Carbon dioxide emissions present a significant obstacle to mitigating climate change. Carbon capture, utilisation, and storage (CCUS) technologies, in conjunction with renewable energy and enhanced energy efficiency, offer pathways to reduce emissions and achieve net-zero industrial production. However, many industrial processes remain reliant on fossil fuels, complicating decarbonisation efforts in sectors such as metallurgy and cement production. This article reviews research advancements in absorption-based CO2 capture technologies from 2015 to 2025 and examines future directions for economically viable and sustainable solutions. Although traditional amine-based absorption processes have been widely implemented, they encounter challenges including high energy requirements for solvent regeneration, solvent degradation, and equipment corrosion. Over the past decade, extensive testing and piloting of advanced emission control and solvent management technologies with high capture rates have aimed to enhance operational predictability and reduce both degradation and costs. Additionally, research has focused on the development and management of new solvent systems, their performance, and CO2 purity control. Recent efforts have also emphasized dynamic modeling, process control, and the critical role of high-quality experimental data from pilot and laboratory studies in model development.

Through the CO2 Hub Nord project in Norway, it is demonstrated for the first time that CO2 capture is technically possible and feasible in Si/FeSi smelters. The project has generated significant learnings from the industrial perspective in terms of evaluating the future installation of a full-scale CO2 capture plant. The current paper describes key elements of CO2 capture from Si plants, including the importance of enabling heat integration between the capture plant and the industry host. Important experiences from the test campaign are summarized.

Currently, scientists and investors consider Direct Air Capture (DAC) as one of the candidates to reduce CO2 emissions. The emissions cut is pressing since 30% of the current greenhouse gas emissions must be addressed by 2030. In seven years, CO2 removal (CDR) technologies are expected to reach a Technology Readiness Level (TRL), relevant to industrial applications. The most promising technologies are at TRL-7, but the jump to TRL-11 in the new IEA scale for disruptive technologies looks unlikely because the scale-up from small pilots to industrial scale requires time and large investments. Moreover, validation on a large scale is still missing or even unplanned. This work also identifies the critical materials supply chain and the competition with the energy transition as limiting factors which could further hinder DAC deployment and reduce DAC contribution in the next years when a first significant emissions cut should be addressed.

DAC deployment is still an open question. Recent publications focused on energy consumption and the relationship between the cost of captured CO2 and operating conditions. These works addressed a preliminary assessment of the best locations but neglected the importance of the local context to succeed in implementing DAC in a specific country. Certainly, levelized costs provide a pointer of the costs but do not point out the impact on the natural resources to be allocated (land use and energy) or if the energy consumption outweighs the environmental benefit. Furthermore, it does not consider if it clashes with planned national strategies. This article aims at predicting the impact of DAC facilities deployment in the Norwegian context by taking advantage of international reports by independent agencies. The estimates are just preliminary but offer an initial rough estimate of Direct Air Capture (DAC) technologies deployment at a national level taking the local resource consumption into account.

Whether in gaseous or aerosol form, mitigation of emissions from absorption-based carbon capture remains a real challenge. Among the available control technologies, water-wash is one of the most conventional and has been shown effective regarding gaseous emissions. This work aims to explore different water-wash designs and experimental conditions to observe the influence of such parameters on the aerosol mitigation capacity. For this purpose, liquid-vapour equilibria (VLE) for dilute aqueous solutions of water and monoethanolamine (MEA), loaded with CO2, were measured. An existing thermodynamic model was then validated with these data for low amine concentrations (30, 6, 3 and 0.6wt%) with CO2 loading between 0.1 and 0.4 mol CO2/mol MEA. Several simulations were carried out for coal- and natural gas-based exhaust using a model reproducing the behaviour of aerosols along the absorber and the water-wash section. Different packing heights in absorber and water-wash sections, and the presence or absence of one or more intercooling stages were studied. Although these operational changes showed significant effects on the outlet aerosol and gaseous emissions, none was able to reduce the emissions to acceptable limits.

