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