There are several ways of producing hydrogen:
- Currently, the most common method is steam methane reforming, in which methane molecules (CH4) are broken down by the addition of water vapour (H2O), from which hydrogen is obtained. In 2021, this method accounted for approximately 50% of global production.
- Coal gasification is another method, in which the molecules are broken down by heat in the presence of water and partial oxidation of petroleum. This method accounts for less than 50% of global production.
- Because the above methods release CO2, processes are used to capture these molecules so that they can be stored or reused instead of being released into the atmosphere. This is known as blue hydrogen.
- Water electrolysis produces H2 by breaking down the water molecule (H2O) using an electric current. It accounts for 4% of hydrogen production. If electricity is produced using renewable energy sources, this method can be used to manufacture green hydrogen.
Source : IRENA (International Renewable Energy Agency)