Natural hydrogen (known as white hydrogen, geologic hydrogen, [1] geogenic hydrogen, [2] or gold hydrogen), is hydrogen that is formed by natural processes [3] [4] (as opposed to hydrogen produced in a laboratory or in industry). By contrast green hydrogen is produced from renewable energy sources, while grey, brown, blue or black hydrogen are obtained from fossil fuels. [5]
Natural hydrogen may be renewable, it is non-polluting, and may offer lower costs than industrial hydrogen. [6] Natural hydrogen has been identified in many source rocks in areas beyond the sedimentary basins where oil companies typically operate. [7] [8] [9]
Sources of natural hydrogen include: [10]
Serpentinization is thought to produce approximately 80% of the world's hydrogen, especially as seawater interacts with iron- and magnesium-rich (ultramafic) igneous rocks in the ocean floor. Current models point towards radiolysis as the source of most other natural hydrogen.
According to the Financial Times, there are 5 trillion tons of natural hydrogen resources worldwide. [1] Most of this hydrogen is likely dispersed too widely to be economically recoverable, but the U.S. Geological Survey has reported that even a fractional recovery could meet global demand for hundreds of years. A discovery in Russia in 2008 suggests the possibility of extracting native hydrogen in geological environments.[ citation needed ] Resources have been identified in France, [12] Mali, the United States, and approximately a dozen other countries. [13]
An accumulation of natural hydrogen was discovered in a water well in Bourakébougou, Mali, that was exploited to power the nearby village. [14] As of August 2024, this remains the only operating hydrogen well in the world. Hydroma, the company responsible for identifying the resource, has since drilled 30 more exploration holes nearby. In 2023 Pironon and de Donato announced the discovery of a deposit they estimated to be some 46 million to 260 million metric tons (several years worth of 2020s production). [14] In 2024, a natural deposit of helium and hydrogen was discovered in Rukwa, Tanzania. [15] , as well in Bulqizë, Albania. [16]
White hydrogen could be found or produced in the Mid-continental Rift System at scale. Water could be pumped down to hot iron-rich rock to produce hydrogen for extraction. [17] Dissolving carbon dioxide in these fluids could allow for simultaneous carbon sequestration through carbonation of the rocks. The resulting hydrogen would be produced through a carbon-negative pathway and has been referred to as "orange" hydrogen. [18]
Natural hydrogen is generated from various sources. Many hydrogen emergences have been identified on mid-ocean ridges. [19] Serpentinisation occurs frequently in the oceanic crust; many targets for exploration include portions of oceanic crust (ophiolites) which have been obducted and incorporated into continental crust. Aulacogens such as the Midcontinent Rift System of North America are also viable sources of rocks which may undergo serpentinisation. [17]
Diagenetic origin (iron oxidation) in the sedimentary basins of cratons, notably are found in Russia.
Mantle hydrogen and hydrogen from radiolysis (natural electrolysis) or from bacterial activity are under investigation. In France, the Alps and Pyrenees are suitable for exploitation. [20] New Caledonia has hyperalkaline sources that show hydrogen emissions. [21]
Hydrogen is soluble in fresh water, especially at moderate depths as solubility generally increases with pressure. However, at greater depths and pressures, such as within the mantle, [22] the solubility decreases due to the highly assymetric nature of mixtures of hydrogen and water.
Vladimir Vernadsky originated the concept of natural hydrogen captured by the Earth in the process of formation from the post-nebula cloud. Cosmogonical aspects were anticipated by Fred Hoyle. From 1960–2010, V.N. Larin developed the Primordially Hydridic Earth concept [23] [ dubious – discuss ] that described deep-seated natural hydrogen prominence [24] and migration paths.
Hydrogen is a chemical element; it has symbol H and atomic number 1. It is the lightest element and, at standard conditions, is a gas of diatomic molecules with the formula H2, sometimes called dihydrogen, but more commonly called hydrogen gas, molecular hydrogen or simply hydrogen. It is colorless, odorless, tasteless, non-toxic, and highly combustible. Constituting about 75% of all normal matter, hydrogen is the most abundant chemical element in the universe. Stars, including the Sun, mainly consist of hydrogen in a plasma state, while on Earth, hydrogen is found in water, organic compounds, as dihydrogen, and in other molecular forms. The most common isotope of hydrogen consists of one proton, one electron, and no neutrons.
