Geologists from the US Geological Survey have conducted a study to estimate the vast potential of natural hydrogen reserves stored underground worldwide. Their stochastic model predicts a wide range of 1 billion to 10 quadrillion tonnes of natural hydrogen, with a most likely value of 5.6 trillion tonnes. While acknowledging the challenges in recovering this hydrogen, even extracting a small percentage could meet the global hydrogen demand for centuries. The study emphasizes that this amount of hydrogen surpasses the energy content of all proven natural gas reserves on Earth. The researchers foresee a slow but steady progress in exploring geologic hydrogen, expecting an acceleration in production as understanding and technology advance. Despite the promising outlook for natural hydrogen as a cost-effective alternative to other hydrogen sources, such as green and blue hydrogen, uncertainties persist. A report by the Oxford Institute for Energy Studies raises concerns about the feasibility of natural hydrogen in achieving net zero due to uncertainties regarding its origin and accumulation mechanism. Nonetheless, ongoing exploration efforts globally indicate a growing interest in tapping into this hidden energy resource.