European Geologist Journal 55

The place of natural hydrogen in the energy transition: A position paper


by Eric C. Gaucher1,*, Isabelle Moretti2, Nicolas Pélissier3, Glen Burridge4 and Nicolas Gonthier5

1  Lavoisier H2 Geoconsult

2  UPPA , Université de Pau et des pays de l’Adour

3  45-8 Energy

4  European Federation of Geologists

5  Pôle Avenia



Natural Hydrogen is a new, clean and low-carbon source of hydrogen that is produced by the Earth, and can migrate and accumulate in geological reservoirs. Its exploration has begun in many countries and its price could be significantly lower than other H2 sources. In this position paper, the earth2 initiative summarizes (i) what natural hydrogen is, (ii) how we explore and produce it, (iii) the benefits of this new resource, (iv) the maturity of the technology, (v) the presence of a very active community, (vi) the potential growth for this business, (vii) the need for regulatory evolution and appropriate taxonomy at European level and (viii) the next steps in natural H2 development, considering the needs for investments in demonstration systems and pilots.

Cite as: Gaucher, Eric C., Moretti, Isabelle, Pélissier, Nicolas, Burridge, Glen, & Gonthier, Nicolas. (2023). The place of natural hydrogen in the energy transition: A position paper. European Geologist, 55.

1. What is Natural Hydrogen? Where can we find it?

The Earth continuously produces natural H2 (also called Native H2) through several chemical reactions that are primarily related to the oxidation of ferrous iron minerals, radiolysis of water, maturation of organic matter and the outgassing from the Earth’s mantle:

  • Redox reactions related to the presence of ferrous iron in certain minerals or to ferrous iron dissolved in aquifers are the most efficient processes for producing H2. In these reactions, the ferrous iron rusts and scavenges oxygen from the water, releasing hydrogen (eq. 1):

2 FeO + H2O = Fe2O3 + H2(aq)   (eq.1)

These reactions can be made with (a) dissolved ferrous iron, (b) olivine and pyroxene minerals of the Earth’s Mantle (serpentinisation), (c) ferrous iron-rich minerals of the Earth’s crust (Biotite, Amphiboles, Pyrite, Pyrrhotite, Magnetite, etc…), and to a lesser extent, with ferrous iron-rich carbonates (Siderite, Ankerite) [1].

  • The radiolysis of water produces H2 by splitting the water molecule through radiation emitted by the decay of natural radioactive atoms (U, Th, etc…) present in several types of rocks [2, 3].
  • The Earth stored hydrogen during its primordial accretion, in the form of hydrides that could gradually decompose and support continuous H2 outgassing over geologic time [4].
  • Over-maturation of organic matter can generate natural H2 [5].
  • The decomposition of volcanic H2S gas into H2 and SO2 explains the concentrations obtained in the fumaroles of volcanos [1].

The exploration strategy for hydrogen should focus on areas where ferrous iron and/or natural radioactivity is present and can react with water [6, 7]. Magmatic rocks are therefore of primary importance, and many occurrences of H2 seepages are known on continental or offshore regions related to these rocks. In an exhaustive review, Zgonnik (2020) [8] recorded H2 occurrences in 465 geo-references worldwide. Extensive reviews of available data are also being conducted on a national level, for example in Australia [9].

Two emblematic sites can illustrate the potential of natural H2:

  • The Bourakebougou site (Mali) has 12 positive boreholes with pure H2 (98%) over a surface of 50 km2 [10].
  • In Iceland, geothermal power plants emit a total of 1.2 kt H2 per year into the atmosphere. If we consider a price of H2 for 2€/kg, the natural H2 emitted by the existing power plants corresponds to a value of €2.3 M/yr [11].

Natural H2 is a viable resource that is observed as being relatively well distributed across the Earth’s surface. Economic reserve assessments are underway in some locations.

N.B.: In this paper, we use the expression “Natural hydrogen” but this is equivalent to Native Hydrogen, GeoH2 or White Hydrogen. We also find “Gold Hydrogen” in some publications for the same natural origin.

2. How do we Explore and Produce Natural H2?

The geological exploration of H2 follows the same approach as for hydrocarbons, starting with the identification of the source rock, followed by the migration pathways, and finally the reservoirs and traps. For the latter, formations such as volcanic sills, clays or salt layers could potentially be capable of trapping hydrogen in crystalline or sedimentary rocks, for example, at the bottom of the sedimentary basins.

