The largest amount of CO2 released into the atmosphere is produced by combustion of fossil fuels in power plants to produce electricity. This acid gas greatly contributes to climate change and its emissions must be limited. The most common capture technology for post-combustion capture is CO2 absorption with aqueous amines, a process characterized by high energy requirements for CO2 release from the solvent and compression of the obtained rich-CO2 stream. Adding a CCS system to a power plant allows advantages from environmental point of view, though the power output is significantly reduced.
This work is focused on a study for determining the best operating conditions of the absorption plant with the aim of limiting the impact of the CO2 capture operation while maintaining substantial reduction of CO2 emissions in a coal-fired power plant. One of the possibilities to achieve this goal is to operate the CO2 removal plant in flexible mode. Since it is located downstream the power system, the process of post-combustion amine scrubbing is well-suited for this type of operation.
Several flexible solutions have been studied and applied to a natural gas combined cycle system located in Italy, considering a chemical absorption system by means of monoethanolamine (30% wt.) aqueous solution. The analysis takes into account both the cost of electricity and the amount of electricity sold during the day.
The results are discussed also on the basis of different values of the carbon tax.