be required to develop all offshore transmission assets, including offshore substations, which will be subsequently transferred to EirGrid.

In addition, beyond phase two and the 5 GW objective, the government is committed to phase three, which targets an initial 2 GW of floating OSW off the south and west coasts and may include projects available for green hydrogen production. DECC intends to launch the phase three policy as well as the longer-term enduring regime for offshore renewable energy in the first quarter of 2024.

Table 1: Summary of demand and supply scenario in Ireland by 2030

By 2030, all thermal capacity using coal, peat and oil as primary fuel will be decommissioned in addition to other ageing thermal plants, which are expected to be replaced by new gas-based generation, LDES, new interconnection capacity and demand-side units. Particularly, the country plans to add 2.75 GW of new LDES over the next eight years in addition to 150 MW of short duration storage. Storage capacity will be used for reserve provision, capacity adequacy, to assist with congestion management, and help manage surplus renewable generation while minimising the amount of RES generation required to deliver the governments’ target.

Network plans

EirGrid, with a transmission line length of approximately 9,500 km (excluding the Dublin 110 kV network and some other specific 110 kV circuits that are treated as part of the distribution system), has a key role to play in transmission of the planned capacity. As of March 2023, it had around 362 projects under various stages of development in its network delivery portfolio (NDP). Several of these projects are required to reinforce the network infrastructure.

Further, the latest plan has added 19 network projects (including three in Northern Ireland) and four large-scale renewable hubs. The latter is a solution to connect RES projects to specific parts of the grid that have spare capacity. Further, as part of its strategy to optimise the use of existing network infrastructure and use innovative technologies to manage network congestion and maximise capacity, EirGrid plans to deploy dynamic line rating (DLR) and power flow controllers (PFCs). In fact, 10 of the 16 network projects added in Ireland are new technology projects based on DLR and PFCs while the remaining pertain to the upgrade of the existing grid. In Northern Ireland, two projects relate to the upgrade of existing circuits and the third to the construction of a new substation.

Renewable hubs and grid reinforcement
High voltage renewable hub substations are proposed to be strategically located to allow significant quantities of new renewable generation in the geographic vicinity to connect into them. The idea is to avoid multiple smaller-scale connections to the 110 kV grid besides additional congestion on the network. The latest roadmap has identified four new hubs, three in the midlands and one in the southeast. These are the 400 kV renewable hub collector substation looped-in to the 400 kV Oldstreet–Woodland circuit; a 220 kV substation looped-in to the Maynooth–Shannonbridge circuit; and two 220 kV hubs each tailed into the Maynooth substation and Great Island substation (in the southeast).

As there are several onshore renewable energy projects coming up in Midlands, EirGrid is upgrading its existing network through uprating and refurbishment projects to bring more capacity to the existing underlying 110 kV network. In the northeast, several uprates and DLR projects have been identified. In the southeast, the application of flexible network technologies besides the renewable hub have been identified.

With regard to the ongoing grid development to facilitate RES connections in the west and northwest, EirGrid is developing the 60-km, 110 kV CP0816 North Connacht project. This is the country’s first long underground cable circuit. It runs from Moy substation in Ballina County, Mayo, to Tonroe substation in Ballaghaderreen County, Roscommon, and will accommodate the renewable generation to be connected in North Mayo. In Cork, several station upgrades and line refurbishments in addition to the planned connection of an interconnector with France (Celtic Interconnector) are underway to ensure security of supply and maintain the necessary levels of reliability and flexibility.

The 400 kV link between Ireland and Northern Ireland (second North South Interconnector – NSI), which will span 138 km to connect Meath in Ireland to Tyrone in Northern Ireland, will increase the transfer capacity between the two countries and improve security of supply. This project will become fully operational by 2026.

Ireland is preparing to connect with the European Union (EU) via the 700 MW Celtic interconnector with France. It involves a 575-km high voltage direct current (HVDC) subsea connection, which will link the coast of Cork and the Ceinture Dorée (Gold Belt) coast in Brittany in France, passing to the west of the Isles of Scilly, UK. It will create a direct link between the French and Irish markets and increase RES integration, once completed in 2027.

Further, private players are building interconnectors to connect the Great Britain (GB) electricity market (England, Northern Ireland, Scotland and Wales) to SEM. In Ireland, MARES Connect plans to develop by 2030 a 750 MW HVDC multi-purpose interconnector (MPI) from Dublin in Ireland to Bodelwyddan, Denbighshire, in Wales, UK, which will also integrate upcoming OSW into the grid. Recently, TI LirIC Limited proposed a 700 MW HVDC interconnection (LirIC) to connect Kilroot substation in Northern Island to Scotland, UK, by 2029.

OSW integration
For OSW integration, EirGrid has commenced work on identifying and developing the offshore connection platforms for the ORESS 2 auction. This approach will further enable EirGrid to ‘future proof’ these offshore connection platforms, enabling it to potentially connect much higher volumes of future OSW when the onshore grid is sufficiently robust to absorb this capacity.

By 2030, EirGrid plans to invest EUR3,396 million and EUR326 million in Ireland and Northern Ireland respectively. Of the EUR236 million proposed to be invested in the revised roadmap, EUR169 million will be utilised towards uprating existing circuits, EUR19 million in PFC and DLRs and the remaining EUR48 million for the new substation in Northern Ireland.

System operations
The roadmap calls for addressing the technical challenges that the system operations would face with the high RES penetration and 95 per cent SNSP by 2030. Additionally, the new HVDC interconnectors as well as onshore and offshore grid expansion will add to the complexity of transmission system operations. Partnerships between the TSOs and distribution system operators will be critical to help release the full potential of demand-side flexibility. Further, setting and clarifying operational standards, including grid codes and system services protocols; enhancing the system services arrangements to introduce new services; removing barriers to entry and enabling the integration of new technologies at scale; and developing new and enhanced control centre tools and systems will help in safely and securely increasing the instantaneous amount of variable RES in the power system.

Electricity markets
The roadmap groups the key changes needed for the evolution of the market design to efficiently achieve the renewable ambition under two pillars. Under the first pillar, markets need to be aligned to the two-part operational challenges of trading large RES volumes. The first involves replacing the technical capabilities that conventional plants inherently provide through a balanced portfolio of other technologies such as RES, demand-side resources, storage and new support technologies. The second part is the new and emerging technical and operational scarcities as the power system transitions to very high RES levels.

Under the second pillar, trading arrangements are needed for integration of SEM into GB and EU markets. Brexit has decoupled the SEM and GB markets from the European day-ahead market, and as a result, there is no longer any day-ahead trading on the SEM-GB border. The pre-existing (interim) intra-day arrangements between SEM-GB are still active, which enables trading across the two interconnectors. Trading arrangements for full SEM integration will involve bringing market structures in line with EU legislation, utilising interconnections efficiently and facilitating effective export and import of large volumes of RES.

Challenges and way forward

To deliver on government renewable energy policies in Ireland and Northern Ireland, it will be necessary to accommodate unprecedented penetration of variable RES whilst keeping curtailment levels to a minimum. This will require a significant evolution of power system operation as well as EirGrid and SONI to deal with unique challenges. Achieving the 2030 RES target will require a seismic change in approach, as the scale of the task is unprecedented and there are significant challenges in terms of deliverability, technical scarcities and economic considerations.