Hydrogen is „just“ an elementary molecule consisting of two hydrogen-atoms. Why is there so much fuss about this simple molecule that even a whole economy should or could be built upon it? The reaction of hydrogen (H2) with oxygen releases a lot of energy while forming pure water. In the other direction, water can be divided into hydrogen (H2) and oxygen with the help of electricity (there are of cause also other hydrogen building reactions mostly built on fossil fuels/biomass); this is simple chemistry. Compared to fossil fuels, water is nearly unlimited on the planet.