For a hydrogen storage tank you need normal rainwater (H2O) and solar energy from a photovoltaic system. Using the process of electrolysis, this produces hydrogen (H2) and stores it long-term in gas cylinders. The "waste" product of this conversion is oxygen (O2).
As soon as energy can no longer be covered by the solar system or the daily storage unit, the hydrogen storage tank switches on and releases electricity for self-consumption via the fuel cell. The result of this process is water (H2O), which is used again for the further production of hydrogen (H2).
So it's a round thing: 100% CO2-free and pure oxygen and clean water are produced as by-products.
We would like to take this opportunity to dispel the myth of "hydrogen", set the facts straight and ask you to take an unprejudiced look at this technology whose resource is actually available worldwide in unlimited quantities: namely water!
In every sheet metal workshop there are oxygen cylinders and they are used for welding work. In every hospital, oxygen (O2) is needed for ventilation. And who is shouting here: Dangerous! Dangerous! Nobody. We find gas cylinders everywhere in our lives. Whether they contain oxygen, propane, methane or hydrogen, we are familiar with their handling and they have proven themselves for almost 100 years. They are considered safe and unproblematic.
We don't know why, but with hydrogen (H2) many people have fears and promote it as extremely dangerous. Yes, it is flammable when mixed with oxygen. It burns, just like any other gas. Did you actually know that oxygen is much more reactive than hydrogen? And that hydrogen usually evaporates faster than it can burn - unlike petrol, which can cause terrible fires. And with this, as a matter of course, we drive on our roads every day by the millions. Hydrogen always escapes rapidly upwards, does not sink to the ground like propane and collect there in dangerous pools of gas. Hydrogen is unproblematic if it is well ventilated.
A normal gas cylinder for domestic use has a pressure of 35 bar. In industrial applications, such as a hydrogen tank for a vehicle, 300 bar is used. Many hydrogen storage systems use commercially available safe 30-bar gas cylinders, such as those used for a normal garden barbecue.