Gas
How the GB gas system moves supply, stores risk, and carries the transition question.
Gas reaches Great Britain through five coastal pipeline terminals, three LNG terminals and three interconnectors, flows 7,660 km through the National Transmission System, steps down through five pressure tiers and arrives at 23 million meters. This route explains the physical system first, then the supply mix, the storage gap, and the three transition pathways the government must choose between by 2026.
04 Route 4 of 12 · System foundationsAfter this route you will be able to
- Trace gas from a terminal through the NTS to a meter, naming the pressure at each step and the mechanism that lowers it.
- Explain where GB gas comes from in 2024 and why the exposure is economic, not physical.
- Say why GB storage sits at about 5 % of annual demand while Germany's is near 25 %.
- Name the four Gas Distribution Networks and their regions.
- Make a reasoned call on managed decline, hydrogen conversion or hybrid, given the 2026 decision window.
1 March 2018Gas Deficit Warning · first issued since 2006
The Beast from the East pushed the GB gas system to the edge of its linepack buffer.
On 1 March 2018 National Grid issued a Gas Deficit Warning, its first in twelve years. An anticyclone sat over Scandinavia, a 4 °C temperature fall pulled gas demand to
The Rough storage site had closed in 2017. Without it, the system leaned harder on
Operators did not run out of gas. Prices tripled on the within-day market, large industrial users were asked to reduce offtake, and the system recovered. But it was the first time in a generation that GB's gas dispatch margin, not its electricity margin, dominated the operator's attention.
No household lost supply. But the buffer that keeps the system upright had halved in twenty-four hours. Where does that buffer come from, and why is so little of it in storage?
The rest of this route answers that question. First, what the physical network actually is. Then, where the gas comes from and how the mix has moved since 2004. Then storage, distribution, and the three pathways for the 2026 decision.
Section 01 · The physical network
Six numbers that describe the whole system.
The GB gas network is one of the most extensive energy networks in Europe. Everything that follows builds on the six quantities below.
One number matters more than its face value. Annual demand in 2024 was the lowest since 1992. Gas consumption has fallen for three reasons at once: a warmer average winter, more efficient boilers, and more renewables on the electricity system displacing gas generation. The system has been shrinking from use even while the pipelines remain exactly as they were.
Section 02 · Pressure and flow
Gas drops from 85 bar to 21 mbar over six steps.
The pressure ratio from the NTS to a domestic meter is greater than 4,000 to 1. Each step is managed by a governor, which is an automatic pressure-regulating valve, and each step is where a different operator takes over.
National Transmission System
7,660 km, 21 compressor stations · NESO-balanced, National Gas-operated
38–85 bar
↓ pressure reduction station
High pressure (HP)
Regional backbone operated by the GDN
>7 bar
↓ district governor
Intermediate pressure (IP)
Feeds major demand centres
2–7 bar
↓ district governor
Medium pressure (MP)
Town and street level. Iron mains replacement happens here.
75 mbar–2 bar
↓ service governor
Low pressure (LP)
Final delivery through service pipes
19–75 mbar
↓ domestic meter regulator
At the meter
11,500 kWh/yr average household (Ofgem typical)
21 mbar
Each step is a deliberate pressure reduction. The governor at each transition is a mechanical safety device as much as a flow controller: if downstream pressure rises above its set point, it closes, isolating the lower-pressure tier from the higher one.
Any person conveying gas to a supply meter installation must not convey gas at a pressure outside the limits prescribed for that installation. For domestic premises the inlet pressure to the meter shall be between 19 mbar and 23 mbar.
Gas Safety (Management) Regulations 1996, Schedule 1
The cascade is the physical answer. Where the gas enters at the top is a different question, and one where the answer has changed more than most people realise.
Section 03 · Where gas comes from
Norway is now as big a supplier as the UK Continental Shelf.
In 2000, UKCS production peaked at
The Norwegian pipelines, Langeled (1,166 km, the longest subsea gas pipeline in the world), Vesterled and FLAGS, supplied 76 % of all GB gas imports in 2024. The three LNG terminals (South Hook and Dragon at Milford Haven, and Isle of Grain on the Thames) together imported 14 % of supply, with the United States overtaking Qatar as the largest single source. LNG volumes fell 47 % on 2023, as European buyers paid above GB spot prices.
Two bidirectional interconnectors move gas with the continent: IUK (Bacton–Zeebrugge) at 25.5 bcm/yr import and 20 bcm/yr export capacity, and BBL (Bacton–Balgzand) at 15 bcm/yr import and 5 bcm/yr export. A third, Moffat, runs 6.2 bcm/yr to Ireland.
