Coal is formed in a way similar to the other fossil fuels, though it goes through a different process called coalification. Coal is made of decomposed plant matter in conditions of high temperature and pressure, though it takes a relatively shorter amount of time to form.
Coal is not a uniform substance either; its composition varies from deposit to deposit. Factors that cause this deviation are the types of original plant matter, and the extent to which the plant matter decomposed.
There are different types of coal such as peat, lignite, sub-bituminous and bituminous. The first kind of coal is peat which is merely a mass of dead and decomposing plant matter. Peat has been used as fuel in the past, as an alternative to wood.
Next, the peat becomes lignite, a brownish rock that contains recognizable plant matter and has a relatively low calorific value. Lignite is basically the halfway point from peat to coal. The next phase is sub-bituminous which is a shade of dull black with very little visible plant matter. This type of coal has a less than ideal calorific value. Bituminous coal is the best quality of coal. It. is jet black, very dense and brittle. This type of coal has high calorific value.
How do we get electrical energy from coal? It is basically by means of coal power plants. These power plants first burn the coal in large furnaces creating tremendous amounts of heat. This heat is used to boil water in boilers so as to convert it into steam. The steam expands, causing pressure to increase in the boiler.
A steam turbine is placed at the exit of the boiler so that the moving steam rotates the turbine. In this process the energy from the moving steam gets converted into mechanical energy. The rotating turbine is used to spin a magnet inside a power generator. This generator is a large electromagnet that encases the spinning magnet.
In this way the electricity is generated and so generated electricity is then sent to the national power grid from where it is distributed in different areas.