Illustration Energiespeicher

Hydrogen could be stored in salt caverns in the future.

Underground salt caverns could provide huge capacity for the storage of renewable energies to support Germany’s Energy Turnaround. Plans are already underway to turn these natural caves into “organic flow” and “redox flow” batteries in some parts of the country. Now scientists are investigating if salt caves – both on land and at sea – could be used for hydrogen (H2) storage.

An interdisciplinary research team from the RWTH Aachen University, the Fraunhofer Institution for Energy Infrastructures and Geothermal Systems IEG and the Forschungszentrum Jülich have just published a study in the International Journal of Hydrogen Energy which outlines the enormous technical potential for storing H2 – a key fuel of the future – in salt caves, salt domes and bedded deposits.

They estimate the total energy storage potential for H2 in geological salt structures throughout Europe at 84.8 petawatt-hours (PWh) – with 23.2 PWh on land and 61. PWh at sea. Germany’s share of the storage potential is 35.7 PWh, of which 9.4 PWh are on land, which means it has the largest land potential in Europe. For comparison, the potential for pumped water storage power plants in Europe is currently around 0.123 PWh.

“Salt caverns are the most promising option for large storage facilities due to their low investment costs, good sealing and low protective gas requirements”, says Peter Kukla, head of the Georesources Department at Fraunhofer IEG and Professor of Geology at RWTH Aachen in an article in PV Magazine. However, he says, more detailed energy system analysis is needed in order to assess the real potential of these caverns – for example, balancing the economic and ecological aspects and correlating high demand locations with available natural resources.