Gas accounted for two-fifths of electricity and was a key back-up for renewable electricity sources last year, new data from Gas Networks Ireland shows.
Gas Networks Ireland, which operates and maintains the country's €3 billion, 14,725km national gas network, said that overall gas demand in Ireland fell slightly last year, declining by 1.5% compared with 2024.
The reduction was reflected across most sectors of the economy, while gas continued to play a central role in supporting electricity generation and meeting seasonal demand throughout the year.
It noted that transport was the exception last year as gas demand rose by 10% in 2025 compared with 2024, on the back of the continued shift towards the use of compressed natural gas (CNG) and renewable BioCNG in heavy transport fleets.
Gas generated 40% of the country's electricity in 2025, slightly down from 41% in 2024, according to Gas Network Ireland's annual gas demand statement.
The contribution of gas to electricity generation peaked at 92% in July and did not fall below 11% at any point during the year, which Gas Network Ireland said underlined the importance of gas in maintaining energy stability when weather dependent renewable energy is unavailable.
Wind energy generated 33% of the country's electricity in 2025, which was unchanged from 2024, and peaked at 78% at times during the year. Solar generation increased its contribution to 3%, up from 2% in 2024.
Gas Network Ireland said that monthly gas demand patterns last year reflected changing weather conditions and variations in electricity generation requirements.
In a cool and sunny month with record breaking wind gusts due to Storm Éowyn, overall gas demand increased by 17% in January, compared to December.
The highest ever gas demand day for the Republic of Ireland was recorded on January 8, with January 9 ranking as the third highest. These peaks were driven by a combination of high gas demand for electricity generation and low temperatures.
February saw a sharp fall in gas demand as milder temperatures and strong wind generation reduced gas use. But gas demand rose again in March due to weather shifts and a fall in wind energy output, increasing by 13% on a monthly basis.
Overall gas demand declined through the spring and early summer months. Demand fell by 12% month-on-month in April and by a further 11% in May. In June, gas demand decreased by 9% compared with May.
During July, gas generated over half of Ireland’s electricity, peaking at 92% and never falling below 17%, ensuring stability during periods of low wind output.
In August, overall gas demand was 9% higher than in August 2024, despite the month being the fourth warmest August on record. Increased gas use for electricity generation contributed to this rise as coal was phased out of the generation mix, it noted.
September saw residential gas demand almost triple as cooler and wetter conditions prompted households to turn on their heating earlier in the season.
In October, overall gas demand increased by 19% compared with September as cooler, wetter weather and the arrival of the first named storm of the winter season Storm Amy, led to higher energy use across homes, offices and commercial sectors.
Meanwhile, November saw a further increase in gas demand of 15% compared with October and the year ended with gas demand remaining the same in December compared to the previous month.
Gas Networks Ireland's Director of Strategy and Regulation, Edwina Nyhan, said the 2025 gas demand figures highlight the continued importance of gas in Ireland’s energy system.
"While overall demand was slightly lower year-on-year, gas remained a critical source of flexibility and security throughout the year, supporting electricity generation during periods of variable renewable output and meeting seasonal heating demand across homes and businesses," she said.
"As Ireland’s energy system continues to evolve, gas will remain essential to maintaining system stability and resilience," she added.