A new absorber column with three measuring sections for aerosol characterization was constructed at Tiller, Norway. Sulfuric acid aerosols were introduced into a flue gas by a Topas atomizer. The flue gas came from a propane burner but was diluted with air to a CO2 composition of 4.4%. The aerosols into and out of the absorber were characterized with ELPI, CPC, and PDI for various Topas settings. The particle number concentrations measured by ELPI and CPC were comparable. The PDI could not measure particles smaller than 0.6 μm and was not suitable for characterizing the aerosols into the absorber. Out of the absorber the PDI measured a substantial number of particles larger than 0.6 μm that were not measured by the ELPI. These particles could explain the high emissions of MEA measured by the FTIR.A new Bluefil demister was constructed and showed to be very efficient to remove aerosol particles and reduced the emissions of MEA with 97% compared to a standard knit mesh demister. The pressure drop increased with 13-20 mbar.

This paper presents results from a comprehensive technical feasibility study of CO2 capture from process industries with significant potential for CO2capture. Important elements include the evaluation potential for utilization of excess heat and the potential for improved overall process efficiency by integration of CO2capture in the overall energy system. Focus is aimed at commercial and near-commercial capture technologies, notably reactive absorption and membrane-based technologies, also representing capture technologies largely driven by thermal energy and mechanical/electrical energy, respectively.

In Norway, the full-scale project Longship will capture CO2 from one or two sources, transport the CO2 by ship to a hub at Kollsnes, where the CO2 is heated and pumped before transported by a pipeline to an offshore storage site. It is likely that other CO2 sources in Norway will adopt the same transport strategy, i.e., transport of captured CO2 from the capture site to the hub at Kollsnes before being transported in a common pipeline to permanent storage. In this paper, the results of an investigation into CO2 ship transport configurations for CO2 sources located in the Nordland County in Norway is presented. Five regional hub locations have been identified, each serving one or more emission sources. These regional hubs are then connected to the Kollsnes hub via ship transport. Each regional hub will be different and are sized according to the CO2 volumes to be transported. There could be many suitable shipping configurations based on the ship size and number of ships used for the operations. Six shipping configurations have been described and cost estimated. The configuration where each regional hubs is served by a dedicated ship, is according to the results the most cost effective alternative. It has the lowest CAPEX and an OPEX in line with the other configurations. The ships are specifically sized according to the CO2 volume at each regional hub. This configuration is also attractive as it does not depend on the readiness of the other hubs as they are operated independently of each other.

A new and improved aerosol model has been developed and tested against experimental data. An e-NRTL equilibrium model for MEA was extended to cover sulphuric acid containing droplets and validated against new eboulliometer data in this work. The droplet model predicts emissions without demister installed in the absorber, within ± 20% and with demister, 30-80% of the measured emissions. The model predicts well the change in emissions from NG-based to coal-based exhaust. Under conditions reported in this work, the droplet number concentration was found to have a small effect on predicted emissions because of more MEA gas-phase depletion with high droplet concentrations and slower growth. The effects counteract each other. With significant MEA depletion in the gas phase, the emissions are largely determined by the mass transfer rate from the bulk liquid. The initial droplet sulphuric acid concentration had a minor effect on the outlet droplet size distribution. The effect on MEA emissions was significant: the emissions went up with increased initial sulphuric acid concentration. The effect of sulphuric acid was stronger for low inlet gas CO2 concentration (NG) than for coal-based exhaust. The increase in emissions is believed to be caused by the increase in overall driving force for MEA between bulk liquid phase and droplets. The log-normal model does not catch small inlet droplet sizes in the range below 20-30nm. These droplet sizes hardly grow in the absorber and water wash and in the total emissions, these droplets have a negligible impact on emissions.

Globally, large private and public funds are invested into CO2 capture and storage (CCS) research to provide the knowledge and technology required to mitigate CO2 emissions below a sustainable level. A pertinent question to ask is whether this is the best way of spending limited resources. This paper presents a study aiming to quantify the potential economic gains from selected CCS innovations created in the international research centre BIGCCS and its successor NCCS. Development of CCS technology is currently driven by technology push and the lack of a market makes it hard to predict future potentials for increased revenue. Consequently, the study investigates potential cost reductions from implementing the innovations in full-scale industry projects based on qualified assumptions. The results show that even with limited deployment of CCS the potential cost savings from implementation of the innovations by far exceed the research investment. Additional value not considered is in this work is expected from commercialisation of the technologies for the technology providers, improved competitive edge for providers of CO2 free products and enhanced safety for people, equipment and environment. By developing illustrative examples from technology innovations, the study aims to contribute to a broader public CCS debate addressing also potential gains and commercial opportunities in addition to the current focus on costs and safety.

