Hydrogen is a gas at room temperature, but changes to a liquid at a temperature of -252.8 ˚C, and from a liquid to a solid at -259.2 ˚C. It contains up to three times more energy per unit mass than diesel and its combustion releases neither CO2, SOx, nor fine particles—it only produces water.
First direct observation of the orbital structure of an excited hydrogen atom using a quantum microscope (Stodolna et al. Physical Review Letters)
1.2. Where to find it
Hydrogen can be found in stars that use it as fuel to produce energy and in “empty” spaces between the Stars. On Earth, it does not typically exist by itself in nature and must be produced from compounds that contain it, for instance, from water (H2O).
The only exception is a very small percentage that exists in the Earth’s atmosphere. This reduced percentage is due to its low density; the Earth’s gravity is not able to hold it and it floats away into outer space. The mass flow rate lost is approximately 95,000 tons of hydrogen per year.
1.3. Where is it used?
The majority of the hydrogen produced worldwide is consumed in the production of ammonia, and in the treatment of petrochemicals and methanol. In addition, almost all energy sources contain carbon and hydrogen. For this reason, renewable hydrogen represents a shift away from the carbon emitting energy sources that became common during the industrial revolution.
Hydrogen is a light and extremely powerful rocket propellant. When combined with an oxidizer such us liquid oxygen, liquid hydrogen yields the highest specific impulse in relation to the amount of propellant consumed of any known rocket propellant.
1.4. Interesting facts
About 10% of the weight of living organisms is made up of hydrogen—mainly water, proteins and fats.
Liquid hydrogen has the lowest density of any liquid.
Hydrogen is the only element that can exist without neutrons.
Hydrogen is believed to be one of three elements produced in the Big Bang.
We owe most of the energy on our planet to hydrogen because the Sun’s nuclear fusion process converts hydrogen to helium releasing large amounts of energy.