William Murdock, constructed the first commercial manufactured gas plant, at Smethwick, Soho District, West Birmingham, England in 1805.  It produced coke and coal gas.

Water Gas Reaction

Historically, the reaction of coke and water was of great importance in the generation of a combustible gas.  Coke can be produced by heating coal in an airtight container.  One of the byproducts produced was coal gas, which could be burned.  An even better method of generating a flammable gas, the water gas reaction, was first discovered in 1780.  This reaction between superheated steam and carbon takes place at high temperatures.

C (s) + H₂O CO (g) + H₂ (g)

The gaseous product, a mixture of H₂ and CO, is known as "water gas", or "synthesis gas".  It is combustible, and was the gas distributed through pipelines to houses in major cities until around 1950 by which time natural gas – methane CH₄ – generally replaced it for use as a household fuel.  One of the major problems with synthesis gas is that it contains carbon monoxide.  Death from carbon monoxide poisoning was not uncommon when synthesis gas was in widespread household use.

Some of  the CO can be removed using the water gas shift reaction

H₂O (g) + CO (g) H₂ (g) + CO₂ (g)

While water gas is no longer used for household purposes, these reactions are still important in the generation of hydrogen.  As well, the in-situ gasification of coal by injecting steam into underground coal deposits has been proposed as a method of recovering coal without mining.  As natural gas reserves become depleted, the water gas reaction may once again become an important method of generating a combustible fuel.

One of the major problems with old gasification plants was the crude method used to dispose of waste materials.  Large quantities of extremely noxious byproducts are produced when coal is heated to produce coke.  In the past, while some of these wastes were recovered and used to make useful products, some of them such as the "coal tar" were simply dumped as waste.  Coal tars contain benzene, and other very carcinogenic compounds.  These old waste dumps cause a major environmental problem.  Today's plants are much cleaner.

In-Situ Gasification of Coal

Worldwide there are enormous reserves of coal.  However, coal is rarely the fuel of choice for household use, and also has serious problems in industrial applications.  Coal is physically dirty and unpleasant to work with.  More seriously it is environmentally dirty as well.

• It often contains large quantities of impurities such as sulfur that cannot be readily separated from solid coal.  When the coal is burned the sulfur produces sulfur dioxide, which is eventually converted into sulfur particulates, or acid rain.
• It produces larger quantities of CO₂ (the main greenhouse gas) than fuels such as oil or gas.

Coal gas is physically clean.  Gasification of coal has the potential to lower the quantity of sulfur pollutants, since methods are well developed to remove sulfur from gases (they have been used for long periods of time in the oil and gas industries).   If the water gas shift reaction could be employed, and the resultant CO₂ trapped at the site and converted into a solid waste product, then coal gasification could produce only environmentally clean H₂ gas. 

Moreover, many coal deposits are considered unfeasible to mine using conventional methods.  They are either too deap, the coal seams are too shallow, or too impure to make normal mining practical.  However, if the coal could be converted into gas underground, then there are enormous quantities of fuel available.  Research is currently being done to make this a practical process.