In this work the corrosion rate of UNS(1) K12000 (DIN(2) 17100 ST 52) low-alloy structural steel in monoethanolamine (MEA) solution was studied. The corrosion testing was mainly performed on a rotating disc electrode, and electrochemical impedance was used to estimate the corrosion rate. The parameters studied were rotation rate, influence of oxygen and degradation of the MEA. The results shows a significant increase in the corrosion rate when oxygen was introduced to the system, especially when the rotation rate was high. The corrosion also increased when the MEA solution was degraded.

Amine based CO2 scrubbing processes have been patented since 1930 but very few process improvements have been reported prior to the oil crisis of 1975-1980, which led to the requirement for more energy efficient processes. Nevertheless most of these patents are solvent oriented. With CO2 capture technology development, a sharp increase of process improvement patents and scientific articles can be witnessed since 2004 in parallel with the development of new solvents. In this work, a thorough review of patent database and open literature has been carried out in order to be as exhaustive as possible. The individual process modifications and patents are analyzed and then generalised into “elementary” modification groups. These elementary modifications are then sorted into main categories related to their effect on the process. In total, 20 elementary modifications have been sorted into three main categories: absorption enhancement (increasing rich loading or reducing absorption driving force difference along column height), thermal integration (minimizing the rejected heat of process and excessive thermal driving force) and heat pump effect (increasing heat quality with electricity). Figure 1 summarizes these modifications and shows an illustrative flow scheme for each of them. In the final paper, their mean of action will be described and discussed in relation to their induced complexity, flexibility, cost and expected performances.

Heat of absorption of CO2 and partial pressure of CO2 with aqueous solutions of MEA has been measured in a reaction calorimeter CPA122 at 40, 80, and 120 oC for 30 wt% MEA solution and at 120 oC for 10 and 70wt % MEA solutions. Heat of absorption measured in this work is also differential in loading, i.e. CO2 has been added to the reactor in steps. An experimental set-up used by Kim and Svendsen (2007) has been used in this work after a small modification. Experiments show that heat of absorption depends both on loading and temperature, though the temperature dependency is not as high as was reported earlier. Application of the Gibbs –Helmholz correlation for the estimation of the heat of absorption based on experimental PCO2 data is discussed.

There are a number of metal-organic compounds that can loosely be considered CA mimics and which are known to absorb CO2 directly from the atmosphere. The metal-organic complex, {Zn[N[CH2(2-py)]3](μ-OH)}2(NO3)2 (I), is one such complex. In the present study, the sorption of CO2 by water solutions of complex I have been studied by NMR (using D2O as solvent and absorbing 99.9% C enriched CO2) and vapor-liquid equilibria measurements to understand the mechanisms of sorption when using such complexes. The potential of I/water solvents for use in CO2 capture has been evaluated by comparison with monoethanolamine (MEA)/water solvents. The metal-organic solvent shows higher sorption capacity than MEA on a molar basis; also, three cycle tests indicate that I/water solvents can be regenerated efficiently at low temperatures giving a potential significant reduction in regeneration energy requirements as compared to MEA/water solvents. On the other hand, due to its more than 14 times lower molar mass, MEA solvents have higher CO2 sorption capacities on a kg solvent basis. The two solvents show similar sorption kinetics. © 2013 The Authors. Published by Elsevier Ltd. Selection and peer-review under responsibility of GHGT.

Reactive absorption of CO2 with MEA (monoethanolamine) has been established as the preferred reference technology in benchmark studies of novel post combustion CO2 capture technologies. However, recent advances in solvents tailored for CO2 capture warrant an updated reference for consistent performance comparisons. Moreover, as innovative solvent concepts require desorption heat at varying temperatures, SRDs (specific reboiler duties) are not directly comparable. This paper estimates the specific capture and compression work for two different solvents with varying SRD as a method to rapidly assess the CO2 capture energy penalty. To confirm the results, full process simulations are presented for the NGCC (Natural Gas Combined Cycle) with post combustion capture using a novel amine-based solvent and compared to MEA. Desorber pressure, exhaust gas recirculation ratio and reboiler approach temperature is varied. For identical operating conditions, the novel solvent increases the net plant efficiency from 49.4% to 50.4% compared to MEA. However, although an increased desorber pressure reduces SRD by 8%, the net efficiency is virtually constant. This illustrates the difference between reduced SRD and improved net plant efficiency and the importance of systems level analysis. The best net efficiency, with EGR (Exhaust Gas Recirculation) and 5 degrees C reboiler approach temperature, for the novel solvent corresponds to a 6.2%pt capture penalty. (C) 2014 Elsevier Ltd. All rights reserved.

