In this paper, by means of thermo-gravimetric analysis(TGA), the desorption kinetics of CO2 absorbed in two kinds of rich amine solutions, MDEA (3.25mol/L) and MDEA+DEA(3.25mol/L-0.3mol/L), were investigated under different heating rates(2.5℃/min, 5℃/min, 10℃/min and 20℃/min). The thermal analysis kinetics was applied to analyze the TG-DTG curves of two rich amine solutions so as to research CO2 desorption kinetics. In addition, the CO2 desorption kinetics parameters have been calculated with model-free method Flynn-Wall-Ozawa (FWO) and model-fitting method Coats-Redfern (CR). The results indicated that CO2 desorption process could be divided into two stages. The CO2 and H2O were released with non-uniform speed in the first stage and MDEA or DEA with higher boiling points were evaporated in the second stage. For MDEA solution the average activation energy E was 50.36kJ/mol, the pre-exponential factor A was 1.68×107, and the most probable integral mechanism function was Gα=α3/2. For MDEA+DEA solution the average activation energy E was 59.68kJ/mol, the pre-exponential factor A was 2.22×107, and the most probable integral mechanism function was Gα=[(1+α)1/3−1]2. The technical feasibility of CO2 desorption performance in rich amine solutions with thermo-gravimetric analysis method was demonstrated.

Combined calcium-copper materials based on calcium zirconate (CaO/CuO/CaZrO3) for Calcium-Copper Chemical Looping (Ca-Cu Looping) have been synthesized using a scalable wet chemical method and characterized by powder X-ray diffraction (PXRD) with Rietveld refinement, temperature-programmed reduction (H2-TPR) and oxidation (O2-TPO), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and 45–50 cycles in a thermogravimetric analyser (TGA) representing realistic Ca-Cu Looping conditions. A material at 50 wt% active CuO loading and a CuO/CaO weight ratio of 2 deactivated due to copper migration and agglomeration, while materials with 40 wt% active CuO loading were stable throughout TGA cycles at CuO/CaO ratios of 2 and 10. 40 wt% CuO loaded combined CaO/CuO/CaZrO3 materials are promising candidates for Ca-Cu Looping with a demonstrated tuneable and stable CuO/CaO ratio (≥ 2 [wt/wt]) that could lead to process intensification. The maximum CuO loading for the investigated materials is likely found in the range of [40, 50) wt%, subject to the constraints of Ca-Cu Looping relevant CuO/CaO ratios (≥ 2 [wt/wt]) and the performed TGA testing.

We analyze four general architectures for electrochemically mediated carbon dioxide capture systems, in each of which the electrophilicity of a redox active absorbent or absorbent blocking species is manipulated to influence the system's affinity for CO2. It is shown that the open circuit potentials of these architectures converge given the appropriate reference - namely a state in which no CO2 is present in the stream. The resulting difference between the open circuit potential of a stream and of that same stream lacking CO2 is referred to as the deviation potential. In the context of this deviation potential, four system process configurations are analyzed. The most efficient process configuration for all four electrochemical architectures is one that employs both a cathodic absorption taking place simultaneously with the reduction process and an anodic desorption that occurs along with the oxidation of the redox active species; decoupled electrochemical reactions and absorption/desorption steps incur significant energetic penalties.

Oxy-combustion typically consists of burning coal with a combination of oxygen and a large amount of recycled flue gas (60–70%) to obtain a similar heat flux profile to that of air-fired systems. As the cost of electricity from first-generation oxy-combustion is relatively high, several new oxy-combustion process concepts have been proposed in recent years, and within these, the proposed amount of flue gas recycle (FGR) has varied from near-zero to 80%. To better understand the fundamental impact of FGR on the efficiency of oxy-combustion systems, a thermodynamic approach is used herein. Second-law losses associated with flue gas recycle are found to be significant and highly non-linear with recycle ratio. A difference in efficiency of up to 10 %-points can be realized, with a maximum efficiency occurring at zero FGR. Furthermore, due to the non-linear relation of plant efficiency with recycle ratio, processes with low recycle (< ∼33%) experience only a small efficiency penalty, compared to no recycle. Additionally, fan power requirements also scale non-linearly with recycle ratio, resulting in significantly lower FGR fan power requirements for low recycle processes as well. These results suggest that for systems employing cold recycle, FGR should be kept below 33%. Due to the recent interest in developing pressurized oxy-combustion (POC) for efficient, low-cost carbon capture, the impact of flue gas recycle on POC systems is also presented, with a discussion on the valorization strategies for the latent heat of flue gas moisture recovery.

A 30-kWth moving-bed chemical looping system has been developed at the Industrial Technology Research Institute of Taiwan. In this system, methane is supplied as a fuel to a reducer, and steam enters an oxidizer to produce hydrogen under ambient pressure. An iron-based oxygen carrier is used and pneumatically transported in the system. In this study, a hydrogen production test was performed on the system, while the methane flow rate was 40 L/min according to the capacity requirement of a 30-kWth system, and the oxygen carrier circulation rate was 2100 g/min for 40-wt% Fe2O3 content. The concentration of carbon dioxide produced in the reducer was 95 %, and the concentration of hydrogen produced in the oxidizer reached 90 %. Partially oxidized oxygen carriers then reacted with air in the combustor, leading to a temperature increase of approximately 120°C. The oxygen carriers in the reducer were reduced to Fe, and the integrating conversion rate was 61.5 %. In the oxidizer, the oxygen carrier contained Fe3O4, and the integrated conversion rate was 22.2 %. 75 % of the oxygen carriers in the combustor exhibited a conversion rate of 5.3 %, indicating a nearly complete oxidation state. By conducting the hydrogen production test while effectively removing small particles of worn oxygen carriers from the system, the moving-bed chemical looping system was evaluated for the circulation and reaction of oxygen carriers. The system development experience will be used for system scale-up design.

It has been suggested that non-aqueous solvents containing amines may provide alternatives to aqueous alkanolamine solvents due to the potentially lower energy requirement for the regeneration of the amine. This paper presents experimental data on the solubility of CO2 and heat of absorption in the organic solvent N-methyl-2-pyrrolidone (NMP) and mixtures of 2-amino-2-methyl-1-propanol (AMP) in NMP. The solubility of CO2 was found to be very low at temperatures above 70 °C, the temperature at which the AMP/NMP solvent can be regenerated. The solubility of CO2 was higher at lower temperatures, particularly when precipitation of the AMP carbamate occurred. The heat of absorption in the AMP/NMP solvent decreased with increasing temperature, from approximately 90 kJ/mol CO2 at 40 °C and low loadings, to approximately 40 kJ/mol CO2 and 65 kJ/mol CO2, at 88 °C and low loadings, for the 15 wt% and 25 wt% AMP in NMP solvents, respectively. The results obtained complement our previous studies, together providing comprehensive data on the vapor–liquid equilibrium and the heat of absorption of CO2, which can be used to model the system.

An almost continuous 13,000 h long-term testing under real operating conditions was conducted at the post combustion capture pilot plant in the Niederaussem lignite-fired power plant, with a 30 wt% aqueous monoethanolamine (MEA) solvent solution. The capture plant at Niederaussem shows lower solvent consumption and emissions in comparison to other testing facilities, which are also part of the ALIGN-CCUS project (capture plant at Technology Centre Mongstad (NOR), pilot rig at Tiller (NOR), PACT facilities at Sheffield (UK)). One of the key activities of the ALIGN-CCUS project is to investigate how the time-dependent degradation products and trace components that might act as catalysts for degradation develop over long-term operation, as well as which countermeasures against degradation could be applied. Particularly, it was tested if critical threshold values for the iron ion concentration from literature could be confirmed. Therefore, partial solvent inventory replacement by “Bleed and Feed” and solvent reclaiming based on ion exchange were applied. Dedicated test campaigns on the dynamic behaviour of the capture plant were also carried out and MEA emissions under transient conditions were investigated. Important results are: (i) the confirmation of the non-linear degradation behaviour of MEA; (ii) a different degradation behaviour of MEA in comparison to shorter testing campaigns at other pilot plants regarding the main degradation product acetate; (iii) no critical threshold concentration of iron in the solvent was detected; (iv) very low emissions of MEA < 3 mg/m³ and <10 mg/m³ even under transient operating conditions could be reached; and (v) no aerosol formation occurred.

