Because Turkey is an energy-important country, external combustion engines for Turkey possess strategic importance. Turkey's annual biomass potential is 32 million tons of oil equivalent. Gasoline is 9.836 fold more expensive than wood in Turkey. Railway transportation that operate with external combustion engines with wood or coal fire is more economic than highway transportation for Turkey. Thermal energy, produced by burning biomass and other low grade fuels, can be used for small-scale power generation using an external combustion engine, such as the Stirling engine.