Eric Gaucher

Can we imitate the natural production of hydrogen from rocks? Can we improve this production? Can we produce industrial volumes? How can we limit energy consumption for this production? What are the most favorable rock types? 

All those questions are the basics of the challenge of this new subject: the Artificial Production of Hydrogen from Rocks. 

The recent call of ARPA-E (USDOE) has lunched the building of a community dedicated to this topic with 16 projects. If we limit this subject to chemical processes only, we need to identify the reduced elements constitutive of minerals that will be able to scavenge oxygen from the water and then release H2. Among these, ferrous iron is a very good candidate, as it is one of the 5 major elements in the Earth's composition. Other metals (Cu, Cr, Zn, Pb…) in their reduced forms could be very interesting but will be restricted to abnormal accumulations, where mining activities take place. If ferrous iron is the main target for artificial production of H2, other metals should be studied in more details. Fe(II) bearing phases are therefore of prime importance. 

A relative abundant literature exists for olivine and pyroxene and the process of serpentinization is thought as well known. However, in their exhaustive review, Barbier et al. (2020) show that only pressure and temperature are well-controlled parameters. The role of chemistry is unclear and for example the presence of carbon can play catalytic role (Andreani et Menez, 2019) but can also be a H2-killer by producing methane as by-product. Carbon poor system could be then be recommended. If H2 production has been observed experimentally with siderite, Milesi et al., (2015) show all the carbonaceous by-products that could polluted the H2-production. 

The quest for low-cost efficient catalysts of Olivine/Pyroxene is launched with some first results with aluminum (Andréani et al., 2013). Nickel appears to be promising (Barbier, 2022), but excess of catalysts can also be a H2-killer. From our provisional findings, it seems that stimulating H2 production with both timing and quantities can be very beneficial, but really fine-tuning will be needed to avoid undesirable phases and secondary hydrogen consumption. 

References: Andreani, M., et al.. (2013). Aluminum speeds up the hydrothermal alteration of olivine. Am. Mineral. 98, 1738–1744. doi: 10.2138/am.2013.4469 Andreani, M., and Ménez, B. (2019). “New perspectives on abiotic organic synthesis and processing during hydrothermal alteration of the oceanic lithosphere,” in Deep Carbon, eds B. Orcutt, I. Daniel, and R. Dasgupta, (Cambridge University Press), 447–479. Barbier, S., et al., (2020). A Review of H2, CH4, and Hydrocarbon Formation in Experimental Serpentinization Using Network Analysis. Frontiers in Earth Science, 8. Barbier S., (2022). PhD Thesis. UCBL Lyon, France. www.theses.fr/2022LYSE1099/document Milesi, V., et al., (2015). Formation of CO2, H2 and condensed carbon from siderite dissolution in the 200-300°C range and at 50MPa. Geochimica et Cosmochimica Acta, 154, 201-211.

Co-auteur : Barbier, Samuel; Andreani, Muriel; Gaucher, Jean, L.