Mitigation of CO2 emissions in the industrial sector is one of the main climate challenges for the coming decades. This work, carried out within the STEPWISE H2020 project, performs a preliminary techno-economic assessment of the Sorption Enhanced Water Gas Shift (SEWGS) technology when integrated into the iron and steel plant to mitigate CO2 emissions. The SEWGS separates the CO2 from the iron and steel off-gases with residual energy content (i.e. Blast Furnace Gas, Basic Oxygen Furnace Gas and Coke Oven Gas) and the produced H2 is sent to the power generation section to produce the electricity required by the steel plant, while the CO2 is compressed and transported for storage. Detailed mass and energy balances are performed together with a SEWGS cost estimation to assess the energy penalty and additional costs related to CO2 capture. Results demonstrates the potential of SEWGS to capture over 80 % of CO2 in the off-gases, which results in entire plant CO2 emission reduction of 40 % with a Specific Energy Consumptions for CO2 Avoided (SPECCA) around 1.9 MJ/kgCO2. SEWGS outperforms a commercial amine scrubbing technology which has a SPECCA of 2.5 MJ/kgCO2 and only 20 % of CO2 avoided. The cost of CO2 avoided calculated on the basis of a fully integrated steel plant is around 33 €/tCO2 compared to 38 €/tCO2 of the amine technology.

Coupled fluid-flow and geomechanical analysis of caprock integrity has gained a lot of attention among scientists and researchers investigating the long-term performance of geologic carbon storage systems. Reactivation of pre-existing fractures within the caprock or re-opening of faults can create permeable pathways which can influence the seal integrity. Stability of the caprock during and after injection of super-critical CO2, and the impact of pre-existing fractures in the presence or absence of one or multiple faults have been investigated in this study. The impact of the wellbore orientation and the injection rate are among other key factors in understanding the structural trapping mechanisms within such geological formations. In this study, we numerically investigated the impact of each of these factors. This study revealed the interplay between joints and faults and how different leakage pathways are formed and under which scenario they play a dominant role in terms of CO2 leakage. This study also highlights the role of one versus multiple faults in the domain and the importance of the fault hydrological property in forming leakage pathway.

CO2 leakage through damaged wellbore cement sheaths is a major risk of geologic CO2 storage (GCS), as conventional wellbore cement is brittle and can be damaged due to acid attack and downhole stresses during CO2 injection. Here we examine a novel fiber-reinforced engineered cementitious composite (ECC) proposed as a substitute to conventional wellbore cement due to its superior ductility and intrinsic crack width control. ECC and conventional wellbore cement coupons were exposed to water in equilibrium with CO2 at 50 °C and 10 MPa. The samples were retrieved after several days and their mechanical performance was evaluated using a four-point bending test, microhardness, and compressive strength analyses. Optical microscopy and mercury intrusion porosimetry were used to characterize the progression of the carbonation front and pore structures of the specimens. Control experiments were conducted under the same temperature and pressure conditions but with a N2 headspace to isolate the impact of CO2. It was found that carbonation increased the ultimate flexural strength of ECC but decreased its ductility. However, the ductility of carbonated ECC remained higher than that of conventional wellbore cements that exhibited brittle failure under all test conditions. Additionally, ECC exhibited minimal material loss and continued resistance to deformation in comparison to conventional wellbore cements. This suggests that while the exposure of ECC to CO2 will alter its mechanical properties, altered ECC will continue to exhibit mechanical performance superior to conventional wellbore cement, and therefore shows promise as a highly durable wellbore cementing material for GCS applications.

Centrifugal Fluid Separation technology, in particular Supersonic Gas Separation (SGS), is one of the potential technologies considered for offshore CO2 capture. SGS has advantages in terms of CAPEX, hydrocarbon losses, footprint, tonnage and power requirement compared to conventional solutions such as membrane. Even though the technology has been developed since 1989, the applications are limited to mainly dehydration and hydrocarbon dew pointing. For CO2 separation from natural gas, substantial development works are needed prior to the field application as there are a lot of uncertainties in the feed conditions to be tackled. In particular, the stringent requirements of cryogenic temperature, high pressure and inlet CO2 composition of its feed require a robust feed conditioning process plant. For a relatively new technology such as SGS for CO2 removal application, it is crucial to investigate and assess the variations of feed and process conditions i.e. temperature, pressure and gas compositions prior to being applied at actual field, as these will impact the CO2 separation performance inside the separator. Hence, this paper investigates the control strategies for the SGS feed conditioning plant subjected to ±15 % disturbances in temperature and pressure, and ±5 mol% variations in feed CO2 composition. Results show that effective disturbances elimination in the first flash separator of the feed conditioning plant is crucial in minimizing the impact to the SGS operation. A comparative study reveals that standard PID controller performs significantly better in disturbance rejection than Model Predictive Control.

Carbon dioxide capture and storage combined with enhanced deep saline water recovery (CCS-EWR) is a potential approach to mitigate climate change. However, its investment has been a dilemma due to high costs and various uncertainties. In this study, a trinomial tree modelling-based real options approach is constructed to assess the investment in CCS-EWR retrofitting for direct coal liquefaction in China from the investor perspective. In this approach, the uncertainties in CO2 prices, capital subsidies, water resource fees, the residual lifetime of direct coal liquefaction plants, electricity prices, CO2 and freshwater transport distance, and the amount of certified emission reductions (CERs) are considered. The results show that the critical CER price for CCS-EWR retrofits is 7.15 Chinese yuan per ton (CNY/ton) higher than that (141.95 CNY/ton) for CCS retrofits. However, the exemption from water resource fees for freshwater recovered from saline water and a subsidy of 26% of the capital cost are sufficient to eliminate the negative impact of enhanced deep saline water recovery (EWR) on the investment economy of CCS-EWR. In addition, when the residual lifetime is less than 14 years, CCS-EWR projects are still unable to achieve profitability, even with flexible management and decision making; therefore, investors should abandon CCS-EWR investments. On the whole, the investment feasibility for CCS-EWR technology is not optimistic despite access to preferential policies from the government. It is necessary to establish a carbon market with a high and stable CER price.

In response to global warming, it is important to explore alternative disposal technologies for greenhouse gas emissions in the geothermal power sector. One alternative which has received widespread focus is co-injection of non-condensable gases with the waste fluids from geothermal operations. Passarella et al. (2015) simulated the interaction between brine with dissolved CO2 and H2S, and a sample of greywacke in their laboratory. The present work aimed to numerically model the results from the experiment using TOUGHREACT. The goal of this study was to develop numerical simulation techniques to investigate the effects of the reinjection of brine with dissolved NCG. The resulting model provided insights into the geochemical interaction of greywacke with brine-NCG solutions under simulated reservoir conditions. The numerical simulations show that mineral dissolution occurred to a greater degree than precipitation, leading to increased permeability and porosity. It was also observed that the mineral reactive surface areas evolved as mineral dissolution progressed, through etch pit formation. Additionally, flow rate had an impact on the overall reaction rates such that a decrease in injection rate led to a corresponding decrease in reaction rates. Lastly, both experimental data and model outputs indicated that CO2 was minimally sequestered in the simulation, while H2S was clearly captured as pyrite. A similar numerical investigation was conducted on the co-injection of NCG with steam condensates subsequently. The modelling results indicate predominant mineral dissolution, CO2 is expected to be captured as magnesite within the reactor, while H2S is still captured as pyrite.

This study investigates the mass transfer intensification in the absorption of carbon dioxide (CO₂) into a monoethanolamine (MEA) solution enhanced by TiO2 nanoparticles in a typical rotating packed bed (RPB). The overall volumetric gas phase mass transfer coefficients (KGa) were investigated in a counter-current RPB with blade packings. The effects of TiO2 and MEA concentrations, rotational speed, initial concentration of CO₂, gas and liquid flow rates on KGa were specified. The rotational speed had positive effects on KGa. It is deduced that TiO2 nanoparticles led to enhanced CO₂ capture efficiency of over 26.9 % and enhancement in KGa from 7.5%–96.1% for MEA based TiO2 suspension in comparison with MEA solution without nanoparticles. Therefore, TiO2 nanoparticles can augment the mass transfer coefficient and intensify the CO₂ absorption, even in a high-efficiency equipment like a high gravity RPB.

