Natural hydrogen from deep underground could be an important building block for the sustainable energy system of the future, but it is currently still difficult to predict where and at what depth elevated concentrations are located. New study results from the Department of Geology at the University of Vienna could make such predictions easier in the future. So-called "fairy circles"—round patches with vegetation damage—could be helpful indicators. This is because these "fairy circles" subside due to the seepage of natural hydrogen.