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The role for open cycle gas turbines in Ireland’s renewables drive

Out-Law Analysis | 06 Oct 2021 | 3:12 pm | 4 min. read

Open cycle gas turbines have an important role to play in providing security of energy supply in Ireland as the country transitions away from relying on fossil fuels as the source of power to an energy system sustained predominantly by renewables.

Solar power, onshore wind and, in time, offshore wind will deliver the lions’ share of Ireland’s electricity needs, under government plans. However, to ensure homes and businesses have access to all the power they need at times when the sun does not shine and wind does not blow, some fossil-fuel-powered sources of electricity will need to remain connected to the grid so they can be brought on-line as and when required.

Open cycle gas turbines have certain advantages over other potential back-up power plants that will be attractive to developers of energy infrastructure, and they may have a role in sustaining Ireland’s thriving data centre industry’s thirst for electricity in the years ahead.

The challenge in balancing Ireland’s energy mix

Ireland has committed to achieving ‘net zero’ emissions in its economy by 2050, and the government has pledged to source at least 80% of Ireland's electricity supply from renewables by 2030. As part of this transition, some carbon-intensive power plants are being wound down and decommissioned.

However, Ireland’s drive to change its energy mix is being complicated by the growing prevalence of data centres and the increasing demands they place on energy requirements because of their operations.

Earlier this year, the Commission for Regulation of Utilities (CRU) warned that “rolling blackouts” could result if steps are not taken to address the rapid rise in demand for electricity from data centres. Recently, the government confirmed plans to turn two traditional power plants back on to address the risk of potential blackouts. Pressure has been building on the Irish government to put a halt to the construction of new data centres in this context. Though it has rejected those calls to-date, it has pledged to introduce sectoral emissions ceilings that are likely to have the indirect effect of stalling data centres development and could yet, if reports are to be believed, go further in the upcoming budget.

If all data centres proposed for development were connected to Ireland’s electricity grid alongside those already in place, it is projected that they would require 3.8GW of power in total to run. The current demand peak for the whole electricity system in Ireland is 5.5GW.

To address this anticipated rise in demand for electricity, the CRU recently proposed that applications for connection to the grid from data centre operators should be prioritised in future in accordance with a series of factors. These factors could include whether the data centres generate enough energy onsite themselves to support their demand for electricity, or can be flexible in reducing their consumption at times of system constraint.

Ireland’s minister for climate, Eamon Ryan, is on record as stating that fossil fuels will continue to be needed to a degree to serve the country’s energy needs “when the wind isn’t blowing or the sun isn’t shining”, while professor Andrew Keane of UCD Energy Institute has warned that energy users face price hikes unless Ireland takes urgent action to bolster the grid, improve connections into British and European energy networks and better harnesses its own offshore wind potential.

Currently, most of the data centres in Ireland are situated in the south and east of the country in proximity to the country’s two largest population centres – Dublin and Cork – and the majority of sites run by major manufacturers and technology companies. However, we expect there to be a greater geographical spread of data centres across Ireland as the CRU’s policy plays out in practice.

We also anticipate that data centre developments could be part of much broader energy parks, and that these will typically envisage the on-site generation of electricity.

It is in this context that we expect flexible lower carbon baseload generation will be important for Ireland and open cycle gas turbines to emerge as a popular technology.

Open cycle gas turbines and their role in Ireland’s electricity market

Open cycle gas turbines are relatively small assets that can take up less space than other technologies and can have efficiencies in relation to installation and operation.

Electricity is derived from open cycle gas turbines by causing the turbines to spin and power a generator. The turbines are caused to spin by mixing compressed air and fuel – typically natural gas – at very high temperatures.

Combined cycle gas turbine systems can deliver greater efficiency and better environmental benefits. However, in the context of an energy market where some traditional power plants will need to be kept online to augment renewable sources, open cycle gas turbines can be a cleaner and/or cheaper technology to install and operate depending on whether they are being compared to other types of gas turbines and other fossil-fuel-based plants.

Another major advantage to open cycle gas turbines is that they can be switched on and off quickly. This means they can be deployed into the electricity grid at short notice to cover any shortfall in supply resulting from the variability and typical profile of solar and wind power.

Security of supply and capacity contracts from the government will provide the business case for investment in open cycle gas turbines. 

As Ireland moves forward with its plans to significantly increase the proportion of electricity demand supported by renewable energy sources and looks to simultaneously balance its energy mix to ensure security of supply – particularly at a time where other promising clean technologies such as hydrogen are still cost-prohibitive and in their relative infancy – open cycle gas turbines represent a pragmatic option for delivering back-up electricity into the grid and for generating on-site electricity for data centre developments, new energy parks or for others involved in repurposing existing generation infrastructure in Ireland.