Hydrogen is a chemical element that has the atomic number 1 in the periodic table. It consists of one proton and one electron.
In its normal state, hydrogen is a gaseous element that is colourless, odourless and much lighter than air. At temperatures below -250 °C, it changes its physical state from gaseous to liquid and solid as the temperature drops. At a temperature of -253 °C hydrogen liquefies and at -259 °C it becomes solid. The energy density of
hydrogen is 33.3 kWh/kg. In the future, hydrogen will be used as a fuel for motor vehicles and also in various industrial applications, for example in steel production. In the automotive industry, it is converted into electrical energy by means of fuel cells, with the PEM fuel cell being favoured for this purpose.