Recently, the excellent performance of ionic liquid and MEA mixed solution as CO2 absorbent has been researched by many scholars, while the corrosion mechanism of the mixed solutions is less discussed. In this work, the corrosion behavior of AISI 1020 steel in MEA and [Bmim]BF4 mixed solutions Containing saturated CO2 was studied by weight loss experiment. Morphology of scales and metal surface was studied by SEM and EDS. The surface state of the electrode was analyzed by electrochemical impedance spectroscopy (EIS) fitting equivalent circuit, and Passivation law of the passivation zone was analyzed by potentiodynamic scanning test. The results show that in the mixed solution saturated with CO2, MEA will degrade and increase the uniform corrosion rate of AISI 1020 steel. When [Bmim]BF4 is added to MEA solution, the uniform corrosion rate is inhibited; however, due to the dissociation of F− in BF4-, as the concentration of [Bmim]BF4 increases, the range of passivation region becomes narrower, and the stability of the passivation film becomes worse, which induces pitting corrosion of AISI 1020 steel.

A novel strategy for efficient CO2 capture by tuning the strength of cation coordination interactions of alkali metal chelated dual functional ionic liquids (DFILs) is reported. CO2 absorption and viscosity experiment, quantum-mechanical calculations showed that the strengthening of the coordination interactions between alkali metal ions and alkanolamine ligands of DFILs containing imidazolide anion ([Im]−) leads to improve the stability of the cheated cation and weaken the chelated cation-anion interaction, resulting in efficient CO2 capture capacity and reducing the viscosity of DFILs. Particularly, [K(DGA)2][Im] has the stronger cation coordination interactions and lower viscosity (249.8 mPa∙s), exhibiting more efficient CO2 capture capacity than other DFILs, with an extremely high capacity of CO2 (∼1.37 mol/mol) in 15 min at T = 333.2 K under atmospheric pressure and good reversibility (5 recycles). Spectroscopic investigations and quantum-mechanical calculations showed that such high CO2 capacity originates from the fact that both [K(DGA)2]+ and [Im]− of [K(DGA)2][Im] react with CO2. Moreover, [Im]− reacts preferentially with CO2 over [K(DGA)2]+.

The Baptiste deposit is located within the Decar nickel district in British Columbia, Canada and is a promising candidate for a CO2 sequestration demonstration project. The deposit contains awaruite (nickel-iron alloy) hosted in an ultramafic complex, which is dominated by serpentine [Mg3Si2O5(OH)4; ∼80 wt.%] and contains reactive brucite [Mg(OH)2; 0.6–12.6 wt.%]. Experiments were conducted using metallurgical test samples and pulps from cores with the aim of determining the potential for this deposit to sequester CO2 via direct air capture of atmospheric CO2 and carbonation using CO2-rich gas. The experimental direct capture rate was 3.5 kg CO2/m2/yr and would sequester 17 kt CO2/yr based on year-round reaction and when extrapolated to the scale of the proposed tailings facility (5 km2). This rate can be increased by ∼5 times (19 kg CO2/m2/yr) when aerating the tailings and would offset CO2 emissions by 95 kt CO2/yr (19–25% offset of projected CO2 emissions). Experimental carbonation rates with 10% CO2 gas could achieve offsets of up to 210 kt CO2/year (42–53% CO2 offset) based on 1 h reaction times and consumption of 0.8 wt% brucite if present. Targeting brucite-rich ore zones and optimizing CO2 delivery would likely lead to greater CO2 offsets.

An in-situ FT-IR based quantitative analysis model has been designed to track the internal state of solvent mixtures in a CO2 capture process. This approach is much faster and easier than using GC or NMR, but conventional linear multivariate analysis is not suitable due to the poor resolution of FT-IR. The conventional PLS regression also exhibits bad performance due to its inability to reflect the nonlinear behavior like peak shift, which is a common characteristic of the systems involving reactions. This paper proposes the artificial neural networks (ANNs) as an alternative nonlinear regression method. Two feature extraction methods, PCA and POD, are applied to reduce the redundancy and dimension of the input data as a preprocessing step. The neural network approach displayed higher accuracies in cross-validation and also in in-situ experiments compared to the PLS regression in a performance test involving three models. In particular, the POD-ANN method showed outstanding results with under 5 % relative error. This model can fulfill the function of an online monitoring system for CO2 capture processes and can provide information on water and solvent loss from evaporation or degradation. Furthermore, it can be utilized for control and fault detection techniques to maintain long-term operational stability of the system.

Coupled modelling, based on laboratory data, indicated that the storage seal above the Captain reservoir of the Peterhead CCS project could be affected by stresses caused by clay swelling due to CO2 interaction. In particular, calculations indicate that, over a period of 100 – 10,000 years, local shear failure in rock exposed to CO2 may occur under unfavourable stress conditions. The likelihood and consequences of local shear failure are however difficult to assess. We therefore defined passive safeguards against this potential risk to seal integrity. The basis for these safeguards is data and information given in the Peterhead CCS Storage Permit Application (storage seal thicknesses, lithologies, reservoir conditions etc.), chemical, thermodynamic and mechanical data from laboratory measurements, as well as the coupled model built and described earlier by Wentinck and Busch (2017). The passive safeguards provided in this study address the mineralogy of the caprock and more specifically its swellable clay content. Furthermore, the geometry of the reservoir is addressed, particularly with respect to the presence of pre-existing faults. Our model shows that for shear failure to be a risk a fault offset on the order of the thickness of the sealing layer needs to be present and in contact with the CO2 plume. It should be noted that swelling stress build-up may relax by creep of the surrounding shale matrix, thereby buffering this effect. Finally, the risk of CO2 to escape the storage container only exists when slip on pre-existing faults leads to permeability enhancement as well as reduction of capillary entry pressures along the fault. Our analyses show that the smectite contents of the unit at the base of the caprock is significant with an average of 57 %, substantiating the threat of clay swelling. Taking the locations of interpreted faults and the total storage seal thickness of 117−165 m, we find no potential offsets similar to this thickness, as identified offsets are up to 33 m. Unquantified uncertainties remain in the creep behaviour of the caprock as well as the fault permeability. Given however that a maximum fault offset is lower than the seal thickness, we classify loss of containment due to fault reactivation caused by swelling clays, and concomitant fluid leakage, to be a low geological risk for the Peterhead CCS project.

Carbon dioxide (CO2) injection into geological formations is gaining global interest. Examples include CO2 storage to mitigate greenhouse gas emissions and water alternating gas (WAG) injection for enhanced oil recovery (EOR) and storage. Injected CO2 inevitably dissolves in water (injected or formation), which results in acidic conditions that can dissolve the rock matrix in carbonate reservoirs. Depending on the dissolution’s location and pattern in the reservoir, this may benefit well injectivity and/or threaten well integrity. Fine-gridded models with detailed physics and chemistry capture the relevant effects but are not suitable for the application to the field scale where instead correlations are used. The correlations that exist, however, are so far not sufficiently constrained to be of practical use. We report new experimental and modelling work that provides the means for qualitative to quantitative field-scale predictions of these effects for all the different combinations of CO2–water injection of interest. These show that, for conventional injection strategies (dry CO2 injection and WAG), there are no material concerns, but there are potential well integrity issues that need more detailed investigation for the proposed alternative strategies of carbonated water injection or co-injection.

This paper assesses the role of carbon dioxide capture and storage (CCS) in addressing challenges in the energy transition in regions reliant on carbon-intensive industries for employment and as an economic base. The assessment is based on semi-structured interviews with relevant stakeholders and experts in the Aberdeen area in Scotland, the Rotterdam harbour (or Rijnmond) area in the Netherlands, and in Norway. The interviews explored challenges around the role of CCS in regional ‘just transitions’, or how to make the transformation of regions relying on carbon-intensive industries to a low-carbon society fair. While significant differences in responses between the Aberdeen area, the Rijnmond area and Norway were found, a common understanding showed that for CCS to contribute to a just transition it has to (a) make a contribution to climate change imperatives; (b) help to mitigate the economic and employment effects arising from declining or maturing industries; and (c) be undertaken in a manner that helps to redress (or at least does not increase) uneven vulnerabilities and inequalities in society. Five key themes that characterise the opportunities and challenges for CCS from a just transition perspective were drawn from the interviews: Skills for a just transition, transition as an opportunity, responsibility, scale of action and viability. We recommend that these are added to earlier work on barriers and enablers of CCS in areas relying on fossil industry.

Carbon Capture and Storage (CCS) is an essential technology for CO2 emissions reductions, which will allow us to continue consuming fossil fuels in the short to medium term. In this work, we developed a multiscale modeling and optimization approach that links detailed models of the capture plant, compression train and pipelines with the CO2 supply-chain network model. This was used to find the cost-optimal CO2 network considering a case-study of meeting a national reduction target in the United Arab Emirates that supplies CO2 for EOR activities. The main decision variables were the optimal location and operating conditions of each CO2 capture and compression plant in addition to the topology and sizing of the pipelines while considering the whole-system behaviour. A key result of our study was that the cost-optimal degree of capture should be included as a degree of freedom in the design of CO2 networks and it is a function of several site-specific factors, including exhaust gas characteristics, proximity to transportation networks and adequate geological storage capacity. This conclusion serves to underscore the need to comprehend the science governing the physical behaviour at different scales and the importance of a whole-system analysis of potential CO2 networks.

