Grey to Blue Hydrogen

Grey hydrogen is produced from fossil fuels (NG, Naphtha, LPG and Coal) and commonly uses steam methane reforming (SMR) method. During this process, CO2 is produced and eventually released to the atmosphere.

In a nutshell, H2 produced from fossil sources without CO2 capture is termed as Grey Hydrogen. In traditional SMR based process for H2 production, according to CertifHy, with best available technology, typical value for CO2emissions is around 91 g CO2/MJ H2.This translated into CO2 emissions about 10.9 tons CO2/ton H2 produced. In other words, 1 Nm3 of H2 produced emits about 0.98 kg of CO2..

As per CertifHy, the threshold for blue hydrogen production mandates the CO2 emissions to be less 36.4 g/ MJ H2.This translated into CO2 emissions about 4.4 tons CO2/ton H2 produced, i.e., 60% less CO2 emissions than Grey H2 production. In other words, for blue hydrogen certification,1 Nm3 of H2 produced should emits less than 0.39 kg of CO2.