Everybody knows that H2, the archetype diatomic molecule, is a colorless gas. In the field of renewable energy however, hydrogen gas is now considered as either “grey”, “blue”, or “green”. This color code descriptor has arisen in order to differentiate hydrogen according to its source, in particular to distinguish hydrogen derived from fossil sources from that derived from renewable energy. Today, exciting steps are being made towards realizing this vision of a hydrogen-powered zero emission infrastructure. See full article at Advanced Science News.