Ofgem acts to avert rare winter gas shortfall

Ofgem and National Gas have set out a plan to address concerns that the UK’s gas system might be unable to meet peak demand on a very cold winter day. The regulator describes this situation as very rare because it assumes both an unusually cold snap and a major fault on the system happening at the same time.

Opposition politicians highlighted Ofgem’s warning that demand might not be guaranteed to be met on a peak winter day, linking this to an accelerated decline in domestic North Sea gas supply. Their comments brought attention to the new document and prompted questions over winter resilience. The plan by Ofgem and National Gas is presented as a response intended to prevent the narrow shortfall identified in the model.

The stress case is built around several limiting assumptions on supply capacity. Ofgem focuses on the country’s biggest single source of gas, two neighbouring LNG terminals in Wales, and assumes they go offline during the cold snap, removing 77 mcm/d from the system. The model also considers reductions in capacity on the INT pipeline to Europe and limits on how much gas can reliably be drawn from storage.

In storage, theoretical deliverability is cited at up to 112 mcm/d, but Ofgem instead bases its assessment on the highest rate actually supplied in the past, 86 mcm/d, judging the theoretical figure as unreliable if all facilities are not sufficiently full and operating at maximum rates simultaneously. A similar precaution is used for an LNG terminal with a theoretical 73 mcm/d capacity, where Ofgem opts to use the historically observed maximum of 61 mcm/d in its modelling. These conservative assumptions contribute to the 403 mcm/d supply figure in the extreme scenario.

A key element in the plan is the decision that a further 25 mcm/d reduction in INT pipeline capacity, which had been planned for October, will now not go ahead. This change alters the balance in Ofgem’s winter outlook by preserving an additional potential inflow of gas to the UK system. The move is described as a medium-term fix designed to offset some of the current pressures on supply margins.

With the INT capacity maintained, Ofgem estimates that supplies to the grid could reach 428 mcm/d this winter even if the two Welsh LNG terminals were to go offline. This level would exceed both the 408 mcm/d demand in the extreme cold scenario and the demand associated with a repeat of the “Beast from the East” weather event, cited at 417 mcm/d. On this basis, the plan is expected to provide more than enough capacity under those modeled peak conditions.

The Ofgem report does not set out what the real-world impacts would be if demand reached 408 mcm/d while supply was capped at 403 mcm/d in the stressed case. The regulator instead concentrates on quantifying capacities and shortfalls without detailing operational or consumer-level consequences.

Ofgem characterises its intervention on pipeline capacity as a medium-term step that eases pressures but does not fully resolve longer-term challenges. It explicitly notes that the plan “does not remove the need for further measures led by Government.” This underscores that, even with the INT pipeline reduction cancelled and conservative capacity assumptions, broader policy decisions will remain important for ensuring gas security in future winters.