TY - THES

T1 - On the risk of hydrogen embrittlement of carbon steels in underground hydrogen storage

AU - Svetina, Max

N1 - no embargo

PY - 2022

Y1 - 2022

N2 - Throughout the energy transition, underground storage as well as use of hydrogen are becoming increasingly important, especially in Europe. Similarly, the oil and gas industry is progressively focusing on renewable energies and thus also on the application of hydrogen. Nevertheless, the use of this element is not without issues, as it also has detrimental effects on steel, which can occur in form of hydrogen embrittlement. The aim of this thesis is to evaluate possible future underground hydrogen storage. Therefore, experiments in the form of special autoclave test are performed to determine which content of hydrogen is absorbed by the carbon steel L80 under specific conditions and how this affects the material. The test conditions include various combinations of gaseous hydrogen, carbon dioxide and hydrogen sulphide, at elevated pressures to which the material is exposed for a test duration of 30 days at temperatures up to 120 °C. Inside the autoclaves, not only specimens for measuring the hydrogen uptake by the material are placed, but also tensile specimens that were constantly loaded with 90% of the specified minimum yield strength. Both are made of the same material, the carbon steel L80. None of the constantly loaded specimens broke, neither within the hydrogen gas atmosphere nor in the other sour gas environments, including hydrogen sulphide under elevated pressures. Nevertheless, the measurements reveal that the specimens absorb more hydrogen in the gaseous hydrogen sulphide atmosphere than in a pure hydrogen gas environment. The presence of an electrolyte (brine) also contributes to this effect. Furthermore, higher temperatures have no significant impact on the hydrogen uptake of the steel, resulting in the highest hydrogen absorption values being observed at 25 °C in a gaseous hydrogen sulphide atmosphere together with an electrolyte. However, literature research indicates the feasibility of infrastructure for underground storage as well as utilisation of hydrogen in the coming years. Besides, the autoclave tests reveal that the material L80 does not fail despite various corrosive environments and demonstrates relatively low hydrogen absorption in gaseous hydrogen at pressures up to 120 bar. Therefore, the material is appropriate for the usage under the tested conditions and thus for underground hydrogen storage. Future research studies could be conducted by further tests under the mentioned conditions with other types of steel, typically applied in the oil and gas business for underground storage of different fluids and gases.

AB - Throughout the energy transition, underground storage as well as use of hydrogen are becoming increasingly important, especially in Europe. Similarly, the oil and gas industry is progressively focusing on renewable energies and thus also on the application of hydrogen. Nevertheless, the use of this element is not without issues, as it also has detrimental effects on steel, which can occur in form of hydrogen embrittlement. The aim of this thesis is to evaluate possible future underground hydrogen storage. Therefore, experiments in the form of special autoclave test are performed to determine which content of hydrogen is absorbed by the carbon steel L80 under specific conditions and how this affects the material. The test conditions include various combinations of gaseous hydrogen, carbon dioxide and hydrogen sulphide, at elevated pressures to which the material is exposed for a test duration of 30 days at temperatures up to 120 °C. Inside the autoclaves, not only specimens for measuring the hydrogen uptake by the material are placed, but also tensile specimens that were constantly loaded with 90% of the specified minimum yield strength. Both are made of the same material, the carbon steel L80. None of the constantly loaded specimens broke, neither within the hydrogen gas atmosphere nor in the other sour gas environments, including hydrogen sulphide under elevated pressures. Nevertheless, the measurements reveal that the specimens absorb more hydrogen in the gaseous hydrogen sulphide atmosphere than in a pure hydrogen gas environment. The presence of an electrolyte (brine) also contributes to this effect. Furthermore, higher temperatures have no significant impact on the hydrogen uptake of the steel, resulting in the highest hydrogen absorption values being observed at 25 °C in a gaseous hydrogen sulphide atmosphere together with an electrolyte. However, literature research indicates the feasibility of infrastructure for underground storage as well as utilisation of hydrogen in the coming years. Besides, the autoclave tests reveal that the material L80 does not fail despite various corrosive environments and demonstrates relatively low hydrogen absorption in gaseous hydrogen at pressures up to 120 bar. Therefore, the material is appropriate for the usage under the tested conditions and thus for underground hydrogen storage. Future research studies could be conducted by further tests under the mentioned conditions with other types of steel, typically applied in the oil and gas business for underground storage of different fluids and gases.

KW - Wasserstoffversprödung

KW - Kohlenstoffstahl

KW - unterirdische Gasspeicher

KW - hydrogen embrittlement

KW - carbon steel

KW - underground gas storage

M3 - Master's Thesis

ER -