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The hydrogen rainbow

Hydrogen offers a potential low-emissions way forward to help decarbonise Australia’s energy, transport and industrial sectors. Hydrogen has been classified into colours related to the greenhouse gas emission profile of the energy source or process used to generate or extract hydrogen, forming a hydrogen rainbow:

  • Gold or white hydrogen – natural hydrogen from geological sources.
  • Green hydrogen – electrolysis of water with no GHG emissions.
  • Blue hydrogen - steam reforming to separate hydrogen from natural gas with Carbon Capture and Storage (CCS).
  • Grey hydrogen – as above but no CCS.
  • Brown and black hydrogen – made from coal gasification (if there’s CCS = blue hydrogen).
  • Turquoise hydrogen – pyrolysis of natural gas produces solid carbon.
  • Yellow hydrogen - direct water splitting.
  • Purple/pink hydrogen - nuclear power.


Natural hydrogen exploration become possible in South Australia on 11 February 2021 via regulatory changes to include hydrogen as a ‘regulated substance’ under the Petroleum and Geothermal Energy Act 2000. South Australia has attracted interest from explorers because it is the only Australian jurisdiction currently with a licensing regime in place and favourable geology which could potentially generate natural hydrogen. In addition, online historical records revealed high hydrogen concentrations in gas samples from old wells.

It is very early days in Australia and globally for natural hydrogen exploration with hundreds of hydrogen indications in wells, mines and seeps but as yet only one producing field in Mali, west Africa. Exploration techniques and methodologies are currently being developed and tested. A diversity of hydrogen plays in South Australia will be explored and evaluated through Petroleum Exploration Licence work programs over the next five years increasing our understanding of this potential new source of energy.

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Historic drilling and exploration

Hydrogen has been detected in wells in the Cooper Basin, Otway Basin, Kangaroo Island and southern Yorke Peninsula (Zgonnik, 2020; Boreham et al. 2021). L.K. Ward, the Chief Government Geologist reported high levels of hydrogen in gas samples taken from shallow bores around the State (Ward 1917,1932, 1933 and 1941) - Robe 1 in the Otway Basin, American Beach Oil Bore 1 drilled on Kangaroo Island in 1921 and the Minlaton Oil Syndicate Bore 1 (Ramsay Oil Bore 1, referred to as Minlaton Oil Bore by Boreham et al., 2021) drilled on central Yorke Peninsula in 1931 (Figure 1 and Tables 1 and 2). The gas samples taken by LK Ward from Robe 1 (drilled in 1915) were analysed by the Department of Chemistry, the samples he took from the other wells were analysed by the Works Chemist at the SA Gas Works. Gas sample volumes were not reported.

Table 1. Analysis of gas samples taken from Robe 1.

WellRobe 1
Sample depth (m) 1240.7
Formation Eumeralla Fm
Gas Composition (%)
Carbon dioxide 1.3
Oxygen 3
Carbon monoxide trace
Olefins and benzenes nil
Hydrogen (by direct determination) 25.4
Methane 39.6
Nitrogen (by difference) 30.7

Table 2. Analysis of gas samples taken from Ramsay Oil Bore 1 and American Beach Bore 1, with hydrogen levels highlighted.

Well Ramsay Oil Bore 1
(Minlaton Oil Syndicate Bore)
American Beach Bore 1
Sample depth (m) 240.8 262.1 507.8 187.4 289.5
Formation Parara Limestone Kanmantoo Group
Gas composition (%):
Carbon dioxide 0.2 0.8 0 5.3 0.52
Oxygen 0 2.4 1.2 4.3 3.55
Ethlyene etc. 0 0 0 0.5 0
Carbon monoxide 0 0 0 0 0
Hydrogen 76 64.4 84 51.3 68.64
Methane 7.5 7 0 2.6 4.68
Nitrogen (by difference) 16.3 25.4 14.8 36 22.61  
Photo of Minlaton Oil prospecting syndicate, Ramsay Oil Bore 1 well, collecting gases from sludge pump. Photo no. N001671.

Figure 1. Collecting gas from the Ramsay Oil Bore 1 near Minlaton in 1931. The well reached ~548m, and a small gas flow of almost pure hydrogen was recorded (SADEM photograph N001671).

