Precipitating Carbonate Process for Post-Combustion CO2 Capture. Techno-Economic Evaluation

Abstract

Abstract Commercially available post-combustion CO2 capture technologies are based on aqueous amine solutions. One of the main cost drivers of such processes is the energy required for solvent regeneration. Most advanced technologies currently claim regeneration energies between 2.7 and 3.2 MJ/kg of CO2 for separation of CO2 from a Natural Gas Combined Cycle (NGCC) power plant flue gas. A system comprising a precipitating carbonate-based solvent has been claimed to have energy consumption well below 2.5MJ/kg of CO2. Here, the concept is evaluated to quantify its potential to bring down the cost of CO2 capture. A process model is developed based on correlation of available thermodynamic data to perform heat and material balances and to define the process operating window. Furthermore, experiments were carried out in a bench scale unit of 25kg/d (2.77x10−4 kg/s) CO2 capture capacity to demonstrate the integrated process concept. Finally, a techno-economic evaluation is performed based on the design of a commercial scale unit of one million tons per year (33.07 kg/s) CO2 capture capacity. The results indicate that the technology has not only higher energy requirements than originally claimed, but also higher capital cost than state of the art amine based systems. Thus, it is decided to stop further development of the technology.