For the target coal depth range of 150m to 300m, Chaucer Energy is using the commercially proven vertical well technology provided by Ergo Exergy, where injection and production wells are first linked by air prior to ignition. Subsequent reverse combustion is used to open internal pathways within the coal seam to achieve low pressure operating conditions. This method was successfully developed over many years in the FSU, and was expanded to commercial scale at the Angren site, where more than 15mt of coal were gasified over more than 20 years of operation.

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More recently, the technology has been modified and used at the first stage Chinchilla test site (35,000 tonnes of coal gasified from 1999 to 2002), and at the Majuba site in South Africa (more than 50,000 tonnes of coal gasified from 2007 to 2012).  It has significant technical and commercial benefits over alternative methods, as has been demonstrated from past operating experience.