Hydrogen is a colorless and odorless gas and is found on earth almost exclusively in bonded form. Its chemical symbol H2 tells us that it occurs mainly as a compound with water (H2O).
Hydrogen is obtained by splitting water, separating hydrogen (H2) and oxygen (O). This process can be done by different methods and each manufacturing process characterizes the types of hydrogen in terms of carbon footprint. How environmentally friendly it is as an energy carrier depends on its production method.
If electricity from renewable sources is used for this electrolysis process, this "green" hydrogen is considered CO2-neutral.
The advantage of hydrogen is that it is easy to produce, store and transport. In addition, it is available in almost unlimited quantities.
The disadvantage of hydrogen lies in its chemical properties. It is the lightest substance in the periodic table, highly diffusive, very explosive and causes material embrittlement in some materials.