Post-combustion CO2 Capture Technology Research Articles

Cerium-MOF-Derived Composite Hierarchical Catalyst Enables Energy-Efficient and Green Amine Regeneration for CO2 Capture.

The excessive energy consumed restricts the application of traditional postcombustion CO2 capture technology and limits the achievement of carbon-neutrality goals. Catalytic-rich CO2 amine regeneration has the potential to accelerate proton transfer and increase the energy efficiency in the CO2 separation process. Herein, we reported a Ce-metal-organic framework (MOF)-derived composite catalyst named HZ-Ni@UiO-66 with a hierarchical structure, which can increase the CO2 desorbed amount by 57.7% and decrease the relative heat duty by 36.5% in comparison with the noncatalytic monoethanolamine (MEA) regeneration process. The composite catalyst of the CeO2 coating from the UiO-66 precursor on the HZ-Ni carrier shows excellent stability with a long lifespan. The HZ-Ni@UiO-66 catalyst also shows a universal catalytic effect in typical blended amine systems with a large cyclic capacity. The HZ-Ni@UiO-66 catalyst effectively decreases the energy barrier of the CO2 desorption reaction to reduce the time required to reach thermodynamics, consequently saving the energy consumption generated by water evaporation. This research provides a new avenue for advancing amine regeneration with less heat duty at low temperatures.

The role of cryogenic carbon capture in future carbon-neutral societies

Utilizing CO2 capture technologies is an essential part of achieving a future carbon-neutral Society. So far, amine-based technologies, which are the most mature post-combustion CO2 capture technologies, have been predominantly applied in large-scale CO2 capture applications. However, the cryogenic process has also been proven to be a potential CO2 capture technology suitable for large-scale applications. Cryogenic carbon capture offers two potential advantages over amine-based technology. First, the efficiency is higher and thus the energy penalty is lower. Next, the flexibility of system integration is also higher, and thus the technology carries the potential of better balancing variable renewable electricity productions. By using the software tool EnergyPLAN and dedicated scenarios of achieving a carbon-neutral Denmark, this paper quantitatively estimates these benefits. It is observed that, from a system perspective, utilizing cryogenic technologies to capture 90 % of CO2 emissions in 2045 can reduce the demand for wind power by approximately 47 %, leading to a decrease in annual system costs by nearly 45 %.

Comparative Assessment of Amine-Based Absorption and Calcium Looping Techniques for Optimizing Energy Efficiency in Post-Combustion Carbon Capture

<p>The escalating levels of atmospheric CO2 have underscored the necessity for developing effective carbon capture and storage (CCS) technologies. This study investigates the advancements in post-combustion CO2 capture technologies, specifically examining the efficiency of amine-based absorption and calcium looping methods. Amine absorbents were synthesized using three amino acids—Lysine, Alanine, and Arginine—supplemented with and without NaOH/KOH additives. Absorption trials were conducted in a bench-scale column across a range of temperatures. The calcium looping process involved repeated carbonation and calcination cycles using CaO to capture and release CO2. A statistical analysis employing ANOVA, was utilized to determine the influence of variables such as amine concentration, base concentration, and temperature on the efficiency of CO2 absorption. The study found that Lysine-based absorbents, adding NaOH, achieved a CO2 capture rate of up to 75% at a temperature of 30°C. Additionally, the calcium looping method exhibited consistent cyclic capacities for over 25 cycles, with a regeneration energy requirement estimated at 3.5 GJ/ton of CO2. While the amine-based systems demonstrated higher capture rates, they also required significant energy for solvent regeneration. The statistical analysis confirmed that amine concentration, base concentration, and temperature are critical factors influencing the efficiency of CO2 absorption. The findings of this study underscore the potential of optimized amine solutions and calcium looping as viable strategies for post-combustion CO2 capture, contributing valuable insights that promote sustainable practices in climate change mitigation.</p>

Membrane-Based Technologies for Post-Combustion CO2 Capture from Flue Gases: Recent Progress in Commonly Employed Membrane Materials.

