Microfracturing of coal due to interaction with CO2 under unconfined conditions

► Microfractures form in unconfined coal samples after exposure to CO2. ► Fracturing caused by heterogeneous swelling and differential accessibility of coal macerals. ► Plasticisation is unlikely to play a significant role. ► In situ stress conditions during ECBM prevent microfractures to open or propagate. ► Permeability during ECBM operations will remain low.