"Green" Helium

This is largely a response to the very interesting post by John Benson on Energy Central at 

https://energycentral.com/system/files/ece/nodes/597074/new_colors_of_hydrogen_from_the_depths.pdf. 

In this article, he discusses natural hydrogen, focusing on a site in Mali.  More detail along the lines of his article is discussed in Eric Hand’s “Hidden Hydrogen”, (which Benson cites), which is available at  https://www.science.org/content/article/hidden-hydrogen-earth-may-hold-vast-stores-renewable-carbon-free-fuel.  This article suggests sites exist in Brazil, Namibia and Australia. 

These sites may not be the most promising for natural hydrogen.  Another, earlier article, which can be easily accessed at https://www.renewablematter.eu/articles/article/natural-hydrogen-a-geological-curiosity-or-the-primary-energy-source-for-a-low-carbon-future, suggests sites in the Phillipines and Oman.  A map from this article, which also suggest other sites exist, including possibilities in the U.S. and Russia, is

Benson argues that natural helium can be considered “green”, since it is produced by natural geological processes.  This gets us into something of a semantic problem, since most “green” processes are considered to use typical renewable energy, such as solar and wind, or possibly ocean tidal power, to produce sources of electricity. Biofuels are closer to this definition, since the sources for the fuel grow naturally.  But they are considered to be under human control, at least as to the magnitude of the fuel produced per site.  The natural hydrogen really is not under human control, unless the entire geological site is occupied and put under some sort of management.

If people will forgive the obvious pun, it is “natural” to wonder whether there are some sort of similar “natural” sites for helium.  The University of Pittsburgh has an excellent introductory discussion of the production of helium at

http://researchservices.pitt.edu/helium/sourcesanduses

As the introduction notes, most helium is produced as a by-product of natural gas drilling, so in that sense it can never be “green”.  The American Chemical Society notes that helium is produced by the decay of uranium and thorium in https://www.acs.org/greenchemistry/research-innovation/endangered-elements/helium.html.  The Bureau of Land Management insists helium is a non-renewable resource in  https://www.blm.gov/programs/energy-and-minerals/helium/about-helium.

But this still leaves the question open.  If we are going to accept hydrogen as “green” if it is produced by geological processes, then isn’t there a possibility that helium will also be considered “green” for the same reason?  The obvious question is whether nuclear waste, especially that buried underground in sites like Yucca Mountain, could produce helium that could be used.  The article by T. Wiss et. al. from OSTI at https://www.osti.gov/etdeweb/servlets/purl/21156656 suggests such helium is produced, although the article notes that the helium is radiogenic.  The article worries about the structural stability of the stored nuclear waste, and certainly gives the impression, which may not be accurate, that the helium is a contributor to instability.

Helium can be used as a cooling mechanism in nuclear power plants.  The case of the Fort St. Vrain nuclear plant, discussed in  https://www.nrc.gov/docs/ML0403/ML040340070.pdf, is perhaps the best known.  The IAEA, in 2017, noted that the only commercial gas-cooled nuclear reactors were in the United Kingdom, in https://www.iaea.org/topics/gas-cooled-reactors.  General Atomics (at  https://www.ga.com/nuclear-fission/advanced-reactors) and Mitsubishi (at  https://www.mhi.com/products/energy/high-temperature_gas-cooled_reactor.html) are doing research on gas-cooled nuclear reactors.  These reactors would use helium as a coolant.  If the helium is going to be produced by the nuclear waste in any case, and has the potential for causing damage to the waste storage site, there may be a case (and of course, this may prove to be wrong) for using the helium produced at the waste sites again as a coolant.  The radiogenic character of the helium produced may rule this out, but if it doesn’t, perhaps the helium can be “recycled”.

These issues are brought to mind by last summer’s events with water-cooled nuclear power in France.  A number of such French nuclear plants were shut down or run under unusual conditions because the cooling water for them was too hot, due to weather, as in https://www.dw.com/en/french-nuclear-plants-break-a-sweat-over-heat-wave/a-62806646.  Moreover, this was not the only time French nuclear plants had been shut down because of heat – see  https://www.independent.co.uk/news/world/europe/france-nuclear-reactors-shut-down-edf-europe-heat-wave-a8477776.html.  This problem is not going to go away, and it will not just affect France.  Forbes insists water-cooled Small Modular Reactors (SMRs) will win the new (nuclear) power generation competition in  https://www.forbes.com/sites/jeffmcmahon/2023/01/13/why-water-cooled-smrs-will-win-the-new-nuclear-competition/?sh=588807fb1b73.  But if they are water-cooled, and there are massive heat waves in the U.S. or other countries that could use them, the SMRs could (at least conceivably) suffer from the same issues as the French nuclear plants in 2022.  There thus may be a case for helium-cooling, and the exploration of unusual ideas, such as helium recycling, to minimize their costs.