In a gas turbine, gas is ignited under pressure and combustible high-pressure, high-temperature gases are produced. The combustible gases power a turbine, which in turn powers a generator. Often, the gases are then directed to a waste heat boiler, where the remaining heat and pressure can be used to produce more electricity and heat for a district heating network, for example.
In a boiler power plant, electricity is generated by heating water to produce steam which, via a turbine, powers a generator.
Gas also used to produce district heat
Another significant application for natural gas is district heat production. Natural gas is used as a fuel to heat the water that is used in the district heating network, where possible combined with the generation of electricity.
Combined heat and power (CHP) systems are used in commercial, industrial, and even residential settings. CHP utilises more of the energy contained in natural gas than does a simple gas turbine, thereby improving energy efficiency and requiring less energy to start with.
Well-developed techniques reduce emissions
Flue gas is produced when natural gas is combusted to generate electricity and heat. This exhaust gas can be cleaned easily before it is emitted into the atmosphere. This is done through well-developed techniques such as particulate filters and flue gas washing to reduce NOx and SO2.
Natural gas extraction
Natural gas is extracted both on land and offshore, either in connection with oil extraction or from separate natural gas deposits.
In more recent deposits, the gas is often forced upward out of the drill hole by natural pressure. In older deposits where pressure has decreased, CO2 or water is often pumped down to increase the pressure that forces the gas upward.
Natural gas must be processed before it can be used
Extracted natural gas varies widely in terms of composition and quality, and must be processed before it can be used. The process itself varies depending on the composition of the extracted gas. Normally, water vapour, gases such as LPG and propane, and other undesirable substances such as mercury and hydrogen sulphide are separated off.
Before natural gas was used on a commercial basis, the gas extracted in connection with oil extraction was burned off or "flared". Today, the goal is to capture all of the natural gas that is extracted and to reduce carbon dioxide emissions as much as possible.