Report on (i) the definition of underground gas storages (UGS)- relevant impurities (ii) recommendations for measurements of hydrocarbon traces and (iii) an
extension of the enhancement factor for hydrogen mixtures.
Hydrogen is seen as an important energy source of the future in politics and business worldwide. In various countries beyond Europe clear targets have been defined for the energy transition towards hydrogen. In order to secure supply underground storage of hydrogen is increasingly becoming the focus
of politics and business. There is nowadays a great deal of experience worldwide in the storage of natural gas to meet medium-term demand and it is expected that some of this experience can be transferred to the storage of hydrogen.
There are basically two storage options for storing hydrogen in the geological subsurface:
• Pore storage (aquifers or depleted natural gas reservoirs) and
• Underground cavern storage (salt caverns or rock caverns).
Currently some 662 UGS facilities are in operation worldwide. Out of them 72 % are deployed in depleted hydrocarbon reservoirs, 15 % in salt caverns and 15 % in deep aquifers [1]. In Europe more than 100 underground gas storages (UGS) exist. For example, there are 49 ones operating currently in Germany,
being porous structures used predominantly. However, so far no hydrogen or hydrogen mixtures are stored there. In contrast, storage in caverns is practiced only at a few selected locations (e.g., Teesside; 95 % H2 + 3–4 % CO2) and mainly for use by the chemical industry.
There is already a long experience accumulated through many years in handling hydrogen mixtures in underground storage facilities. This concerns mainly town gas (about 50 % H2, 50 % CO), which has been stored underground in various types of storage facilities. This yields confidence on the feasibility of
underground hydrogen storage, at least, in principle.
Projections of UGS demands for hydrogen are still uncertain. In general, the required total UGS-hydrogen working volume would be in a range of 580 – 600 bcm and this is similar or slightly greater than the total working volume of UGS available today.
When discussing about USG, a distinction must be made between storing pure hydrogen in new caverns or hydrogen + natural gas mixtures. Furthermore, because of the large investment necessary for new storages, the use of existing gas storage facilities and thus the successive transition to hydrogen is currently seen as the most realistic option.
The aim of this MefHySto work package, WP5, is to address metrological and thermodynamic issues in the large-scale storage of hydrogen in underground gas storages and the conversion of existing UGS from natural gas to hydrogen. WP5 will provide missing information on the thermodynamics in UGS studies. Additionally, it will develop and evaluate measurement methods for the conversion and subsequent use of the UGS for hydrogen.
Download report from Aug 2023 (M36)
DBI, NPL, BAM, UDC, CMI, Reganosa