We investigated the relationship between amine structure and corrosion rates in a study of the corrosion behaviour of carbon steel in CO2-loaded 4-amino-1-propyl-piperidine (4A1PPD) solution and a series of related amines. Electrochemical measurements showed that 4A1PPD displayed the lowest corrosion rate of the amines studied, and that the corrosion rate decreased with the increase of the number of substituents on amino groups and a structural change from linear amines to cyclic amines. We also carried out a hydrothermal corrosion study using selected amines to analyse the surface morphology and composition formed on the surface of corroded carbon steel. The results suggested that the formation of a protective film was dependant on the ratio of bicarbonate/carbamate species. We confirmed that a dense FeCO3 protective film was produced on the carbon steel surface after hydrothermal corrosion treatment with CO2 rich 4A1PPD solution. Our results demonstrate that the 4A1PPD designer amine with a cyclic structure shows good corrosion properties for use in post-combustion CO2 capture and resulted in significantly reduced corrosion on carbon steel compared to the benchmark amine, monoethanolamine.

The combustion of fuel in oxygen rather than in air is one route to allow for the large-scale capture and storage of CO2. An alternative to the conventional air separation to produce oxygen, which imposes a significant energy penalty, is chemical looping air separation (CLAS). CLAS exploits the cyclic oxidation and reduction of solid oxygen materials. Here, the equilibrium partial pressure curves and the redox behavior for two potential materials (the perovskites SrFeO3-δ and SrMn0.1Fe0.9O3-δ) are derived from experiments. For the redox tests, a low dead volume micro reactor, operated as a differential packed bed, was used. This system enabled measuring the process of reduction at the 10 ms scale. Experiments were carried out between 798 and 898 K, with pO2 varied between 0 and 0.21 atm. All perovskites showed good performance during experiments lasting 1000 cycles. Despite similar chemical composition, the measured oxygen chemical potential and reduction kinetics differed between the tested materials significantly.

Geologic CO2 sequestration sites usually have large uncertainty in geological properties, such as uncertainty in permeability and porosity fields. Geological uncertainty leads to significant uncertainty in predicted risk metrics such as CO2 plume extent, CO2/brine leakage rates through wellbores, and impacts to drinking water quality in groundwater aquifers due to CO2/brine leakage, all of which will impact the approach for post injection site care (PISC). Pre-injection risk assessment can be used to quantify the amount of uncertainty in different predicted risk metrics. However, it cannot account for the potential value of monitoring data (e.g., CO2 saturation and pressure measurements) acquired during the operation of CO2 storage. In this study, we demonstrate how uncertainty in predicted risks can be reduced by performing monitoring data assimilation. An ensemble of geological reservoir models, constrained by direct measurements (such as permeability estimates from exploratory wells), are generated by geostatistical conditional simulation. As the monitoring data from the storage site become available, they are assimilated into models using a recently developed data assimilation method, ES-MDA with geometric inflation factors (ES-MDA-GEO). The reservoir models, calibrated through multiple data assimilation iterations, are used to predict future risks and reduction in their uncertainties. The proposed approach for the quantification of uncertainty reduction in risk assessment is demonstrated with two examples: a generalized 3D synthetic case and a synthetic field case based on the Rock Springs Uplift site in southwestern Wyoming.

The Upper Silesian Coal Basin in Poland is one of the major European hotspots of CH4 release. Until now, no data concerning short-term CH4 emissions from coal mines have been accessible worldwide. They are available only on a yearly timescale. No values are provided on a higher temporal scale, that’s why the measurements presented here are of great importance. This paper discusses short-term CH4 emissions from ventilation shafts of three mining fronts (Mf) divided into two periods. The concentrations of CH4 in shafts varied from 0.05 to 0.4 %. The highest levels occurred in Shaft IV (Mf I) and Shaft VI (Mf II): from 0.15 to 0.38 % (Period 1). These values correspond to emission levels ranging from 27 to 75 m3/min (Shaft IV) and from 18 to 40 m3/min (Shaft VI). In Period 2, the highest concentrations of CH4 occurred in Shaft VI (Mf II and III): from 0.2 to 0.4 %. The most significant CH4 emissions were recorded for Shaft VI (Mf II) and ranged from 29 to 54 m3/min. Presented data have been used to validate the measurements obtained in the CoMet campaign, which aimed at verifying the sensitivity of the test equipment operating from aircraft. During the test flights of HALO in 2015, the CoMet team achieved a remarkable consistency of measurements conducted with airborne equipment (26 ± 3m3/min) and the emission data (24.34 m3/min), for Shaft VI (Mf II). The analysed short-term data for individual shafts are more reliable and can improve CH4 flux estimates during the CoMet campaign in 2018.

The technical feasibility of removing heat stable salts (HSS) such as total organic acids (TOA) from industrial lean methyldiethanolamine (MDEA) solutions using calcium alginate/clay hybrid (CAH) composite adsorbent in a continuous fixed bed adsorber has been investigated. The effect of process parameters such as bed diameter, bed height, feed flow rate, and flow direction on breakthrough time, adsorption capacity, and exhaustion time of the fixed-bed sorption system was analyzed. Experimental results showed that higher bed diameter and height, lower flow rate along with up-flow column mode resulted in increased uptake capacity and breakthrough time. Progressive reduction in adsorption capacity from 3.6 mg/g to 2.83 mg/g after three adsorption/desorption cycles using 4.0 wt. % CaCl2 confirmed the practicability of the adsorbent. Simulation of breakthrough curves using general reaction rate models such as Bohart-Adams and Yoon-Nelson yielded a high correlation coefficient (R2 > 0.93), and thus validating the applicability of these models to predict the break through curves under various operating conditions. Furthermore, foaming experiments confirmed the vital role of CAH composite in reducing the foamability of lean MDEA solutions through the synergistic effect of successive biosorption and robustness of the saturated composites to multiple in-situ regeneration using CaCl2.

Quantifying the petrophysical properties of low-permeability sedimentary units helps to determine the possibility of upward flow of supercritical carbon dioxide when evaluating a site for safe confinement of geologic carbon storage. This research examines fine-scale pore characteristics that affect the sealing capacity of the Upper Ordovician Maquoketa interval, a thick and heterogeneous sequence of carbonates, siltstones, and clay-rich rock units in the Illinois Basin. This unit has been previously identified as a regional caprock that would likely isolate and effectively store any CO2 injected into underlying reservoirs. We applied a multi-technique approach to quantify pore-size distribution, pore surface area, porosity, permeability, and capillary entry pressure. These laboratory-based techniques include mercury porosimetry, gas adsorption, portable X-ray fluorescence, X-ray diffraction, total organic carbon analyses, and, to a lesser extent, scanning electron microscopy and petrography. In addition, we developed a lithofacies model that interpreted the combined wireline responses from multiple well locations. This model confirms that the Maquoketa Group is dominated by muddy limestone, dolomitic/calcitic shale, and silty shale. The results of these evaluations indicate that these sequences have low porosity (0.4–3.1 %) and low permeability (0.04–7.1 mD) values and capillary entry pressures adequate to inhibit invasion of supercritical CO2 driven by buoyancy forces. Laboratory results also indicate that portions of the Maquoketa Group may also function as a low-volume reservoir for CO2. That is, should supercritical CO2 migrate upward and percolate into this unit, most of the CO2 will likely be securely trapped by means of capillary mechanisms.

Mineral carbonation is a carbon utilisation technology in which an alkaline material reacts with carbon dioxide forming stable carbonates that can have different further uses, for instance as construction material. The alkaline material can be a residue from industrial activities (e.g. metallurgic slags) while CO2 can be recovered from industrial flue gasses. Mineral carbonation presents several potential environmental advantages: (i) industrial residues valorisation, (ii) CO2 sequestration and (iii) substitution of conventional concrete based on Portland cement (PC). However, both the carbonation and the CO2 recovery processes require energy. To understand the trade-off between the environmental benefits and drawbacks of CO2 recovery and mineral carbonation, this study presents a life cycle assessment (LCA) of carbonated construction blocks from mineral carbonation of stainless steel slags. The carbonated blocks are compared to traditional PC-based concrete blocks with similar properties. The results of the LCA analysis show that the carbonated blocks present lower environmental impacts in most of the analysed impact categories. The key finding is that the carbonated blocks present a negative carbon footprint. Nonetheless, the energy required represents the main environmental hotspot. An increase in the energy efficiency of the mineral carbonation process and a CO2 valorisation network are among the suggestions to further lower the environmental impacts of carbonated blocks production. Finally, the LCA results can promote the development of policy recommendations to support the implementation of mineral carbonation technology. Further research should enable the use of mineral carbonation on a broader range and large volume of alkaline residues.

