ABSTRACT
As some 50% of the energy to convert coal to liquid fuel is consumed in the process, there is a great incentive to burn coal directly in mobile applications. The railway is probably more convenient than the road, but neither are impossible. We would not suggest returning to the traditional steam engine because of its low cycle efficiency even with the high temperatures that are possible with modern alloys. However, because of the ash content external combustion vehicles would seem to be most appropriate. The Stirling engine and the gas turbine are the most likely candidates. There is considerable technical knowledge and experience with both these power units, but there is a great need for research into a suitable coal combuster, perhaps of the fluidised-bed type.
