Green hydrogen (GH2 or GH2) is hydrogen generated by renewable energy. Green hydrogen has significantly lower carbon emissions than grey hydrogen, which is derived from fossil fuels without carbon capture. Green hydrogen may be used to decarbonize sectors that are hard to electrify, such as cement and iron production. Green hydrogen can be used to produce green ammonia, the main constituent of synthetic fertilizer. It can also be used for long-duration grid energy storage, and for long-duration seasonal energy storage.

As of 2021, green hydrogen accounted for less than 0.2% of total dedicated hydrogen production. Its cost relative to hydrogen derived from fossil fuels is the main reason green hydrogen is in less demand. Several governments and international organizations have adopted policies to promote the commercialization of green hydrogen, and green hydrogen production is expected to increase significantly in the coming years.

Definition

Green hydrogen is produced by using renewable energy to power the electrolysis of water It is generally considered distinct from pink hydrogen, which is produced from the use of nuclear power in electrolysis.

Certified green hydrogen requires an emission reduction of >60-70% (depending on the certification body) below the benchmark emissions intensity threshold (= GHG emissions of grey hydrogen, for example benchmark values according to renewable energy directive RED II).

The EU Commission's hydrogen strategy defines renewable hydrogen as hydrogen produced through the electrolysis of water powered by electricity from renewable sources or through the reforming of biogas or biochemical conversion of biomass. In EU legislation, renewable hydrogen and hydrogen-derived fuels produced without the use of biomass are referred to as renewable fuels of non-biological origin (RFNBO). The hydrogen strategy defines low-carbon hydrogen as having significantly reduced full life-cycle greenhouse gas emissions.

In the United Kingdom, just one standard is proposed, for ‘low carbon’ hydrogen. Its threshold GHG emissions intensity of 20g CO2 equivalent per megajoule should be easily met by renewably-powered electrolysis of water for green hydrogen production, but has been set at a level to allow for and encourage other ‘low carbon’ hydrogen production, principally blue hydrogen. Blue hydrogen is grey hydrogen with added carbon capture and storage, which to date has not been produced with carbon capture rates in excess of 60%. To meet the UK’s threshold, its government has estimated that an 85% carbon capture rate would be necessary.