A hydrogen clathrate is a

clathrate A clathrate is a chemical substance consisting of a lattice that traps or contains molecules. The word ''clathrate'' is derived from the Latin (), meaning ‘with bars, latticed’. Most clathrate compounds are polymeric and completely envelop t ...

containing hydrogen in a water lattice. It is not possible to store commercial quantities of hydrogen by this method

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

in a

hydrogen economy The hydrogen economy is using hydrogen to decarbonize economic sectors which are hard to electrify, essentially, the "hard-to-abate" sectors such as cement, steel, long-haul transport etc. In order to phase out fossil fuels and limit climate ch ...

. A recent review that accounts the state-of-the-art and future prospects and challenges of hydrogen storage as clathrate hydrates is reported by Veluswamy et al. (2014). Another unusual characteristic is that multiple hydrogen molecules can occur at each cage site in the ice, one of only a very few guest molecule that forms clathrates with this property. The maximum ratio of hydrogen to water is 6 H₂ to 17 H₂O. It can be formed at 250K in a

diamond anvil A diamond anvil cell (DAC) is a high-pressure device used in geology, engineering, and materials science experiments. It enables the compression of a small (sub-millimeter-sized) piece of material to extreme pressures, typically up to around 10 ...

at a pressure of 300MPa (3000 Bars). It takes about 30 minutes to form, so this method is impractical for rapid manufacture. The percent of weight of hydrogen is 3.77%. The cage compartments are hexakaidecahedral and hold from two to four molecules of hydrogen. At temperatures above 160K the molecules rotate around inside the cage. Below 120K the molecules stop racing around the cage, and below 50K are locked into a fixed position. This was determined with

deuterium Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two Stable isotope ratio, stable isotopes of hydrogen (the other being Hydrogen atom, protium, or hydrogen-1). The atomic nucleus, nucleus of a deuterium ato ...

in a

neutron scattering Neutron scattering, the irregular dispersal of free neutrons by matter, can refer to either the naturally occurring physical process itself or to the man-made experimental techniques that use the natural process for investigating materials. Th ...

experiment. Under higher pressures a 1:1 ratio clathrate can form. It crystallises in a cubic structure, where H₂ and H₂O are both arranged in a diamond lattice. It is stable above 2.3 GPa. Under even higher pressures (over 38 GPa) there is a prediction of the existence of a clathrate with a cubic structure and a 1:2 ratio: 2H₂•H₂O. More complex clathrates can occur with hydrogen, water and other molecules such as

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...

, and

tetrahydrofuran Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water-miscible organic liquid with low viscosity. It is ma ...

. Since hydrogen and water ice are common constituents of the universe, it is very likely that under the right circumstances natural hydrogen clathrates will be formed. This could occur in icy moons for example. Hydrogen clathrate was likely to be formed in the high pressure nebulae that formed the

gas giant A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are also called failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" ...

s, but not to have formed in comets.

References

External links

*{{cite journal, last=Vos, first=Willem L., author2=Larry W. Finger, author3=Russel J. Hemley, author4=Ho-kwang Mao, name-list-style=amp, date=8 November 1993, title=Novel H2-H2O Clathrates at High Pressure, journal=Physical Review Letters, volume=71, issue=19, pages=3150–3153, url=http://people.gl.ciw.edu/hemley/101VosPRL1993.pdf, doi=10.1103/physrevlett.71.3150, pmid=10054870, bibcode=1993PhRvL..71.3150V Clathrate hydrates Energy technology Natural gas technology Hydrogen