Carbon dioxide (CO2), which results from fossil fuel combustion and industrial processes, accounts for a substantial part of the total anthropogenic greenhouse gases (GHGs). As a result, several carbon capture, utilization and storage (CCUS) technologies have been developed during the last decade. Chemical absorption, adsorption, cryogenic separation and membrane separation are the most widely used post-combustion CO2 capture technologies. This study reviews post-combustion CO2 capture technologies and the latest progress in membrane processes for CO2 separation. More specifically, the objective of the present work is to present the state of the art of membrane-based technologies for CO2 capture from flue gases and focuses mainly on recent advancements in commonly employed membrane materials. These materials are utilized for the fabrication and application of novel composite membranes or mixed-matrix membranes (MMMs), which present improved intrinsic and surface characteristics and, thus, can achieve high selectivity and permeability. Recent progress is described regarding the utilization of metal-organic frameworks (MOFs), carbon molecular sieves (CMSs), nanocomposite membranes, ionic liquid (IL)-based membranes and facilitated transport membranes (FTMs), which comprise MMMs. The most significant challenges and future prospects of implementing membrane technologies for CO2 capture are also presented.

A comparative study of polyamine and piperazine as promoter for CO2 absorption performance in aqueous methyldiethanolamine blend system: 430 MW power plant data simulation and economic assessment

Fossil fuel power plants play a significant role in fulfilling global energy demands but are also responsible for high CO2 emissions. Amine-based post-combustion CO2 capture (PCC) is one of the technologies used in such power plants to reduce CO2 emissions. However, high energy consumption in amine-based PCC technology causes a reduction in the overall energy efficiency of power plants. The energy consumption significantly depends on the solvents used in the PCC process. Therefore, in this work, we performed CO2 absorption in the piperazine (PZ), triethylenetetramine (TETA), and N-methyldiethanolamine (MDEA) blend and tri-blend solvents. For the absorption performance and energy consumption calculation, a simulation is performed for the 430 MW power plant data in the DWSIM software. Initially, solvent screening was done, and four solvents are selected based on the optimum energy consumption of various solvents. Further, the solvents’ performance in terms of energy consumption is done based on the effect of different temperatures, CO2 composition in feed, and %CO2 recovery. Overall, the TETA+PZ MDEA tri-blend solvent showed optimum energy consumption for most of the conditions. Additionally, a techno-economy assessment was done considering annual capital cost and annual operating cost, and results revealed that the cost per ton of CO2 capture in 5 %TETA+ 5 %PZ+ 20 %MDEA solvent is 27.33 % lesser than industrial MEA solvent, and 1.56 % lower than 10 %PZ+ 20 %MDEA.

Amine Adsorbents Stability for Post-Combustion CO2 Capture: Determination and Validation of Laboratory Degradation Rates in a Multi-staged Fluidized Bed Pilot Plant.

Alternative to current liquid amine technologies for post-combustion CO2 capture, new technologies such as adsorbent-based processes are developed, wherein material lifetime and degradation is important. Herein a robust method to determine degradation rates in a laboratory setup is developed, which was validated with a continuous multi-staged fluidized bed pilot plant designed to capture 1 ton CO2 per day. An amine functionalized polystyrene adsorbent showed very good agreement between the experimental 1000-hour laboratory degradation rates and 2200 hours of degradation in a pilot plant. This validates how laboratory experiments can be extrapolated for sorbent screening and for scale-up. Resulting, the oxidative degradation in the desorber at high temperatures (120 °C) and low O2 concentrations (150 ppmv) is 3 times higher compared to the adsorber at low temperatures and high O2 (56 °C, 7 vol %). Laboratory degradation experiments can hence be used to further optimize process operations to limit degradation or screen for potential new adsorbents.

Revealing co-promotion mechanism of Mn/Ca3Al2O6 on CO2 adsorption performance of CaO in calcium looping by density functional theory

Calcium looping (CaL) is a promising technology for post-combustion CO2 capture and concentrated solar energy storage. The transition metal and calcium aluminate co-doped CaO materials have drawn a lot of attention due to the superior CO2 adsorption capacity. In this work, the co-promotion mechanism of Mn and Ca3Al2O6 on the CO2 adsorption of CaO-based materials in the calcium looping process was investigated by density functional theory. The structural properties and CO2 adsorption performance of CaO, Ca3Al2O6 doped CaO, and Mn/Ca3Al2O6 co-doped CaO structures were determined. The formation of O–Al and O–Mn bonds plays a crucial role in preventing the doped CaO from sintering. The adsorption energy of the CaO cluster on the Ca3Al2O6 and Mn/Ca3Al2O6 surface is −5.66 and −11.15 eV, respectively, which is 2.4 and 4.7 times higher than that on the CaO surface, indicating the enhanced structural stability of the doped CaO. The presence of Ca3Al2O6 has less contribution to CO2 adsorption. The adsorption energy and charge transfer for CO2 on Ca3Al2O6–CaO (−2.03 eV, −0.73 e) is the same as pure CaO (−1.93 eV, −0.71 e). Introducing Mn remarkably improves CO2 adsorption performance by enhancing electron transport. The adsorption energy and charge transfer for CO2 on Mn/Ca3Al2O6–CaO are the highest with −4.45 eV and −0.81 e, respectively. The Mn/Ca3Al2O6 co-doped CaO demonstrates superior structural stability and enhanced CO2 adsorption performance, which seems promising for efficient CO2 adsorption in the CaL process.

