In this study, first and second laws of thermodynamics were performed in the turboprop and is analysed and discussed with the mathematical model of sustainability performance of a turboprop engine using a mixture of alternative fuel (Methanol CH3OH) and conventional fuel (Kerosene C12H26). The results showed when the excess air is kept constant, with the increases of the alternative fuel, mixture is enriched with oxygen as a source of methanol and the actual air-fuel ratio decreased was determined. When the rate of alternative fuel in mixture was increased, it was observed that the fuel flow started to increase, because Lower Heating Value of methanol is lower than kerosene. Therefore, increasing of fuel consumption was found to obtain the same power in propeller as negative effect. ESIs - waste exergy ratio, exergy destruction factor and environmental effect factor- is increased with the increasing ratio of methanol in the mixture.