France has seen a flurry of applications for exclusive mining exploration permits to uncover naturally occurring deposits of hydrogen and other elements, with four companies seeking to measure potential reserves in the country.
But does this explorative activity mean that France will actually produce much natural hydrogen?
Natural underground stores of hydrogen can be built up through a number of different routes (see table below), which means seeps have been found in a variety of different geographies from the US Midwest to South Australia to most notably Mali, the first to drill for H2 and use it to generate electricity.
However, putting an actual number on how much natural hydrogen exists in the world — let alone in France — is more difficult.
So what makes France so attractive for natural hydrogen prospecting?
Natural underground stores of hydrogen can be built up through a number of different geological and biological forces (see panel below), which means H2 has been found seeping out of the ground in a variety of different geographies — from the US Midwest to South Australia to most notably the African nation of Mali, where natural hydrogen has been extracted and used to generate electricity.
However, putting an actual number on how much natural hydrogen exists in the world — let alone in France — is virtually impossible.
“I completely refuse to give numbers [on recoverable resource], because nobody has drilled yet,” says Isabelle Moretti, a natural hydrogen expert and researcher at the University of Pau in the Pyrénées-Atlantiques region of southwest France. “Nobody can give estimates without wells, without reservoir appraisals.
“In terms of global resources, everything is speculative up to now.”
Rough estimates from incidental hydrogen discoveries during oil & gas exploration, and seepage to the surface via so-called “fairy circles”, could indicate enough natural hydrogen to meet anywhere from a quarter to five times the current global demand.
“[But] there can only be proven reserves when you have enough data to confirm it”, says Moretti.
In fact, the French boom in permit applications may have much more to do with policy than possible reserves.
In April last year, as part of a series of amendments to its mining code, France added “native hydrogen” to the list of substances that could be mined.
“France is the only country in Europe where hydrogen has been introduced in these laws. If people want to take a permit [for exploration], they cannot do it in the UK, in Norway, Germany… the lack of permits in other countries is not linked to the geology, but to the policy,” Moretti noted, adding that the change in the law was partly due to existing research such as from the University of Lorraine and company activity.
“The cheapest hydrogen right now is grey, produced from methane and water... but if you manage to produce hydrogen the same way you produce natural gas, then you save money on the [steam methane reformation] process,” Moretti noted, citing estimates that H2 in Mali has been extracted at a cost of $0.50/kg, making it the cheapest form of hydrogen in the world.
In addition to the measurement campaign for a site in Lorraine in the country’s northeast launched by FDE, permit applicants in France include:
- TBH2 Aquitaine, which is seeking to explore 226sq km of land in the southwestern Pyrénées-Atlantiques region for hydrogen, helium and “related substances
- 45-8 Grand Rieu and Storengy, which are seeking to explore 266sq km also in the Pyrénées-Atlantiques region for hydrogen and “possible related substances”
- SUDMINE, which is seeking to explore 5.9sq km of land in the Puy-de-Dôme region of central France to develop lithium and natural hydrogen mines
The flurry of applications in France mirrors South Australia’s boom in natural hydrogen exploration licenses, which followed the expansion in 2021 of the state’s petroleum and geothermal energy regulations to include H2 and related compounds or by-products.
However, the Australian state’s prospectors have been clustered around Kangaroo Island and the Yorke and Eyre peninsulas, near the Adelaide geological superbasin, going off historical records of high hydrogen concentrations found during drilling for oil & gas.
Moretti noted that the Pyrénées-Atlantiques region has the “same generating rock” for natural H2 as the Monzon field in Spain discovered during oil & gas exploration in the 1960s, for which developer Helios Aragon is planning to drill an appraisal well to confirm hydrogen reserves next year.
There are six known ways in which hydrogen is produced naturally:
In which the mineral olivine located in mid-ocean ridges or ophiolites (a geological formation where sections of the Earth’s mantle rise above sea level) is weathered to form hydrogen-rich fluids. This has been seen in the Semail ophiolite, in the Hajar Mountains of Oman. Under pressure and high tempertures, water can react with these iron-rich rocks to produce H2.
Radiolysis of water
Radioactive elements in the Earth’s crust — for example in crystalline basement rocks with high content of uranium, thorium or potassium — decompose water molecules trapped in causing a hydrogen pocket, as happened in South Australia.
In which “primary” hydrogen (a single hydrogen atom attached to a single carbon atom) escapes from deep within the Earth’s crust. This has been seen in Nebraska, in the US.
Iron reduction and sulphur oxidation
Ferric iron in a black smoker (a subsea hydrothermal vent formed from iron sulphide deposits) is reduced to ferrous iron and hydrogen sulphides.
Thermal decomposition of organic matter
In which ammonium compounds located in deep sendiments decompose under high temperatures to form hydrogen and nitrogen, for example in hydrogen-nitrogen gas seeps in Oman.
Hydrogen is produced by microbes living in the Earth’s crusts, usually co-existing with hydrogen-consuming microbes and found via sediment or aquifers. This has been observed in the coal beds of the Powder River Basin in Montana, US.