Fossil-Fuel

A fossil-fuel power station is a power station that burns fossil fuels such as coal, natural gas or petroleum (oil) 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 (except for MHD generators) have some kind of rotating machinery to convert the heat energy of combustion into mechanical energy, which then operate an electrical generator. The prime mover may be a steam turbine, a gas turbine or, in small isolated plants, a reciprocating internal combustion engine. All plants use the drop between the high pressure and temperature of the steam or combusting fuel and the lower pressure of the atmosphere or condensing vapour in the steam turbine.

Byproducts of power thermal plant operation need to be considered in both the design and operation. Waste heat due to the finite efficiency of the power cycle must be released to the atmosphere, using a cooling tower, or river or lake water as a cooling medium. The flue gas from combustion of the fossil fuels is discharged to the air; this contains carbon dioxide and water vapour, as well as other substances such as nitrogen, nitrogen oxides, sulfur oxides, and (in the case of coal-fired plants) fly ash, mercury and traces of other metals. Solid waste ash from coal-fired boilers must also be removed. Some coal ash can be recycled for building materials.

Fossil fueled power stations are major emitters of CO₂, the most important greenhouse gas (GHG) which according to the consensus of scientific organisations is a major contributor to the global warming observed over the last 100 years. Brown coal emits 3 times as much CO₂ as natural gas, black coal emits twice as much CO₂ per unit of electric energy. Carbon capture and storage of emissions are not expected to be available on a commercial economically viable basis until 2025.

Vocabulary

Natural, gas, petroleum, produce, electricity, central, large, continuos, operation, designed, many, energy, machinery, combustion, generator, turbine, plants, temperature, atmosphere, vapour, thermal, considered, efficiency, cycle, medium, substances, nitrogen, mercury, metals, removed, materials, important, scientific.