The share of Great Britain’s electricity generated by burning fossil fuels plummeted to unprecedented lows this month, ahead of plans to begin running a “zero-carbon grid” for short periods from next year.

Electricity generated by burning gas and coal fell to a record low of just 2.4% for an hour at lunchtime on Monday 15 April, according to an analysis of data from National Grid’s electricity system operator (ESO).

The same data has revealed that earlier this month the share of fossil fuels in the generation mix taken over an entire day fell to a record low of 6.4%, on 5 April.

The findings lend support to the aims of the ESO to begin the “groundbreaking and world-leading” step of running a zero-carbon electricity grid for Great Britain for short periods from next year.

Craig Dyke, the director of system operations at the ESO, said Britain had made “excellent progress” towards this goal and there had already been periods when the grid had run safely on more than 90% zero-carbon power.

The new records mark a dramatic shift from 15 years ago, when gas and coal power plants made up 75% of the electricity mix, while renewables accounted for only 2%. Last year only a third of Great Britain’s electricity came from fossil fuels, compared with 40% from renewables.

The research, undertaken by Carbon Brief, found a dramatic increase in the frequency of short periods when fossil fuels made up less than 5% of Great Britain’s electricity generation in recent months.

There have been 75 half-hour periods in the year to date when fossil fuels have accounted for less than 5% of the country’s electricity needs, more than four times the number recorded last year. Just five ultra-low carbon half hours were recorded in 2022, the analysis said.

The new record low took place amid a glut of renewable energy, according to the ESO. At the time, wind power made up about half of electricity generation while solar power accounted for just over 30%. Britain’s nuclear reactors generated more than 13%.

The low-carbon generation squeezed gas-fired power to just 1.8% of Great Britain’s electricity generation while the country’s last remaining coal power plant, at Ratcliffe-on-Soar in Nottinghamshire, generated 0.6%. The plant is due to close in September.

Dyke said: “This is a culmination of a significant amount of effort over a number of years. It’s not just about technologies, it’s about hearts and minds and processes and systems and people working together across the industry, the energy regulator and government.

“Getting to the 2025 ambition has been a significant engineering challenge, which we are solving.”