Thermal power plants are
classified by the type of fuel and the type of prime mover installed.
● Nuclear power plants use a nuclear reactor's heat to operate a steam turbine generator.
About 20% of electric generation in the USA is produced by nuclear power plants.
● Fossil fuelled power plants may also use a steam turbine generator or in the
case of natural gas fired plants may use a combustion turbine. A coal-fired
power station produces electricity by burning coal to generate steam, and has
the side-effect of producing a large amount of carbon dioxide, which is
released from burning coal and contributes to global warming. About 50% of
electric generation in the USA is produced by coal fired power plants
● Geothermal power plants use steam extracted from hot underground rocks.
● Renewable energy plants or Biomass Fuelled Power Plants may
be fuelled by waste from sugar cane, municipal solid waste, landfill methane,
or other forms of biomass.
● In integrated steel mills, blast furnace exhaust gas
is a low-cost, although low-energy-density, fuel.
● Waste heat from industrial processes is occasionally
concentrated enough to use for power generation, usually in a steam boiler and
turbine.
● Solar thermal electric plants use sunlight to boil water, which turns the generator.
● Steam turbine plants use the dynamic pressure generated by expanding steam to turn the
blades of a turbine. Almost all large non-hydro plants use this system. About
80% of all electric power produced in the world is by use of steam turbines.
● Gas turbine plants use the dynamic pressure from flowing gases (air and combustion
products) to directly operate the turbine. Natural-gas fuelled (and oil fueled) combustion turbine plants can start rapidly and so
are used to supply "peak" energy during periods of high demand,
though at higher cost than base-loaded plants. These may be comparatively small
units, and sometimes completely unmanned, being remotely operated. This type
was pioneered by the UK, Princetown being the world's first, commissioned in
1959.
● Combined cycle plants have both a gas turbine fired by natural gas,
and a steam boiler and steam turbine which use the hot exhaust gas from the gas
turbine to produce electricity. This greatly increases the overall efficiency
of the plant, and many new baseload power plants are combined cycle plants
fired by natural gas.
● Internal combustion Reciprocating engines are used to
provide power for isolated communities and are frequently used for small
cogeneration plants. Hospitals, office buildings, industrial plants, and other
critical facilities also use them to provide backup power in case of a power
outage. These are usually fuelled by diesel oil, heavy oil, natural gas and
landfill gas.
● Microturbines, Stirling engine and internal combustion
reciprocating engines are low-cost solutions for using opportunity fuels, such
as landfill gas, digester gas from water treatment plants and waste gas from
oil production.