<P> A fossil fuel power station is a power station which burns fossil fuel such as coal, natural gas, or petroleum to produce electricity . Central station fossil fuel power plants are designed on a large scale for continuous operation . In many countries, such plants provide most of the electrical energy used . Fossil fuel power stations have machinery to convert the heat energy of combustion into mechanical energy, which then operates an electrical generator . The prime mover may be a steam turbine, a gas turbine or, in small plants, a reciprocating internal combustion engine . All plants use the energy extracted from expanding gas, either steam or combustion gases . Very few MHD generators have been built which directly convert the energy of hot, moving water into electricity . MHD means Magnetohydrodynamics, which is the study of the magnetic properties of electrically conducting fluids . Examples of such magnetofluids include plasmas, liquid metals, salt water and electrolytes . </P> <P> By - products of thermal power plant operation must be considered in their design and operation . Waste heat energy, which remains due to the finite efficiency of the Carnot, Rankine, or Diesel power cycle, is released directly to the atmosphere or river / lake water, or indirectly to the atmosphere using a cooling tower with river or lake water used as a cooling medium . The flue gas from combustion of the fossil fuels is discharged to the air . This gas contains carbon dioxide and water vapor, as well as other substances such as nitrogen oxides (NO), sulfur oxides (SO), mercury, traces of other metals, and, for coal - fired plants, fly ash . Solid waste ash from coal - fired boilers must also be removed . Some coal ash can be recycled for building materials . </P>

Where does the energy stored in fossil fuels come from