Inner-selective polyethersulfone-polydimethylsiloxane (PES-PDMS) thin film composite hollow fiber membrane for CO2/N2 separation at high pressures

Carbon dioxide (CO2) is the dominant greenhouse gas (GHG) and thus CO2 capture from flue gas of power plants, the main anthropogenic source of emission, is a key approach to mitigating the climate change. Thin-film composite (TFC) membranes have received extensive research attention recently as a promising post-combustion CO2 capture (CO2/N2) technology owing to its energy-efficiency, design versatility and upscaling potential. However, studies with the most industrially relevant membrane configuration, the hollow fibers, are rather limited for this application. Herein, we developed an inner-selective polyethersulfone-polydimethylsiloxane (PES-PDMS) TFC hollow fiber membrane by inner coating PDMS in the lumen of PES hollow fibers and then pressurizing the hollow fibers for CO2/N2 separation. The optimal PES-PDMS TFC membrane can achieve a CO2 permeance of 2150 GPU and a CO2/N2 selectivity of 20 when the operating pressure was between 20–22 bar, which holds good potential for post-combustion CO2 capture. The high separation performance arises from a combination of the stretched PES and PDMS layers. The micro-deformation of both layers under high pressures at the lumen side could possibly reduce the selective layer thickness. It may also induce polymer chain orientation, increase the fractional free volume, and potentially create free volume with smaller sizes, thus enhancing the CO₂ permeability and CO₂/N₂ selectivity from the PDMS and PES layers.

Proposal and investigation of CO2 capture from fired heater flue gases to increase methanol production: A case study

In a petrochemical complex in Iran, for production of 209575 kg of MeOH/h, 154,712 kg/h of flue gas with a CO2 concentration of 10.74 mol% enter the atmosphere through a fired heater. The target of this study is to investigate the effect of using post-combustion CO2 capture technology to reduce carbon dioxide emissions and use it to increase methanol production. In order to, the proposed process was simulated and effect of three different solvents, including piperazine (PZ) 30 wt%, monoethanolamine (MEA) 30 wt%, and a blend of MEA 20 wt %+ PZ 10 wt % were investigated. This study investigated solvent regeneration energy, CO2 absorption rate, energy efficiency, and exergy efficiency of stripper column. Simulation results showed PZ with 93% energy efficiency, 55.45% exergy efficiency of stripper column, CO2 emission intensity equal to 0.01 tCO2/tMeOH and lowest solvent regeneration energy equal to 2.6 GJreb/tCO2 has better performance than the other two solvents. Also, the simulation results showed that blending CO2 output from PZ solvent with syngas increases methanol production by 7.8%. The techno-economic analysis also indicated proposed process is more profitable than original process.

Molten salt-mediated carbon capture and conversion

The post-combustion capture is a promising technology to reduce industrial CO2 emission. This review articles concluded the recent advances in molten salt strategies for CO2 capture and conversion. In terms of CO2 capture, MgO-based sorbents can efficiently capture CO2 through a reversible carbonation/calcination reaction at intermediate temperatures (300–500 °C). The addition of alkali metal molten salt to MgO-based sorbents can greatly promote the CO2 uptake, which are promising candidates applied in the post combustion CO2 capture technology. Besides, molten salts such as ZnCl2/NaCl can be served as both activating agents and templates for synthesis of porous carbons from biomass and plastics. Particularly, N-doped porous carbons with highly microporous structures are more suitable for CO2 capture under ambient conditions. In terms of CO2 conversion, the electrochemical reduction in molten salts has been widely developed for producing carbon materials and fuels. Additionally, molten salts (normally single and mixed alkali metal carbonates) acting as both catalysts and heat transfer mediums can enhance the CO2 gasification of carbon feedstocks to produce CO-rich syngas. A significant challenge in the CO2 gasification of biomass/coal and their chars in molten alkali metal carbonates is the potential agglomeration between alkali metal species and minerals in the ash under high temperatures. To achieve sorbents regeneration and CO2 utilization, it is strongly recommended that more further researches should be performed on the integrated CO2 capture and in-situ electro-/thermo-chemical conversion processes for selectively production of high-value chemicals and fuels, which can alleviate the crisis of fossil fuels shortage and reduce the greenhouse gas emission.