Leakage of carbon dioxide (CO2) vessel can significantly affect the safety in the field of carbon capture and storage technology (CCS). Studies of small rupture leakage in the early accidental release stage are required. In this study, to investigate the release from small rupture under different working conditions, an experimental CO2 blowdown device was presented, transient pressure and mass flow rate were respectively measured and calculated, and also a pressure vessel release model was built. Besides, homogeneous model and phase separation model were employed to analyze the phase distribution in the vessel. According to the experiment results, the phase separation model shows a better applicability in small scale rupture leakage. The effect of initial pressure on pressure release is not obvious, while the effect of the initial temperature and nozzle location on pressure release is significant. When nozzle is located in the bottom of the vessel, pressure release becomes faster and more dangerous.

Chemical absorption is currently the most promising large-scale CO2 capture technology due to its high capture efficiency, mature process, and good compatibility. While this process uses solvent to absorb the CO2 from flue gas in absorption column, part of the solvents and its degradation products are discharged with the flue gas, causing new environmental pollution. This paper introduces the pollutants emission situation of chemical absorption CO2 capture process. The characteristics of three typical emission forms, including physical entrainment, gas and aerosol, are systematically depicted. Then, the formation mechanism and influencing factors of pollutant emissions are discussed. And the effect of flue gas nuclei and absorber conditions on aerosol emissions are also described. Finally, the paper summarizes the effects, advantages, and disadvantages of different emission control methods. This review can provide guidance for industrial applications of chemical absorption systems.

For the concerns of global warming, there is an urgent need of green, low-cost, and sustainable ways for the conversion and utilization of fossil energy. Holding the merit of inherent CO2 separation during carbonaceous fuel conversion, chemical looping technique is emerging as a perfect alternative to conventional fossil fuel conversion processes. Central to this technique is the design of high-performance oxygen carriers and suitable reactors that can efficiently realize the cyclic redox loop involved. To date, plenty kinds of (over 1200) oxygen carriers have been screened, synthesized and investigated by different research groups worldwide. Dozens of chemical looping reactors with thermal power ranged from kWth to MWth were also constructed and successfully operated. All these help to support the commercial demonstration and even industrial application of this innovative fuel conversion and carbon capture technique. The chemical looping related research at Huazhong University of Science & Technology (HUST) has experienced rapid development during the past 10 years, from rational synthesis of oxygen carrier to inter-connected fluidized bed reactor design and operation. In this article, the development of tailor-made oxygen carriers and active design of reactors at HUST is comprehensively reviewed and appraised, including the screening and optimization of oxygen carriers, reduction kinetics of oxygen carriers with gaseous fuels, microcosmic level understanding of the reaction mechanism in chemical looping via density functional theory (DFT) calculation, rational design and controllable synthesis of a hierarchically-structured oxygen carrier, and negative effects of pollutants (like sulfur and chlorides) on oxygen carriers. Moreover, experience gained from the design, macro simulation and modeling as well as continuous operation of inter-connected fluidized bed reactors is also provided. Overall, more than 100 different oxygen carriers based on Fe-, Cu-, Mn-, Ni-, as well as mixed oxides and natural ores, are systematically reviewed in terms of different chemical looping processes. The rational design route of a representative CuO@TiO2-Al2O3 oxygen carrier is proposed from the bottom up, on the basis of DFT calculation, molecular dynamic (MD) simulation, and detailed kinetics analysis. Over 300 h of continuous operation experience of the inter-connected fluidized bed reactor contributes to the demonstration of this technique. Numerical simulation via commercial computational fluid dynamics (CFD) software further helped the design, optimization, and scale-up of the reactor. In general, this review paper outlines the research route of chemical looping at HUST in details, which is expected to provide useful reference and guidance for the relevant readers.

The U.S. Environmental Protection Agency’s Class VI regulations for underground carbon dioxide (CO2) injection require owners and operators of storage projects to identify (1) an Area of Review (AoR) that represents the region that may be affected by the injection of CO2, and (2) leakage risks that might impact the quality of underground sources of drinking water (USDWs). This article describes how such risks can be determined by accounting for the physical and chemical properties of all components of a CO2 storage site using elements of the National Risk Assessment Partnership Integrated Assessment Model for Carbon Storage (NRAP-IAM-CS). We used practical data from three sites that are part of two CarbonSAFE (Carbon Storage Assurance Facility Enterprise) projects to demonstrate application of the NRAP-IAM-CS toolset to determine project risk areas. NRAP-IAM-CS was used to estimate the project risk area that could represent the AoR and the impact of leakage through legacy wells to overlying drinking waters at these candidate CO2 storage sites. Our study shows that risk to USDWs is minimal despite (1) the presence of multiple legacy wells at these sites where the AoR approximates the maximum extent of injected CO2 or (2) the presence of a much larger AoR approximating the pressure front caused by the injection of CO2.

Solvent-based post-combustion carbon capture (PCC) with packed column is the most commercially ready CO2 capture technology. To study commercial-scale PCC processes, validated pilot scale models are often scaled up to commercial-scale using the generalized pressure drop correlation (GPDC) chart which requires assuming the column pressure drop. The GPDC method may lead to either over-estimation or under-estimation of the column diameter. In this paper, a new method for estimating the packed column diameter without assuming the pressure drop has been proposed and used for model scale-up. The method was validated by scaling between two existing pilot plant sizes. The CO2 capture process was simulated in Aspen Plus® and validated at pilot scale. The validated model was scaled up to commercial CO2 capture plant capable of serving a 250 MWe combined cycle gas turbine power plant using the new method proposed in this study. The results obtained from the scale-up study were compared to those obtained when the GPDC method was used to design the same commercial CO2 capture plant. The results showed that the GPDC method overestimated the absorber and stripper diameter by 1.6 % and 8.5 % respectively. Process simulation results for the commercial-scale plant showed about 2.12 % and 5.63 % lower solvent flow rate and reboiler duty with the proposed method. Therefore, the capital and operating costs for the process using the newly proposed scale-up method could be lower based on our estimates of the column dimensions, solvent flow rate and specific reboiler duty.

Petroleum refineries and petrochemical plants are major CO2 sources, however, they are also significant capital and employment assets that are unlikely to be replaced in the near term. As a result, nations and states that are interested in reducing the carbon intensity of their economies will need to find ways to reduce the emissions of their existing industrial capacity. Industrial carbon capture provides one potential mechanism for reducing the carbon intensity of existing industrial facilities, however, an economically feasible capture system requires that the captured CO2 be integrated into a system of transport and storage with income generated either through tax credits, enhanced oil recovery (EOR), or both. Here, we present a cash-flow model of an integrated system with industrial capture, pipeline transport, and EOR, and we parameterize the model with data from Louisiana. Given a $50/bbl oil price, an integrated capture, transport and EOR system that uses ethylene oxide production, ammonia production, or natural gas processing as sources is predicted to have a net present value of about $500 million; hydrogen-based capture has a cash flow of −$214 given the same assumptions. Further, we find that the recent 45Q Tax Credit expansion has a positive impact on the cash flow of the system but does not change the overall profitability of the systems under the specified assumptions such that without the tax credits natural gas processing, ammonia production and ethylene oxide production-based capture systems remain cost-effective, while hydrogen-based capture remains unprofitable with or without the tax credit.

Reduced-order models (ROMs) are a widely used and powerful approach to reducing the complexity of predictive physics-based numerical simulations for a wide range of applications, including electronics and fluid mechanics such as geologic CO2 sequestration (GCS). ROMs are critical for optimization, sensitivity analysis, model calibration and uncertainty quantification where full-order models cannot be feasibly executed many times. Traditional approaches generate a single ROM for each simulated response (e.g., CO2 injection rates, pH changes) based on a set of training simulations. Here, we demonstrate that a single ROM can display excellent overall predictive statistics, but have predictions that dramatically and unacceptably deviate from simulator responses especially when the response variable has a large range (i.e., vary over multiple orders of magnitude). For example, we show that a traditional statistically-high-performing GCS ROM (coefficient of determination R2 of 0.99) can have average absolute relative errors of over 200%. To address this, we propose a new and novel approach where a set of sub-ROMs are generated to overcome the potential pitfalls in traditional single ROM development. The effectiveness of the proposed approach—the ROMster framework—is demonstrated using a case study of predicted CO2 injection rates for GCS. We find our approach is a robust and general framework for ROM development, reducing the average “error” from 200% to only 4% in our case study.

