Renewable energy sources such as wind and solar are important to combat climate change. Because their output is variable over time, storing energy when there is a surplus to use at times of high demand would be very valuable. A promising technology to do this at large scale is to pump compressed air or hydrogen in the pores of subsurface rock formations. However, salts from the brine originally present in these pores may crystallize out and block the flow of storage gas. Despite its large impact on storage operations, it is currently poorly understood where and in which circumstances this takes place, due to the interplay between the physics of the process and geological heterogeneity. Here, we propose to investigate this from the scale of pores up to storage reservoirs (km-scale). We will contribute a better fundamental understanding of salt blockage by tracking salt precipitation on a pore-by-pore basis with high-resolution X-ray imaging, and directly linking this to gas flow. We hypothesize that successful upscaling of this pore-scale model has to take small-scale heterogeneity (e.g. mm-scale “layering”) into account. We will do this through a combined experimental-numerical approach. Finally, we will test the impact of the newly developed models by implementing them in reservoir-scale simulations. This will give novel and accurate
insights on the impact of salt crystallization on these promising energy storage technologies.