The Miller–Urey experiment (or Miller experiment) was an experiment in chemical synthesis carried out in 1952 that simulated the conditions thought at the time to be present in the atmosphere of the early, prebiotic Earth. It is seen as one of the first successful experiments demonstrating the synthesis of organic compounds from inorganic constituents in an origin of life scenario. The experiment used methane (CH4), ammonia (NH3), hydrogen (H2), in ratio 2:2:1, and water (H2O). Applying an electric arc (the latter simulating lightning) resulted in the production of amino acids.
Geomicrobiology is the scientific field at the intersection of geology and microbiology and is a major subfield of geobiology. It concerns the role of microbes on geological and geochemical processes and effects of minerals and metals to microbial growth, activity and survival. Such interactions occur in the geosphere, the atmosphere and the hydrosphere. Geomicrobiology studies microorganisms that are driving the Earth's biogeochemical cycles, mediating mineral precipitation and dissolution, and sorbing and concentrating metals. The applications include for example bioremediation, mining, climate change mitigation and public drinking water supplies.
The abiogenic petroleum origin hypothesis proposes that most of earth's petroleum and natural gas deposits were formed inorganically, commonly known as abiotic oil. Scientific evidence overwhelmingly supports a biogenic origin for most of the world's petroleum deposits. Mainstream theories about the formation of hydrocarbons on earth point to an origin from the decomposition of long-dead organisms, though the existence of hydrocarbons on extraterrestrial bodies like Saturn's moon Titan indicates that hydrocarbons are sometimes naturally produced by inorganic means. A historical overview of theories of the abiogenic origins of hydrocarbons has been published.
Mechanochemistry is the initiation of chemical reactions by mechanical phenomena. Mechanochemistry thus represents a fourth way to cause chemical reactions, complementing thermal reactions in fluids, photochemistry, and electrochemistry. Conventionally mechanochemistry focuses on the transformations of covalent bonds by mechanical force. Not covered by the topic are many phenomena: phase transitions, dynamics of biomolecules, and sonochemistry.
Water splitting is the chemical reaction in which water is broken down into oxygen and hydrogen:
The hydrogen cycle consists of hydrogen exchanges between biotic (living) and abiotic (non-living) sources and sinks of hydrogen-containing compounds.
Radiolysis is the dissociation of molecules by ionizing radiation. It is the cleavage of one or several chemical bonds resulting from exposure to high-energy flux. The radiation in this context is associated with ionizing radiation; radiolysis is therefore distinguished from, for example, photolysis of the Cl2 molecule into two Cl-radicals, where (ultraviolet or visible spectrum) light is used.
Ammonia production takes place worldwide, mostly in large-scale manufacturing plants that produce 183 million metric tonnes of ammonia (2021) annually. Leading producers are China (31.9%), Russia (8.7%), India (7.5%), and the United States (7.1%). 80% or more of ammonia is used as fertilizer. Ammonia is also used for the production of plastics, fibres, explosives, nitric acid, and intermediates for dyes and pharmaceuticals. The industry contributes 1% to 2% of global CO
2. Between 18–20 Mt of the gas is transported globally each year.
Hydrogen gas is produced by several industrial methods. Nearly all of the world's current supply of hydrogen is created from fossil fuels. Most hydrogen is gray hydrogen made through steam methane reforming. In this process, hydrogen is produced from a chemical reaction between steam and methane, the main component of natural gas. Producing one tonne of hydrogen through this process emits 6.6–9.3 tonnes of carbon dioxide. When carbon capture and storage is used to remove a large fraction of these emissions, the product is known as blue hydrogen.