Recently, it has been shown that solutions of amino acid salts are suitable absorbents for CO2 separation. Potassium carbonate is an economic solvent; however, it has a slow reaction rate with CO2. In this work, potassium carbonate promoted with l-Proline, as an amino acid, is applied as a CO2 absorbent using a hollow fiber membrane contactor. Experimental results showed that recovery can rise up by adding l-Proline. Effects of parameters such as gas and liquid flow rates and concentration of absorbents on CO2 recovery and CO2 molar flux were investigated. The effect of wetting parameters, CO2 percent in feed gas and temperature on CO2 recovery were investigated by mathematical model. Results show that CO2 recoveries near 100 % can be reached at the l-Proline concentration of 0.1 mol/l, which reveals the potential of this amino acid as promoter of K2CO3.

In this work, the focus is given to the study of sequestration potential and recovery improvement in depleted NFRs using CWI. Initially a number of CWI experiments on reservoir cores with different wettabilities were modeled to verify physical aspect of the suggested simulation approach. Afterward, a modeling procedure was suggested to make an insight into the engineering parts of this process. In summary, it defined a 3 × 3×3[m3] reservoir rock matrix (a single matrix block, SMB) surrounded by carbonated water in fractures. The numerical aspects of the model were verified by a mesh independent study, in addition. The effects of several key parameters such as anisotropy, permeability, CO2 fraction in water, wettability alteration and block height were studied and compared for matrix blocks with different wettabilities. These effects were studied by incremental oil recovery and the amount of trapped CO2 in the matrix block. As indicated in this study, by implementing CWI, 10.6% incremental oil recovery can be achieved for a water-wet sample and 4.7% for an oil-wet sample during a period of 10 years. Moreover, about 3000[mol] CO2 were trapped in oil and water of the matrix after 10 years and this was increased to more than 8000[mol] after 100 years for the water-wet matrix block with a volume of 27[m3]. During the same period, by increasing the CO2 concentration from 1% to 2% in CW, oil recovery factor increased by 8.4% in water-wet sample. Subsequently, the amount of trapped CO2 grew from 850 to 3000[mol] in 10 years.

Faulting processes produce a complex fault damage zone (FDZ) having permeability variations over several orders of magnitude within a very short distance. In this study we use an example normal fault system from a depleted oil field in southern Louisiana with multiple stacked sand beds along the fault structure. Geostatistical techniques are used to introduce heterogeneities of several orders of magnitude over very short distances that honor the across- and along-fault architecture of the system. A total of 15 cases are simulated to account for the impact of a fragmented core, an intact core and a naturally fractured core on inter-sand leakage rates. The presented results show the complex nature of CO2 migration within the fault structure, where an interplay between overcoming the fault core’s high capillary entry pressure and stress propagation in the vertical direction dictates the leakage direction and rates. It is observed that hydromechanical evolution of fracture flow properties may result in significant leakage from the storage zone. In one case with small caprock thickness, a loss of 18% of the total injected mass is observed. The results presented highlight some unique features of representative fault related leakage in stacked sand systems and thus will be beneficial for storage integrity analysis in these systems.

Coal-fired chemical looping combustion (CLC) is a promising technology with inherent CO2 separation with a low energy penalty. One of challenges for coal-fired CLC is that char particles with slow gasification kinetics can be easily transferred into the air reactor (AR) by circulated oxygen carrier (OC), thereby decreasing the carbon capture efficiency. An annular carbon stripper (CS) was proposed to efficiently separate the char particles from the mixture of OC and char. A hot system of 10 kWth CLC unit coupled with an annular CS was designed, built, and operated in order to investigate the separation performance of an annular CS at high temperature (850-950 °C). Vietnamese ilmenite was used as OC to burn Shenfu bituminous coal. The system achieved a stable solid circulation at a high temperature with steady coal feeding, and total operation reached 100 h with a thermal input of 3-5 kWth. A 90%-95% char separation efficiency was achieved by the annular CS in various tests, and the carbon capture efficiency reached 95% at 950 °C. A special particle sampling device was designed to collect solid particles from the dense phase of CLC reactor during the continuous operation stage. It was found that the char mass faction in the FR dense phase was 0.45%-5.5% and a fraction of char adhered to the ilmenite surface, which was difficult to separate by the annular CS. Additionally, the sintering and agglomeration of ilmenite was not observed during continuous operation at 850-950 °C. Furthermore, through extrapolating experimental results, it is predicted that 90% carbon capture efficiency can be achieved by using this new annular CS in a scaled-up CLC system.

In most conceptual models of dissolution trapping of CO2, it is assumed that mixing of dissolved supercritical CO2 and formation brine occurs through density-driven convection. In our previous modeling study, we showed that the presence of continuous low-permeability shale layers in the formations causes convective shutdown through disruption of fingers, which impacts the effectiveness of mixing and trapping processes. However, these layers are naturally heterogeneous due to variations in compositional and textural properties. In the present study, we investigate the potential effects of heterogeneity present within semi-confining low-permeability layers on the overall mixing and trapping of dissolved CO2. Since accurate field experimentation in deep geologic formations is difficult due to inability to adequately characterize geology and define boundary conditions of the formation, we designed well-controlled experiments using NaBr solution and water under laboratory conditions. We conducted intermediate-scale 3D laboratory experiments under two homogeneous and one heterogeneous multilayered sand packing configurations. The results of these experiments show that connectivity of relatively higher permeability material within the semi-confining low-permeability layers contributes to mixing through (1) brine leakage between upper and lower aquifers (reverse convection), and (2) trapping through diffusion and back diffusion of initially trapped mass due to reversed concentration gradients in the long term. These findings suggest that when estimating the effectiveness of dissolution trapping in CO2 sequestration one needs to consider possible deviations from the traditional convective mixing theory in homogeneous media. Under some conditions of natural formation heterogeneity, diffusion can contribute to trapping; in some others, it may not.

The Paluxy formation is being considered as a prospective CO2 reservoir at the Kemper County CO2 Storage Complex. Here, the pore and pore-throat size distributions and connectivity of the Paluxy formation is evaluated through analysis of 3D X-ray Computed Tomography images. In spite of resolution limitations that constrain the pore-throat sizes detectable by imaging, the permeability contributing pore-throats are successfully characterized through 3D imaging analysis. Image-obtained pore and pore-throat size distributions and pore connectivity are then utilized to construct pore network models and simulate permeability. After CO2 is injected, it will dissolve into formation brine and create conditions favorable for dissolution of primary minerals and precipitation of secondary minerals. These reactions will alter the porosity and permeability of the system to varying degrees depending on the spatial location of reactions. Here, the possible porosity-permeability evolution is simulated using pore network models considering mineral reactions occurring uniformly and non-uniformly throughout the network. For a given change in porosity, there is a large range of possible permeability outcomes. Depending on the extent and spatial location of mineral reactions, permeability may decrease by more than one order of magnitude as minerals precipitate. During dissolution, simulated permeability increases as much as 500%.

This paper explores the viability of Carbon Capture and Storage (CCS) in Italy by examining two different scenarios. The first scenario evaluates the investments on traditional power generation technologies, i.e. USC (Ultra Super Critical), NGCC (Natural Gas Combined Cycle) and IGCC (Integrated Gas Combined Cycle), with and without CCS, and on wind farms; the second scenario studies the convenience of retrofitting existing Italian power plants with respect to the construction of new capture-ready plants. To the scope, a techno-economic analysis based on the calculation of the LCOE (Levelised Cost Of Electricity), the CCAV (cost of CO2 avoided) and the CCAP (cost of CO2 captured) is assessed. Beyond these measures, the analysis in both scenarios accounts for the calculation of the so-called LACE (Levelised Avoided Cost of Electricity) in order to evaluate the profitability of CCS systems and, therefore, to properly orient CCS investment decision in Italy.

