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Énergie & Climat

Types d'hydrogène

Résumé en bref les types d'hydrogène et leurs noms de couleur selon la voie de production.

Terminologie de l'hydrogène

La couleur de l'hydrogène n'est pas une propriété physique, mais un contexte de production

L'hydrogène est incolore. green/blue/grey sont des raccourcis sectoriels qui résument la matière première, la source d'énergie et la gestion du carbone.

Cette référence associe les étiquettes couleur à la voie de production et aux conditions de gestion du CO2 pour ne pas juger la propreté seulement par le nom.

Une même étiquette peut correspondre à des intensités carbone différentes selon la part d'énergies renouvelables, le taux de captage carbone et la maîtrise des fuites.

Il s'agit d'un glossaire rapide pour interpréter les termes liés à l'hydrogène.

Interpréter les noms de couleur

Green, blue, grey, turquoise, pink, yellow, white, orange sont des codes de route, pas la couleur physique de la molécule d'hydrogène.

L'importance de la voie

Électrolyse, reforming, gazéification, pyrolyse, chaleur nucléaire et routes gaz naturel ont des apports énergétiques différents, donc la même couleur peut avoir un sens différent.

Vérifier l'intensité carbone

Pour les émissions, vérifiez d'abord la frontière système, le périmètre du cycle de vie, ainsi que capture, stockage et contrôle des fuites.

Note de glossaire

Les définitions peuvent varier selon la source ; les noms de couleur ne doivent pas être considérés comme des standards globaux fixes.

Les noms de couleur ne sont pas un classement de propreté; comparez d'abord la voie et les conditions de gestion du carbone.

Types 15
Catégories 7
Variantes de définition 5
Sources 12

TABLEAU

Aperçu des données

15 lignes
Green hydrogen Electrolysis Early commercial Water electrolysis. Some references also include renewable bio-based low-emission pathways. Near-zero direct CO2 during operation, but lifecycle emissions from equipment, electricity matching, and water supply still matter. The core question is whether the electricity is truly additional renewable power.
Blue hydrogen Fossil-based Pilot Natural gas reforming (SMR/ATR), and in some taxonomies coal gasification, combined with CCS or CCUS. Lower than grey when capture rates are high, but upstream methane leakage and uncaptured CO2 remain. Actual capture rate, methane leakage, and kgCO2e/kgH2 matter more than the color label.
Grey hydrogen Fossil-based Commercial Mostly steam methane reforming (SMR) or autothermal reforming (ATR). CO2 from production is emitted to the atmosphere. No emissions at the point of use does not mean low emissions at production.
Brown and black hydrogen Fossil-based Commercial Lignite or hard-coal gasification Very high CO2 and air-pollutant emissions. Some references split brown and black; others group them under fossil grey hydrogen.
Turquoise hydrogen Fossil-based Pilot Methane pyrolysis Produces solid carbon instead of CO2; emissions depend on energy input, methane leakage, and carbon handling. Climate benefit drops if solid carbon is oxidized later or used in short-lived products.
Pink, purple, and red hydrogen Nuclear-based Research Nuclear-powered electrolysis, nuclear electricity plus heat for high-temperature electrolysis, or nuclear heat-driven water splitting. Low direct emissions, but nuclear lifecycle, waste, and safety considerations remain separate questions. Definitions overlap across sources, so grouping them as nuclear-based hydrogen is often clearer.
Yellow hydrogen (solar) Electrolysis Pilot Water electrolysis using solar power Low direct emissions, with lifecycle solar equipment, storage, and grid balancing to consider. Some references instead define yellow hydrogen as grid-powered electrolysis.
Yellow hydrogen (grid) Electrolysis Early commercial Water electrolysis using grid electricity Can be low or high depending on the grid emissions factor. Actual emissions depend on grid carbon intensity and hourly power mix.
White or gold hydrogen Geologic hydrogen Early exploration Exploration, drilling, extraction, or capture of naturally occurring hydrogen. Manufacturing energy can be small, but exploration, drilling, leakage, and purification require lifecycle assessment. Academic and institutional sources often prefer natural or geologic hydrogen over white/gold labels.
Orange hydrogen (geologic) Geologic hydrogen Research Injecting water into iron-rich formations to stimulate mineral reactions. Potentially low-emission, but drilling, pumping, purification, and leakage must be assessed. Orange hydrogen can also mean waste-derived hydrogen in other references.
Orange hydrogen (waste) Bio and waste Pilot Waste or biomass pyrolysis, gasification, or reforming. Biomass carbon can be biogenic, but plastic waste can still emit fossil carbon. CCS and the fossil-carbon share of feedstock must be checked together.
Biohydrogen Bio and waste Pilot Biomass gasification, biogas reforming, fermentation, and microbial or photobiological routes. Can be low or even negative with sustainable feedstock and CCS, but land-use change matters. References classify it differently: green, orange, or a separate biohydrogen category.
By-product hydrogen By-product Commercial Recovery from primary-product processes such as brine electrolysis. Emissions depend on electricity emissions factors and allocation method. No stable color label; allocation rules matter.
Low-carbon or clean hydrogen Policy and certification Policy standard Eligible pathways can include renewables, nuclear, fossil plus CCS, and bio plus CCS. DOE targets 4.0 kgCO2e/kgH2, while the EU uses a framework based on at least 70% GHG savings versus a fossil comparator. Check system boundary, kgCO2e/kgH2, and certification conditions before trusting the label.
Renewable hydrogen Policy and certification Policy standard Usually renewable-powered electrolysis, with requirements such as additionality, temporal correlation, and geographic correlation under EU RFNBO rules. EU rules include GHG accounting requirements such as at least 70% savings. Often overlaps with green hydrogen, but legal renewable hydrogen can be stricter.