An experimental and modeling study of the application of membrane contactor reactors to methanol synthesis using pure CO2 feeds

We describe here a post-combustion CO2 capture and utilization (CCU) technology that converts the CO2 into methanol (MeOH), a valuable chemical, thus providing a way to monetize the carbon captured to offset process costs. Methanol synthesis (MeS) has been discussed recently for application to CCU, but thermodynamic limitations make it difficult to convert in a single pass a large CO2 fraction. Conventional catalysts show slow kinetics in converting CO2-rich syngas (or pure CO2) into MeOH. Our Group developed (Li and Tsotsis, 2019) a novel MeS process, employing a membrane contactor reactor (MCR) system that attains carbon conversions significantly higher than equilibrium. Our focus here is to process pure CO2 streams by combining the MCR with a separate reactor, which converts the CO2 into a syngas via the reverse water gas shift (RWGS) reaction. In this preliminary effort, the RWGS reactor (RWGSR) is assumed to reach equilibrium. Additional MeS kinetic rate data are generated validating experimentally the ability of the MeS-MCR to process as a feed the RWGSR exit stream. The performance of the combined (RWGSR/MeS-MCR) system is then simulated using a recently developed MeS-MCR model (Zejarbad et al., 2002). The findings are encouraging, and research is currently ongoing to experimentally validate the RWGSR/MeS-MCR system performance.

Investigation of membrane wetting for CO2 capture by gas–liquid contactor based on ceramic membrane

In recent years, global climate change caused by excessive CO2 emissions has attracted wide attention. Within this context, CO2 capture by gas–liquid contactor based on membranes is one of the most promising technologies for post-combustion CO2 capture. However, mass transfer deterioration due to membrane wetting becomes one of barriers for its development. In this paper, based on Laplace-Young equation, reliable individual membrane pore wetting model is constructed to demonstrate detailed wetting process inside membrane pores, which is verified by molecular dynamic (MD) numerical simulation. The wetting conditions of ceramic membrane with 1.26 µm average pore size and 51.4° contact angle are investigated in experiments. The results show that neither average nor maximum pore diameters can accurately predict liquid and bubble breakthrough pressures of ceramic membrane. The actual liquid and bubble breakthrough pressures of ceramic membrane are slightly lower than critical liquid and bubble breakthrough pressures corresponding to the maximum pore size. The wetting state of ceramic membrane can be determined by combining individual pore wetting model and actual membrane pore distribution. In addition, for practical application process of CO2 capture by gas–liquid contactor with ceramic membrane, some suggestions to avoid membrane wetting are proposed for selection of ceramic membrane and system operation perspective. The membrane wetting analysis method proposed in this paper not only contributes to future applications of ceramic membrane in CO2 capture, but is also widely applicable to other gas–liquid contactors in membrane separation process.

Novel PEI@CSH adsorbents derived from coal fly ash enabling efficient and in-situ CO2 capture: The anti-urea mechanism of CSH support

Solid amine adsorption is considered to be the most promising technology for post-combustion CO2 capture, but it still has drawbacks due to the high cost of supports and the easy occurrence of CO2-induced chemical deactivation. Herein, we propose a novel eco-friendly method for realizing efficient and stable solid amine adsorbents. A calcium silicate hydrate (CSH) support with a pore volume of 3.0 cm3 g−1 is synthesized from coal fly ash (CFA) with the pore-expanded assistance of azeotropic distillation, and then the PEI@CSH adsorbents are prepared by impregnation. The adsorption capacity of the prepared 60%PEI@CSH-0.1 adsorbent reaches 198 mg g−1 and exhibits an excellent cyclic stability, with an attenuation of only 1.9% after 10 cycles under ideal regeneration conditions. Even under realistic regeneration conditions, the CO2 uptake remains at 103 mg g−1 after 10 cycles, which shows obvious advantages over that of commercial SiO2 supports. By using FT-IR, solid-state NMR and DFT calculations, we found that the CSH support promotes the conversion of primary amines to secondary amines in PEI molecules, and thus effectively inhibits the inactivation induced by the formation of urea compounds. Therefore, the PEI@CSH adsorbents provide a low-cost and high-efficiency approach for both in-situ CFA utilization and CO2 mitigation inside coal-fired power plants.

