ELSAFRA II S.p.A.
Green
Process: Electrolysis
Energy source: Renewable energy
Carbon footprint: 0 tCO2/tH2
Grey
Process: Steam reforming
Energy source: Methane gas
Carbon footprint: 9-10
0 tCO2/tH2
Turquoise
Process: Pirolisi
Energy source: Renewable
Carbon footprint: 0 tCO2/tH2
Brown
Process: Gasification
Energy source: Carbon
Carbon footprint: 18-20
0 tCO2/tH2
Blue
Process: Steam reforming or gasification with CCUS
Energy source: Methane gas Carbon
Carbon footprint: from 1 to > 6
0 tCO2/tH2
Blue Hydrogen
Grey Hydrogen
The production of blue hydrogen involves the installation of a Carbon Capture Utilization and Storage (CCUS) plant in Steam Methane Reforming or coal gasification processes, which occurs at temperatures of approximately 700°C. Despite being an interesting alternative to green hydrogen, this method is not able to capture all CO2 emissions.
Green Hydrogen
Green hydrogen is obtained through the splitting of water via electrolysis, using electricity from renewable energy sources, and produces no CO2 emissions during the process or its use. When used in a fuel cell, the only byproduct produced is pure water, used to produce the hydrogen itself. Although it is considered a completely eco-friendly process, green hydrogen production requires significant structural investments due to the high amount of energy required.
Currently, grey hydrogen production represents the most common method to produce hydrogen. It is produced from fossil fuels, often using the Steam Methane Reforming (SMR) method, which involves the production and release of CO2 into the atmosphere. Although less harmful to the environment than black or brown hydrogen, the grey hydrogen production process produces more emissions than the green hydrogen.
Brown Hydrogen
On the other hand, brown hydrogen production through coal gasification is a well-developed and established process, used for many years in the chemical and fertilizer industries to produce ammonia. This highly polluting process takes place at high temperatures (over 700-800°C), in the presence of an oxidizing agent such as oxygen or steam, in sub-stoichiometric percentages.
