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While the Bourakébougou site in Mali is currently the only facility producing white hydrogen commercially - and is only harvesting around five tonnes per year - there are moves to exploit reserves more widely.

Known as natural hydrogen, gold hydrogen or white hydrogen, natural deposits could be an important source.

Frothing in the water table below was an exciting find: champagne-size bubbles that signaled a potentially mammoth cache of so-called white hydrogen, one of the cleanest-burning fuels in nature.

Whether white hydrogen lives up to the hype remains to be seen.

The hope is that white hydrogen could one day flow through them.