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The hydrogen cycle consists of hydrogen exchanges between biotic (living) and abiotic (non-living) sources and sinks of hydrogen-containing compounds. Hydrogen (H) is the most abundant element in the universe. [1] On Earth, common H-containing inorganic molecules include water (H 2 O), hydrogen gas (H 2), hydrogen sulfide (H 2 S), and ammonia ...
The natural cycle of hydrogen production and consumption by organisms is called the hydrogen cycle. [131] Some bacteria such as Mycobacterium smegmatis can use the small amount of hydrogen in the atmosphere as a source of energy when other sources are lacking. Their hydrogenase are designed with small channels that exclude oxygen and so permits ...
The concept of a society that uses hydrogen as the primary means of energy storage was theorized by geneticist J. B. S. Haldane in 1923. Anticipating the exhaustion of Britain's coal reserves for power generation, Haldane proposed a network of wind turbines to produce hydrogen and oxygen for long-term energy storage through electrolysis, to help address renewable power's variable output. [15]
Given the ubiquity of hydrogen atoms in inorganic and organic chemical compounds, the hydrogen cycle is focused on molecular hydrogen (H 2). Nitrogen The nitrogen cycle is the process by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere , terrestrial , and marine ecosystems .
Natural hydrogen is generated from various sources. Many hydrogen emergences have been identified on mid-ocean ridges. [22] Serpentinisation occurs frequently in the oceanic crust; many targets for exploration include portions of oceanic crust which have been obducted and incorporated into continental crust.
In most hydrogen-fusing stars, including the Sun, a chemical cycle involved in stellar nucleosynthesis occurs which is known as a carbon-nitrogen-oxygen or . In addition to this cycle, stars also have a helium cycle. [1] Various cycles involving gas and dust have been found to occur in galaxies. [2]
Simplified diagram of the Copper–Chlorine cycle. The copper–chlorine cycle (Cu–Cl cycle) is a four-step thermochemical cycle for the production of hydrogen. The Cu–Cl cycle is a hybrid process that employs both thermochemical and electrolysis steps. It has a maximum temperature requirement of about 530 degrees Celsius. [1]
In this method, iodine-sulfur (IS) thermo-chemical cycle for splitting water and high-temperature steam electrolysis (HTSE) were selected as the main processes for nuclear hydrogen production. The S-I cycle follows three chemical reactions: [100] Bunsen reaction: I 2 +SO 2 +2H 2 O→H 2 SO 4 +2HI HI decomposition: 2HI→H 2 +I 2