Can you please explain why it violates the second law of thermodynamics? I thought the 2nd law would only apply if you are reversing the reaction, i.e. CO2 -> C

Can you please explain why it violates the second law of thermodynamics? I thought the 2nd law would only apply if you are reversing the reaction, i.e. CO2 -> C + O2 , whereas we are simply moving the CO2 underground. To me the critical measure would be how much energy the CO2 needs to be compressed to get it underground.