Technoeconomic Assessment of an Advanced Aqueous Ammonia-Based Postcombustion Capture Process Integrated with a 650-MW Coal-Fired Power Station

Using a rigorous, rate-based model and a validated economic model, we investigated the technoeconomic performance of an aqueous NH₃-based CO₂ capture process integrated with a 650-MW coal-fired power station. First, the baseline NH₃ process was explored with the process design of simultaneous capture of CO₂ and SO₂ to replace the conventional FGD unit. This reduced capital investment of the power station by US$425/kW (a 13.1% reduction). Integration of this NH₃ baseline process with the power station takes the CO₂-avoided cost advantage over the MEA process (US$67.3/tonne vs US$86.4/tonne). We then investigated process modifications of a two-stage absorption, rich-split configuration and interheating stripping to further advance the NH₃ process. The modified process reduced energy consumption by 31.7 MW/h (20.2% reduction) and capital costs by US$55.4 million (6.7% reduction). As a result, the CO₂-avoided cost fell to $53.2/tonne: a savings of $14.1 and $21.9/tonne CO₂ compared with the NH₃ baseline and advanced MEA process, respectively. The analysis of energy breakdown and cost distribution indicates that the technoeconomic performance of the NH₃ process still has great potential to be improved.