Recent model predictions suggest that Earth's subsurface may contain billions of tonnes of natural hydrogen, offering a promising source of carbon-free energy. Geoscientists believe that hydrogen, being the most abundant element in the universe, could be a game-changer in the quest for sustainable energy. While traditional methods of obtaining hydrogen, such as from water or natural gas, come with a carbon cost, the discovery of geologic hydrogen reserves presents a cleaner alternative. The accidental discovery of almost pure hydrogen gas in Mali challenged the previous notion that natural accumulations of hydrogen were unlikely. By studying natural occurrences of hydrogen and leveraging knowledge from fields like petroleum exploration, researchers were able to develop a global model estimating the potential reservoirs of geologic hydrogen in the Earth's crust. These reservoirs, primarily found in crystalline rock settings and associated with radioactive rocks, could offer vast amounts of energy within reach. Despite the uncertainties surrounding the extraction and distribution of geologic hydrogen, the findings indicate a substantial energy potential that could rival existing natural gas reserves. If even a fraction of the estimated hydrogen reserves could be recovered, it could significantly contribute to the global energy supply while reducing carbon emissions. The research opens up new possibilities for sustainable energy development and underscores the importance of exploring alternative sources of clean energy for a greener future.