On the use of carbon steel P355NH for underground hydrogen storage (RIP2026-00034)

Luisa Mateus, Gerald Sam, Benedikt Hasibar, Santiago Ledesma-Mateo, David Fernández-Toledano, Julia van Winden, Lajos Erdelyi, Gregor Mori

RAG Austria, RAG Austria AG, Trinity Energy Storage, Trinity Energy Storage, Shell Global Solutions International B.V., Hungarian Gas Storage Ltd., Montanuniversität Leoben

The energy transition from fossil fuels to cleaner alternatives is a high-priority topic in Europe. Hydrogen replacing natural gas is considered one sustainable solution to reach this goal. The EUH2STARS project will demonstrate the seasonal storage of hydrogen gas in depleted natural gas fields at a technology readiness level of 8. Most of the materials used in natural gas storage facilities have not been tested for hydrogen use, and shall be evaluated with respect to hydrogen embrittlement (HE).
In this study, carbon steel P355NH has been investigated regarding HE, mimicking the environmental conditions expected in service. Constant Load Tests (CLT), Ripple Load Tests (RLT), and Slow Strain Rate Tensile Tests (SSRT) have been performed with high-pressure gas charging. Additionally, SSRT with electrochemical charging has been performed to investigate the impact of higher hydrogen uptake.
CLT specimens tested in wet conditions with high pH2 show higher, but still acceptable, hydrogen uptake when compared to testing in dry conditions. For SSRT and RLT at 300 bar hydrogen, the material shows a minor susceptibility for HE, but no failure occurs after 500 cycles. SSRT with electrochemical charging exhibits higher HE susceptibility than hollow probe SSRT in a dry hydrogen environment.