Porter’s analysis centers on a warning from the National Energy System Operator (NESO), issued around the time of the UK Autumn Budget in late 2025.

NESO highlighted an “emerging risk” to gas supply security due to potential premature closures of offshore pipeline infrastructure in the North Sea.

As UK Continental Shelf (UKCS) gas production rapidly declines—accelerated by factors like high windfall taxes (Energy Profits Levy extended to 2030), limited new licensing, and low exploration activity (2025 was the worst year on record)—key pipeline systems face low throughput.

The Watt-Logic has the story.

On the same day that Rachel Reeves was announcing her Autumn Budget, the National Energy System Operator, NESO, quietly issued a bombshell warning about the risks the UK might start running out of gas on cold winter days as a result of the possible closure of offshore pipeline infrastructure. National Gas has been warning about these risks for some time, saying privately they may manifest as early as next winter. NESO is more optimistic. I sit somewhere in between.

Britain’s gas pipelines are at risk

The gas system in GB today depends on four main supply routes into the National Transmission System (“NTS”):

• The UK Continental Shelf (“UKCS”): gas from North Sea and East Irish Sea fields enters the NTS via onshore terminals at St Fergus, Teesside, Bacton, Easington, and Barrow. UKCS production has fallen from around 100 bcm /year in 2000 to around 30 bcm more recently – roughly 35–40% of GB annual demand
• LNG imports: Milford Haven (South Hook, Dragon) and Isle of Grain can deliver a combined 130–150 mcm /day, equivalent to around half of GB’s theoretical peak-day demand, but only if tanks are full and send-out is not constrained by regas capacity, shipping delays or NTS constraints
• Norwegian pipelines: Langeled, Vesterled, and the Tampen Link bring Norwegian gas mainly to Easington and St Fergus. Combined they can supply roughly 80–100 mcm /day, though actual flows vary with continental nominations
• Interconnectors: the Bacton–Zeebrugge (“IUK”) and Bacton–Balgzand (“BBL”) pipelines connect GB to northwest Europe. In theory they allow imports of 60–70 mcm /day. They typically export gas to Europe in the summer and import in the winter (effectively using European gas storage facilities although there are no explicit contracts behind that)

The North Sea Transition Authority’s (“NSTA’s”) latest projections show accelerating UKCS decline through the 2020s, and 2025 was the worst year for exploration on the UKCS since the basin began to be developed. According to Wood Mackenzie, no exploration wells were drilled in UK waters this year, the first time there has been no fresh exploration activity in the basin since oil and gas was found there in the 1960s.

The UKCS is in a much sharper decline than had previously been expected, primarily as a result of a punitive fiscal regime and current Government policy against new exploration. This not only threatens energy security in terms of access to molecules, it also threatens the viability of offshore pipeline infrastructure. The key issue isn’t simply that UKCS output is declining, but that the offshore gathering and transmission system has fixed costs and physical interdependencies – as throughput falls, it becomes progressively harder to maintain and justify these assets.

These pipelines were designed for high throughput and depend on tariffs from producers for their economic viability. As volumes decline, unit tariffs rise to recover fixed costs. At some point, remaining producers face uncompetitive transportation tariffs which accelerates field decommissioning, leading to a “death spiral” where loss of one anchor field undermines the economics of the whole system.

“We think Neso forecasts are too optimistic. We forecast gas production to decline by 70pc by 2030 due to the impact of the windfall tax. That suggests the UK will run out of LNG import capacity as early as 2031, as the current import terminals reach the maximum rate they can deliver gas into the UK grid during winter. The best way to ensure security of gas supply is to maximise domestic gas production,”
– Chris Wheaton, analyst at Stifel

Read the full story here.