Hydrogen production:
what is the carbon impact?

When hydrogen is used, it emits only water. This is a huge advantage, with no CO2 emissions. However, in its production phase, it is not completely carbon-neutral. Across its entire lifecycle, CO2 emissions from hydrogen vary depending on the production process and, of course, the energy source used.

A colour spectrum is often used to differentiate between the various methods of production but it does not convey the full carbon impact of hydrogen. That is why the regulations make a distinction between three categories:

• Renewable hydrogen is produced through electrolysis, using electricity generated from renewable sources, or any other technology using these sources but without any conflict of use. The amount of CO2 emitted must be below the threshold of 3 TCO2/TH2
• Low-carbon hydrogen is produced using a process that emits less than 3 TCO2/TH2
• Carbonated hydrogen is neither renewable nor low-carbon

CO2 emissions per Tonne of hydrogen produced (in TCO2/TH2)


Sources: ADEME Carbon Base / 2019 Multi-annual Energy Programme (PPE) / JRC 2021 Well-To-Tank Study