Gas critical to Britain’s energy security during periods of low renewables, analysis shows

Today (Tuesday 23 June 2026), National Gas has published its Gas Winter Review for 2025/26. The report shows that Great Britain's gas system operated safely and reliably over winter, continuing to provide a secure and resilient foundation for the energy system despite a more volatile operating environment.

While National Gas does not procure Britain's gas supply, it plays a key role as Gas System Operator, publishing demand and supply forecasts to inform the market.

Over the course of the winter, the network transported around 500 TWh of energy across Great Britain, powering millions of homes and businesses. While overall demand marginally declined, the system experienced sharp and more frequent swings in demand, driven by fluctuations in gas-fired power generation and increased heating demand during colder periods.

Despite an overall warmer winter, short periods of intense cold pushed peak demand above the previous year, placing greater stress on the system at times of highest need.

During these conditions, analysis shows that gas played a vital role in maintaining energy security across the electricity system, supporting security of supply as renewable output fluctuates. 

Notably, on 5 January, the coldest day of the winter, gas-fired generation ramped up from around 2.3GW the previous day to 26.1GW, as the system responded to falling renewable output. This 23.8GW swing formed part of the largest swing in gasfired generation ever recorded over a 36hour period, illustrating the role of the gas transmission network in providing flexible capacity and maintaining stability during periods of system stress. 

As renewable generation continues to grow, these kinds of rapid swings in demand are expected to become more common, reinforcing the need for a flexible and highly responsive gas network to underpin system resilience and support a clean, low-carbon electricity system at short notice.

Key demand and supply trends:

• Great Britain's gas demand declined by around 4% and total NTS demand (which includes exports) declined by around 2%, largely reflecting milder weather and higher renewable output. 
• Demand became significantly more volatile with peak daily demand reaching 407 mcm/d, higher than the previous winter despite lower overall demand.
• Gas-fired generation swung between around 2GW and 26GW across consecutive days, the largest swing (23.8GW) ever recorded over a 36-hour period and close to the record output of Britain's gas-fired power fleet. 
• Non-daily metered (NDM) demand, primarily associated with heating in homes and smaller businesses, continued to account for the largest share of gas use accounting for almost 70% of Great Britain's demand, reflecting the essential role the network plays in keeping homes warm across Great Britain.

• UK Continental Shelf production declined by around 3%, continuing its long-term trend.
• LNG imports increased by 15%, reflecting greater reliance on flexible supply sources. The United States remained the dominant source (~80%), with the balance supplied by a range of other international exporters.
• Storage levels were over 70% full ahead of the highest demand day in January.
• Flexible supply sources, including LNG, storage and continental imports, responded as expected, increasing output during periods of high demand.

Glenn Bryn-Jacobsen, Director of Energy Systems and Resilience at National Gas, said:

Our analysis reaffirms both the ongoing resilience and reliability of the gas network in safeguarding Britain's energy security in the present and the extent to which it is undergoing a profound structural transition. Operating conditions are becoming increasingly dynamic, with the system no longer characterised by steady demand patterns but by sharp swings driven by weather and renewable output.

We observed gas-fired power generation ramp up from very low levels to close to record output in the across two consecutive days, and these kinds of swings are becoming more common. 

Gas is therefore playing an increasingly critical role in maintaining energy security within a more renewable-led system, both in providing flexible, responsive capacity at times of low renewable output and in meeting the day-to-day heating needs of millions of homes and businesses across Britain. While this demonstrates the strength of the current system, it also underscores the increasing complexity of operating and balancing the network.

Ian Radley, Chief Commercial Officer at National Gas,said:

This winter reinforces the growing importance of flexibility and responsiveness across the energy system, particularly as renewable generation becomes a larger proportion of the supply mix. The ability to respond dynamically to unforeseen changes in supply and demand is now a defining feature of system resilience. 

At the same time, the supply picture continues to evolve. Domestic production from the UK Continental Shelf continues to decline, while reliance on flexible sources such as LNG, storage and imports increases.

Taken together, these trends continue to highlight longer-term structural challenges across the energy system and reinforce the need for coordinated action across government, regulators and industry to safeguard Britain's future energy security.

We remain committed to working with Government, Ofgem and across the sector to ensure the network delivers the reliability and flexibility Britain needs, now and in the future.

The National Energy System Operator (NESO) has also published its Winter Review and Early Winter View today, which shows the electricity system is expected to remain secure, with a sufficient margin to meet demand in line with the government's reliability standard and broadly consistent with recent winters.

The findings in this Winter Review build on National Gas's Winter Outlook, published in October 2025, which pointed to tightening future supply margins associated with declining UK Continental Shelf production and an increasing reliance on global imports. 

These findings are supported by NESO's Gas Supply Security Assessment, published in November 2025, which identified the need for mitigations to protect future supply resilience.

In February 2026, National Gas published its response to the Government's Gas System in Transition: Security of Supply consultation&nbs;setting out policy options to support long-term energy security.

Attention has understandably turned to the potential implications of the conflict in the Middle East, raising questions about Britain's gas supply. Our recently published Gas Summer Outlook 2026 indicates the market has capacity to meet near-term demand, and we continue to have no immediate operational concerns.

We will continue to monitor developments and provide further analysis in our next Gas Winter Outlook later this year.