Potential Natural Hydrogen Resources of Italy

Natural hydrogen has been identified in a variety of geological settings worldwide, including orogenic belts with ophiolites, hydrothermal systems, and cratonic regions. These diverse environments reflect multiple mechanisms for natural hydrogen generation and entrapment. Do to the strong interplay between geology, tectonics, and magmatism, Italy represents a particularly promising region for investigating the processes that govern the formation, migration, and accumulation of natural hydrogen. However, a comprehensive, national-wide assessment of prospective areas for hydrogen exploration is still lacking. The NHEAT (Natural Hydrogen for Energy trAnsiTion) project, funded by the Italian Ministry of University and Research (MIUR) under the PRIN PNRR 2022 program, aims to fill this gap. By integrating existing geological, lithological, and geochemical datasets, we have developed thematic maps to identify the most promising regions in Italy for potential natural hydrogen exploration. Among these, Tuscany region emerges as a key area of interest due to: 1) exceptionally high heat flow (up to 1,000 mW/m²), associated with iron-rich granitoid intrusions currently exploited in the Larderello and Mt. Amiata geothermal fields; and 2) the occurence of hyperalkaline springs—considered reliable indicators of hydrogen generation—linked to exposed ophiolite lenses. To investigate this promising region, we employ a multidisciplinary approach that combines: a) structural-geological analyses; b) studies of fluid inclusions in hydrothermal mineralizations; and c) geochemical characterization of peralkaline springs and their associated dissolved and dry gaseous phases. Raman spectroscopy of fluid inclusions reveals the presence of natural hydrogen within fault-related hydrothermal mineralizations, highlighting the potential of this region as a natural hydrogen resource. In the next phases of the project, we will further assess this potential by integrating the chemical-physical properties of paleo-fluids (trapped in inclusions) with those of present-day fluids, to reconstruct the long-term fault-fluid-rock interactions that drive natural hydrogen generation.