astora operates the Jemgum natural gas storage facility near the East Frisian town of Leer. There, natural gas is safely stored in underground cavities – so-called caverns. The special feature is that astora can react flexibly to customer requirements thanks to large injection and withdrawal rates.
astora would like to transfer this advantage to the future hydrogen energy system in cooperation with the grid operators and thus continue to make an important contribution to Germany's energy supply.
As part of a feasibility study, astora analysed whether an existing cavern of the Jemgum natural gas storage facility would be suitable for storing hydrogen.
The study was initiated in 2021 with the aim of identifying suitable processes for injection and withdrawal of hydrogen which meet all relevant safety and quality standards of gas-based systems.
The results show that the existing geological formations are suitable for storing hydrogen and that the construction of a hydrogen storage facility could be implemented.
Hydrogen has different chemical properties than natural gas. Therefore, different requirements are placed on the technical components for the injection and withdrawal of hydrogen. In Jemgum, an additional surface facility to the existing one would therefore be necessary to meet the requirements for hydrogen.
If hydrogen is stored, compressors are also required – comparable to natural gas – which allow it to be inserted into caverns. Therefore, an analysis of the suitability of different compressor types for injection has been carried out. Both piston and turbo compressors are suitable for this purpose and could be used in a hydrogen storage facility, depending on the capacity requirements. In addition, process simulations were carried out to determine the energy required to drive the compressors and thus the costs of injecting hydrogen.
In the case of withdrawal, particularly high-quality requirements are placed on the purity of the hydrogen. This requires drying plants that can meet these requirements and provide the necessary withdrawal rates. Various processes for drying hydrogen were investigated. One process (adsorption) turned out to be particularly suitable and will therefore be considered in further planning.
If the use of existing caverns is rededicated from natural gas to hydrogen, the necessary permits from the competent authorities must be obtained accordingly. Therefore, it was analysed which permits are required for operation as hydrogen caverns. Furthermore, the analysis includes the investigation of the geological structures to ensure tightness as well as an assessment of the required surface components and their suitability for operation with hydrogen. In addition to the filling of the cavern with water, the first filling with gas was evaluated in the preliminary planning in terms of time. Finally, thermodynamic calculations were carried out to determine possible hydrogen storage capacities (volumes) under the given geological boundary conditions. Taking the investigated cavern as an example, the result brought a possible capacity of up to 48 million m³ of hydrogen.
To substantiate the market and capacity requirements, astora is planning a survey of potentially interested customers.
Details will be published in good time.