Geologic hydrogen is commonly known as native, natural, white or even golden hydrogen. The colour is not yet settled in the eyes of the marketers,  that preferret the term ‘white hydrogen’. 

Geological hydrogen. Native - white or stimulated - gold/orange.

Natural hydrogen has been found in many geological environments, including ocean spreading centres, transform faults, passive boundaries, convergent margins and intraplate settings, etc. The potential of natural hydrogen in the Earth's interior has not been evaluated so far due to the existing prejudice that free hydrogen in nature is rare and in low concentrations and therefore has not attracted much attention of researchers. Hydrogen exploration is currently in its infancy, similar to oil and gas exploration in the late 19th century. Hydrogen exploration is likely to use many of the same technologies as oil and gas exploration, with some additional mineral exploration and geothermal technologies. The search for potential hydrogen deposits requires approximately the same skills as in the oil and gas industry, and drilling rigs for exploration are needed to extract hydrogen from underground or at sea. There are potentially huge reserves of geological hydrogen in the world, but the search for large accumulations of geological hydrogen has not been resolved. As with exploration, new cost-effective technologies need to be developed to produce efficient hydrogen.

However, unlike the final deposits of oil and gas, natural hydrogen is formed constantly. Hydrogen is a practically inexhaustible resource due to the continuous and abundant hydrogen degassing of the Earth, otherwise it is also called “Hydrogen respiration of the Earth”. There are different theories about exactly how this happens. The natural degassing of hydrogen from the Earth occurs constantly. With increasing stresses in the Earth's crust, the release of gases in mid-oceanic ridges and faults increases, which account for up to 90% of the hydrogen released from the bowels of the Earth. The remaining geological hydrogen degassing is distributed between volcanoes 2% and ring structures 8%. Fluxes of molecular hydrogen where it leaves the Earth significantly affect soil properties and sea silt, sediment, etc.

The lithosphere, as a dense layer of oxides, is a difficult barrier preventing hydrogen from reaching the surface. Scientific studies of hydrogen-resistant rocks (which do not allow hydrogen to reach the surface), such as volcanites, salt domes and fine-grained shales, have been completed. When prospecting and developing deposits, three types of rocks that do not allow hydrogen to pass through should be taken into account: volcanic, salt domes, fine-grained coal shales. As a result, gas accumulates under the "domes" of such rocks, and it enters into chemical reactions with other substances, which is accompanied by additional heat generation. 

Using stimulated mineralogical processes could lead to the production of more underground hydrogen, which could become a significant source of clean energy. For example, golden hydrogen and orange hydrogen:

• Golden hydrogen is given specifically to hydrogen produced by microbial activities in depleted oil wells and gas wells. Golden hydrogen has a particularly unique production method. This type of hydrogen is extracted from depleted oil and gas wells. These wells contain residual oil and gas hydrocarbons that cannot be profitably extracted in their current form. To produce golden hydrogen, proprietary mixes of nutrients and bacteria are pumped into the depleted wells. The bacteria then break the oil residue down into hydrogen and CO2. This process can bring new life to wells with existing infrastructure. However, ensuring that the CO2 is captured from the wells is a priority in order to ensure this type of hydrogen is carbon neutral. Through this method, golden hydrogen allows for oil and gas companies to make “second use” of old oil and natural gas assets, extending the profitability of drilling projects. Process will revolutionize biomining and subsurface biomanufacturing.

• Orange hydrogen is hydrogen produced by injecting a CO2-enriched aqueous solution into reactive, iron-rich rocks. Orange hydrogen combines hydrogen generation with CO2 sequestration by creating a chemical reaction in iron-rich geological formations. Water, including saltwater, is charged with CO2 and injected into the target formation where it reacts with the iron ore, leaving the CO2 behind and enriching the material with hydrogen that can then be extracted. This is, in effect, artificially creating the conditions for white hydrogen development, all while sequestering CO2, giving it a net-negative emissions profile. 

Most of this hydrogen is likely inaccessible due to its deep burial, offshore locations, or small accumulations. Scientists have developed a global resource model to estimate the volume of hydrogen available. This model predicts that the Earth could potentially supply the global hydrogen demand for thousands of years.

Past observations of natural hydrogen were mostly accidental, a side effect of geothermal, water, and oil-and-gas wells that were drilled with other objectives in mind. These wells are unlikely therefore to be optimally located for hydrogen exploration and production. For the emerging hydrogen industry, further studies are required that monitor, log and even drill hydrogen seeps and potential reservoirs. 

Detection methods used in hydrogen exploration are critical for production natural hydrogen from deep layers and reservoirs. Exploration for geologic hydrogen resources draws from existing strategies used in petroleum exploration, with additional elements from mineral and geothermal resource exploration. Surface exploration approaches include remote sensing and surface geochemistry to refine our understanding of hydrogen accumulations in the subsurface. Most used method – presence of hydrogen in soils or aquifers horizons near the earth's surface. These detection methods are limited. Geological hydrogen is difficult to detect due to its high volatility in the atmosphere and due to absorption by microbes living in the soil and on the seafloor. Hydrogen-eating organisms include AM1116 Caminibacter Hydrogeniphilus (habitat - hydrothermal vents of the East Pacific Rise), Kol5a Aquifex pyrophilus (habitat - hydrothermal vents of the Mid-Atlantic Ridge), TK-6 Hydrogenobacter thermophilus (habitat - soil of Izu sharp), MA-48 Hydrogenibacillus schlegelii (habitat - mud surface of the Alps) and many others. The use of biogeochemical methods makes it possible to quickly explore large areas of prospecting work and identify promising areas with a possible release of natural hydrogen flows, including finding hidden objects. 

It is not surprising that White and gold (geological) hydrogen has been overlooked because it is a colorless, odorless gas, and microbes are very efficient at eating it below the soil surface, water or silt as it rises to the top.

Geological hydrogen is constantly being formed. Most likely various underground conditions that lead to the appearance of hydrogen, but are often accompanied by the release of inert gases that do not absorb geological formations and microorganisms.

When explorers find natural hydrogen, especially in contexts that suggest deep geological processes, it's increasingly prudent to also test for helium and, specifically, its isotopic signature. The discovery of elevated helium-3 levels alongside hydrogen not only confirms a deep, potentially renewable source for the hydrogen but also adds a significant, high-value byproduct (helium-3) to the overall resource potential of the discovery. This synergy makes natural hydrogen exploration even more economically attractive and scientifically intriguing.

HydITEx is developing a geological exploration concept for detailed searches over large areas for hydrogen deposits, where the likelihood of their geological discovery has received sufficient geological justification, by analyzing the biomass of hydrogen bacteria, the presence of noble gases and their isotopes, as well as their composition.

The project is under development