Does the Earth contain enormous clean energy reserves? For many years the received logic was that hydrogen does not occur naturally in significant quantities without being bound to other atoms (such as in H20, water, or CH4, methane). To obtain the gas — whether as a fuel or for use in fertilizers — we need to strip it from those molecules, typically by electrolysis and steam reformation. But our understanding may be ripe for change. Rūta Karolytė is at the vanguard of prospectors looking for large, naturally occurring reservoirs of hydrogen. She's a researcher from Oxford specializing in the geochemistry of the Earth and she enlightens us to the mechanisms that are likely to be producing hydrogen in the crust: radiolysis and serpentinization. In reviewing the evidence for naturally occurring hydrogen Ruta leads us through exotic terrain: a Soviet-era theory of hydrocarbon production, fairy rings, hydrothermal vents, and chemosynthetic life. If Rūta and her colleagues are correct, the tapping of natural hydrogen could have transformative consequences for the Hydrogen economy such as cutting out the substantial fossil fuel emissions associated with deriving fertilizers from methane or creating a cheap basis for building synthetic fuels. In the first half of the show, we also delve into carbon sequestration — another cool climate topic. But I've got so excited writing up the first half, that I'll leave it here. Notes: * Rūta's Twitter: @rkarolyte [https://twitter.com/rkarolyte] * Show notes at multiverses.xyz [https://www.multiverses.xyz/podcast/mv9-the-hunt-for-h2-ruta-karolyte/] Outline: (00:00) Introduction (3:00) Geological carbon sequestration (50:40) Natural hydrogen