>WHAT ELSE have they been hiding from us?
HIDDEN HYDROGEN
Does Earth hold vast stores of a renewable, carbon-free fuel?
… historically, when well loggers cataloged their borehole emanations, they rarely bothered to measure for hydrogen. “The bottom line—they weren’t really looking for hydrogen,” says Geoffrey Ellis, an organic geochemist at USGS. “We weren’t looking in the right places with the right tools.”
THE MAIN ENGINE of natural hydrogen production is now thought to be a set of high-temperature reactions between water and iron-rich minerals such as olivine, which dominate Earth’s mantle. One common reaction is called serpentinization, because it converts olivine into another kind of mineral called serpentinite. In the process, the iron oxidizes, grabbing oxygen atoms from water molecules and releasing hydrogen.
He thinks Earth produces orders of magnitude more hydrogen each year than the 90 million tons that humans manufacture. But it’s not only that flow that matters—it’s the size of the underground stock. “How much can be trapped in the subsurface that we can actually go after?” Ellis asks. “That’s a much more difficult question to answer.”
He and his USGS colleague Sarah Gelman gave it a try using a simple “box” model borrowed from the oil industry. The model accounted for impermeable rock traps of different kinds, the destructive effect of microbes, and the assumption—based on oil industry experience—that only 10% of hydrogen accumulations might ever be tapped economically. Ellis says the model comes up with a range of numbers centered around a trillion tons of hydrogen. That would satisfy world demand for thousands of years even if the green-energy transition triggers a surge in hydrogen use.
https://www.science.org/content/article/hidden-hydrogen-earth-may-hold-vast-stores-renewable-carbon-free-fuel
The contribution of the Precambrian continental lithosphere to global H2 production
https://www.nature.com/articles/nature14017
Hydrogen emissions from hydrothermal fields in Iceland and comparison with the Mid-Atlantic Ridge
More recently the H2 content within the Larderello geothermal zone of Italy has been studied and the authors concluded that the H2 observed in the steam is due to the serpentinization of the ophiolitic nappes involved in the Apennines thrusts. Native hydrogen has also been discovered in the western Pyrenean foothills and is attributed to mantle rocks serpentinization, in Mount Chimaera (Spain), Tablelands (Canada) and Happo (Japan), but also in Prony Bay (New Caledonia, in the Voltry massif hyperalkaline springs (France) and in Oman.
https://www.sciencedirect.com/science/article/abs/pii/S0360319922001938