Clean Fuels are alternate fuels which are less harmful to the environment than the traditional fossil fuels. E.g CNG, Natural gas, Clean coal etc.. It primarily consists of following subsectors: 1 CNG Compressed natural gas aka CNG  is made by compressing Natural gas to less than 1% of its volume. Consisting mostly of methane, CNG is odorless, colorless and tasteless 2 Natural Gas Natural gas is a gas consisting primarily of methane. It is found associated with other hydrocarbon fuel, oil wells, in coal beds, and is an important fuel source and a major feedstock for fertilizers 3 Hydrogen and Fuel Cells An electrochemical cell in which the energy of a reaction between a fuel, such as liquid hydrogen, and an oxidant, such as liquid oxygen, is converted into electrical energy. 4 Nuclear Energy Also called as atomic energy is energy that is generated through the use of Uranium, a natural metal that is mined all over the world. Nuclear energy is created through complex processes in nuclear power stations. 5 Clean Coal Natural coal is treated in multiple ways to achieve significant reductions in air emissions of harmful gases to reduce the environmental impact of coal energy generation.