Energy & Green Tech

GM expands market for hydrogen fuel cells beyond vehicles

General Motors is finding new markets for its hydrogen fuel cell systems, announcing that it will work with another company to build mobile electricity generators, electric vehicle charging stations and power generators for ...

Energy & Green Tech

Our next renewable energy source could be an artificial leaf

LSU researchers are exploring new ways to use the oldest energy source on our planet—sunlight—to create truly green energy on demand. You've already heard of solar cells and solar panels, but David Vinyard, assistant ...

Energy & Green Tech

Estimating the future cost of hydrogen fuel for transport in India

A mid-level outlook for the at-the-pump price of "green" hydrogen produced from water electrolysis powered by solar electricity in India declines to around $5 per kilogram (kg) hydrogen (or INR 350 per kg hydrogen) in 2050, ...

Energy & Green Tech

Performance analysis of evolutionary hydrogen-powered aircraft

Liquid hydrogen (LH2) combustion aircraft could provide carbon-free air travel on 31%–38% of passenger kilometers flown in 2050, a new study from the International Council on Clean Transportation (ICCT) says. The study ...


Hydrogen (pronounced /ˈhaɪdrədʒən/) is the chemical element with atomic number 1. It is represented by the symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H2. With an atomic weight of 1.00794 u, hydrogen is the lightest element.

Hydrogen is the most abundant chemical element, constituting roughly 75% of the universe's elemental mass. Stars in the main sequence are mainly composed of hydrogen in its plasma state. Elemental hydrogen is relatively rare on Earth. Industrial production is from hydrocarbons such as methane with most being used "captively" at the production site. The two largest uses are in fossil fuel processing (e.g., hydrocracking) and ammonia production mostly for the fertilizer market. Hydrogen may be produced from water by electrolysis at substantially greater cost than production from natural gas.

The most common isotope of hydrogen is protium (name rarely used, symbol H) with a single proton and no neutrons. In ionic compounds it can take a negative charge (an anion known as a hydride and written as H−), or as a positively-charged species H+. The latter cation is written as though composed of a bare proton, but in reality, hydrogen cations in ionic compounds always occur as more complex species. Hydrogen forms compounds with most elements and is present in water and most organic compounds. It plays a particularly important role in acid-base chemistry with many reactions exchanging protons between soluble molecules. As the only neutral atom with an analytic solution to the Schrödinger equation, the study of the energetics and bonding of the hydrogen atom played a key role in the development of quantum mechanics.

Hydrogen is important in metallurgy as it can embrittle many metals, complicating the design of pipelines and storage tanks. Hydrogen is highly soluble in many rare earth and transition metals and is soluble in both nanocrystalline and amorphous metals. Hydrogen solubility in metals is influenced by local distortions or impurities in the crystal lattice.

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