Since its establishment 25 years ago, EirGrid has been responsible for the safe and secure supply of electricity to homes, businesses and communities across the country. The organisation’s National Control Centre is at the heart of that work.

“The National Control Centre keeps the lights on, balancing supply and demand every minute of the day as the energy mix becomes increasingly renewable and variable,” says EirGrid director of system operations, Diarmaid Gillespie.

The centre’s work has changed greatly over that time, but not the basic principles, he says. “Its job is to ensure supply meets demand every second of the day. Faults happen on the network due to storms, lightning strikes or other unforeseen events like a generating station going offline. When you see the lights dip at home, that indicates a fault on the system that has been detected and fixed within 80 to 100 milliseconds.”

Changes to the nature of power generation and the dramatic increase in demand present significant challenges. “Back in 2001 when EirGrid was established, system demand was just over 4 gigawatts (GW),” says Gillespie. “We experienced rapid demand growth between 2001 and 2005. It increased to 4.8GW in just four years. Demand peaked in 2010 at about 5GW during a very cold winter.”

Electricity demand is correlated with economic activity, and it fell quite significantly after that peak. “It took 10 years to get back to the 2010 level.”

Since then, demand hit a record of more than 6GW in January 2025 and is projected to reach 7GW by 2034. “The centre needs to ensure that demand is met at all times.”

On the generation side, several older power stations have shut down while there has been a substantial increase in renewables on the system. “In 2001 there was very little wind on system,” he says. “There was about 100MW in total. A new record of 3.89MW of wind generation was set on February 14th, 2026.”

Solar has also grown. “The solar story is huge. Over 1.2GW of electricity was provided by grid-connected solar in June. In 2001 there was almost no solar at all.”

In the coming years, EirGrid will connect large amounts of offshore wind to the system. “This comes with its own challenges,” he says. “From a grid perspective it’s just another wind farm that happens to be at sea. But the scale of the wind farms is much greater than onshore, at 800MW-1,000MW. But wind is more consistent offshore, and it will boost our security of supply.”

In addition to traditional and renewable power generation, there are two interconnectors with Britain providing additional supply sources, while the Celtic Interconnector to Brittany is under construction. Power supply from these sources can also vary.

All these variables, including intermittent renewable sources and demand fluctuating due to rooftop solar and other factors, make the job of the control centre all the more difficult.

“It was much more straightforward 25 years ago. We could predict demand very accurately, and we knew pretty much exactly what generation would be available on the system. There’s a lot more variability on both sides of the equation now. We have new tools at our disposal to manage fluctuations, including batteries. They can provide very fast response to events and provide energy during tighter periods of the day.”

EirGrid and the control centre also have access to emergency generating capacity to meet sudden demand surges or drop-offs in supply.

Grid stability is another issue. The transmission system operates at a frequency of 50hz. If that changes too quickly, it could have severe consequences. Traditional generating stations have large turbines rotating 50 times per second (50hz) and helping support system stability. Renewables are fundamentally different. To maintain stability at times when a traditional generator goes offline, or other problematic events occur, EirGrid has connected two synchronous condensers to the system.

Gillespie says that these are essentially large pieces of metal rotating at 50hz. They do not generate power, but they do provide all-important stability. “We will have a lot more of these on the system in future. We have also invested a lot in prediction tools for the control centre.”

While keeping the system secure at all times remains the number one priority, accommodating increasing levels of renewables is also of critical importance. “We are now able to allow up to 75 per cent of electricity to be generated from variable renewable sources at any one time and brought onto the grid. Looking forward, there is a programme to increase this to 95 per cent so that we can reach the Government target of meeting 80 per cent of national electricity demand from renewables. We are also managing growth in demand to support Ireland’s economy and society.”

While technology plays a role in keeping the system safe and secure, the human dimension is vital. “We have a great team of people with experience going back over 30 years and more. They have seen it all and consistently meet the challenge of keeping the lights on during storms and other difficult periods.”