Boreham et al. (2021) published a comprehensive review of the diverse abiogenic and biogenic sources of natural hydrogen. They have used isotopic analyses to distinguish different sources of hydrogen occurrences in Australia and proposed a source-migration-accumulation model for hydrogen exploration. Their review of the hydrogen occurrence in Ramsay Oil Bore 1 concluded that “The Minlaton Oil Bore encountered moderately saline (NaCl rich with 9.44 g/L total salts) groundwater at 160 ft (48.77 m). Water radiolysis associated with a high radioactive element content of the granite basement is the most likely source for the H2. However, a contributing H2 source possibly results from the interaction of the heavy brines with the biotite granite within the fractured basement rocks of the Tickera Granite. The available seismic data  suggest that the basement faults in the vicinity of Minlaton Oil Bore extend into the Cambrian sediments (Fig. 8a). These faults could provide migration pathways for downward movement of heavy brines from the saline swamps as confirmed by the fact that the saline aquifer was penetrated by the Minlaton Oil Bore.” (Boreham et al., 2021).

The hydrogen occurrence recorded in Robe 1 may be related to high displacement basement faults, such as those bounding the Robe Trough and Lake Eliza High (Fig. 2). Elsewhere in the basin, basement faults have acted as migration pathways for mantle-derived carbon dioxide and trace gases like helium and nitrogen. The produced CO2 and the occurrences do not contain anomalous hydrogen contents, so there may not be a link with the hydrogen recorded in Robe 1, the source of which is not currently understood. Mantle-derived carbon dioxide was produced from Late Cretaceous reservoirs in the Caroline Field for decades and the gas contained only trace amounts of hydrogen, nitrogen and helium. CO2 was produced with natural gas from the Ladbroke Grove Gas Field for some years and again, hydrogen was not reported from multiple gas analyses.

In their paper presenting a screening methodology to scout for hydrogen occurrences in stable intracratonic settings above Archean to Proterozoic basement Moretti et al. (2021) referred to Ward’s reports on the hydrogen shows and identified ‘fairy circles’ on Yorke Peninsula, Kangaroos Island and in WA. ‘Fairy circles’ are depressions on land caused by venting of hydrogen or gas. They concluded that “The comparison suggests that Australia could be one of the most promising areas for H2 exploration, de facto a couple of wells already found H2, whereas they were drilled to look for hydrocarbons. The sum of areas from where H2 is seeping overpasses 45 km2 in Kangaroo Island as in the Yorke Peninsula.”

The fairy circles identified by Moretti et al. (2021) are roughly circular, pink ephemeral salt lakes (Jack, 1921) that occur on the downthrown side of the Warooka Fault and elsewhere on Yorke Peninsula and Kangaroo Island  (MAITLAND and KINGSCOTE 1:250,000 Map sheets and MAITLAND Explanatory Notes).

A salt lake on Sundown Lake Rd during summer 2021, Yorke Peninsula

Figure 3. A salt lake on Sundown Lake Rd during summer 2021, Yorke Peninsula.

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Potential natural hydrogen plays

Bendall (2022) provides a recent synopsis of the geology of natural hydrogen occurrences and exploration methodologies. Potential exists for natural hydrogen plays in South Australia – Gaucher (2020) indicated that there are two main geological settings where hydrogen could be generated - Proterozoic crystalline shields and serpentinized ultramafic rocks in mid-ocean ridges and in land-based ophiolite-peridotite massifs. Potential natural hydrogen source rocks include ultrabasic rocks and iron-rich cratons (hydrogen generation from the oxidation of Fe(II) bearing mineral such as siderite, biotite, or amphibole by water) and uranium-rich basement with hydrogen generated by radiolysis of water (Gaucher, 2020).

Using a hydrocarbon play analogue, once generated in basement source rocks, hydrogen needs a migration pathway to a trap with a reservoir (e.g. fractured basement, petroleum type reservoirs in sedimentary cover) and effective seal (e.g. intrusive volcanics, salt, shale/siltstones, aquifers) to accumulate and then be preserved in geological timeframes. Alternatively, explorers may seek to delineate fluxes of natural hydrogen as it is being generated in basement source rocks - a very different concept to our understanding of hydrocarbon generation and plays which will require different exploration approaches.

