In addition, if its production is based on renewable energy, the above processes are part of a cycle which is environmentally friendly, the so-called
hydrogen cycle.
The researchers noted that there is "uncertainty" about the effects of hydrogen gas on the atmosphere because "scientists still have a limited understanding of the
hydrogen cycle." Caltech assistant geochemistry professor and study co-author John Eiler said the impact of the hydrogen gas will depend largely on the Earth's ability to consume "anthropogenic hydrogen."
The end result would be a clean, natural
hydrogen cycle, with renewable energy used to split water into oxygen and hydrogen, with the latter used in fuel cells to produce electricity and water--which then would be available to repeat the process.