A record-breaking commercial-scale hydrogen-powered plane has taken off in the UK, with more set to take off soon. With that flight, ZeroAvia, the California-based start-up that had developed the aircraft with partners in Britain and elsewhere, was ready to move to the next stage in the journey toward zero carbon aviation. Governments and companies are investing in the potential of hydrogen as a fuel for transportation. While questions exist about the cost competitiveness of hydrogen and the carbon footprint of producing it, ZeroAvia expects to offer commercial flights on a similar plane as early as 2023. Hydrogen is one of several fuels being considered as ways to transition air travel to zero emissions. Biofuels are the other promising avenue currently being pursued to get the aviation industry to zero emissions.