There are a number of metal-organic compounds that can loosely be considered CA mimics and which are known to absorb CO2 directly from the atmosphere. The metal-organic complex, {Zn[N[CH2(2-py)](3)](mu-OH)}(2)(NO3)(2) (I), is one such complex. In the present study, the sorption of CO2 by water solutions of complex I have been studied by NMR (using D2O as solvent and absorbing 99.9% C-13 enriched CO2) and vapor-liquid equilibria measurements to understand the mechanisms of sorption when using such complexes. The potential of I/water solvents for use in CO2 capture has been evaluated by comparison with monoethanolamine (MEA)/water solvents. The metal-organic solvent shows higher sorption capacity than MEA on a molar basis; also, three cycle tests indicate that I/water solvents can be regenerated efficiently at low temperatures giving a potential significant reduction in regeneration energy requirements as compared to MEA/water solvents. On the other hand, due to its more than 14 times lower molar mass, MEA solvents have higher CO2 sorption capacities on a kg solvent basis. The two solvents show similar sorption kinetics. (C) 2013 The Authors. Published by Elsevier Ltd.

Modeling of membrane contactors as absorber units requires a rigorous absorption model where the liquid phase is discretized in the radial direction. The current paper describes such a model for absorption of CO2 into aqueous alkanolamines. The model is validated with a large volume of experimental data for absorption of CO2 in membrane contactor units. A simplified version of the model is developed to enable fast design and scale up assessment of membrane contactor systems. Simulations are used to show the importance of introducing mixing points in order to avoid mass transfer limitations on the liquid side. This can be achieved by a novel design of the membrane fibers or by operating the contactors with liquid flow on the shell side and gas on the tube side.

The use of amine solvents in post-combustion carbon capture (PCCC) pilot and demonstration plants has increased over the last several years, and subsequently a clear understanding of the potential human and environmental impacts of those solvents has become increasingly more important. EPRI convened a workshop of international stakeholders in 2011 entitled “Health and Environmental Toxicity of Amines for Post-Combustion Carbon Capture: Launching a Dialogue on Research Needs”. A main goal was to bring together members of the solvent development community, government agencies, environmental organizations, academic researchers, industry, and other stakeholders to discuss different approaches to evaluating toxicity of solvents for CO2 capture, particularly in face of proprietary issues. Several research needs were identified, including improved risk assessment methodologies, additional pilot plant emissions data, improved understanding of atmospheric chemistry and losses. However despite these critical knowledge gaps the key outcome was that these gaps are “fillable” and are not “deal- breakers” for the technology. Another critical need identified by a majority of the 2011 Workshop attendees was to standardize stack sampling and analytical methods for amines and their degradation products. This led to the development in early 2012 of an international “Amine and Amine Degradation Products Methods Standardization Working Group”. The group goals are to collaboratively evaluate efficacy of methods that already have or could be applied in power plant stacks, to discuss how to improve characterization of sampling artifacts, and to design a testing program to evaluate various sampling and analytical methods. The long-term goal of the working group is to produce guidelines for more accurate and consistent determination of emissions of amines, related compounds, and their degradation products. Methods reviewed included both online (e.g. Fourier transform infrared spectroscopy; proton- transfer-reaction and other types of mass spectrometry) and offline or manual (e.g. sorbent trapping and thermal desorbtion) analysis for both gas and particle phase compounds. The overall themes that emerged included the dependence of emissions and appropriate methods on the design and major components of the pilot facilities, the potential impacts of mist formation, and the need for additional laboratory and in-situ method comparison and evaluation testing programs. The results of EPRI's community-based efforts will be used to help direct future research on amine emissions, sampling and analysis methods, environmental fate and transport, and health impacts.