Postcombustion CO₂ Capture: A Comparative Techno-Economic Assessment of Three Technologies Using a Solvent, an Adsorbent, and a Membrane

Abstract

This work compares three postcombustion CO2 capture processes based on mature technologies for CO2 separation, namely, (i) absorption using an aqueous piperazine solution, (ii) adsorption using Zeolite 13X in conventional fixed beds (either vacuum swing adsorption or temperature swing adsorption), and (iii) multistage membrane separation using a polymeric material (with CO2/N2 selectivity of 50 and permeability for CO2 of 1700 GPU). All three capture plants are assumed to be retrofitted to a generic industrial CO2-emitting source with 12% CO2 v/v (with 95% relative humidity at the inlet temperature and pressure of 30 °C and 1.3 bar, respectively) to deliver CO2 at 96% purity. In the cases of adsorption and membranes, the flue gas is dried before feeding it to the CO2 capture unit. In a first step, the capture processes (i.e., components and design parameters) are optimized based on their technical performance, defined through process exergy requirement and plant productivity; exergy–productivity Pareto fronts are computed for varying CO2 recovery rates. Second, the economic performance of the processes is assessed through a cost analysis. Estimates of CO2 capture costs are provided for each process as a function of the plant size and CO2 recovery rate. The comparative assessment shows that, although the adsorption- and membrane-based processes analyzed may become cost competitive at the small scale (i.e., below sizes of 100 tons of flue gas processed per day) and low recovery rates (i.e., below ca. 40%), the absorption-based process considered is the most cost-effective option at most plant sizes and recovery rates.

Direct air capture: process technology, techno-economic and socio-political challenges

“…98 Numerous high-quality review articles cover the development of CO 2 separation processes from concentrated sources, 98,[159][160][161][162][163] with recent articles providing a detailed history of the pre-eminent aqueous amine sorption process, 156 and a TEA of the most mature absorption, adsorption and membrane processes. 164 CO 2 separation from the air; comparison with 'concentrated' sources. Considering the separation of CO 2 from air, the most obvious difference is the concentration of CO 2 at the source (B0.04% or B419 ppm in air), ¶ some 2 to 3 orders of magnitude lower than that found in the previously mentioned sources.…”

“…98 Numerous high-quality review articles cover the development of CO 2 separation processes from concentrated sources, 98,159–163 with recent articles providing a detailed history of the pre-eminent aqueous amine sorption process, 156 and a TEA of the most mature absorption, adsorption and membrane processes. 164…”

Perspective on Sorption Enhanced Bifunctional Catalysts to Produce Hydrocarbons

“…Some solid sorbents used to capture and convert CO 2 usually operate at elevated temperatures (above 100 °C) and generally have a reduced regeneration energy penalty compared to other capture technologies. There are several pathways in which solid sorbents have been used to capture CO 2 , including precombustion (CO 2 capture from reforming or syngas), , postcombustion (CO 2 capture from flue gas), , and oxyfuel-combustion (CO 2 capture from combusted fuel) . Additional capture strategies from CO 2 emission sources include chemical looping combustion (CLC) and direct air capture (DAC) (Figure ).…”

Experimental and simulation study of CO2 breakthrough curves in a fixed-bed adsorption process

“…Fixedbed column sizing, resulting in large column trains for large flue gas throughput, may be overcome by TSA cycles. These cycles have received increasing attention due to the proliferation of research in alternative bed concepts enabling faster cycling by better heat propagation or processing of larger amounts of gas in a single column, as in the case of rotary adsorbers [3,13]. Furthermore, temperature swings allow to operate on a wider range of working capacities, for example, of metal-organic frameworks (MOFs) [14].…”

“…Post-combustion technologies represent a group of non-carbon methods to capture CO 2 from an off-gas downstream of the original plant. Conventional methods are CO 2 scrubbing (e.g., using amine or ammonia solvents), adsorption, and membrane separation [3]. Apart from the principle of CO 2 separation itself, these technologies differ in the field of application where their deployment is the most efficient [4,5].…”