Salt has been identified as the most effective seal and Geoscience Australia have been undertaking a review of Australian subsurface salt occurrences to identify potential sites for underground hydrogen storage (e.g. Feitz et al. 2022) - this work will also inform natural hydrogen exploration. Volcanic intrusives could seal hydrogen – e.g. dolerite sills in the shallow (~30-140m deep) Bourakebougou Hydrogen Field in Mali, where groundwater also seems to act as permeability barriers. Hydrogen is insoluble at low temperatures and pressures (Prinzhofer et al., 2018). Watkins et al. (2022) concluded that despite hydrogen’s low density and small molecular size, its seal capacity was similar to that of methane and potentially greater than carbon dioxide.

Potential natural hydrogen source rocks may occur in South Australian basement provinces and cover as revealed by high level screening (Tables 3 and 4; Bendall, 2022). For more information on basement provinces:

Visit the Minerals website for maps and information on basement geology, and access spatial datasets from SARIG.

Table 3. High level screening of SA basement provinces.

High level screening of SA basement provinces. Kanmantoo Province is the only mineral province with hydrogen shows.

Table 4. High level screening of SA basins.

High level screening of SA basins. Stansbury, Eromanga and Otway Basins contain wells with hydrogen shows.

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Potential exploration methodologies


  • Company exploration reports, well completion reports, maps, geophysical surveys, datasets, historical records (SARIG, PEPS).
  • Satellite imagery/Google Earth to identify possible seeps.
  • Source rocks – solid geology: mafics, granites, iron and uranium – geological maps, existing gravity, radiometric and aeromagnetic datasets.
  • Seals - subsurface salt, but can shales (Watkins et al, 2022) or aquifers seal hydrogen?
  • Cores – fluid inclusions, mineralogical studies.
  • Analyses of existing gas samples (e.g. Boreham et al, 2021, 2022).

Field work


  • Geophysics – aeromagnetic, gravity, radiometric, resistivity surveys, magnetotelluric surveys, seismic.


  • Well bore design, engineering, drilling operations etc.
  • Specialised hydrogen detection equipment (e.g. Buru’s Currajong 1 and Rafael 1 exploration wells drilled in 2021).

Natural hydrogen legislation

On 11 February 2021 the Petroleum and Geothermal Energy Regulations 2013 were amended to declare hydrogen, hydrogen compounds and by-products from hydrogen production regulated substances under the Petroleum and Geothermal Energy Act 2000 (PGE Act). Companies are now able to apply to explore for natural hydrogen via a Petroleum Exploration Licence (PEL) and the transmission of hydrogen or compounds of hydrogen are now permissible under the transmission pipeline licencing provisions of the PGE Act (Fig. 3). Generation of green hydrogen will be covered by the Hydrogen and Renewable Energy Act. The consultation period closed on 10 February 2023, the draft Bill will be prepared in Q1/2 2023 and shared for public comment.

You can find information about current hydrogen exploration projects in Petroleum Exploration Licences in the state under Projects of Public Interest.

Proposed hydrogen legislation framework

Figure 4. Proposed hydrogen legislation for natural (gold, white), blue, grey and green hydrogen.

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Current licences

Since February 2021, over 40 ‘over the counter’ applications for petroleum exploration licences (PELs) primarily targeting natural hydrogen have been lodged (Fig. 5). The first of these licences (PEL 687) over Kangaroo Island and southern Yorke Peninsula was granted to Gold Hydrogen Pty Ltd on 22 July 2021. Gold Hydrogen listed on the ASX on 13 January 2023 after a successful $20 million IPO. They will initially focus exploration on Yorke Peninsula with roadside soil sampling and an extensive airborne geophysics survey over the peninsula and Kangaroo Island this year. PEL 691 was granted to H2EX on Eyre Peninsula on 15 June 2022 and roadside soil gas sampling will commence in Q1/2 this year.

