A diagram in German illustrating types of hydrogen: green, red, yellow, and white (top, electrolysis); grey, brown/black, blue, and turquoise (bottom, conventional). Each is linked to different energy sources such as gas, coal, or renewables.

A diagram in German illustrating types of hydrogen: green, red, yellow, and white (top, electrolysis); grey, brown/black, blue, and turquoise (bottom, conventional). Each is linked to different energy sources such as gas, coal, or renewables.