Question: Modeling Natural H₂ Generation via Serpentinization in TOUGHREACT (EOS5/EWASG)

Dear TOUGHREACT Users,

I would like to ask for guidance regarding the simulation of natural hydrogen (H₂) generation associated with serpentinization and Fe-mineral redox reactions using TOUGHREACT (v4.13).

Specifically, I am interested in modeling hydrogen production in situ resulting from water–rock interaction processes, such as the oxidation of Fe-bearing minerals (e.g., olivine) during serpentinization.

I understand that EOS5 and EWASG include hydrogen as a component in multiphase systems (gas–liquid mixtures), and therefore hydrogen transport can be simulated. However, I am unsure whether hydrogen generation from mineral alteration can be directly implemented within the geochemical reaction framework.

In particular, I would appreciate clarification on the following:

1. Is it possible to simulate H₂ generation from Fe-bearing silicate minerals using kinetic or equilibrium reactions in TOUGHREACT?

2. Would EOS5 or EWASG be more appropriate for modeling such processes?

3. Has anyone successfully modeled serpentinization-driven hydrogen production and could share references or example input files?

4. Can the approach used in iron corrosion studies (e.g., nuclear repository simulations) be adapted to water–rock interaction systems?

I have reviewed several example problems but have not found a clear case study demonstrating hydrogen generation using EWASG.

Any guidance, references, or example inputs would be greatly appreciated.

Thank you very much in advance.