Fuel-related issues concerning the future of aviation

The paper discusses some major fuel-related issues which will influence the development of aviation over the next 50 years. Provided that global economic development is not halted by world-scale war or crisis, the demand for civil air transport is likely to continue to expand. The consequent rising requirement for aviation fuel is considered in relation to the projection that the total oil extraction rate from relatively accessible fields will reach a peak and then decline. The fuel options for aviation, against such a scenario, are explored. It is concluded that if the aviation demand cannot be met economically from conventional oilfield sources, supplementation by kerosene-like fuel synthesized from other feedstocks is much more likely, in the timeframe considered, than the radical step of a move to liquid hydrogen. The latter could be delayed until much later unless necessitated by constraints on carbon emissions. Other issues relating to aero-engine emissions are discussed, including the present uncertainties regarding the environmental significance of injection into the atmosphere at aircraft operating altitudes. The implications of restricting operations to the troposphere, to avoid the lower mixing rates of the stratosphere, are considered briefly.