Large deposits of coal in the world enable to utilize in composite fuel with water and diesel, which help reducing the demand of petroleum fuels. This composite used in different thermal machines, especially in plant combustion engines with no change in the fuel combustion technology. A carbon powder containing small molecules dissolved in water in –coal-water- fuel (CWF) -is good fuel for applying in large capacity engines in electrical plants. This paper gives necessary information about obtaining of water-coal emulsion including its physical properties and focuses on the action of sea water vapor in CWF. The experimental tests indicate a higher thermal efficiency of engine fueled by water–coal-fuel emulsion than engine fueled by black oil lonely. The increased emission of CO2 or NOx can be reduced in the plants simply by chemical reduction. The paper explains the appropriate ratios leading to effective combustion process. This paper is a certain challenge for finding a new fuel sources as a competition for crude oil. The thermal behavior of different ratios of composite fuel were measured in thermo-gravimetric station under normal atmosphere pressure, to determine the appropriate ratio of CWF. The results show that the addition of 30% sea water as vapor in CWF decrease NOx and gives high thermal efficient.