The topic of hydrogen use is becoming more and more popular on the market every day, so we offer you to get acquainted with its most popular shades.

GREY HYDROGEN is produced with fossil fuels (i.e. hydrogen produced from methane using steam methane reforming (SMR) or coal gasification). The use of grey hydrogen entails substantial CO2 emissions, which makes these hydrogen technologies unsuitable for a route toward net-zero emissions. 

During early stages of the energy transition, the use of BLUE HYDROGEN (i.e. grey hydrogen with carbon capture and storage [CCS]) could facilitate the growth of a hydrogen market. Around three-quarters of hydrogen is currently produced from natural gas. Retrofitting with CCS would allow the continued use of existing assets while still achieving lower GHG emissions. 

TURQUOISE HYDROGEN combines the use of natural gas as feedstock with no CO2 production. Through the process of pyrolysis, the carbon in the methane becomes solid carbon black. A market for carbon black already exists, which provides an additional revenue stream. Carbon black can be more easily stored than gaseous CO2. At the moment, turquoise hydrogen is still at the pilot stage. (Philibert, 2020; Monolith, 2020).

Among the different shades of hydrogen, GREEN HYDROGEN – meaning hydrogen produced from renewable energy – is the most suitable one for a fully sustainable energy transition. The most established technology options for producing green hydrogen is water electrolysis fuelled by renewable electricity. This technology is the focus of this report. 

Green hydrogen production through electrolysis is consistent with the net-zero route, allows the exploitation of synergies from sector coupling, thus decreasing technology costs and providing flexibility to the power system. 

 

Source: https://www.irena.org/publications/2020/Nov/Green-hydrogen