Climate change and the war in Ukraine have conferred special urgency to the issue of “energy transition”, an expression that indicates the need for mitigation strategies concerning our civilization’s carbon dioxide emissions. Among these strategies, indeed at their forefront, is hydrogen. Hydrogen is an energy carrier, not an energy source, a molecule that is abundant in nature but only when combined with other atoms. Its production is as varied as the colours of the rainbow: black if extracted from coal, brown from lignite, green from renewable sources, and even turquoise, blue, grey, pink or yellow. What are the differences between these “coloured hydrogens”? How do diverse production methods affect the economic and environmental costs of rainbow energy and therefore its applicability? What are the real prospects for the use of hydrogen in the immediate and more remote future?

Alessandro Lanza heads the ENI Enrico Mattei Foundation and teaches Energy and Environmental Policy at the Guido Carli Free International University of Social Studies (LUISS) and the LUISS Business School in Rome. He was formerly chief economist at ENI, chief executive officer at the ENI Corporate University and principal administrator at the International Energy Agency (Energy and Environment Division).