Some basins with potential for petroleum, natural hydrogen, geothermal energy and gas storage (e.g. Polda, Arrowie and Arckaringa Basins) were designated as Competitive Tender Regions (CTR) in late 2022 (Figure 6). Previously only the Cooper and Otway basins were under CTRs for petroleum exploration. CTRs now apply to all three categories of exploration licence: petroleum (regulated substances include natural hydrogen, helium, CO2), geothermal energy and gas storage exploration. CTRs do not affect existing licences and applications.

Underground storage

The regulatory changes made in 2021 also enabled underground storage of hydrogen and some hydrogen explorers have applied for Gas Storage Exploration Licences to secure these rights for their potential project areas. Geoscience Australia stimulated interest in the potential to develop hydrogen storage in the thick salt discovered by Mercury 1 in the offshore Polda Basin (Feitz et al. 2023), however Commonwealth and State offshore regulatory regimes require amendment to enable this activity. Duffy et al. (2023) provide a review of the importance of salt for gas storage in salt caverns (e.g. hydrogen and compressed air), CO2 sequestration and geothermal energy generation.

Current petroleum and gas storage tenements and applications with Competitive Tender Regions (CTR)

Figure 6. Current petroleum and gas storage tenements and applications with Competitive Tender Regions (CTR).
Alternatively, download larger tenement map (1.4 MB).

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Front cover of South Australia's Hydrogen Action Plan

Hydrogen Action Plan

South Australia’s world class renewable energy resources give the state a competitive edge in the race to supply green renewable hydrogen. In September 2019 South Australia’s Hydrogen Action Plan launched with an initial focus on green hydrogen from renewable energy sources. SA also offers a free Hydrogen Export Prospectus and Online Modelling Tool, released in October 2020.

CCS and hydrogen in the Cooper Basin

Santos are progressing clean (blue) hydrogen and by 2030 aim to use Carbon Capture and Storage (CCS) technology to improve economic feasibility of clean hydrogen while reducing Cooper Basin emissions. Santos state that Moomba has “the lowest-cost carbon capture and storage project in the world” with potential to inject 20 million tonnes of CO2 per year for 50 years.

Hydrogen in Australia

The Australian Department of Industry, Science, Energy and Resources provides information on Australia’s national hydrogen strategy, hydrogen hubs and useful web links.

Geoscience Australia has developed an Australian hydrogen mapping portal - the HEFT tool, and there is more information about the geology of hydrogen in Australia on their website.

The CSIRO’s Dr Ema Frery is currently undertaking research about field methodologies to better understand Australian hydrogen systems.

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This interview with Dr Viacheslav Zgonnik, whose company has drilled an exploration well in Nebraska, gives insights into natural hydrogen exploration basics. Episode 61, 'Natural Hydrogen Wells', HydrogenNowCast, dated 16 Sep 2022.

Alexander, E., 2022. Natural hydrogen exploration in South Australia. PESA SA Branch technical meeting, 23 June 2022.

Alexander, E., 2022. Natural hydrogen exploration in South Australia. National Hydrogen Conference, 1 June 2022.

Alexander, E., 2022. Natural hydrogen exploration in South Australia. H-NAT 2022 Conference. YouTube narrated presentation.

Ball, P. and Czado, K., 2022. Natural hydrogen: the new frontier. Geoscientist.

Bendall, B., 2022. Current perspectives on natural hydrogen: a synopsis. MESA Journal 96, pp 37–46.

Boreham, C. J., Edwards, D. S., Czado, K., Rollett, N., Wang, L., Van Der Wielen, S., Champion, D., Blewett, R., Feitz, A. and Henson, P. 2021. Hydrogen in Australian natural gas: occurrences, sources and resource. The Australian Production and Petroleum Exploration Association Journal 61, 163–191.

Crawford, 1965. The Geology of Yorke Peninsula. Geol. Surv. S. Aust Bulletin 39.

Darrah, T., Whyte, C and Darry, B. 2021. Lessons learned and knowledge gaps. H-Nat 2021 Conference. Vimeo presentation.

Duffy, O.B., Hudec, M.R., Peel, F., Apps, G., Bump, A., Moscardelli, L. Dooley, T.P., Fernandez, N. Bhattacharya, S. Wisian, K. and Shuster, M.W., 2023. The Role of Salt Tectonics in the Energy Transition: An Overview and Future Challenges. Tektonika 1(1).