In the case of Bourakébougou, boreholes of less than 1000 m seem to be effective in finding significant quantities of natural hydrogen. However, H2 is a very reactive molecule, that can be consumed by many oxidants, and therefore, it is destroyed during its migration. Bacterial growth can also be promoted by natural hydrogen, as it acts as an energy provider for the microbes. Therefore, a temperature above 120°C can preserve the resource by eliminating microbial activity while increasing the kinetics of the reactions. Future exploration and production schemes should integrate the chemical and biological reactivity of this molecule. However, if the H2 flux is high, the reactivity of the molecules will be less crucial.

Some players are also contemplating the co-production of He with natural H2, as they are commonly found together. Geothermal power plants could enhance their value chains by co-producing natural H2 and mineral substances, such as lithium. Coupling H2 production with the storage of CO2 in ultrabasic rocks will add additional benefits to natural H2 production [12].

3. The benefits of Natural Hydrogen

The earth2 members are convinced that the energy transition requires all sources of clean hydrogen to succeed. Natural hydrogen offers specific advantages:

  1. Natural hydrogen is clean, as there is no carbon in the production chain, and does not require anthropogenic electricity or water. Furthermore, extraction and separation at production sites have a limited footprint.
  2. It is not an energy vector, but a resource in itself, and does not require the destruction of one energy source for another. It does not depend on anthropogenic energy or specific raw materials.
  3. Recent research targeting various countries worldwide suggests the presence of multiple viable plays and cost-effective exploitable resources.
  4. The production sites available within the European continent, such as France, Spain, Italy, Poland and Romania, offer diversity and flexibility. It can complement other low carbon H2 production means and it can contribute to securing energy supply and avoiding the supply’s intermittency.
  5. Natural H2 does not require purified water (electrolysis-based Green H2 production), or CO2 storage (Blue H2). Additionally, it does not involve waste disposal (nuclear-driven Pink H2).
  6. No production intermittency.
  7. The production costs of natural H2 are expected to be lower than all other forms of proposed H2 production, which can help in unlocking the hydrogen economy [12]. The very competitive production cost is reinforced by a joint valorisation potential of resources, such as helium, geothermal energy and high-value brines.

4. Maturity of the Technology

Our ultimate goal is to produce a commercial H2 resource at a limited cost and with minimal environmental impacts. To achieve this, we can use the Technology Readiness Levels scale (TRL) to assess its maturity (Figure 1).

We assign a TRL of 9 to the ultimate achievement of commercial production of natural H2.

The TRL 0 corresponds to the discovery of H2 seepages at the Earth’s surface, with the idea that larger volumes can be produced underground [14].

The TRL 1 corresponds to the systematic search of H2 seepages in various geological environments [8].

The TRL 2 corresponds to the first short-term monitoring of H2 fluxes [7, 15].

The TRL 3 corresponds to a global understanding of the origin of H2 emissions in continental settings, as demonstrated by the model of production proposed by Lefeuvre et al. [16] for the West Pyrenees, or the potential for economic production of natural H2 in the geothermal fields of Iceland [11].

The TRL 4 corresponds to the implementation of permanent monitoring sites that couple hydrogeology, hydrochemistry and gas chemistry in very well-characterised geological structures coupled with well tests to determine the reserve volume.

The TRLs 5 and 6 correspond to investments that will enable to access depths where active H2 production processes are taking place. A TRL 5 or 6 can be assigned to the Bourakébougou site in Mali [10, 17], where perennial H2 production has been demonstrated with 12 wells showing its presence. However, the local company HYDROMA has not reported a reserve estimate at the production site.

After delineation at a regional scale (TRL7), commercial production tests can be carried out (TRL 8), and finally, the H2 gas can be commercialised (TRL9). Several exploration companies are making rapid progress towards this ultimate goal.

Figure 1: Evaluation of the technology maturity using the Technology Readiness Levels (TRL) method.

5. A Very Active Scientific Community

A scientific community dedicated to natural H2 already exists in France, the United Kingdom, the USA, Brazil, Australia and other countries. This community consists of research groups that have worked on water-rock interaction processes (such as serpentinisation and radiolysis) or economic geology (such as in oil and gas or mining industries). The number of publications presenting data showing explicit natural H2 presence in soils, aquifers or wells is rapidly increasing (Figure 2).

