INTRODUCTION

Any material that can be burned to release thermal energy is called a fuel. Most familiar fuels consist primarily of hydrogen and carbon, called hydrocarbon fuels. Hydrocarbon fuels exist in all phases; some examples are coal, gasoline, and natural gas. Fuels are the materials which ignite in presence of oxygen and produce heat. The heat energy is then converted into various forms of energy. The different types of fuels like liquid, solid, and gaseous fuels are available for firing in boiler’s furnaces and other combustion equipments. The selection of right type of fuels depends on various factors such as availability, storage, handling, pollution, and landed cost of fuel.

The knowledge of the fuel properties helps in selecting the right fuel for the right purpose and efficient use of the fuel. The increasing worldwide demand for energy has focused attention on fuels, their availability and environmental effects. The fuels available to produce electricity are largely nuclear and fossil, both essentially non-renewable. Fossil fuels take millions of years to form. Fossil fuels originate from the earth as a result of the slow decomposition and chemical conversion of organic material. They exist in nature in three basic forms—solid (coal), liquid (oil), and natural gas. Coal represents the largest fossil fuel energy resource in the world.