Comment by phenol

sure, and I'm saying that it's not a well-defined number because it's not a closed thermodynamic process. it's kinetically limited, so your H2 yield is a function of how much time you're willing to wait. it also obviously will depend on the type of rock, electrohydraulic fracturing parameters (pressure, voltage, pulse sequence) and so on. and in practice one of the biggest challenges in this field is actually capturing and collecting the hydrogen you stimulate, which is difficult to model and can depend on the precise geology and downhole microbiology. you simply can't compare it to electrolytic H2 on an atoms-per-joule basis.