Environmental impact assessment of post-combustion CO2 capture technologies applied to cement production plants

Decarbonizing the cement manufacturing sector presents an interesting and pressing challenge as it is one of the largest energy consumers in industry (i.e., 7%), emitting considerable amounts of anthropogenic carbon dioxide (i.e., 7%). This paper performs a technical and environmental assessment of decarbonisation of cement production through process modelling and simulation, thermal integration analysis, and Life Cycle Assessment (LCA). Integration of three post-combustion capture methods for a conventional cement plant with an annual productivity of one million tons and a carbon capture rate of 90% is evaluated in comparison to the reference case without carbon capture and storage (CCS). Mass and energy balances derived from simulations are used for the assessment of three innovative capture systems: reactive gas-liquid absorption using Methyl-Di-Ethanol-Amine, reactive gas-solid adsorption using calcium looping (CaL) technology and membrane separation. For the LCA study, a “cradle-to-gate” approach is carried out using GaBi software, according to the ReCiPe impact assessment method. The general conclusion is that integrating the CCS methods into the cement production process leads to a decrease in global warming potential (GWP) in the range of 69.91%–76.74%. Of the CCS technologies analysed, CaL technically outperforms the others as it requires 34% less coal and provides 1.6 times higher gross energy efficiency. From an environmental perspective, CaL integration ranks first, with the lowest scores in six of the nine impact categories and a GWP reduction of 76.74% compared to the baseline scenario without CCS.

Current status and advances in membrane technology for carbon capture

Membrane gas separation is a promising next-generation technology for post-combustion CO2 capture that can significantly reduce energy consumption, instrument, and chemical footprint relative to mature amine scrubbing that is in widespread use. Nevertheless, despite many studies commercially viable membranes are not widely implemented at a large scale. This review presents a systematic overview of the current status and advances of membrane technologies for CO2 capture from post-combustion flue gas. In particular, the potential for recent developments in membranes for scale-up based upon required performance parameters in these settings will be reviewed. The challenges and barriers to the upscale of membrane technologies are discussed with respect to both materials and engineering perspectives. The technology readiness level of various technologies and remaining barriers to their implementation are provided.

Recent advances on the modeling and optimization of CO2 capture processes

This work presents a critical review on the recent developments in the design and optimization of efficient post-combustion CO2 capture processes from point sources, focusing on absorption, adsorption, and membrane separations. Emphasis is placed on the efficient modeling and simulation frameworks, synthesis and design studies, and model-based optimization approaches. Furthermore, the interactions between material (solvent, adsorbent, membrane) development and process design and optimization, are explored. Comparison among the different carbon capture processes, shows that absorption is still the most mature technology for post-combustion CO2 capture. Amines are the most appropriate solvents for CO2 absorption, although significant amount of energy is required for solvent regeneration. On the other hand, the development of materials used in adsorption and membrane-based separations has not reached a mature level that can lead to efficient CO2 capture, employing simple process configurations. Consequently, more complex configurations and design specifications are necessary in these processes, which usually result in an increased separation cost.

Macroscopic model-based design and techno-economic assessment of a 300 MWth in-situ gasification chemical looping combustion plant for power generation and CO2 capture

The in-situ gasification chemical looping combustion (iG-CLC) is a potential combustion technology for solid fuels that facilitates CO2 separation process. In this study, A 300 MWth iG-CLC unit has been designed for combustion of bituminous coal with ilmenite oxygen carrier, and integrated with a subcritical steam cycle for power generation. The reactor system was modeled by employing mass and energy balances as well as a macroscopic model for fuel reactor that has been adapted for fluid dynamics of large-scale circulating fluidized beds. The developed model was used to predict CO2 capture efficiency and analyze the effect of key operating parameters of the unit, namely, composition of fluidizing gas, reactor temperature, solid inventory and particle size. Achieving the CO2 capture efficiency of 85% with a carbon stripper efficiency of 98% leads to a net thermal efficiency of 37.94% and a levelized cost of electricity (LCOE) about 98.082 $/MWh. Use of a higher-efficiency carbon stripper or more reactive fuels is recommended to obtain greater capture rates more economically. Nonetheless, at 90% CO2 capture efficiency, the designed iG-CLC plant has 3.74% higher net thermal efficiency and 4.827 $/MWh lower LCOE than the conventional post-combustion CO2 capture technology integrated with a coal-fired power plant.

