MikeThere are fundamental difference between the two imo:CSG...

Mike

There are fundamental difference between the two imo:

CSG brings up Sydharbs of groundwater for surface disposal that is often highly saline and contains other undesireable analytes including naturally occuring benzene in some cases ... this can result in depressurising of overlying alluvial or other aquifers.

UCG may only have relative bathtubs of water in contact with combustion products in the immediate vicinity of a burn cell that can contain transitory benzene, toluene and other products that dissipate quickly with time when the burn is completed ... there is no surface disposal ... there is no depressurising of overlying alluvial or other aquifers.

Cheers
Dex