An in-situ CO2 sequestration method using coal ash ponds located in coastal regions is proposed. The CO2 sequestration capacity of coal fly ash (CFA) by mineral carbonation was evaluated in a flow-through column reactor under various conditions (solid dosage: 100-330 g/L, CO2 flow rate: 20-80 mL/min, solvent type: deionized (DI) water, 1 M NH4Cl solution, and seawater). The CO2 sequestration tests were conducted on CFA slurries using flow-through column reactors to simulate more realistic flow-through conditions. The CO2 sequestration capacity increased when the solid dosage was increased, whereas it was affected insignificantly by the CO2 flow rate. A 1 M NH4Cl solution was the most effective solvent, but it was not significantly different from DI water or seawater. The CO2 sequestration capacity of CFA under the flow-through conditions was approximately 0.019 gCO(2)/g CFA under the test conditions (solid dosage: 333 g/L, CO2 flow rate: 40 mL/min, and solvent: seawater). (C) 2012 Elsevier B.V. All rights reserved.