CG: n

CT: Natural gas is a fossil fuel formed when layers of buried plants and animals are exposed to intense heat and pressure over thousands of years. The energy that the plants and animals originally obtained from the sun is stored in the form of carbon in natural gas. Natural gas is combusted to generate electricity, enabling this stored energy to be transformed into usable power. Natural gas is a nonrenewable resource because it cannot be replenished on a human time frame.
The natural gas power production process begins with the extraction of natural gas, continues with its treatment and transport to the power plants, and ends with its combustion in boilers and turbines to generate electricity.
Initially, wells are drilled into the ground to remove the natural gas. After the natural gas is extracted, it is treated at gas plants to remove impurities such as hydrogen sulfide, helium, carbon dioxide, hydrocarbons, and moisture. Pipelines then transport the natural gas from the gas plants to power plants.
Power plants use several methods to convert gas to electricity. One method is to burn the gas in a boiler to produce steam, which is then used by a steam turbine to generate electricity. A more common approach is to burn the gas in a combustion turbine to generate electricity.
Another technology, that is growing in popularity is to burn the natural gas in a combustion turbine and use the hot combustion turbine exhaust to make steam to drive a steam turbine. This technology is called “combined cycle” and achieves a higher efficiency by using the same fuel source twice.

S: http://www.epa.gov/cleanenergy/energy-and-you/affect/natural-gas.html (last access: 19 December 2014)

N: 1. natural (adj): c.1300, naturel, “of one’s inborn character; hereditary, by birth;” early 14c. as “of the world of nature (especially as opposed to man),” from Old French naturel “of nature, conforming to nature; by birth,” and directly from Latin naturalis “by birth, according to nature,” from natura “nature”.
gas (n): 1650s, from Dutch gas, probably from Greek khaos “empty space”. The sound of Dutch “g” is roughly equivalent to that of Greek “kh.” First used by Flemish chemist J.B. van Helmont (1577-1644), probably influenced by Paracelsus, who used khaos in an occult sense of “proper elements of spirits” or “ultra-rarified water,” which was van Helmont’s definition of gas.
Modern scientific sense began 1779, with later specialization to “combustible mix of vapors” (1794, originally coal gas); “anesthetic” (1894, originally nitrous oxide); and “poison gas” (1900). As short for gasoline, it is American English, first recorded 1905.
2. A flammable gaseous mixture of straight-chain hydrocarbons, in which methane predominates; it occurs in association with petroleum.
3. Huge volumes are now pipelined for use as residential heating and cooking fuel. It is also available in liquid form (LNG). In the chemical industries it is an important source of the synthesis gas used in making synthetic organic materials and natural gasoline. Carbon black of the channel or impingement type is manufactured by combustion of natural gas. Natural gas can also be made synthetically (SNG) from petroleum fractions such as naphtha and by gasification of coal. Do not confuse with natural gasoline.

S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=natural&searchmode=none (last access: 19 December 2014). 2 & 3. GDT (last access: 19 December 2014).

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CR: anthracite, biogas, blue hydrogen, carbon , coke, coking-plant, fracking, hydrocarbon, lignite , peat, petroleum, primary energy, shale gas, shale oil, soft brown coal.