Without it, solar and wind power would have a hard time. Since last week, RAG AG, which actually specialises in natural gas storage, has been testing how green hydrogen can make a name for itself on a large scale as an energy storage system for volatile producers in the "Underground Sun Storage" project. Two years after the start of the project, it has commissioned the world's first underground storage facility for green hydrogen in Gampern, Austria. The volatile gas is extracted from solar power in summer and stored for the winter in the pore deposit, a natural layer of porous rock, which is about 1000 meters deep.

Anna-Lena Niemann

Editor in the "Technology and Engine" department.

  • Follow I follow

The demonstration plant will use 4.2 GWh of green electricity to produce hydrogen by means of electrolysis, compress it and store it geologically under pressure. In a previous project, the company had injected the gas with carbon dioxide, which was supposed to lead to methanation underground.

The new plant is not yet particularly large. The amount of electricity corresponds to the summer surplus of 1000 photovoltaic systems that work on the roofs of single-family homes, according to RAG. In addition, only part of this energy can actually be stored, since electrolysis usually only achieves an efficiency of no more than 70 percent.

Nevertheless, the process has advantages over other storage technologies. Especially in this country, the potential for classic pumped storage power plants is as good as exhausted. And especially compared to batteries, converted underground gas storage facilities could provide a lot of seasonal capacity faster and in a more resource-efficient way. Germany's cavern and porous storage facilities for natural gas alone have a capacity of more than 250 TWh, which could be converted if the Austrian model proves itself economically and technically.

The demonstration plant in Gampern is initially scheduled to test operation until 2025. In addition, the site wants to investigate how the hydrogen, once it has been removed from the subsurface, can also be reprocessed.