Characteristics of an ideal fuel The parameters like calorific value and rate of combustion make one fuel better than the other. Some attributes of an ideal fuel are: High calorific value Proper ignition temperature Moderate rate of combustion Low content of non - volatile material Absence of poisonous products on combustion Ready availability Low cost Abundant availability and Easy storage and transport No available fuel has all the above said characteristics. Hence a comparative study is made to choose a good fuel. Advantages of liquid and gaseous fuels over solid fuels Unlike solid fuels liquids and gaseous fuels leave behind no ash. They have low ignition temperature compared to solid fuels. The calorific value of liquid and gaseous fuels is higher and can be easily transported through pipelines. They also produce very little smoke. Disadvantages of liquid and gaseous fuels over solid fuels Liquid and gaseous fuels form explosive mixtures making them difficult to handle. Since they require special leak proof containers their storage is difficult. They are expensive compared to solid fuels.