Produzione e distribuzione di elettricità e calore
Low-carbon Hydrogen from Sources other than Renewables
Autors: Marco Cavana, Pierluigi Leone, Viviana Cigolotti
Production and Distribution of Electricity and Heat
At present, global hydrogen demand is met almost entirely by fossil fuel-based technology. In 2020 it peaked 90 Mt of which 79% came from dedicated hydrogen plants while 21% was produced as by-product from refineries. There are four main processes that are currently use in the industry today: Steam Methane Reforming, (SMR) Autothermal Reforming (ATR), Partial Oxidation (POx) and Gasification. Almost all the hydrogen produced today can be defined grey (if it originates from natural gas) or black (if it is from coal), meaning that it is produced in a carbon emission-intense way, making it responsible for around 900 Mt of direct CO2 emission in 2020. Hydrogen production plant equipped with technologies for Carbon Capture and Sequestration (CCS) or Utilization (CCU) are a very marginal share of the present market (around 0.7%). Methane reforming is the most widespread process for hydrogen production at scale today and it is likely to remain the dominant technology for large-scale hydrogen production in the near term because of its favourable economics and the large number. Among reforming technologies, Steam Methane Reforming (SMR) is the most common one. In view of CCUS adoption to reduce the carbon footprint of the hydrogen production sector, Autothermal Reforming may become more frequently adopted as it would be easier to couple with carbon capture systems. Partial Oxidation is also an already available technology for production at scale and it especially suitable when feedstock is oil residues, thus in combination or to serve the refinery sector. A demonstration project of CCUS coupled with Partial Oxidation is currently running in The Netherlands. In places where coal is available at very low cost, such as India and China, producing hydrogen from coal rather than natural gas is the most viable option. Today, China is the largest producer of hydrogen from coal gasification with around 80 coal gasifiers that can produce about 8 MtH2/yr, which is equivalent to 12% of global dedicated hydrogen production today. Coal gasification is the most carbon intensive pathway for hydrogen production, with an emission factor of more than 20 kgCO2/kgH2. The implementation of CCUS in this sub-sector would get the most significant results, being able to cut emission intensity to 2 kgCO2/kgH2. Gasification can also be adapted to solid biomass feedstock to obtain hydrogen. This pathway, still not fully developed yet, may be boosted by the integration of CCUS technologies that would allow the production of hydrogen with negative carbon dioxide emission factor.