Coal combustion waste materials

Coal is the most widely used fuel for electrical generation in the world, responsible for more than 40% of the world’s electricity generation (IEA, 2011). Although the technologies used to accomplish this task are varied, the principles are basically similar. Coal is burned in a boiler or furnace to generate heat in order to produce steam. The steam is generated by circulating water through a network of tubes located throughout the boiler. Superheated steam is then directed into a turbine where it expands to turn the turbine shaft, which is coupled to the shaft of a generator, which turns to produce the electrical current. Condensed water and low-pressure steam are recirculated back to the boiler where they are reheated to produce additional steam in a continuous closed heating loop.