Green
Electrolysis from renewable electricity
Water electrolysed using wind, solar or other renewables. Net carbon dependent on the electricity mix; under the GB Low Carbon Hydrogen Standard, the threshold is <20 gCO₂e per MJ H₂.
Hydrogen
Four colours, one uncertain market, and a 2026 strategic decision on home heating.
Great Britain produced about 27 TWh of hydrogen in 2024, almost all of it grey (from natural gas, unabated). The Hydrogen Strategy target is 10 GW of low-carbon hydrogen by 2030, half electrolytic, half blue. Meanwhile the industry waits for the government to decide whether hydrogen belongs in the gas grid for heating. This route separates what the evidence actually says.
05Route 5 of 12 · Energy vectorsAfter this route you will be able to
- Name the four production colours, the inputs each needs and the carbon intensity each produces.
- Identify the current GB demand centres: refineries, ammonia, steel, and the near-term industrial clusters.
- Describe what HAR Rounds 1 and 2 funded, and what the 10 GW by 2030 target implies.
- Explain why H100 Fife is evidence for hydrogen heating and why that evidence is contested.
- Make a reasoned call on the 2026 hydrogen-for-heating decision.
31 October 2025H100 Fife · first 100% hydrogen village network goes live
Three hundred households in Levenmouth now heat, cook and wash with green hydrogen. The first boiler fired at 09:47.
After nine years of planning, two regulatory derogations under GS(M)R 1996, and the quiet cancellation of two comparable projects (Whitby 2023, Redcar 2024),
The engineering worked. No-one expected otherwise: PE network gas distribution has been hydrogen-compatible at up to 100 percent by volume since the 1970s. The boilers, made by Worcester Bosch and Baxi to the Annex A specification, started first time. Appliance certification, gas safety, metering, billing: all adapted smoothly.
What the trial does not yet tell us is whether a network-scale rollout at the cost of
Hydrogen works in a village trial. Does that evidence translate to the national scale where electrolyser capacity is a binding constraint and heat pumps compete for the same low-carbon electricity?
The answer depends on understanding what the four hydrogen colours actually are. Three of them use fossil fuels. One is electrolytic. Only two of the four are counted as low-carbon.
Section 01 · The colours
Four production pathways. Two count as low-carbon.
Hydrogen itself is colourless. The colours label the production process. The policy line between low-carbon and not runs through the middle of this list.
Blue
SMR with carbon capture
Steam methane reforming of natural gas, with CO₂ captured and geologically stored. Low-carbon only if capture rate >85 percent; in practice 90-95 percent is the policy test.
Pink
Electrolysis from nuclear electricity
Water electrolysed using nuclear electricity. Technically identical to green. Categorised separately because of source. Not currently a major GB production route.
Grey
SMR from natural gas (unabated)
Steam methane reforming with CO₂ vented. The default today; almost all of GB's 27 TWh in 2024. Not classified as low-carbon under any current standard.
The 2024 GB Low Carbon Hydrogen Standard v3 tests production against lifecycle emissions. The low-carbon bar is <20 gCO₂e per MJ of hydrogen produced, tested against upstream methane leakage, process emissions and energy inputs.
Section 02 · Who uses hydrogen today
Refineries, ammonia, and some chemicals. Nobody heats a home.
All of the 27 TWh GB produced in 2024 went to industrial uses. Three sectors account for almost all of it.
Refineries use hydrogen to desulphurise petroleum products. This is the largest single use, concentrated at the six major GB refineries (Fawley, Stanlow, Pembroke, Grangemouth, Humber, Lindsey).
Ammonia production for fertiliser uses hydrogen as a feedstock. CF Industries' Billingham site is the primary GB producer. All of the hydrogen is made on site.
Chemicals and glass use hydrogen for process heating and as a feedstock for specialty products. This is the most dispersed demand and the hardest to electrify.
What is absent from this list: steelmaking (British Steel Scunthorpe and Port Talbot still use coal-fuelled blast furnaces, with Port Talbot converting to electric arc from 2025), transport (fuel cell vehicles remain a niche), and heating (H100 Fife is a trial at 300 homes out of 30 million).
The transmission and distribution of natural gas within Great Britain is subject to a gas composition standard that limits hydrogen content to 0.1 % by volume. Any increase above this limit requires regulatory derogation and an evidence-based case for consumer safety.
Gas Safety (Management) Regulations 1996, Schedule 3
Section 03 · The HAR pipeline
Two rounds awarded. Another four to reach 10 GW by 2030.
The Hydrogen Allocation Round is the GB equivalent of the CfD auction for renewables: long-term price support for approved low-carbon hydrogen projects. Contracts pay the difference between a strike price and a reference price, for 15 years.
HAR 1 (December 2023): 125 MW of electrolytic hydrogen projects, supporting roughly 0.2 TWh/year. Eleven projects across Scotland, Wales, North West and Yorkshire. Strike price weighted average £21.0/kg, but projects individually ranged from £9/kg to over £30/kg.
HAR 2 (April 2025): Results announced with 875 MW awarded. A larger envelope than HAR 1 was expected given the trajectory required for the 10 GW 2030 target.
HAR 3 (late 2025 or early 2026): Expected to open with a similar envelope to HAR 2. Blue hydrogen (Track-1 clusters) is procured through a separate Industrial Carbon Capture process.
For context: reaching 10 GW by 2030 requires roughly 2 GW awarded per year across the next four HAR rounds. The supply chain for large-scale electrolyser manufacturing is still building out globally.
Common misconception
Green hydrogen is always zero-carbon.
Green hydrogen is zero-carbon only if the electricity input is zero-carbon. When an electrolyser draws from the GB grid at an average of 160 gCO₂/kWh, the hydrogen carries upstream emissions. The GB Low Carbon Hydrogen Standard requires additionality (the electrolyser cannot displace existing low-carbon generation from other uses) and temporal matching (renewable input must be produced in the same period). Without both, green hydrogen can easily exceed the 20 gCO₂e/MJ threshold.
Section 04 · The 2026 decision
Hydrogen for heating, industrial only, or pause the question.
The government committed to make a strategic decision on hydrogen's role in home heating by 2026. The H100 Fife trial is the primary GB-origin evidence. International evidence is thin and mixed.
Check your understanding
Three questions on what you have just read.
Key takeaways
- Four colours. Only green and blue (at high capture rates) are low-carbon. Grey dominates today's ~27 TWh.
- GB demand is industrial: refineries, ammonia, chemicals. Home heating is a 300-household trial.
- HAR 1 (125 MW) and HAR 2 (875 MW) are the first two rounds. Four more are needed by 2030 to reach 10 GW.
- The 2026 heating decision is the most consequential policy question. The CCC advises industrial-only.
- GS(M)R 1996 caps hydrogen at 0.1 percent in the public network. Any rollout needs regulatory derogation.
References
- DESNZ: UK Hydrogen Strategy
10 GW 2030 target, HAR timeline, low-carbon hydrogen standard.
Primary policy source.
- DESNZ: Low Carbon Hydrogen Standard v3
20 gCO₂e/MJ threshold, additionality and temporal matching rules.
Statutory definition of low-carbon hydrogen.
- SGN: H100 Fife
300-household green hydrogen village trial.
Primary evidence for hydrogen heating.
- Climate Change Committee: Seventh Carbon Budget
Heat pathway analysis, hydrogen vs heat-pump system comparison.
Independent advisory source.
- Gas Safety (Management) Regulations 1996
Schedule 3 gas composition standards.
Regulatory cap on hydrogen in public gas network.
The next route covers heat networks. The quiet alternative to both hydrogen heating and individual heat pumps.