Coal fired power plants utilize coal to generate electricity. They are the most commonly used of all power plant types. They have been used for so many years by countries in Europe and the US but because of global warming concerns and environmental pollution these plants are being closed down in phases and replaced by other power plant types. They are however still being built in Asia but expectation is that the construction of new plants will slow and will be replaced by other power plants.
Coal fired plants use coal which has been grounded into powder form and burned in a furnace with a boiler. The heat from the furnace converts boiler water into steam. The steam then moves from the boiler under high pressure and impacts on a set of turbine blades. The turbine is connected to a generator which produces electricity. As the turbine blades rotate, the generator produces electricity. Thus chemical energy stored in coal is converted to thermal energy produced by steam from the boiler which is then converted to mechanical energy of the rotating turbine blades and electrical energy produced by the generator.
Transportation of coal
Coal is delivered by rail, barge, trucks,collier ship or slurry pipeline. Generating stations are sometimes built close to a mine, where it is not feasible or very expensive to transport the coal. Hence the coal can be delivered to the mine by conveyor belt or diesel- electric trucks. A large coal train may be 2km long and contain 140 cars with each car each carrying 100 tonnes of coal. This is the amount usually required for large power plants especially during periods of high demand for electricity such as during winter periods when these plants will be supplied with three to five trains a day.
Collier ships which carry up to 40,000 tons of coal may take several days to offload their cargo. Some collier ships may have their own conveyor belt to offload their cargo, others may depend on equipment from the plant. To transport coal through the inland waterways, coal is loaded unto barges which rely on tugboats to move them through these waters to the site of the power plant.
Coal is still the cheapest power generation plant to build, with governments around the world still subsidizing their building and construction and it will take years of investment in other sources of power generation to rid the world from coal power plants.