EirGrid and SONI assess future demand and generation landscape

Transmission system operators (TSOs) EirGrid and SONI have issued the All-Island Generation Capacity Statement 2020-29 that sets out expected electricity demand together with the level of generation capacity that will be required over the next ten years. 

Issued on 27 August, the Statement said RoI demand is increasing, and is forecast to increase significantly, largely due to the continued expansion of large energy users primarily data centres, although this growth will be subject to a review once the full impacts of COVID-19 are known later in the year. EirGrid’s analysis indicates that demand from data centres could account for 27% of all demand in RoI by 2029 in the medium demand scenario. This forecast is aligned with EirGrid’s Tomorrow’s Energy Scenarios which predicts a Total Energy Requirement (TER) of 41TWh by 2030.

By contrast, demand in NI is relatively flat, and expected to continue so in the medium scenario until 2023 when the connection of some data centre load drives demand growth. Over the next ten years, demand rises by 4% under the medium scenario, falls by 3% under the low scenario and rises by 12% under the high demand scenario (Figure 1).

For generation, the TSOs seek to paint a picture of how the all-island portfolio might evolve from the present situation of surplus while ensuring the system is adequate to an eight-hour Loss of Load Expectation standard. The report examines the status of each type of generation and issues that impact their future deployment.

In RoI, around 1,900MW of conventional plant is expected to close before the end of 2025, including 885MW at Moneypoint at the end of that period. New conventional plant that has been successful in T-4 auctions and assumed available from 2023-24 totals nearly 1,400MW at its de-rated capacity. In NI, Kilroot ST1 and ST2 will cease operation in 2023, representing 476MW, as it did not qualify for the T-4 2023-24 auction, while EP Kilroot at 383MW is due to come online from 2024.

The North-South Interconnector is assumed to be available in 2024; currently the capacity reliance value on the existing interconnector is 100MW north to south and 200MW south to north. The East-West Interconnector and Moyle Interconnectors are assumed to be de-rated at 60% to 300MW and 270MW, respectively. Two further interconnectors are planned: Greenlink, with target availability 2023-24 and the Celtic Interconnector, with target availability 2026-27.

The report assumes that RoI’s renewable targets will be achieved largely through the deployment of additional wind-powered generation. Connected, contracted and in-progress grid connections amount to around 9GW, including 6GW of wind, around 2.5GW of solar and around 0.5GW of battery projects.

This year’s Statement presents an example renewable generation portfolio for RoI which could achieve the 2030 target of 70% renewable electricity (RES-E) (Figure 2). In 2019, renewable generation reached 35.7%, with a target of 40% by 2020. The projection is based on this year’s median demand forecast, and the statement says that under it, the diversity of the renewables mix increases due to reducing levelised costs and from auction designs. Large scale onshore wind, offshore wind and solar PV are expected to be most prevalent, while carbon capture and storage could be developed to further decarbonise fossil fuel generation. The first Renewable Electricity Support Scheme auction (RESS-1) provisionally awarded 2,237GWh of contracts in August, which accounts for around 10% of the amount forecasted to be required to meet the 2030 targets.

For NI, the Statement notes that draft policy options with respect to energy policy and decarbonisation are due from the DfE this winter, with any target expected to be similar to those set in other regions of the UK. In 2019, 39% of electricity consumption came from renewable sources, most of it from wind power. In the absence of an approved energy strategy, the TSOs have based the expected growth of wind capacity on the volumes of applications that have accepted a grid connection offer: 245MW of wind generation has accepted a grid connection offer (excluding generation under 5MW). This increases installed capacity from a little under 1,300MW in 2019 to just over 1,500MW from 2024 onwards.

For its generation adequacy studies (Figure 3), the TSOs have assumed that the second North South Interconnector will be available from 2024. The all-island system will then be capable of operating electrically as one, meaning all the generation capacity from both jurisdictions can meet the combined load. New generation that was awarded a contract in the T-4 20203-24 auction is included in the studies. Any existing plant that entered any capacity auctions to date are also included, even where unsuccessful, unless formal notices of closure have been received.

For RoI, the system starts in a position of significant surplus, but this is eroded as demand is forecast to increase and some generation plant is shut. To meet specific security of supply issues, from the T-4 2023-24 auction a Dublin regional location requirement is included. Noting how the adequacy situations worsens, the report said this demonstrates the need for new low-carbon plant to be commissioned from 2026, with only the low demand scenario remaining in surplus. For NI, the median demand scenario is in a surplus of around 290MW for most years, reflecting the flat demand forecast. In the all-island scenarios from 2024, all scenarios see reducing surpluses over time due to increasing demand and assumed plant closures. The low availability and high demand scenarios show deficits from 2026 and the Demand Level 8 (which matches the level of demand chosen by the Least Worst Regrets methodology for the calculation of the Capacity Requirement in the 2023-24 T-4 auction) shows deficits from 2028.

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