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01. Hydrogen
Hydrogen is the simplest, lightest atom - since it consists of a nucleus containing a proton and a peripheral electron - and the most abundant in the universe: It represents 75% of the mass of the universe and two thirds of all molecules on our planet. Fuel for the stars and fuel for the "empty spaces" between the stars, hydrogen is not a primary energy but an energy carrier. Unlike other sources, such as fossil or renewable energies, it is a secondary energy without CO2 emissions.
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