Review of methanol and compressed natural gas (CNG) as alternative for transportation fuels

Concern over the environment and a potential oil shortage has resulted in an intensified research for alternative fuels for the transportation sector. Two fuels given strong consideration are methanol and compressed natural gas (CNG). This paper is a comprehensive comparative study of methanol and CNG as transportation fuels. The physical properties of methanol and CNG are discussed. The various concerns, such as source and potential fuel supply, safety, toxicity and health hazards, engine performance and emissions, fuel storage, fuel tank and refueling of these alternative fuels are addressed briefly in this paper. We find that no single alternative fuel is best in all categories. The merits and drawbacks of each fuel are tabulated and the vehicle characteristics are compared with gasoline. The study concludes that the neat methanol may be considered as an alternative for passenger cars and CNG may be considered for fleets, light and heavy-duty vehicles as the best near-term solution.