Several methods exist for storing hydrogen. These include mechanical approaches such as using high pressures and low temperatures, or employing chemical compounds that release H2 upon demand. While large amounts of hydrogen are produced by various industries, it is mostly consumed at the site of production, notably for the synthesis of ammonia. For many years hydrogen has been stored as compressed gas or cryogenic liquid, and transported as such in cylinders, tubes, and cryogenic tanks for use in industry or as propellant in space programs. The overarching challenge is the very low boiling point of H2: it boils around 20.268 K (−252.882 °C or −423.188 °F). Achieving such low temperatures requires expending significant energy.
Biohydrogen is H2 that is produced biologically. Interest is high in this technology because H2 is a clean fuel and can be readily produced from certain kinds of biomass, including biological waste. Furthermore some photosynthetic microorganisms are capable to produce H2 directly from water splitting using light as energy source.
Hydrogen-oxidizing bacteria are a group of facultative autotrophs that can use hydrogen as an electron donor. They can be divided into aerobes and anaerobes. The former use hydrogen as an electron donor and oxygen as an acceptor while the latter use sulphate or nitrogen dioxide as electron acceptors. Species of both types have been isolated from a variety of environments, including fresh waters, sediments, soils, activated sludge, hot springs, hydrothermal vents and percolating water.
Hydrogen purification is any technology used to purify hydrogen. The impurities in hydrogen gas depend on the source of the H2, e.g., petroleum, coal, electrolysis, etc. The required purity is determined by the application of the hydrogen gas. For example, ultra-high purified hydrogen is needed for applications like proton exchange membrane fuel cells.
Solid hydrogen is the solid state of the element hydrogen, achieved by decreasing the temperature below hydrogen's melting point of 14.01 K. It was collected for the first time by James Dewar in 1899 and published with the title "Sur la solidification de l'hydrogène" in the Annales de Chimie et de Physique, 7th series, vol. 18, Oct. 1899. Solid hydrogen has a density of 0.086 g/cm3 making it one of the lowest-density solids.
A solid oxide electrolyzer cell (SOEC) is a solid oxide fuel cell that runs in regenerative mode to achieve the electrolysis of water by using a solid oxide, or ceramic, electrolyte to produce hydrogen gas and oxygen. The production of pure hydrogen is compelling because it is a clean fuel that can be stored, making it a potential alternative to batteries, methane, and other energy sources. Electrolysis is currently the most promising method of hydrogen production from water due to high efficiency of conversion and relatively low required energy input when compared to thermochemical and photocatalytic methods.
The Southern Pacific Gyre is part of the Earth's system of rotating ocean currents, bounded by the Equator to the north, Australia to the west, the Antarctic Circumpolar Current to the south, and South America to the east. The center of the South Pacific Gyre is the oceanic pole of inaccessibility, the site on Earth farthest from any continents and productive ocean regions and is regarded as Earth's largest oceanic desert. With an area of 37 million square kilometres, it makes up approximately 10% of the Earth's ocean surface. The gyre, as with Earth's other four gyres, contains an area with elevated concentrations of pelagic plastics, chemical sludge, and other debris known as the South Pacific garbage patch.
The reported presence of methane in the atmosphere of Mars is of interest to many geologists and astrobiologists, as methane may indicate the presence of microbial life on Mars, or a geochemical process such as volcanism or hydrothermal activity.
Hydrogen evolution reaction (HER) is a chemical reaction that yields H2. The conversion of protons to H2 requires reducing equivalents and usually a catalyst. In nature, HER is catalyzed by hydrogenase enzymes. Commercial electrolyzers typically employ supported platinum as the catalyst at the anode of the electrolyzer. HER is useful for producing hydrogen gas, providing a clean-burning fuel. HER, however, can also be an unwelcome side reaction that competes with other reductions such as nitrogen fixation, or electrochemical reduction of carbon dioxide or chrome plating.
Éric Claude Gaucher, born in November 1970, is a French geochemist with an international reputation in the field of geo-energy and geological storage. He is a specialist in the calculation of water-rock-gas interactions. He is actively involved in the energy transition through his work on the exploration of natural hydrogen.