With the growing share of renewable energies, the need for energy storage systems that can absorb excess electricity and balance grid fluctuations is increasing. Against this backdrop, underground hydrogen storage facilities are gaining importance because they can store large amounts of energy over long periods of time. However, this requires that the storage facility and the associated boreholes remain permanently sealed. Researchers at the Karlsruhe Institute of Technology (KIT) therefore conducted experiments as part of the SAMUH2 collaborative research project to determine whether hydrogen can affect the borehole cements underground.

Thermodynamic modeling had suggested possible reactions between hydrogen and cement. With their study, the Karlsruhe researchers have now demonstrated that under the experimental conditions, neither significant chemical changes nor any deterioration in mechanical or physical properties could be detected. “We were able to show that the well cements used in practice remain stable under abiotic conditions and are fundamentally suitable for underground hydrogen storage,” says lead author Sebastian Bruckschlögl from the Institute of Structural Engineering and Building Materials Technology at KIT.

In the experiments, the researchers exposed conventional and polymer-modified cements to hydrogen—under high pressure and elevated temperatures, as would realistically occur in underground storage facilities. They then analyzed the samples using a wide range of measurement methods. “The results represent another important step toward the future planning of underground hydrogen storage facilities,” says Dr. Chaojie Cheng from the Institute of Applied Geosciences at KIT, summarizing the findings.

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