Gasworks

Gasworks are industrial facilities for producing gas for illumination and heating by gasification of coal or other feedstocks. Historically common in urban areas before widespread use of natural gas, they supplied town gas via a network of pipelines and gas holders. With the shift to natural gas in the late 20th century, many gasworks were closed or redeveloped.

Coal was heated in retorts in an oxygen-starved environment to produce gas, tar, and coke. The resulting gas, often called town gas, contained hydrogen, carbon monoxide, methane, and other hydrocarbons. Some plants used water gas, produced by reacting steam with hot coke to yield hydrogen and carbon monoxide. Gas purification removed impurities such as hydrogen sulfide, ammonia, tar, and moisture; parts of the system included gas holders for storage, condensers, and scrubbers.

Coal tar was collected for chemical industries; coke was produced for fuel; solid residues were disposed of or used as fuel. Purification also produced marketable byproducts. Ancillary structures included retort houses, tar decantation works, purifiers, and gasometers.

In many regions, natural gas networks replaced town gas, leading to closures and repurposing of former gasworks as residential, commercial, or park sites. Contamination from coal tar and other byproducts has required remediation on many sites. Some former gasworks are preserved as industrial heritage sites or museums.