Chapter 01 · Climate & transitionEnergy & Transition
Grey hydrogen
Definition
Grey hydrogen is hydrogen produced from fossil fuels without carbon capture of the main process emissions.
References
This reference provides supporting context for how “Grey hydrogen” is defined and used.
Overview
What it means in practice
Grey hydrogen should be read as an energy-transition term. Its meaning depends on the technology, market, accounting boundary, contract structure and emissions method being used.
In practice, users should state the boundary, source, measurement basis and evidence. That keeps grey hydrogen specific enough for review without turning it into a broader claim.
Why it matters
Grey hydrogen matters because energy claims can affect emissions accounting, procurement, infrastructure choices and public communication. Clear wording helps distinguish physical energy use from certificates, contracts and market instruments.
Common misconception
A common error is to treat Grey hydrogen as a complete emissions claim. The stronger approach is to state the production route, accounting boundary, instrument and evidence.
Review questions
What source, boundary or measurement method gives the term meaning? What evidence supports it? What limitation would change how a reader interprets the claim?
How it is used
The term appears in climate strategies, transition plans, emissions inventories, scenarios and investment decisions, where governments, companies, investors and technical teams use it to classify, assess or communicate hydrogen produced from fossil fuels without carbon capture of the main process emissions.
Its correct use depends on the relevant methodology, emissions boundary, baseline, timeframe and underlying data.