OWithout it, solar and wind power would have a hard time. Since last week, RAG AG, which actually specializes in natural gas storage, has been testing how green hydrogen can be used on a large scale as energy storage for volatile producers in the “Underground Sun Storage” project. Two years after the start of the project, it put the world‘s first underground storage facility for green hydrogen into operation in Gampern, Austria. The volatile gas is obtained from solar power in summer and stored for the winter in the pore reservoir, a natural layer of porous rock, around 1000 meters deep.
The demonstration plant is to use 4.2 GWh of green electricity to generate hydrogen by means of electrolysis, to compress it and store it geologically under pressure. In a previous project, the company had compressed the gas with carbon dioxide, which was supposed to lead to methanation underground.
The new facility is not particularly large. According to RAG, the amount of electricity corresponds to the summer surplus of 1000 photovoltaic systems that work on the roofs of single-family houses. In addition, only part of this energy can actually be stored, since electrolysis usually only achieves a maximum efficiency of 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 compared to batteries in particular, converted underground gas storage facilities could provide much seasonal capacity more quickly and with less use of resources. Germany’s cavern and pore storage facilities for natural gas alone account for a good 250 TWh, which could be converted if the Austrian model proves itself economically and technically.
The demonstration plant in Gampern will initially test operation until 2025. In addition, they want to investigate at the site how the hydrogen can be processed again once it has been removed from the underground.