2.1 Hydrogen and different Hydrogen Production models

As stated in the table above, hydrogen in its molecular form rarely occurs in nature and is chiefly found in chemical bonds. Therefore, production processes are necessary to yield pure hydrogen. Both different primary materials and different processes are used to generate hydrogen.
Today, as highlighted in the pie chart below, most of the globally produced hydrogen originates from natural gas (about 48 %). Hydrogen production from coal amounts to 18 % and 30 % of dedicated hydrogen production is from Oil. The remaining 4 % are produced from electricity with respect to water electrolysis. However, as stated in the previous chapter, this ratio has to change in the future, if emission-free hydrogen should contribute to achieving the climate targets.

In order to differentiate renewably produced hydrogen from hydrogen which was produced by use of fossil energy carriers, a declaration system was developed which uses different colours. What each colour stands for is explained in the figure below. Renewable hydrogen is labelled green hydrogen, when it is produced from renewably generated electricity. In case of hydrogen production based on biomass, no consistent colour declaration exists, however, some sources use the green label as well for hydrogen from biomass.