Petroleum-based fuels have dominated all forms of transport for over a century. In recent decades, three alternative fuels have gained market share: liquid bio fuels, natural gas, and electricity, although all three have also been around for many decades. Nevertheless petroleum-based fuels still account for around 92% of final demand for global transport energy. In the coming decades, will any of the alternatives displace oil? Or could hydrogen be the transport fuel of the long-term future?