Number of large fossil-fuel generators that must operate on Ireland’s grid reduced

EirGrid has reduced the minimum number of large conventional fossil-fuelled generators that must operate on Ireland’s electricity grid at any one time from five to four. 

The new operational policy came into place on Sunday 7 April.

This follows a successful trial from May 2023 to March 2024, as part of a large programme of work to help make the grid ready to meet the higher percentages of electricity coming from wind and solar over the remainder of the decade, as set out by government targets.

A minimum number of large conventional fossil-fuelled generators are required to run to ensure the stability of the power system.  

EirGrid has now successfully demonstrated that this minimum requirement can be reduced from five to four generators.  

This will allow for a reduction in carbon emissions and create more opportunity for renewable generators to meet power requirements.  

When system conditions allow, EirGrid will now be able to operate the grid with just four large conventional fossil-fuelled generators when there is sufficient power available from renewable generators such as wind and solar.  

During the ten-month trial, these conditions were met for approximately 11% of the time.  At times of lower renewable generation availability, a larger number of fossil-fuelled generators will still be required to operate to meet power demand.

The reduction means that the all-island electricity grid can now operate with seven large conventional fossil-fuelled generators in total, four in Ireland (down from five) and three in Northern Ireland (unchanged).

EirGrid is aiming to further reduce this minimum requirement for conventional fossil-fuelled generation over the coming years.

At the moment, up to 75% of Ireland's electricity generation can come from variable renewables, such as wind and solar, at any one time. 

This is known as the system non-synchronous penetration (SNSP) limit. The reduction in the requirement to run fossil-fuelled generation will support EirGrid’s plans to further increase the SNSP limit in the future.

EirGrid Executive Liam Ryan said: “This significant milestone marks another step towards allowing more renewable energy onto the electricity grid.

"Our Shaping Our Electricity Future Roadmap sets out the changes required to integrate greater amounts of renewable energy onto the grid. 

"Ultimately, more renewable generators need to be connected to the power system. This will require reinforcements, upgrades and new infrastructure across the country.

"While doing this, we also need to operate the grid with fewer conventional generators that use fossil fuels like coal, gas and oil. This is complex, given the variable nature of renewable energy, as we also need to ensure the security of electricity supply. 

"With that in mind, it’s positive to be able to implement this change after the successful trial, I would like to acknowledge this was achieved in collaboration with the System Operator in Northern Ireland, the regulatory authorities and industry participants.”