In Europe, the Green Deal targets a complete decarbonisation of electricity networks by 2050. This is to answer agreed global targets to moderate climate change to a maximum of 1.5 °C. The rapid deployment of renewable electricity is underway to achieve this goal, partly thanks to the drastic recent cost reductions. However, due to the intermittent nature of renewables, energy storage solutions and/or back-up combustion power plants will be needed to ensure the power supply in the future largely expanded carbon-free grids. Today´s combustion solutions to solve the back-up power will not be allowed in scenarios aiming at zero or even negative CO2 emissions, because even such intermittent combustion systems will need deep decarbonisation.

A solution to avoid fugitive emissions of CO2 in back-up power systems would be to capture CO2 from the flue gases emitted by the back-up combustion system. However, most of the current CO2 capture technologies are designed for base load operation, trying to find optimum configurations with a minimum energy penalty, and they will be largely penalized due to their complexity and their inherent capital investment intensity when operating with low capacity factors. Thus, there is a need for developing CO2 capture technologies that can be adapted this kind of back-up power plants.


BackCaP process is based on Calcium looping technology and uses Ca(OH)2 as sorbent. Main advantages of this sorbent the high reactivity towards CO2 and the very low cost, which allows integrating a large-scale storage system. The CO2 capture and sorbent regeneration steps are fully decoupled. Thus, during the short periods when the power plant enters into operation, the sorbent is fed from the Ca(OH)2 storage into the carbonator to react with the CO2 present in the flue gas. Meanwhile, the carbonated solids leaving this reactor are sent to the CaCO3 storage, thus storing the CO2 captured from the power plant in solid form. In contrast, the sorbent regeneration step operates in steady state. Solids from the CaCO3 storage are fed into an oxy-fired calciner, to release the CO2 and the produce CaO which is sent to a small hydrator to regenerate the Ca(OH)2.

                                              CAPTURE STEP                                                                                      SORBENT REGENERATION

This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 101034000

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Dr. Borja Arias
CO2 Capture group, Carbon Science and Technology Institute (INCAR – CSIC)
C/ Francisco Pintado Fe, 26, 33011 OVIEDO, Spain