Captured CO2 from large industrial emitters may be used for enhanced oil recovery (EOR), but as of yet there are no European large-scale EOR systems. Recent implementation decisions for a Norwegian carbon capture and storage demonstration will result in the establishment of a central CO2 hub on the west-coast of Norway and storage on the Norwegian Continental Shelf. This development may continue towards a large-scale operation involving European CO2 and CO2 EOR operation. To this end, a conceptual EOR system was developed here based on an oxyfuel power plant located in Poland that acted as a source for CO2, coupled to a promising oil field located on the Norwegian Continental Shelf. Lifecycle assessment was subsequently used to estimate environmental emissions indicators. When averaged over the operational lifetime, results show greenhouse gas (GHG) emissions of 0.4 kg CO2-eq per kg oil (and n kWh associated electricity) produced, of which 64 % derived from the oxyfuel power plant. This represents a 71 % emission reduction when compared to the same amount of oil and electricity production using conventional technology. Other environmental impact indicators were increased, showing that this type of CO2 EOR system may help reach GHG reduction targets, but care should be taken to avoid problem shifting.

Calcium Looping (CaL) is a technology that makes use of CaO to capture CO2 from industrial flue gas sources in a carbonator, after which the CO2 is released in a concentrated form in an oxyfired calciner. The CO2 carrying capacity of the particles circulating between the carbonator and calciner is a key variable, as it is intimately linked to CO2 capture efficiency in the carbonator reactor. Therefore, the ability to predict dynamic changes in the CO2 carrying capacity of the sorbent is required to understand the dynamic performance of CaL systems. This work investigates the dynamic evolution of the average CO2 carrying capacity of the sorbent (Xave) during transient scenarios in a large CaL pilot plant. Several experimental campaigns with extensive solids sampling and analyses were carried out to analyse the evolution of Xave with time when the make-up flow fed into the calciner is modified (between 0–2.7 kmol CaCO3/h). Variations in Xave were tracked and the observed trends were interpreted using two residence time distribution models of different complexity. The main characteristics and limitations of each model are discussed in this study. The choice between the two modelling approaches developed in this work depends on the input information available and the degree of accuracy required for each specific application.

One of the great challenges in carbon capture and storage (CCS) development is the monitoring and determination of the underground CO2 plume migration. We show that time-lapse 2D vertical seismic profiling (VSP) technology can support the monitoring and numerical modeling of CO2 plume migration at a storage site. Using the Shenhua CCS demonstration project in China as a case study, we predicted the physical parameters of the main reservoir, including the distribution of bodies of sandstone and their porosity and permeability, required to upgrade the geological model. We also interpreted the characteristics of historical CO2 plume migration in one seismic profile of the second and third periods of VSP monitoring. Based on a new upgraded geological model, we simulated the historical CO2 plume migration characteristics under the actual injection scenario of the demonstration project. The results of the simulation exhibited good consistency with the time-lapse VSP monitored in the profile, thus indicating that both the geological and numerical models have a certain degree of credibility. We further simulated the characteristics of CO2 plume migration after the injection well shutoff before 2035.

An important leakage risk associated with CO2 geological sequestration is the potential transport and fate of organic contaminants due to the CO2 leakage. In this paper, a precipitation and deposition dynamic model was constructed using COMSOL to evaluate the potential impacts of organic contaminants in response to the leakage of CO2 and brine into a shallow aquifer. The Span-Wagner equation and Peng-Robinson equations were adopted to estimate the partitioning behavior of organic contaminants. Numerical simulations with naphthalene as a representative contaminant show that the dissolved component is transported with the equilibrium concentrations at the thermodynamic conditions built by the fluid phase, while the precipitated solid particles are either transported with carrier fluid or deposited in the leakage pathway according to the deposition dynamic model. The sharp decrease of solubility promotes the precipitation impetus while the deposition rate mainly depends upon the leakage velocity and pore structure. Local blockage may occur due to the accumulation of deposited particles, and the potential location is most likely to be near the outlet of the leakage pathway in current scenario. Sensitivity analyses indicate that pressure difference and temperature buildup would influence both the leakage velocity and deposition dynamics, while the pore structure of leakage pathway, represented by porosity and permeability, will affect the leakage characteristic so as to the deposition rate. The presented models are generic in nature for naphthalene transport, demonstrating a methodology that can explore the generation of a potential third organic phase in contaminant transport for risk assessments.

CCS is expected to be one of the major measures contributing to carbon reduction and meet net zero emission in near future. Fossil fuel power plants equipped with CCS can be considered to be zero-carbon power generation if nearly full CO2 recovery is feasible. The objective of this paper is to investigate the process performance and plant economics at 99.5% CO2 capture ratio that has not been studied before using MHIENG’s CO2 capture technology. It is expected that this work using experiences and empirical data that MHIENG has accumulated is more indicative of current commercial CCS technology and economics than previous work. The near-zero emission design proposed in this work using 50% additional absorption packing achieves 99.5% capture ratio with similar normalized OPEX ($/tonne CO2) and 6% higher normalized CAPEX compared to base case at 90% capture ratio. Near-zero emission coal-fired power plant is technically feasible using the Advanced KM CDR Process™ and KS-1™ solvent and will increase cost of CO2 captured by 3% compared to default design at 90% capture ratio.

In chemical looping combustion (CLC), the chosen oxygen carrier’s (OC) reactivity maintenance and attrition propensity play key roles in determining its lifetime in such systems. Jet and cyclonic attrition are two main mechanisms of attrition in CLC systems, which typically use fluidized beds and cyclones. In contrast to standardized tests, that assess attrition characteristics under ambient and non-reacting conditions, a realistic evaluation must include the behavior under relevant high temperatures and cyclic oxidation-reduction. In this study, separate jet and cyclonic attrition test units were constructed to investigate the effects of temperature, fuel gas concentration and velocity on the performance of ilmenite, a natural ore-based OC in CLC. Testing showed that thermal and chemical effects were crucial to accurately determine the performance of ilmenite. For experiments conducted between 820°C and 970°C, the intermediate temperature of 895°C provided the best balance between high reactivity and material durability. Additionally, fuel gas concentration affected particle morphology evolution. Iron migration to the surface of the ilmenite particle was enhanced at higher fuel gas concentrations and resulted in reduced attrition rate, presumably due to sintering of the more highly reduced enriched iron phase on the particle surface. The laboratory jet and cyclonic attrition evaluation test units tested in this study can be used to investigate multiple parameters relevant for OC performance, including the degree of reduction, oxygen carrying capacity, attrition resistance, agglomeration, and optimum material operability conditions, as well as to extrapolate test data to determine OC replacement costs in a commercial CLC system.

Carbon dioxide (CO2) capture and storage (CCS) technology and renewable power are indispensable in China’s power sector to limit global warming to 2°C. Because the two technologies have their own merits and weaknesses, it is important to understand their investment benefits and choose a cost-effective portfolio. Therefore, we conducted an investment evaluation of CCS retrofitting of coal-fired power plants (CFPP) with hypothetical subsidies and renewable power generation projects (RPP) by using a real option trinomial tree pricing model and compared their economic benefits in different provinces in China. The results showed that when subsidies for the desulfurization price or the feed-in tariff of wind power were adopted, the CCS retrofitting of CFPP did not achieve the optimal investment value, even in 2027. If the decarbonized electricity price increases to 0.75 CNY/kWh, equal to the feed-in tariff of solar photovoltaic and biomass power, the CCS retrofitting of CFPP would be commercially viable, and their investment value would exceed that of wind power generation projects. In this situation, Ningxia, Xinjiang, and Gansu Provinces would be most suitable for the development of CCS retrofitting pilot projects; the advantages of the CCS retrofitting of CFPP were not significant, whereas RPP was a better investment choice in many provinces. This paper provides a perspective on feed-in tariffs for policy makers to use in formulating a subsidy system to support the development of CCS in China, with policy implications for other countries.

Understanding of flow barriers in a saline aquifer evaluated for geological storage of carbon dioxide is the key point for decision making and designing injection operations. The barriers may significantly limit injection capacity, while their dynamic behavior during the operational phase, like fault reactivation and leakage out of the target formation, may cause unexpected completion of injection phase and have negative environmental consequences. The pressure data obtained in real-time during well testing and main phase of injection with installation of Permanent Downhole Gauges (PDG) may be utilized to characterize and monitor reservoir boundary conditions. Here, Pressure Transient Analysis (PTA) can be employed as interpretation tool. In this work, the case of faults acting as flow barriers including scenarios of sealing and leaking faults is studied using the history of CO2 injection into the Tubåen formation of the Snøhvit field as testing data set. The paper starts from answering general questions on applicability of PTA for CO2 injection, related to capabilities and limitations of single-phase flow models. It continues with suggesting and testing approximate approaches to improve the capabilities of such models to deal with CO2 injection cases (brine replica). Finally, an integrated workflow (or a technology, if combined with well surveillance system) for characterizing and monitoring flow barriers in geological storage projects is suggested. This workflow uses advantages of the models above for real-time data analysis. The paper concludes with recommendations for pre-injection well testing and surveillance during main injection phase, closing the loop with application guidelines.

