The difference between LCK and both Cougar and Linc is the...

The difference between LCK and both Cougar and Linc is the quality of the substructure as well as the ability to control the subsurface burn. Basically being able to produce syngas without over pressuring the local structure means that none of the potentially harmful combustion by-products can enter the natural structure instead flowing to surface where the gas can be treated. Part of the LCK approval is to monitor the region at around 100m from the burn for both overpressure and overtemperature, which to date has showed no signs of contamination. The basin is also inward sloping so any water entering the region would flow to the bottom of the basin and not make it's way to groundwater. Old article linked below discusses the natural positives for ISG in this region, and why the SA government provided approval at a time when issues existed with the technology in Queensland.
https://smallcaps.com.au/leigh-creek-energy-exceptional-environmental-results-syngas-demonstration/