Common misconception
GB's gas problem is physical scarcity.
GB has 141 bcm/yr of import capacity against 63 bcm of actual demand. The system has more than enough physical capacity even if UKCS production falls to zero. The remaining vulnerability is economic: GB is exposed to global LNG prices, and in August 2022 that meant domestic wholesale costs rose above 540 p/therm even while pipelines were full. Overcapacity buys resilience against outages. It does not buy resilience against price shocks.
Section 04 · The storage gap
GB stores about 5 % of annual demand. Germany stores 25 %.
Total working gas storage in the UK is 3.2 bcm, with a maximum deliverability of 127 mcm per day. Over half of that working volume comes from one site, Rough, which closed in 2017 and reopened at reduced capacity in 2022.
Sources: Gas Infrastructure Europe AGSI+ (2024 averages). GB storage is dominated by Rough (1,530 mcm, a depleted offshore field) with salt-cavern sites at Stublach (400 mcm), Aldbrough (280 mcm) and Holford (242 mcm). Salt caverns cycle fast; Rough cycles slowly.
The short answer for why GB's storage is small is geology and history. The Rough field was chosen because it was a convenient, pre-existing offshore formation; there are few others. Salt-cavern formations are concentrated around Cheshire. And when North Sea production was plentiful, pipeline gas was cheaper to produce than stored gas was to keep. None of those facts required political choice. Closing Rough in 2017, and deciding not to subsidise its reopening until the 2022 crisis, did.
Section 05 · Distribution
Four companies run the 284,000 km that reaches your street.
Eight regional Gas Distribution Networks (GDNs), operated by four companies, manage every metre of low- and medium-pressure pipe between the NTS and 23 million premises. They are regulated by Ofgem under RIIO-GD2 (2021–2026), with the next price-control period, RIIO-3 (2026–2031), committing
GDN boundaries differ from the 14 electricity Distribution Network Operator licence areas. Cadent alone runs more pipe than several European countries. The RIIO-3 iron-mains commitment continues a programme running since 2002: replace the Victorian cast-iron network with polyethylene, which is both safer and, crucially, hydrogen-compatible up to 100 % by volume.
Section 06 · The 2026 decision
Three pathways, one decision window, uneven evidence.
The government plans a strategic decision on hydrogen for heating by 2026, informed by the H100 Fife village trial, the cancelled Redcar and hydrogen town pilots, and international evidence from the Netherlands and Germany.
Check your understanding
Three questions on what you have just read.
Key takeaways
- The GB gas network is 7,660 km of high-pressure transmission plus 284,000 km of distribution, serving 23 million meters at a final pressure of 21 mbar.
- Linepack, the gas held inside NTS pipes, is the buffer that absorbs the first hours of any demand spike. Storage absorbs days to weeks.
- The 2024 supply mix is roughly UKCS 43%, Norway 43%, LNG 14%. The vulnerability is economic, not physical.
- GB storage at 5% of annual demand is the lowest ratio among large European economies. It is a policy choice as much as a geology one.
- The 2026 hydrogen decision is constrained by GS(M)R 1996, by the pace of heat-pump deployment, and by two cancelled village trials. The pipes are ready; the evidence base is not.
References
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National Gas: The National Transmission System
Operator reference for 7,660 km pipeline, 21 compressor stations, linepack behaviour.
Primary source for physical network facts.
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DESNZ , Digest of UK Energy Statistics (DUKES) 2025
Chapter 4: Natural gas. UKCS production, Norwegian imports, LNG volumes, demand.
Authoritative UK government statistics, updated annually.
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Ofgem , RIIO-3 Final Determinations (Dec 2025)
£5.9 bn iron mains commitment, 2026–2031 price control.
Regulatory source for distribution-network spending plan.
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Gas Safety (Management) Regulations 1996
Schedule 1 (pressure limits) and definition of gas composition (hydrogen 0.1% cap).
Statutory instrument governing GB gas operations.
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Gas Infrastructure Europe , AGSI+
European storage inventory and injection/withdrawal data.
Source for European comparator figures in the storage chart.
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Climate Change Committee , Seventh Carbon Budget (2024)
Heat pathway analysis, 1 million/year heat pump installation assumption.
Independent advisory body to government on decarbonisation paths.
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H100 Fife
SGN-led 300-household, 100% hydrogen village trial in Fife.
Live evidence base for the hydrogen-conversion pathway.
The next route opens the hydrogen question properly. How it is produced, where the electrolyser capacity will come from, and what the industrial clusters need before the public-network decision can be made.