Hydrogen gas has long been heralded as a potential transport fuel. It is seen as offering a lowcarbon alternative to refined oil products and natural gas, and complementing other alternatives like electricity and advanced biofuels. Hydrogen fuel cell electric vehicles (FCEVs) would reduce local air pollution because – like battery electric vehicles (BEVs) – they have zero tailpipe emissions. Synthetic liquid fuels produced from electrolytic hydrogen are often referred to as “power-to-liquid”.