The major environmental concerns for UCG stem from subsidence, water contamination and greenhouse gas emissions.
However these issues can be resolved by targeting deeper coal seams; most current UCG projects focus on shallow reserves.
Subsidence decreases with the depth of the coal seam, and deeper coal seams are less likely to be in contact with aquifers.
UCG cavities deeper than 800 metres could also be used for CO2 sequestration, where cap rock and overburden layers can restrain the CO2.
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