Another go for underground coal gasification

By Paul Grad |

Leigh Creek Energy (Adelaide, South Australia; has received final approval from the South Australian government to start a three-month trial of underground coal gasification (UCG) at the site of the old Leigh Creek Coalfield, about 550 km north of Adelaide.

The proposed project has been a contentious issue due to environmental concerns associated with UCG. An UCG project at Chinchilla, Queensland (Chem. Eng., June 2009, p. 15;, operated by Linc Energy Ltd. (Brisbane, Australia;, was banned by the Queensland government. Linc Energy (now in liquidation) was charged with causing great environmental harm at Chinchilla, releasing contaminants into the soil, air and water. It injected air into underground combustion chambers at pressures that were too high, causing the rock surrounding the coal seam to fracture and allowing the escape of toxic gases. Workers at the site reported several health issues.

The Queensland government imposed an excavation exclusion zone on more than 300 km2 around the Linc facility where landowners were banned from digging deeper than 2 m. The zone was lifted earlier this year. Linc Energy was fined A$4.5 million (approximately $3.2 million).

In light of what happened at Chinchilla, environmental groups have been strongly opposed to the proposed Leigh Creek Energy project and disappointed by its approval by the South Australian government. However, according to Leigh Creek Energy, its proposed project is vastly different from that at Chinchilla. A detailed report by the South Australian government said “… it is unreasonable to draw an association between the two projects due to material differences related to the site suitability, operational practices and the level of regulatory oversight … the Leigh Creek site represents one of the strongest opportunities for low-risk commercial UCG anywhere in the world. On the merits of the site suitability and operational assurances, the demonstration carries minimal risk and should be approved.”

The report notes that Leigh Creek Energy has used leading practices regarding well design to minimize the risk of well leakage, including the use of high temperature casing, premium gas-tight threads, high temperature cements and high temperature well heads. The company has a clear definition of the operating pressure guided by the installation of vibrating wire piezometers. The report considers the risk of fracturing due to pressurization is low.


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