What are the main mechanisms behind natural hydrogen formation, and what research efforts are still needed to better understand these processes?
The report reviews four main processes identified as responsible for the natural generation of H₂: the alteration of specific minerals, the radiolysis of water, volcanic activity, and the high-temperature maturation of organic matter in sedimentary systems.
These mechanisms remain poorly constrained and insufficiently quantified. The reaction pathways involved in hydrogen generation, as well as its fate in the subsurface—specifically, the processes governing its migration from source zones to accumulation in geological traps, or its release at the surface—require further research efforts.
How is natural hydrogen exploration and exploitation developing internationally? Which countries are leading the way?
Currently, Mali is the only country producing natural hydrogen, at a rate of 1,500 m³ per day. This hydrogen, which is 98% pure, is used to generate electricity.
However, growing demand for low-carbon hydrogen has sparked rapid developments since the first hydrogen exploration well was drilled in the United States in 2019. In countries where the mining code permits it, companies have begun to actively explore for natural hydrogen—this is the case in South Australia, the United States, and France.
Other countries across all continents have amended their mining codes to encourage exploration (e.g. Poland, South Africa, Philippines, Indonesia, United Arab Emirates), and others are currently working on it (Colombia, Brazil, China, etc.).
Momentum is building in South Australia and the U.S.
Two wells have been drilled near Adelaide, and more than twenty wells have now been drilled across the United States.
Major national oil companies are now taking interest in the field, including Saudi Aramco, RAKGAZ (UAE), Ecopetrol (Colombia), Petronas (Malaysia), and Sinopec (China). At the same time, the oil services sector is beginning to adapt to this emerging market.
What methods are currently being used to best estimate this resource?
One particular feature of natural hydrogen is that deep hydrogen flows may feed shallower reservoirs whose characteristics resemble those of hydrocarbons. In such cases, current exploration methods are adapted from established oil and gas industry practices.
Another potential type of accumulation is “dissolved gas,” where hydrogen is dissolved in brine within an aquifer. In these cases, hydrogeological characterization techniques need to be used.
Is there hydrogen in France? What remains to be done to assess national potential?
To date, diffuse hydrogen emissions have been detected in various regions of France. An inventory of these areas has been compiled using a classification based on geological criteria: sedimentary basins, Permian-Carboniferous basins, ancient basement zones, and volcanic systems.
As a result, the Aquitaine Basin, the Pyrenean Piedmont, and the Lorraine coal basin have been identified as promising areas for exploration in mainland France.
However, it is essential to note that these indications were derived from oil drilling data, which were not initially intended for natural hydrogen exploration. Additional studies and dedicated drilling campaigns are necessary to accurately determine the true potential of these zones.
What is the legal status of hydrogen, and what are the implications for its exploitation? How do French citizens perceive natural hydrogen?
Legally, native hydrogen was officially recognized as a mineral resource during the 2021–2022 reform of the French Mining Code. As a result, the standard legal framework for mining activities—covering exploration, exploitation, and mining operations—now applies to natural hydrogen.
As for public perception, surveys and studies reveal concerns around safety and health, along with difficulty in understanding hydrogen’s role in the energy mix.
The development of a native hydrogen sector will therefore require a balanced approach: one that accelerates deployment in response to the energy transition, while ensuring social acceptance, which is essential for swift and successful implementation.