Understanding opportunities for carbon capture and storage (CCS) across sectors is important for choosing among greenhouse gas mitigation strategies. This study explores the cradle-to-gate life cycle environmental impacts of amine solvent based carbon capture systems on U.S. ammonia production, petroleum refineries, supercritical and subcritical pulverized coal power plants, and natural gas combined cycle plants. We use publicly available data to create comprehensive life cycle inventories for petroleum refining and ammonia production for 2014. We use these processes and additional modeled carbon capture processes to compare carbon capture on ammonia production and petroleum refining to inventories for coal and natural gas fired electricity with carbon capture. This analysis found that particulate matter formation potential, eutrophication potential, and water consumption increase in all sectors as a result of installation and operation of CCS technologies per kg CO2e abated, while the effect on acidification potential and particulate mater formation potential is mixed. The differences in tradeoffs among systems are driven primarily by three factors: the combustion emissions from fuel used to operate the capture unit, the upstream supply chain to obtain that fuel, and the relative impact of the carbon capture unit on baseline flue gas emissions (i.e. possible co-benefits from capture).

Carbon dioxide enhanced oil recovery (CO2-EOR) can capture, transport and store CO2 emitted by high energy consumption enterprises. Therefore, the use of CO2-EOR enhances oil recovery and is also an effective means of reducing CO2 emissions. Currently, energy and environmental assessments of CO2-EOR have been rare in China. In this study, partial life cycle assessment (LCA) is used to evaluate the energy consumption and air emissions gate to grave in a CO2-EOR test station for extralow permeability reservoirs in northern China. The gate to gate of CO2-EOR defines 5 stages: transportation, liquefaction, injection, oil production and recycling. Through the analysis of these stages, the results show that producing one metric ton of crude oil gate to gate consumes 2472.56 kW hours of electricity and emits 2532.63 kilograms of CO2, 74.18 kg of SO2 and 37.38 kg of NOx. Water flooding that occurs under similar geological conditions is selected and compared with CO2-EOR for energy consumption and air emissions. In the case of producing one metric ton of crude oil, CO2-EOR gate to gate consumes more electricity than water flooding gate to gate and emits more CO2, SO2 and NOx. Compared with the amount of CO2 injection, the net CO2 emissions of CO2-EOR gate to gate to produce one metric ton of crude oil are -1675.15 kg, and the net CO2 emissions of water flooding gate to gate to produce one metric ton of crude oil are 775.83 kg. When considering energy consumption in the downstream segments of CO2-EOR, the net CO2 emissions of CO2-EOR gate to grave to produce one metric ton of crude oil are 0.53 metric tons. The results of this study provide valuable insights into the policy implications and sustainable development of CO2-EOR in China.

Underground coal gasification (UCG) has the potential to provide a source of energy or chemical feedstock derived from coal seams, where traditional mining methods are not suitable or are uneconomical. This paper presents the life cycle inventory models developed for the UCG processes and three alternative syngas utilisation options with and without CO2 capture and storage. The paper compares the life cycle carbon footprint of two different conventional above ground coal fired power generation options with UCG Integrated Gasification Combined Cycle power generation with/without CCS for two different lignites and one bituminous coal. One of the lignites is then used to compare the life cycle performance of different syngas utilisation options: power generation, ammonia production with power generation, and methanol production with power generation. It was found that the life cycle carbon footprint of conventional above ground coal fired power generation is very much dependent on the in-situ methane content of the coal used, and methane emissions experienced during mining and accompanying upstream processes, whereas the same for UCG-IGCC power depends more on the process dependent syngas composition. UCG methanol production with associated power and CCS is shown to release more life cycle CO2-eq emissions per tonne of lignite consumed than that of UCG ammonia production with associated power and CCS and UCG CCGT power generation with CCS. Furthermore, when chemicals production from UCG is considered as the main objective, the most substantial improvements in comparison to conventional methods are associated with UCG ammonia process per tonne of chemical produced.

In this review paper, an extensive overview of solar assisted carbon capture systems is presented. The focus of this paper is on possible integration schemes between solar thermal collectors and carbon capture systems. In its entirety, solar assisted carbon capture systems can be categorized into direct and indirect systems. This classification is applicable to all three possible processes, namely post-combustion, pre-combustion, and oxyfuel combustion. Key factor in designing solar assisted carbon capture systems is to match the thermal-grade between the collector and gas separation process. Possible future research direction for solar assisted carbon capture systems can be classified into solar collectors cost reduction research and innovative integration scheme research.

Injection of CO2 into brine-saturated reservoir rocks reduces their elastic moduli and thus changes the seismic response. However, estimation of the stiffness reduction and 3D plume morphology have large uncertainty for regular Signal-to-Noise Ratio (SNR) and amount of prior geological information. This paper examines achievable accuracy of the time-lapse seismic inversion based on Stage 2C of the CO2CRC Otway Project, which was specifically designed to test the sensitivity of seismic monitoring. Thanks to rich geological dataset, we could build a set of adequate subsurface models to optimise the inversion workflow and assess its capability. Firstly, 1D stochastic simulations and analytical models are used to estimate the effects of imperfect repeatability and limited bandwidth of the seismic (SNR ≈ 4). Then, we test a prototype inversion workflow on a virtual seismic survey - full-scale time-lapse synthetic seismic produced by 3D simulations in a detailed full-earth model. This test shows that the errors associated with approximate nature of the seismic inversion algorithm reduces SNR to 2.1. Furthermore, detectable thickness of the plume reduces to 10 m when the plume is laterally finite. The key findings of the synthetic study help design the inversion workflow for the Stage 2C field data. Inverted parameters of the CO2 plume agree well with independent measurements, including repeat pulsed-neutron logging, in- and above-zone pressure monitoring and borehole seismic. To extract the plume body from the noisy inversion output, we use a Neyman-Pearson detector augmented by a spatial connectivity constraint. The proposed extraction criterion is then employed to compare history-matched reservoir with the monitoring data. For the simulated CO2 distribution, the proposed workflow would detect 70% of the plume areal footprint. The missed samples correspond to thin parts of the plume with low saturation, and hence their effect on the estimated total mass of CO2 in the reservoir is minimal.

This paper describes two indoor shelter models – an analytical model and a Computational Fluid Dynamics (CFD) model - that can be used to predict the level of infiltration of carbon dioxide (CO2) into a building following a release from an onshore CO2 pipeline. The motivation behind the development of these models was to demonstrate that the effects of shelter should be considered as part of a Quantitative Risk Assessment (QRA) for CO2 pipeline infrastructure and to provide a methodology for considering the impact of a CO2 release on building occupants.A key component in the consequence modelling of a release from a CO2 pipeline is an infiltration model for CO2 into buildings which can describe the impact on people inside buildings during a release event. This paper describes the development of an analytical shelter model and a CFD model which are capable of predicting the change in internal concentration, temperature and toxic load within a single roomed building that is totally engulfed by a transient cloud of gaseous CO2. Application of the models is demonstrated by comparison with experimental measurements of CO2 accumulation in a building placed in the path of a drifting cloud of CO2. The analytical and CFD models are shown to make good predictions of the average change in internal concentration. Furthermore, it is demonstrated that the effects of shelter should be taken into account when conducting QRA assessments on CO2 pipelines.

Quantum chemical calculations was used for efficiently screening of the corrosion inhibitors from a series of organic and inorganic inhibitors for 20# carbon steel in CO2-saturated [TETAH][Lys] solution in the this work, which was different from the traditional usage by employed for confirming the experimental results. The inhibitors of MBI and Na2MoO4 were emerged as the best alternatives, inhibiting the corrosion by provided a layer of protection between the carbon steel and the solution. It was found that the greatest contribution to the adsorption of MBI and Na2MoO4 was S15 and Mo1, and these two inhibitors were of the mixed and anodic type inhibitor, respectively. The adsorption of them on carbon steel obeyed the Langmuir isotherm and involved competitive physisorption and chemisorption. The kinetic of the adsorptions were investigated, and the thermodynamic parameters had been calculated. The experimental results demonstrated a reasonably good agreement between theory and experiment, and a reference was provide for the optimum additive agent in the technical design.