Abstract:Based on the Gibbs free energy (GFE) theory, an indicator of “Free Energy Dissipation” Ω is proposed for thermodynamic accessment of route of CO₂ emission reduction (CER). It is pointed out that the value of CER is to reduce the dissipation.A linear function relating power output and the dissipation is derived as,w=－(1/ε)·（Ω/α）=－(1/(1－β))·(Ω/α).where the parameters of ε,β,and αrepresent the ratio of GFE dissipation and reservation as well as the irreversibility. It is revealed, according to the analytic calculation with this function, that the 5.7% extra GFE dissipation will be added to CCS process then be loaded to the environment. Therefore CCS is not a favorable choice from thermodynamics point of view. Contrarily, originated from CO₂Cycling Utilization, the route of CCU emphasizes converting GFE from industrial wastes into regenerated products, therefore realizes GFE recovery and reduces the environment load. So CCU is advantageous to CCS thermodynamically. It is demonstrated by a case investigation to a project in which 8×10⁴ t/a of CO₂will be mineralized by phosphogypsm, that CCU could be an economic profitable route of CER plus considerable resource and environment benefits.