This work summarises the results of the design of novel separation processes for CO₂ removal from flue gas based on precipitating amino acid solvents. The processes here described (DECAB, DECAB Plus and pH-swing) use a combination of enhanced CO₂ absorption (based on the Le Chatelier;s principle) and / or enhanced CO₂ desorption (based on pH-shift), which contribute substantially to the reduction of regeneration energy. An evaluation of these processes has been developed based on literature data, thermodynamic principles and experimental data. As solvent example, the potassium salt of taurine was selected. The results show that these processes are environmentally friendly (no emissions to the air, lower ecotoxicity) and have lower energy consumption than conventional MEA. The DECAB Plus process has been identified as the option with lower energy consumption (66% of conventional MEA- ie ca 2.4 GJ/t CO₂). This study has established the potential of precipitating amino acids as an energy effective alternative to alkanol amines. The future work will focus on determining the cost of CO₂ avoidance and investigating other solvents that will further lead to benefits over conventional processes.

Potential production and emission of nitrosamines during post-combustion CO₂ capture has drawn some attention due to their toxicity and potential carcinogenicity. One of the possible ways to reduce the concentration of nitrosamines is irradiation of the liquid streams of the capture plant with UV light. This paper shows experimental results of the degradation of nitrosamines such as N-nitroso-diethanolamine (NDELA) and N-mononitroso- piperazine (MNPZ) in different solvent matrices. These solvent matrices include water and laboratory grade monoethanolamine (MEA) aqueous solutions, as well as aqueous MEA solution and wash water that had been used in a CO₂ capture pilot plant connected to a coal-fired power plant. Experiments were conducted in dedicated batch set-ups and in a continuous mini CO₂ capture plant. Results show that the UV absorbance of impurities (degradation products and/or dissolved metals) present in MEA solvent that had been used in a pilot plant significantly reduces the UV degradation rate of nitrosamines. Furthermore, UV light seems to accelerate the degradation of the capture solvent itself. For these reasons, if UV light treatment is to be used in full-scale post-combustion CO₂ capture plants, suitable locations would be the absorber's washing section or the stripper's condensate. At these locations, less interference of degradation products can occur and there is less solvent to be degraded.

CO₂ capture based on post-combustion capture has the potential to significantly reduce the CO₂ emissions from coal-fired power plants. However, this capture process reduces considerably the energy efficiency of the power plant. To reduce this energy penalty, this paper studies different post-combustion CO₂ capture process configurations combined with different levels of heat integration with the power plant. The cases studied were based on a 1070MW_e power plant connected to a demo size capture plant (250MW_e equivalent - approximately 1.1Mton CO₂ captured/year). The integral evaluation of the energy needed for the capture plant together with the electrical and heat integration with the power plant is a suitable methodology for determining overall power plant efficiency. This approach gives a good overview of the effect of different capture options and integration levels, that cannot be obtained when evaluated independently.