Natural hydrogen emanations in northern Bavaria – soil gas surveys across three fault systems

Natural hydrogen (H2) is increasingly discussed as a potential contributor to a future sustainable energy system. We present the results of the first comprehensive soil gas survey targeting natural hydrogen seepage in Northern Bavaria, Germany. Our study focuses on three major fault zones: the Franconian Line, the Heustreu Fault Zone and the Staffelstein Fault, and investigates their role as potential migration pathways for natural hydrogen.

From 303 soil gas measurements, we identified several hydrogen hotspots with concentrations exceeding 1000 ppm at 1 metre depth. These anomalies show spatial correlations with known fault structures and reveal a heterogeneous hydrogen distribution, suggesting that only hydraulically active fault segments serve as effective conduits. Elevated hydrogen levels at distances from mapped fault traces may indicate lateral migration within aquifers or the influence of unmapped or inclined faults.

Although we considered potential hydrogen source rocks such as serpentinites and radiogenic granites, our findings suggest that structural permeability plays a more dominant role than proximity to source rocks. Weak correlations between hydrogen and carbon dioxide, along with a strong land use effect on CO2, confirm that CO2 is not a reliable hydrogen proxy. Low methane concentrations and noble gas measurements support a geogenic rather than microbial hydrogen origin.

Our results demonstrate the area’s considerable potential for natural hydrogen exploration and highlight the need for further research. Such research should include hydrogeological investigations, soil gas surveys and geophysical studies to better understand the extent, origin, migration pathways and flux rates of natural hydrogen in the region.