A dedicated congress now exists on this subject (H-Nat), which was held online in 2021 and 2022. Special sessions have been organised at the AAPG Europe Regional Conference in Budapest (May 2022), at the Goldschmidt Conference in Hawaii (2022) and in Lyon (2023).

Figure 2: (a) Progress of the number of publications related to natural H2 and (b) repartition of natural H2 publications by country.

6. Potential Growth of a Natural Hydrogen Business

The economic sector is in the process of being structured for natural H2 and the earth2 initiative is a good example of this in Europe. The earth2 initiative brings together energy groups like Engie, exploration and production start-ups such as 45-8 Energy, H2Au, Helios Aragon, service providers including the CVA group and Schlumberger, and independent consultants. The earth2 initiative is composed of 40 members actively working in this field. This initiative was born under the aegis of the Avenia cluster and these actors develop exploration methods, geochemical sensors and geophysical methods dedicated to natural H2 exploration. earth2 is a forum for fruitful discussions on the commercial development of natural H2 through permanent working groups, workshops and field trips, launching innovative, and collaborative projects and lobbying public institutions.

In Australia, several start-ups and oil and gas companies now have an exploration strategy for natural H2, including Petrex, Buru Energy and Gold Hydrogen. In South Australia, more than 20 permits have been applied for, with two already granted to Gold H2 and one to H2EX. The first wells are expected in 2023. Further north, in the Amadeus Basin, Santos, an oil company, has “accidentally” encountered a mixture of methane, helium and hydrogen and will drill three wells in 2023 to evaluate the resource.

In the USA, two companies have reported significant discoveries: Natural Hydrogen Energy LLC in Nebraska in 2019 and Desert Mountain Energy in Arizona in 2022.

By the end of 2022, 27 companies have been identified as active in natural hydrogen exploration, up from three companies three years ago.

The American Association of Petroleum Geologists has also established a “Natural Hydrogen” task force led by the US Geological Survey. Meanwhile, the International Energy Agency has accepted a technical task on natural H2 in its H2 collaboration program.

The costs of natural hydrogen production are expected to be significantly lower than the production costs of steam-methane reforming (brown H2: 1.5$/kg). Indeed, the exploration and production costs of natural hydrogen are anticipated to be very similar to those of natural gas, without the need for refinery transformation or CO2 storage (blue hydrogen: 3$/kg = brown H2 + costs of CO2 storage). Currently, green H2 from renewables costs over $6/kg and requires electricity transformation that could be used directly for other purposes. Our best estimate for the price of natural H2 is less than $1/kg.

7. Regulatory Aspects of H2 Exploration

The development of H2 exploration requires changes in legislation to allow companies to obtain permits and perform exploration works. Mali is a pioneer country, where the first permit was granted in the area of Bourakébougou in 2017. South Australia opened its mining code to natural hydrogen exploration in 2021. In April 2022, it was France’s turn to include natural H2 as a natural resource in its mining code and the US law on natural substances also appears to be flexible enough to allow for H2 exploration permits.

8. Recommended Next Steps of Natural H2 Development

Natural Hydrogen is a topic that is rapidly shifting from pure research to economic development. This new energy source is clean with very low-carbon emissions and should be considered as a form of renewable hydrogen in European taxonomy. Its potential is already demonstrated and significant volumes have been identified in regions such as Iceland, Mali and the Pyrenees, where exploration licenses have been granted. However, public support is still needed to develop demonstration systems and pilots in promising areas. Access to financing means, available for the hydrogen economy, could accelerate the maturity and the number of projects. Ultimately, regulation changes are required to facilitate the development of this subject.

The members of the earth2 initiative are optimistic about the potential for this new resource and believe that it will require support to demonstrate and contribute to the energy transition.

Author Contributions: “Conceptualisation, earth2 initiative management board; methodology, all authors; validation, earth2 initiative management board; writing—original draft preparation, E.C.G.; review and editing, I.M, N.P., G.B., N.G.; visualisation, E.C.G., N.P.; All authors have read and agreed to the published version of the manuscript.”

Funding: This research received no external funding.

Acknowledgments: earth2 initiative, Pôle Avenia.

Conflicts of Interest: The authors are all members of the earth2 initiative promoting the development of natural H2 exploration and production.


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This article has been published in European Geologist Journal 55 – The role of geology in the transition to clean energy – The contribution of hydrogen and carbon capture, storage and utilisation

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