A review of developments in pilot-plant testing and modelling of calcium looping process for CO2 capture from power generation systems
A nearly complete decarbonisation of the power sector is essential to meet the European Union target for greenhouse gas emissions reduction. Carbon capture and storage technologies have been identified as a key measure in reducing the carbon-intensity of the power sector. However, no cost-effective technology has yet been developed on a commercial scale, which is mostly due to high capital cost. Moreover, the mature technologies, such as amine scrubbing or oxy-combustion technologies, impose a high projected efficiency penalty (8–12.5% points) upon integration to the power plant. The calcium looping process, which is currently being tested experimentally in bench- and pilot-scale plants worldwide, is regarded as a promising alternative to the chemical solvent scrubbing approach, as it leads to the projected efficiency penalty of 6–8% points. The calcium looping concept has been developing rapidly due to the introduction of new test facilities, new correlations for process modelling, and process configurations for improved performance. The first part of this review provides an overview of the bench- and pilot-plant test facilities available worldwide. The focus is put on summarising the characteristics and operating conditions of the test facilities, as well as extracting the key experimental findings. Additionally, the experimental data suitable for validation or verification of the process models are presented. In the second part, the approaches to the carbonator and the calciner reactor modelling are summarised and classified in five model complexity levels. Moreover, the model limitations are assessed and the needs for modelling baselines for further process analyses are identified. Finally, in the third part the approaches for the integration of calcium looping to the power generation systems and for the improvement of the process performance are identified and evaluated. This review indicates that calcium looping integration resulted in the projected efficiency penalty of 2.6–7.9% points for the coal-fired power plants and 9.1–11.4% points for the combined-cycle power plants. Also, it was found that the calcium looping process can be used to develop a novel high-efficiency (46.7%LHV) coal-fired power generation system, making this technology even more promising compared to the other CO2 capture technologies.