Process modelling and techno-economic analysis of natural gas combined cycle integrated with calcium looping

Calcium looping is promising for large-scale CO₂ capture in the power generation and industrial sectors due to the cheap sorbent used and the relatively low energy penalties achieved with this process. Because of the high operating temperatures the heat utilisation is a major advantage of the process, since a significant amount of additional power can be generated from it. However, this increases its complexity and capital costs. Therefore, not only the energy efficiency performance is important for these cycles, but also the capital costs must be taken into account, i. e. techno-economic analyses are required in order to determine which parameters and configurations are optimal to enhance technology viability in different integration scenarios. In this study the integration scenarios of calcium looping and natural gas combined cycles are explored. The process models of the natural gas combined cycles and calcium looping CO₂ capture plant are developed to explore the most promising scenarios for natural gas combined cycles-calcium looping integration with regard to efficiency penalties. Two scenarios are analysed in detail, and show that the system with heat recovery steam generator before and after the capture plant exhibited better performance of 49.1% efficiency compared with that of 45.7% when only one heat recovery steam generator is located after the capture plant. However, the techno-economic analyses showed that the more energy efficient case, with two heat recovery steam generators, implies relatively higher cost of electricity, 44.1 €/MWh, when compared to that of the reference plant system (33.1 €/MWh). The predicted cost of CO₂ avoided for the case with two heat recovery steam generators is 29.3 € per tonne of CO₂.