HOME

TheInfoList



OR:

A gas-fired power plant or gas-fired power station or natural gas power plant is a thermal power station which burns
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon di ...
to generate electricity. Natural gas power stations generate almost a quarter of world electricity and a significant part of global
greenhouse gas emissions Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and lar ...
and thus climate change. However they can provide seasonal
dispatchable generation Dispatchable generation refers to sources of electricity that can be programmed ''on demand'' at the request of power grid operators, according to market needs. Dispatchable generators may adjust their power output according to an order. Non-disp ...
to balance variable renewable energy where hydropower or interconnectors are not available.


Basic concepts: heat into mechanical energy into electrical energy

A gas-fired power plant is a type of fossil fuel power station in which chemical energy stored in natural gas, which is mainly methane, is converted successively into: thermal energy, mechanical energy and, finally,
electrical energy Electrical energy is energy related to forces on electrically charged particles and the movement of electrically charged particles (often electrons in wires, but not always). This energy is supplied by the combination of electric current and electr ...
. Although they cannot exceed the
Carnot cycle A Carnot cycle is an ideal thermodynamic cycle proposed by French physicist Sadi Carnot in 1824 and expanded upon by others in the 1830s and 1840s. By Carnot's theorem, it provides an upper limit on the efficiency of any classical thermodyna ...
limit for conversion of heat energy into useful work the excess heat may be used in
cogeneration Cogeneration or combined heat and power (CHP) is the use of a heat engine or power station to generate electricity and useful heat at the same time. Cogeneration is a more efficient use of fuel or heat, because otherwise- wasted heat from elec ...
plants to heat buildings, produce hot water, or to heat materials on an industrial scale.


Plant types


Simple cycle gas-turbine

In a simple cycle gas-turbine, also known as open-cycle gas-turbine (OCGT), hot gas drives a gas turbine to generate electricity. This type of plant is relatively cheap to build and can start very quickly, but due to its lower efficiency is at most is only run for a few hours a day as a peaking power plant.


Combined cycle gas-turbine (CCGT)

CCGT power plants consist of simple cycle gas-turbines which use the
Brayton cycle The Brayton cycle is a thermodynamic cycle that describes the operation of certain heat engines that have air or some other gas as their working fluid. The original Brayton engines used a piston compressor and piston expander, but modern gas tur ...
, followed by a
heat recovery steam generator A heat recovery steam generator (''HRSG'') is an energy recovery heat exchanger that recovers heat from a hot gas stream, such as a combustion turbine or other waste gas stream. It produces steam that can be used in a process (cogeneration) or u ...
and a
steam turbine A steam turbine is a machine that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Charles Parsons in 1884. Fabrication of a modern steam turbin ...
which use the
Rankine cycle The Rankine cycle is an idealized thermodynamic cycle describing the process by which certain heat engines, such as steam turbines or reciprocating steam engines, allow mechanical work to be extracted from a fluid as it moves between a heat sour ...
. The most common configuration is two gas-turbines supporting one steam turbine. They are more efficient than simple cycle plants and can achieve efficiencies up to 55% and dispatch times of around half an hour.


Reciprocating engine

Reciprocating internal combustion engines tend to be under 20MW, so much smaller than other types of natural gas-fired electricity generator, and are typically used for emergency power or to balance variable renewable energy such as wind and solar.


Greenhouse gas emissions

In total gas-fired power stations emit about of per kilowatt-hour of electricity generated. This is about half that of
coal-fired power station A coal-fired power station or coal power plant is a thermal power station which burns coal to generate electricity. Worldwide, there are about 8,500 coal-fired power stations totaling over 2,000 gigawatts capacity. They generate about a th ...
s but much more than
nuclear power plant A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a generator that produces ele ...
s and renewable energy. Life-cycle emissions of gas-fired power stations may be impacted by methane emissions such as from
gas leak A gas leak refers to a leak of natural gas or another gaseous product from a pipeline or other containment into any area where the gas should not be present. Gas leaks can be hazardous to health as well as the environment. Even a small leak into ...
s.


Carbon capture

very few power plants have
carbon capture and storage Carbon capture and storage (CCS) or carbon capture and sequestration is the process of capturing carbon dioxide (CO2) before it enters the atmosphere, transporting it, and storing it ( carbon sequestration) for centuries or millennia. Usually ...
or carbon capture and utilization.


Hydrogen

Gas-fired power plants can be modified to run on hydrogen and according to General Electric a more economically viable option than CCS would be to use more and more hydrogen in the gas turbine fuel. Hydrogen can at first be created from natural gas through steam reforming, or by heating to precipitate carbon, as a step towards a
hydrogen economy The hydrogen economy is using hydrogen to decarbonize economic sectors which are hard to electrify, essentially, the "hard-to-abate" sectors such as cement, steel, long-haul transport etc. In order to phase out fossil fuels and limit climate ch ...
, thus eventually reducing carbon emissions.


Economics


New plants

Sometimes a new
battery storage power station A battery storage power station is a type of energy storage power station that uses a group of batteries to store electrical energy. Battery storage is the fastest responding dispatchable source of power on electric grids, and it is used to sta ...
together with
solar power Solar power is the conversion of energy from sunlight into electricity, either directly using photovoltaics (PV) or indirectly using concentrated solar power. Photovoltaic cells convert light into an electric current using the photovoltaic e ...
or wind power is cheaper in the long-term than building a new gas plant, as the gas plant risks becoming a
stranded asset Stranded assets are "assets that have suffered from unanticipated or premature write-downs, devaluations or conversion to liabilities". Stranded assets can be caused by a variety of factors and are a phenomenon inherent in the 'creative destructi ...
.


Existing plants

a few gas-fired power plants are being retired because they are unable to stop and start quickly enough. However, despite the falling cost of variable renewable energy most existing gas-fired power plants remain profitable, especially in countries without a
carbon price Carbon pricing (or pricing), also known as cap and trade (CAT) or emissions trading scheme (ETS), is a method for nations to reduce global warming. The cost is applied to greenhouse gas emissions in order to encourage polluters to reduce the co ...
, due to their
dispatchable generation Dispatchable generation refers to sources of electricity that can be programmed ''on demand'' at the request of power grid operators, according to market needs. Dispatchable generators may adjust their power output according to an order. Non-disp ...
and because
shale gas Shale gas is an unconventional natural gas that is found trapped within shale formations. Since the 1990s a combination of horizontal drilling and hydraulic fracturing has made large volumes of shale gas more economical to produce, and some a ...
and liquefied natural gas prices have fallen since they were built. Even in places with a carbon price, such as the EU, existing gas-fired power stations remain economically viable, partly due to increasing restrictions on coal-fired power because of its pollution.


Politics

Even when replacing coal power the decision to build a new plant may be controversial.


See also

* List of natural gas power stations


External links


Global gas plant tracker
by
Global Energy Monitor Global Energy Monitor (GEM) is a San Francisco-based non-governmental organization which catalogs fossil fuel and renewable energy projects worldwide. GEM shares information in support of clean energy and its data and reports on energy trends ...


References

{{Authority control Natural gas-fired power stations Greenhouse gas emissions Hydrogen