This podcast describes an exploration project for natural hydrogen in the Pyrenees foothills of France, a promising but understudied clean energy source.  To overcome the challenge of limited data, researchers deployed a dense network of lightweight, cost-effective autonomous seismic nodes in a 3-component configuration to record passive seismic data.  Analysis of the collected data, including the detection and precise localization of small microseismic events, allowed for the creation of high-resolution images of subsurface geological structures, which are crucial for understanding the origin and potential migration pathways of natural hydrogen.  The project highlights the effectiveness of this method for crustal imaging and fault characterization, potentially aiding future natural hydrogen exploration and seismic risk assessment.