A new paper by Global Energy Solutions also fits in with Katherina Reiche’s discussion on the “colour theory” of hydrogen. It deals with the production of turquoise hydrogen by means of methane pyrolysis. This process does not produce any CO2. If methane from biogenic sources is used instead of natural gas, even negative CO2 emissions are possible. Methane pyrolysis is a third option to produce hydrogen: besides conventional steam reforming with water gas shift (grey hydrogen) and electrolysis (green hydrogen, if the energy source is green).