23. 05. 2023 | Kristýna Bezděková

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The first underground storage of “green” hydrogen, which will enable the transfer of surplus electricity from summer to winter, has been commissioned. The “Underground Sun Storage” project was built on the site of a former porous natural gas storage facility in Rubensdorf, Austria, and the local natural gas storage operator RAG Austria AG is using it to demonstrate that this form of seasonal electricity storage will be viable in the future.

Some two years after the project started, Austrian natural gas storage operator RAG Austria AG has commissioned an underground hydrogen storage facility to be used for seasonal storage of electricity in the form of hydrogen. According to published information, the facility should be able to store summer surpluses from around 1,000 rooftop solar power plants, with a stored volume of 4.2 GWh (1.2 million m3) of hydrogen.

Seasonal electricity storage is an important area to be addressed in the transition to a largely solar and wind-dependent electricity system. Indeed, during the winter months, which are already characterised by higher electricity consumption than in the summer, solar generation is very low and wind generation is erratic. Moreover, with the increasing electrification of heating, electricity consumption in winter will continue to rise.

Ensuring security of electricity supply will therefore require not only a sufficiently rapid development of wind power plants to meet part of the growing demand for electricity in the winter months, but also the construction of a sufficient number of back-up controllable sources, such as hydrogen-fired or natural gas-fired plants using CO2 capture and storage technologies.

“The rapid development of hydrogen is essential. It is not enough to push for the development of renewable energy sources. The electricity generated by solar and wind power plants in the summer months must be stored and usable in the winter, when the wind does not blow consistently and solar and wind power plants do not provide enough electricity to meet the growing demand… “Underground Sun Storage” is a first step in this direction that must be followed by others,” said Markus Mitteregger, CEO of RAG Austria.
According to RAG Austria, which currently operates natural gas storage facilities with a total volume of 6.2 bcm, around 10 TWh of electricity will need to be transferred from summer to winter in Austria alone around 2030.

In theory, if RAG Austria converted all of its current natural gas storage facilities to hydrogen storage, the volume of stored hydrogen would be just under 22 TWh. This means an electricity production of 12 TWh with a steam power plant efficiency of around 54 % (in relation to the heat of combustion).

The need to develop hydrogen storage facilities is also highlighted in Germany
The German association of gas storage operators INES, the oil and gas association BVEG and the gas and water association DVGW estimated last year that Germany would need to build up to 40 new hydrogen storage facilities. This assumes that all suitable existing natural gas storage facilities are also used for this purpose.
According to the published study, around 31 TWh of hydrogen can be stored in Germany’s existing 31 natural gas caverns, which can also be used for hydrogen storage relatively easily.

According to the study, the more complex situation for the transition from natural gas to hydrogen is for porous storage, where the study estimates that only 4 of the existing 16 such storage facilities can be used for hydrogen storage. The available storage capacity in these four facilities could be around 1.7 TWh.

Source, photo: uss-2030.at, underground-sun.com

Kristýna Bezděková

Kristýna is a student of marketing and communication in an undergraduate program. She writes and translates content into the Czech language