Great Britain is expected to have sufficient gas supply capability this winter, with a forecast margin of 99 million cubic metres per day (mcm/d) above peak demand, according to National Gas.
Its Gas Winter Outlook 2026, published on 23 October, assesses total supply capability at 592 mcm/d against peak demand of 493 mcm/d. The margin is wider than the 83 mcm/d forecast for last winter, largely because of increased liquefied natural gas import capability.
The assessment also shows a positive margin if exceptionally high demand coincides with the loss of the largest single piece of gas transmission infrastructure. However, National Gas said longer-term changes in production, imports and demand required further action on security of supply.
Peak demand rises despite lower seasonal consumption
Peak demand is forecast to increase by around 2% compared with last year’s assessment, driven primarily by gas-fired electricity generation.
The figure represents demand on a “1-in-20” winter day, a severe-weather planning standard, rather than expected consumption on a typical day.
Peak gas demand for electricity generation is forecast to rise by 7%. Gas-fired power output could reach around 27GW at its highest point on a day of peak gas demand, supporting electricity supplies when renewable generation is low.
Overall domestic gas demand across the winter is nevertheless expected to fall by around 1%.
The forecasts illustrate the different requirements facing the network: lower seasonal consumption does not necessarily reduce the capacity needed during cold weather and periods of low renewable output.
LNG capacity strengthens supply margin
Supply capability has increased from 565 mcm/d in last year’s assessment to 592 mcm/d.
National Gas has raised its assessed maximum LNG contribution from 150 mcm/d to 174 mcm/d following terminal expansions at South Hook and Isle of Grain and an assessment of network capability during peak demand.
That increase concerns the capacity to receive and transport gas. Actual LNG imports across the winter are forecast to rise by around 6%.
UK Continental Shelf production is expected to decline by approximately 5%, continuing the long-term reduction in domestic output. Norwegian imports, storage withdrawals and continental interconnectors remain important components of the supply mix.
Continental import capability totals 83 mcm/d. National Gas said arrangements to maintain Interconnector Limited’s capacity supported the assessment, subject to regulatory approval following Ofgem’s statutory consultation.
Margin remains positive after infrastructure loss
The report tests the simultaneous occurrence of 1-in-20 peak demand and an 81 mcm/d infrastructure loss.
Under that scenario, known as N-1, the remaining supply margin is 18 mcm/d, compared with 11 mcm/d in last year’s outlook.
These figures assess physical supply capability. They do not mean every source will necessarily deliver its maximum volume, as commercial decisions and international market conditions also determine flows.
National Gas transports gas and balances the network; market participants are responsible for securing production, imports and storage supplies.
The operator said a rare combination of extreme weather and major supply disruption could still create material security challenges. It maintains operational, commercial and emergency measures to respond.
Operator calls for longer-term security reforms
National Gas said declining domestic production and continued peak demand were increasing the importance of imports and flexible supplies.
It called for timely publication of the government’s full response to the Gas System in Transition: Security of Supply consultation.
The report expects peak demand to remain broadly unchanged for years, even as total consumption falls. Maintaining infrastructure and commercial arrangements capable of meeting those short periods of high demand therefore remains a central planning requirement.
The outlook is an assessment of supply resilience, rather than a forecast of energy prices. International disruption could affect market conditions even when Britain retains sufficient physical supply capability.
