Natural Hydrogen : a Paradigm Shift for the Energy Transition

Faced with the need to find solutions for our energy future, many studies and proposals are aimed at eventually replacing the carbon-based fossil fuels that have enabled our demographic and technological development over the last two centuries. Renewable energies such as photovoltaics and solar power are primary energy sources that have long been known, but which are used today with modern technologies requiring raw materials that are often scarce. Geothermal and hydroelectric energy can only be developed in specific geological or geomorphological contexts, and cannot be generalized to the whole planet. Hydrogen, used today essentially as a man-made product, and for mainly chemical applications, is often presented as an energy carrier, but this perspective still requires primary energy in order to manufacture this hydrogen gas, with an efficiency still well below 100%. These projects therefore do not solve our need to find other, more virtuous energy sources than those used today, even if hydrogen combustion produces only water, and of course no CO ₂ . However, natural hydrogen, made available to us thanks to our planet's geological activity, is proving abundant and distributed across every continent. This time, we're talking about a genuine primary energy source, the quantitative importance of which in our energy future is not yet clear from very recent research. We take stock of the state of knowledge concerning this new natural resource discovered by mankind, and conclude with a look at the prospects that could be envisaged if science were to take up this new subject sufficiently effectively.