GREY HYDROGEN¹ 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 CO 2 emissions, which makes these hydrogen technologies unsuitable for a route toward net-zero emissions.
H 2 GREY HYDROGEN H 2 BLUE HYDROGEN
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. This is an option is to produce hydrogen with lower GHG emissions while reducing pressure on the renewable energy capacity installation rate to produce green hydrogen. Notably, industrial processes like steel production may require a continuous flow of hydrogen; blue hydrogen could be an initial solution while green hydrogen ramps up production and storage capacity to meet the continuous flow requirement. However, blue hydrogen has limitations that have so far restricted its deployment: it uses finite resources, is exposed to fossil fuel price fluctuations, and does not support the goals of energy security. Moreover, blue hydrogen faces social acceptance issues, as it is associated with additional costs for CO 2 transport and storage and requires monitoring of stored CO 2 . In addition, CCS capture efficiencies are expected to reach 85-95% at best,² which means that 5-15% of the CO 2 will still be emitted. And these high capture rates have yet to be achieved. In sum, the carbon emissions from hydrogen generation could be reduced by CCS but not eliminated. Moreover, these processes use methane, which brings leakages upstream, and methane is a much more potent GHG per molecule than CO 2 . This means that while blue hydrogen could reduce CO 2 emissions, it does not meet the requirements of a net-zero future. For these reasons, blue hydrogen should be seen only as a short-term transition to facilitate the uptake of green hydrogen on the path to net-zero emissions. TURQUOISE HYDROGEN combines the use of natural gas as feedstock with no CO 2 production. Through the process of pyrolysis, the carbon in the methane becomes solid carbon black. A market for carbon black already exists,³ which provides an additional revenue stream. Carbon black can be more easily stored than gaseous CO 2 . 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. Other renewables-based solutions to produce hydrogen exist. However, except for SMR with biogases, these are not mature technologies at commercial scale yet (IRENA, 2018) . 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. Low VRE costs and technological improvement are decreasing the cost of production of green hydrogen. For these reasons, green hydrogen from water electrolysis has been gaining increased interest.
H 2 TURQUOISE HYDROGEN H 2 GREEN HYDROGEN
1 Sometimes referred to as black or brown hydrogen. 2 An alternative route to SMR could be a process called autothermal reforming, for which it is estimated that a possible capture rate up to 94.5% of the CO 2 emitted is possible (H-Vision, 2013). 3 For example, biomass gasification and pyrolysis, thermochemical water splitting, photocatalysis, supercritical water gasification of biomass, combined dark fermentation, and anaerobic digestion. Figure 3 A breakdown of the different types of hydrogen
Refining as an anchor demand sector Among industrial sectors, refining is uniquely positioned to act as an anchor customer for green hydrogen. Hydrogen is already deeply embedded in refinery operations, supporting hydrocracking, hydrotreating, hydrodesulphurisation, and product quality
compliance. Importantly, this demand is continuous, high-purity, and central to core process performance. Replacing fossil-derived hydrogen with green hydrogen enables refineries to reduce Scope 1 and 2 emissions without altering throughput, product slate, or fundamental process
Refining India
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