An analytical model of the free H2 produced by serpentinization within oceanic lithosphere

The free H2 produced by serpentinization within oceanic lithosphere figures prominently in theories regarding (1) the origin and early evolution of life of earth, (2) the basal fuel-source sustaining the sub-seafloor biosphere, (3) the formation of abiogenic hydrocarbons as well as (4) native metal alloys, (5) the geochemical cycles of various elements, and (5) the future use of H2 as a substitute for fossil fuels. Here we present an analytical model that ties H2 production to seafloor spreading rates and the cooling of oceanic lithosphere. If the assumptions underpinning our simplistic model are largely correct, we estimate that global H2 production by the serpentinization of peridoitite within oceanic-lithosphere may be as large as ~9.7x1012 moles H2/year, which is within one or two orders of magnitude of any previous estimates. The model, however, also predicts where globally H2 production should be greatest as well as how far from the axis of a mid-oceanic ridge H2 production should remain significant. We could not rigorously test our model due to sparse and varied measurements of H2 globally however the model suggests a number of systematic relationships and testable predications for future field-based studies. To demonstrate the potential validity and implications our results, we evaluate where all the free-H2 predicted by the model may go given the limited amount known about the H2 budget within the oceans.