Ireland’s energy transition: Gusty winds alone won’t cut it

Dubbed the ‘green island,’ Ireland is known for its old castles, luscious meadows and harsh weather. The last in the list provides the country with enormous potential for wind power. The share of electricity generation accounted for by this source of energy dropped from 36 percent in 2020 to 31 percent in 2021 on account of unusually low wind speeds.

Nevertheless, wind remains the single-largest source of renewable energy, good for roughly one-third of all power produced. Brian Ó Gallachóir, Director of the Energy, Climate and Marine Research Centre MaREI at University College Cork claims that wind power expansion is definitely one of the greatest accomplishments of the Irish energy transition: “We need to accelerate further wind energy deployment in order to meet the [emissions] target.”

Ambitious emission targets enshrined in law

In July 2021, the Irish government enacted a law establishing the republic’s emission goals. They envisage the country reducing greenhouse gas released into the atmosphere by 51 percent by 2030 compared to 2018. Ireland aims to become entirely carbon neutral by 2050.

Moreover, the law obliges the government to grant affected sectors suitable carbon dioxide budgets. The timing and extent of emission reductions by energy, transportation and agriculture will be established in a Climate Action Plan which will be updated once a year. Details will be determined by the ministers in charge.

20 percent less conventional fuel by 2025

One thing is already for certain: As in many other European countries, the electricity sector will lead the way. The law stipulates that 70 to 80 percent of all power produced must come from renewable sources by 2030. Since the British government is also pursuing ambitious emission targets, over 20 percent of the island’s conventional generation capacity is to be taken offline by the middle of the century.

According to EirGrid, the operator of the joint transmission system of the Republic of Ireland and Northern Ireland (United Kingdom), the island’s oil, coal, gas and peat power stations currently have a total capacity of just under 10 gigawatts (GW), 7.5 GW of which are located in the republic. In its latest Generation Capacity Statement (GCS), EirGrid expects that some 1.5 GW and nearly 0.6 GW of conventional capacity will be decommissioned by the middle of the decade in Ireland and Northern Ireland, respectively.

Irish transmission system operator warns of bottlenecks

EirGrid cautions in the current GCS that, however, this could face the island with supply problems. The report further states that electrification of the heat and transport sectors as well as new datacentres and other big power users will increase electricity consumption by 37 percent from 2022 to 2031.

This is contrasted by planned shutdowns and sputtering expansion of new on-demand generation assets, said EirGrid CEO Mark Foley when the report was published in early October: “The number of system alerts will increase.” To avoid bottlenecks, lifetime extensions for up to 1.2 GW of conventional capacity are being considered.

Everything is pointing to wind

Potential for renewable energy in and around Ireland is enormous. “Geographically, we are particularly fortunate to have such high and envious wind speeds – being an island means we also have access to immense ocean energy resources,” says energy expert Ó Gallachóir. In the next few years, the Irish Republic could become a net exporter of electricity on the strength of wind energy alone.

While ocean energy does not factor into the plans of the Republic of Ireland at all, the country has established goals for wind power: Onshore capacity is set to grow from 5.8 to 8.2 GW by 2030. During the same period, plans envisage construction of wind farms with over 5 GW in capacity offshore – especially off the east coast. One such farm is the Dublin Array, which will have a capacity of up to 900 megawatts (MW) and is 50 percent owned by RWE. The capacity of existing offshore wind turbines has been hardly worth mentioning thus far.

Expansion of storage capacity

In the medium run, wind energy should thus play a dominant role in Irish electricity supply. But despite wind being a more reliable source of energy between the Atlantic and North Sea than at most European locations, it does have its own set of shortcomings.

For starters, wind is a source of energy capable of producing electricity mainly depending on the weather instead of on demand. To offset generation bottlenecks and export surplus generation, for years Ireland has been linked to the British power grid via two direct-current interconnectors, each with a transmission capacity of 500 MW.

Another submarine cable is scheduled to be commissioned in 2026, enabling Ireland to exchange a maximum of 700 MW with the transmission grid on the European continent: the Celtic Interconnector between Ireland and Brittany. In addition, Ireland seeks to build 1.65 GW of battery storage capacity by 2030, with a view to bridging short-term bottlenecks. The country’s largest storage system to date has a capacity of 60 MW and is operated by RWE in Lisdrumdoagh near the border to Northern Ireland.

Minor grid, major challenge

The second drawback is that, as things presently stand, wind farms are incapable of acting as an instantaneous reserve. This limits their ability to offset sudden fluctuations in grid voltage. Energy researcher Ó Gallachóir thus considers the current state of wind energy expansion to be commendable: “Gridwise it’s been hugely challenging to integrate high levels of wind power on a relatively small power system not having the ‘cushion’ that comes with a large power system.”

The smaller a transmission system, the lower its tolerance for major events that cause unforeseeably significant interruptions in the balance between power production and consumption such as a fault in a substation. Neither wind farms, nor PV arrays, nor battery stores can offset such voltage fluctuations in real time. Direct-current interconnectors are not a remedy, either.

So far, the instantaneous reserves in all major transmission systems are primarily provided by the rotating mass of the synchronous generators of conventional power stations or – to a lesser degree – by hydroelectric turbines. “We have taken these challenges as an opportunity to integrate innovative solutions in our electricity system,” claims Ó Gallachóir. For instance, Ireland increased its instantaneous reserve capacity this summer by connecting the world’s largest flywheel as a rotating mass to its transmission system.

Authority sees urgent need for action

Nevertheless, according to EirGrid, the situation has become exacerbated since the last GCS which was published a year ago – in part because investors withdrew from licensed projects.

To place electricity supply on firm footing, the Commission for the Regulation of Utilities, which is the relevant regulatory authority in Ireland, proposed cross-border measures. Alongside the aforementioned lifetime extensions, these encompass 700 MW in reserve capacity and inviting tenders for 2 GW of flexible gas power plant capacity. Furthermore, auctions are to be held, at which big power users undertake to reduce load on demand. Energy expert Ó Gallachóir has yet another suggestion: “We need to reduce demand and rapidly accelerate energy efficiency.”