Operating expenses carbon capture

This characteristic will govern, to a large extent, the operating expenses (OPEX) of the process. Standard post-combustion capture processes, such as gas liquid absorption in a chemical solvent (MEA), typically require 3.5 GJ (thermal basis) per ton of recovered CO2, and 2 GJ ton is often considered as a target. The importance of energy requirement considerations in the carbon capture process selection results from the secondary CO2 emissions which are generated by the capture process. Figure 2.5 summarizes the interplay between CO2 emissions by the reference plant and secondary, additional CO2 emissions due to the capture step. 

The costs of CCS are the additional costs associated with the installation and operation of a CO2 capture facility. The amount of CO2 avoided represents the net CO2 reduction taking into account energy consumption losses. Thus, the specific avoidance costs correspond to the specific carbon credit that would be required to match the present value of the respective capital and operating expenses. Rao and Rubin introduced a commonly used method for the calculation of the avoidance costs. As eqn (7.3) indicates, it relates the costs of electricity (COE) generation with and without CO2 capture to the respective emission reduction. 

Both systems typically recover 99.9% of vapor and liquid solvent from the work chamber during a single cycle of operation. The remaining amount is very expensive of capital and energy to recover. So it is purged from the vessel with air or nitrogen and may be captured by activated carbon (Chapter 4). 

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