Time- and temperature-dependence of the anticorrosion effect of sodium sulfide on Q235 steel for post-combustion CO2 capture system

As a heat stable salt, sodium sulfide remains thermally-unregenerable during the regeneration process for post-combustion capture. Therefore, it became important to undertake a full assessment of its potential presence in the system. The paper investigates the mechanism and influence of sodium sulfide on the corrosion behavior of Q235 steel in amine-based post-combustion CO2 capture technology with respect to exposure time and temperature. The inhibitive influence of sulfide in the system was first confirmed by electrochemical techniques, while gravimetry was used to evaluate the effect of time and temperature on the inhibitive actions. SEM/EDX and XPS were used to characterize the corrosion product films on the steel surface. The behavior of sulfide was largely dependent on its concentration as its inhibition ability decreased with increasing concentration, and this is credited to the presence of FeS corrosion film layer. Time-dependent corrosion studies of steel conducted at 50 °C for the solution with 0.05 M and 0.1 M sulfide showed that the inhibition efficiency decreased from 89.1% and 75.0% to 82.4% and 68.6%, respectively, after 7 and 14 days immersion. At 80 °C, the inhibition efficiency of 0.05 M sulfide decreased from 89.1% to 48.9% after 7 days immersion and 82.4% to 46.1% after 14 days immersion. Together with FeS layer, FeCO3, Fe2O3 were also confirmed on the steel surface by XPS measurement. The research provides practical information on the influence of sulfide in the absorber and rich-lean heat exchanger sections of a CO2 capture unit.

Reducing Heat Duty of MEA Regeneration Using a Sulfonic Acid-Functionalized Mesoporous MCM-41 Catalyst

Amine-based CO2 capture is a promising method to limit global CO2 emissions. However, large thermal energy consumption for CO2 desorption during amine regeneration has limited large-scale worldwide applications. Here, we show that an efficient MCM-41-SO3H-0.6 catalyst presented a superior catalytic performance, decreasing the relative heat duty by one-third and enhancing the instantaneous desorption rate by up to 195% in comparison with the monoethanolamine (MEA) regeneration without catalysts. The excellent catalytic activity is related to the combination of the properties of mesopore surface area × total acid sites, and a possible catalytic mechanism is proposed for the MCM-41-SO3H catalysts. Furthermore, the experimental results in the MEA solution regeneration process were consistent with density functional theory calculations in revealing the catalytic desorption mechanism. This work demonstrated that MCM-41 functionalized with sulfonic acid group catalysts could play an essential role in the post-combustion CO2 capture technology using aqueous MEA for industrial applications.

Comparative Techno-Economic Analysis of Carbon Capture Processes: Pre-Combustion, Post-Combustion, and Oxy-Fuel Combustion Operations

Evaluation of economic aspects is one of the main milestones that affect taking rapid actions in dealing with GHGs mitigation; in particular, avoiding CO2 emissions from large source points, such as power plants. In the present study, three kinds of capturing solutions for coal power plants as the most common source of electricity generation have been studied from technical and economic standpoints. Aspen HYSYS (ver.11) has been used to simulate the overall processes, calculate the battery limit, and assess required equipment. The Taylor scoring method has been utilized to calculate the costliness indexes, assessing the capital and investment costs of a 230 MW power plant using anthracite coal with and without post-combustion, pre-combustion, and oxy-fuel combustion CO2 capture technologies. Comparing the costs and the levelized cost of electricity, it was found that pre-combustion is more costly, to the extent that the total investment for it is approximately 1.6 times higher than the oxy-fuel process. Finally, post-combustion, in terms of maturity and cost-effectiveness, seems to be more attractive, since the capital cost and indirect costs are less. Most importantly, this can be applied to the existing plants without major disruption to the current operation of the plants.