Properties of hydrogen
- Lightest, simplest, most abundant element in the universe (accounting for 75% of all normal matter) consisting of one proton and one electron (H1)
- Forms a diatomic molecule (H2), a molecule composed of two atoms of the same element
- Readily forms compounds with most nonmetallic elements, so most of the hydrogen on Earth exists in molecular forms such as water or organic compounds
- Highest energy content of any common fuel by weight (three times that of gasoline), but the lowest energy content by volume
- Nontoxic, colorless, odorless, tasteless gas at standard temperature and pressure
- Liquifies completely when chilled to –252.87 °C or compressed to 13 atmospheres
Conventional hydrogen production
The vast majority of hydrogen production in the world is done through the steam reforming of hydrocarbons such as natural gas, oil, and coal. All the energy generated to produce steam to reform these hydrocarbons comes from burning burning hydrocarbons—a carbon-intensive process.
In a world without constraints on carbon emissions, steam methane reforming is the cheapest way to produce hydrogen. As the price of carbon rises, however, use of hydrocarbons to produce hydrogen will become less advantageous—and eventually be overtaken by RH2, produced through processes such as electrolysis.
Steam-methane reforming reaction (SMR)
CH4 + H2O (+ heat) → CO + 3H2
Production of one tonne of H2 with natural gas generates 10 tonnes of CO2.
Conventional uses of hydrogen
Hydrogen is a versatile commodity used as a gas or liquid in a myriad of primarily industrial applications, including: