Gasification is a long-established technology with a fascinating future. As an early example at industrial scale, the Seattle Gas Light Company coal gasification plant in the State of Washington came into operation in 1906. At its peak 40 years later, it was producing 7,000 Nm³ per hour of town gas which was used for heating and lighting in nearby suburbs.
Town gas was the name given to the flammable mixture of hydrogen and carbon monoxide generated by the gasification process. In modern industrial gases terminology, this would be called syngas.
To understand the chemistry of gasification, we can consider a spectrum of processes ranging from combustion to pyrolysis. Combustion is the high temperature reaction of a hydrocarbon with an excess of oxygen. It yields primarily heat, carbon dioxide and water. It is common in electrical power generation to produce steam. At the other extreme, pyrolysis is a high temperature decomposition of a hydrocarbon to form solid carbon in the absence of oxygen. It is used to produce coke from coal in steelmaking and to create charcoal from wood. Gasification also occurs at high temperatures and fits somewhere between the two extremes of combustion and pyrolysis because a precisely controlled amount of oxygen is used.
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