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Hydrogen Explained

What is Hydrogen?

Hydrogen is a colorless, highly flammable gas. Like many other gases, hydrogen rarely appears in a pure form on Earth. Some of hydrogen's characteristics are summarised below: 

  • Identified by the symbol H on the periodic table
  • Hydrogen's atomic number is 1
  • It is the lightest chemical element
  • It makes up approximately 75% of the universe by volume
  • Appears in a large number of compounds (especially those which make up various organic materials)

Hydrogen has a number of uses including:

  • Refinement of petroleum
  • Soldering and brazing
  • Weather balloons
  • Rocket fuel
  • Clean fuel for automotive vehicles
  • Fertilizer production (NH3)
  • Energy storage

Probably the most familiar use in the above list is as a clean fuel for automotive vehicles. Hydrogen can either be burnt in an internal combustion engine (like a conventional petrol car) or used in a fuel cell to produce electricity and drive electric motors. The latter option is the more efficient of the two but also the more expensive. The following energy matrix highlights how hydrogen compares to other energy sources used in the automotive sector:


Fossil Fuel Battery Hydrogen
Refuelling time 3-5 mins Upto 8 hours 3-5 mins
Emissions CO2,NOX *No direct emissions, although the electricity stored in the battery is likely to have come from conventional fossil fuels Water. No other emissions, provided that the hydrogen came from a green energy source.
Risks in the event of an accident Prolonged Fire, Explosion, Fuel spillage, Inhilation (damage to lungs) Chemical burns from battery acid, pollution of the surrounding environment

Rapid Fire, Explosion
*Because hydrogen is buoyant in air, hydrogen flames tend to ascend rapidly and cause less damage than hydrocarbon fires.

Sustainability Finite resource which is becoming increasingly difficult to obtain Lithium and other chemicals which make up the batteries are finite resources 75% of the universes volume is believed to consist of hydrogen. The only challenge is how to produce it in an efficient manner
Storage Typically stored in a plastic or metal tank Metal/Plastic housing combination Pressurised vessel, commonly 350bar ranging up to 700bar
Disposal N/A Batteries must be disposed of in a proper recycling plant and protective clothing worn N/A


As well as transport, hydrogen can also be used for energy storage. This is most useful with intermittent energy sources such as wind, wave and solar. The energy generated is converted to hydrogen via a process called electrolysis and later converted back to electricity via a fuel cell when it is required.