A holistic approach to the total energy and cost for carbon capture and sequestration

Carbon capture and sequestration from a stationary source comprises four distinct engineering processes: separation of CO2 from the other flue gases, compression, transportation, and injection into the chosen storage site. An analysis of the thermodynamic and transport properties of CO2 shows that dissolving this gas in seawater at depths more than 600 m is, most likely, an optimal long-term storage method; and that for transportation, the CO2 must be in the denser supercritical state at pressures higher than 7.377 MPa. The separation, compression, transportation, and injection processes require significant energy expenditures, which are determined in this paper using realistic equipment efficiencies, for the cases of two currently in operation coal power plants in Texas. The computations show that the total energy requirements for carbon removal and sequestration are substantial, close to one-third of the energy currently generated by the two power plants. The cost analysis shows that two parameters – the unit cost of the pipeline and the discount factor of the corporation – have a very significant effect on the annualized cost of the CCS process. Doubling the unit cost of the pipeline increases the total annualized cost of the entire CCS project by 36% and increasing the discount rate from 5% to 15% increases this annualized cost by 32%.