Uncovering the opportunity space for hybrid CO₂ capture processes: A techno-economic exploration

There exists a portfolio of technologies that can be deployed for post-combustion CO₂ capture. Each technology performs optimally at specific conditions, which will hardly coincide with exact industrial applications. Hybrid processes combine two (or more) technologies to perform the CO₂ separation. The goal is to design processes that allow each technology in the hybrid configuration to operate optimally, resulting in cost-effective CO₂ capture solutions. This study explores the feasibility of realizing this potential by mapping the techno-economic potential of selected hybrid processes across a wide spectrum of CO₂ concentrations, plant scales and energy system contexts. The four hybrid processes considered are: vacuum pressure swing adsorption (VPSA)-membrane, membrane-VPSA, VPSA-CO₂ liquefaction and membrane-CO₂ liquefaction. A consistent techno-economic optimization framework is developed to identify the optimal process characteristics and associated minimum cost for each case considered. The performances are compared against those of conventional standalone capture technologies – VPSA, membranes and chemical absorption. Hybrid processes show promising results for medium-to-high CO₂ concentrations (≈13–30 % CO₂), where costs in the range 40–70 €/t_CO2 appear achievable. However, even when different levels of electricity price and emission intensity are considered, chemical absorption and membranes remain the two most cost-efficient processes in most of the cases considered with hybrid processes at least 15 % more expensive. The material properties of membranes and adsorbents proved to have a significant impact on the expected performance. The sensitivity analysis showed how changing material properties assumption within relevant boundaries could modify the relative performance and advance hybrid processes, such as VPSA-membrane, as potentially attractive solutions, with the potential to decrease cost of >10 % at specific industrial conditions.