4 year PhD: Underground hydrogen storage – investigating the thermal effects to hydrogen injection and extraction

To keep global warming within limits, our energy portfolio is transitioning from fossil fuels (coal, oil and natural gas) towards low-carbon, renewable energy. Common renewable energy sources, such as wind and solar energy, depend on weather conditions and diurnal-nocturnal variation. These intermittent energy sources demand solutions for grid energy storage. Underground storage of hydrogen provides a valuable solution. Hydrogen can be stored underground in man-made salt caverns. Salt rock has proven to be a very effective impermeable rock for trapped natural gas on geological time scale (tens to hundreds of million years). However, cyclic injection and extraction of hydrogen in salt caverns is different from long-term gas storage in natural systems which does not involve pressure cycling. To ensure safe field deployment of underground hydrogen storage technology, we need to address environmental concerns of gas storage in salt caverns, especially gas leakage to the surface or into aquifers. The project concentrates on thermodynamics of hydrogen storage in salt caverns, in particular investigating thermal effects linked to cycling of hydrogen injection and extraction, as well as thermal effects linked to composition and heterogeneity of the salt rocks.