Dupont, M-A., Baudia, E., Daynac, N. and Eliis. 2022. Adapting conventional E&P workflows to scale up hydrogen and helium exploration. GeoExpro 5.

Feitz, A., Wang, L., Rees, S. and Carr, L. 2022. Feasibility of underground hydrogen storage in a salt cavern in the offshore Polda Basin. Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra.

Frery E Langhi, L. and Markov, J.(2022). Natural hydrogen exploration in Australia – state of knowledge and presentation of a case study. The APPEA Journal 62(1), 223–234.

Gaucher, E.C., 2020.  New Perspectives in the Industrial Exploration for Native Hydrogen. Elements 16(1):8-9.

Hand, E., 2023. Hidden hydrogen – does Earth hold vast stores of carbon-free fuel? Science. Vol. 379 Issue 6633.

Jack, R.L., 1921. The Salt and Gypsum Resources of South Australia. Geol. Surv. S. Aust. Bull 8, 118.

King, D., 1952. Lake Fowler Gypsum Deposits. S. Aust. Min. Rev. 92, pp. 60·67.

Moretti, I., Brouilly, E., Loiseau, K. and Deville, E. 2021. Hydrogen Emanations in Intracratonic Areas: New Guide Lines. Geosciences 2021, 11, 145.

Moretti, I. and Webber, M.E. 2021.  Natural hydrogen: a geological curiosity or the primary energy source for a low-carbon future?. Renewable Matter, online article.

Prinzhofer, A. 2021. Natural hydrogen generation. H-NAT 2021 Conference. Vimeo presentation.

Prinzhofer, A., Ciss, C.S.T. and Diallo, A.B. 2018. Discovery of a large accumulation of natural hydrogen in Bourakebougou (Mali). International Journal of Hydrogen Energy 43: 19315-19326.

Reitsma, M. 2022. The natural hydrogen field without pressure depletion. GeoExpro News.

Stalker L., Talukder. A., Strand, J., Jos, M. and Faiz, M. 2022.  Gold (hydrogen) rush: risks and uncertainties in exploring for naturally occurring hydrogen. The APPEA Journal 62(1), 361–380.

Vidavskiy, V. and Rezaee, R. 2022. Natural Deep-Seated Hydrogen Resources Exploration and Development: Structural Features, Governing Factors, and Controls. Journal of Energy and Natural Resources, 2022; 11(3): 60-81.

Ward L.K., 1917. Report on the prospects of obtaining supplies of petroleum by boring in the vicinity of Robe  and elsewhere in the south-eastern portion of South Australia. Geol. Surv. S. Aust  Report Book No. 5/191.

Ward L.K., 1922. Prospects of the American Beach (KI) Oil Co. NL at the boresite, Section 134 Hundred Dudley. Geol. Surv. S. Aust Report Book 8/151.

Ward, L.K., 1932a. Inflammable gases occluded in the pre-palaeozoic rocks of South Australia. Geol. Surv. S. Aust Report Book 13/137.

Ward, L.K., 1932b. Government Geologist, 1932. The search for oil—notes by the Government Geologist. Geol. Surv. S. Aust, Mining Review 55, pp 39-42.

Ward, L.K., 1933. Inflammable gases occluded in the pre-palaeozoic rocks of South Australia. Trans. R. Soc. S. Aust. 1933, 57, pp 42–47.

Ward, L.K., 1941. Report on search for petroleum in South Australia. Geol. Surv. S. Aust Report Book 18/135.

Watkins, J., Kaldi, J. and Watson, M. 2022. Geological storage of gas: evaluation of seal properties for containment of Carbon Dioxide, Methane and Hydrogen. 16th International Conference on Greenhouse Gas Control Technologies, GHGT-16. 23-27 October 2022, Lyon, France.

Yedinak, E.M, 2022. The Curious Case of Geologic Hydrogen: Assessing its Potential as a Near-Term Clean Energy Source. Joule.

Zgonnik, V., 2020. The occurrence and geoscience of natural hydrogen: a comprehensive review. Earth Science Reviews 203, 103140.

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