“Basically a perfect fuel, but not entirely problem-free”

Hydrogen (H2) is basically a perfect fuel, since its combustion with oxygen (O2) generates no carbon dioxide (CO2), but only water (H2O). Hydrogen can be obtained from methane (CH4), although that does produce CO2 again.
Another method is the electrolysis of water (H2O). This involves passing a direct electric current through water between two electrodes immersed in the water. Two gases, hydrogen and oxygen, are evolved at the two electrodes  – separated from one another – but no carbon dioxide. In conjunction with electricity generated from wind or the sun, this allows the ‘storage’ of a large amount of the electrical energy that is generated.
So, when considering this energy chain – the generation of hydrogen from wind or solar energy, and the production of the energy needed in the baking oven from hydrogen – this really forms no CO2 in the entire process.
However, using hydrogen is not entirely problem-free on safety grounds. There is a good reason why a mixture of two parts of hydrogen and one part of oxygen is called detonating gas: it is highly explosive!
An added factor is that although hydrogen burners already exist, they are available only for 600 kW and above, i.e. for rather large plants. Developments are also ongoing for burners up to 40 kW. Currently, in the baking ovens area, there are still no practicable solutions with burner powers in the range between 60 and 200 kW. As soon as these become available, everything really favors the use of hydrogen in the baking ovens area. The costs required for this remain to be seen.