A Power plant in which the heat required to make steam to drive turbines (to make electricity) is obtained by burning fuels (coal, oil or gas) is called thermal Power plant.
Coal (fuel oil or natural gas) is burned in a furnance F to produce heat. This heat boils the water in boiler B to form steam. The steam formed from the boiling water builds up pressure. The hot steam at high pressure is introduced into a turbine chamber having a steam turbine T. The steam passes over the blades of the turbine as a high pressure jet making the turbine rotate. The shaft of turbine is connected to a generator G. which the turbine rotates and drives the generator. The generator produces electricity. The spent steam coming out of turbine chamber is cooled on cooling, steam condenses to form water. This water is again sent to the boiler to form fresh steam. This process is repeated again and again.