Gas is a fossil fuel formed over millions of years from the remains of marine microorganisms, which broke down into hydrocarbons (i.e. natural gas) as they were mixed with sediment and buried.
In MegaWatt, gas is a low cost option with moderate environmental impact.
The use of gas in power plants is growing faster than any other fossil fuel worldwide. A large proportion of this is due to the growth in shale gas exploration, extraction and use in the US.
Gas power stations are usually combined-cycle gas turbine (CCGT) plants. CCGT plants have two turbines, gas and steam. Gas is combusted in the gas turbine, and the chemical energy is converted into kinetic energy. The kinetic energy in the spinning turbine shaft is transferred to a generator, where the conversion to electrical energy takes place.
This process produces a lot of exhaust heat, but it doesn't go to waste! The heat is used to generate steam for a steam turbine, and means that more energy is extracted to produce electricity in a second generator.
Gas is the main source of dispatchable power in the UK grid. In 2019, it accounted for 40.6% of UK generation, up from 39.5% in 2018.
Over half of this gas is imported, mostly from Norway. The domestic portion is sourced from North Sea oil and gas fields.
Once coal is phased out (by 2024), gas power stations will be the primary source of electricity generation emissions. It is expected that carbon capture and storage (CCS) technology will play a big role in its future.
There are also several minor sources of gas, such as methane clathrates (also known as fire ice). Attempts to extract this so far have been expensive and difficult.
The UK's Climate Change Committee just released the Sixth Carbon Budget, which includes how the use of gas will need to change by 2050 in order to reduce emissions to reach Net Zero targets. There are some interesting graphs that show what UK energy grid could look like in the future.
If you want to learn more, here are some examples of gas plants around the world.
Pembroke Power Station in Wales has 5 units, with a net capacity that can power 4 million homes (2,160 MW).
In Belgium, Engie Electravel is planning to build four new gas plants. This is because the government has decided to phase out nuclear power (which currently supplies roughly 50% of the country's power) by 2025.
All of the numbers we used for the UK statistics can be found in the Digest of United Kingdom Energy Statistics 2020 which is from the Department for Business, Energy & Industrial Strategy (the people in government who look after our energy policy).