The study will provide information on which components may be relevant and in what concentration, compare possible treatment steps and compare this with hydrogen quality standards.

All relevant categories of underground storage facilities will be considered, i.e.
- freshly salted salt caverns,
- converted natural gas salt caverns (originally filled with crude oil blanket, diesel blanket or nitrogen blanket),
- converted oil or product salt caverns and
- converted or newly constructed pore storage facilities (former gas reservoirs and aquifers) for the storage of hydrogen.

It will also be assessed whether the inputs from the surface facility are relevant to the overall inputs. In addition to a literature review, the study will also carry out its own calculations and analyses based on the present variety of storage conditions in Germany and Europe, as obtained from the participating operators.