CO2 Stream Research Articles

Techno-Economic Aspects of Noble Gases as Monitoring Tracers

A comprehensive monitoring program is an integral part of the safe operation of geological CO2 storage projects. Noble gases can be used as geochemical tracers to detect a CO2 anomaly and identify its origin, since they display unique signatures in the injected CO2 and naturally occurring geological fluids and gases of the storage site complex. In this study, we assess and demonstrate the suitability of noble gases in source identification of CO2 anomalies even when natural variability and analytical uncertainties are considered. Explicitly, injected CO2 becomes distinguishable from shallow fluids (e.g., subsea gas seeps) due to its inheritance of the radiogenic signature (e.g., high He) of deep crustal fluids by equilibration with the formation water. This equilibration also results in the CO2 inheriting a distinct Xe concentration and Xe/noble gas elemental ratios, which enable the CO2 to be differentiated from deep crustal hydrocarbon gases that may be in the vicinity of a storage reservoir. However, the derivation has uncertainties that may make the latter distinction less reliable. These uncertainties would be best and most economically addressed by coinjection of Xe with a distinct isotope ratio into the CO2 stream. However, such a tracer addition would add significant cost to monitoring programs of currently operating storage projects by up to 70% (i.e., from 1 $US/t to 1.7 $US/t).

Power-Generating Electrochemical Anion Exchange CO2 Separator for Practical AEMFC Application

Anion exchange membrane fuel cells (AEMFCs) have been widely touted as a low- cost alternative to existing proton exchange membrane fuel cells. However, one of the limitations of this technology has been the severe performance penalty related to the introduction of CO2 to the cell (typically from air in the cathode feed). A low cost, low energy solution is needed that is able to remove CO2 from the incoming air before it is fed to the AEMFC system.1,2 Many approaches to removing CO2 from the cathode inlet would consume valuable energy and complicate the systems-level balance-of-plant. However, recently3, an electrochemical approach was proposed that i) is able to generate power; and ii) takes advantage of the carbonation phenomena that harms AEMFCs. Such a device can be called an anion exchange CO2 separator (AECS).An AECS operates on the same principles as an AEMFC. H2 is fed to the anode and O2/air is fed to the cathode. As OH- is formed from the oxygen reduction reaction at the cathode, it is converted to carbonates by reaction with carbon dioxide. The carbonates are transported to the anode by migration where they are eventually released as CO2. Ideally, an AECS operates on waste H2 and a high concentration CO2 stream leaves the anode and an air stream devoid of CO2 leaves the cathode. By design, the AECS is smaller than the primary AEMFC. Because carbonates are present, the AECS operates at a lower power density than the AEMFC, but the method has the promise to use waste to generate energy while removing CO2.In this work, the effectiveness of an AECS in lowering the CO2 concentration of an incoming stream of 400ppm air is investigated. Several parameters are changed, including the AECS active area and anode flowrate. The primary focus of these experiments was to develop operating conditions that lead to very low ppm CO2 concentrations leaving the AECS cathode. In addition to showing significant CO2 removal, we also show an AECS that operates with a stable output for over 150 h. Finally, AEMFC operation on AECS-purified industrial air is successfully demonstrated. References Zheng, T. J. Omasta, X. Peng, L. Wang, J. R. Varcoe, S. Pivovar, and W. E. Mustain, Energy Environ. Sci., 12, 2806–2819 (2019).R. Gerhardt, L. M. Pant, H.-S. Shiau, and A. Z. Weber, ECS Trans., 86, 15–24 (2018).Yan, B. Setzler, Y. Zhao, M. S. R. Carbonell, and S. Gottesfeld, U.S. Patent No. 10,811,711. 20 Oct. 2020.

A highly carbon‐efficient and techno‐economically optimized process for the renewable‐assisted synthesis of gas to liquid fuels, ammonia, and urea products

Carbon dioxide conversion into beneficial products has received very much attention in recent years to decrease industrial CO2 emissions. In this context, integration of gas to liquids (GTL) process with an iron-based Fischer-Tropsch (FT) reactor with ammonia and urea synthesis plants was investigated. The main motivation of the proposed integration is to reuse a released CO2 stream from the GTL process and to enhance the commercial process economy. The required hydrogen for ammonia comes from polymer electrolyte membrane (PEM) electrolyzers running by solar power. Latin hypercube design (LHD) approach was applied to model the profitability and carbon efficiency of the process. Optimization was conducted to maximize the carbon efficiency and profit index of the overall process using the model-based calibration (MBC) toolbox of MATLAB. The results demonstrated that at the optimum case, the proposed integration is capable of producing 48 t/h of urea and also utilizing about 35 t/h of CO2 produced in the GTL process. The results were compared with another configuration in which a cobalt-based FT reactor was integrated with ammonia and urea processes. The results suggest that profitability, carbon efficiency, and urea production of the process configuration with a Co-based FT reactor is higher than the iron-based configuration while the wax production rate of the iron-based configuration is higher than that of the Co-based process. Techno-economic feasibility study of the zero CO2 emission process represents that the carbon efficiency of around 100% could be obtained.

CO 2 mineral trapping comparison in different regions: predicted geochemical reactivity of the Precipice Sandstone reservoir and overlying Evergreen Formation

Injected CO 2 streams may have geochemical reactivity to different rock types in a CO 2 storage complex depending on solubility and formation water chemistry. The Precipice Sandstone and Evergreen Formation are a low-salinity reservoir–seal pair in the Surat Basin, Australia, targeted for potential CO 2 storage. The kinetic geochemical CO 2 reactivity of different rock facies from three regions were predicted over 30 and 1000 year time periods. No material CO 2 mineral trapping in the quartz-rich Precipice Sandstone reservoir was predicted, owing to the low rock reactivity. Predicted CO 2 mineral trapping in the Evergreen Formation was more variable due to different amounts of more reactive feldspars, clays, calcite and siderite. Predicted mineral trapping as siderite and ankerite was between 0.03 and 8.4 kg m −3 CO 2 , and mainly depends on chlorite and plagioclase content. Predicted pH was between 5 and 7.5 after 1000 years. Pyrite precipitation was also predicted with SO 2 present in the injectate. QEMSCAN and SEM-EDS (scanning electron microscopy and energy-dispersive spectroscopy) spot imaging of samples from the seal containing natural fractures filled by siderite, pyrite, clays, ankerite, calcite, barite and apatite represent a natural analogue for natural mineral trapping. These are in good agreement with our model predictions. This study suggests that, from a geochemical perspective, the Precipice Sandstone is a suitable storage reservoir, whereas mineral trapping would occur in the overlying Evergreen Formation. Supplementary material: Additional model inputs, characterization and model images, and an excel file of QEMSCAN mineral and porosity components, are available at https://doi.org/10.6084/m9.figshare.c.5395393 Thematic collection: This article is part of the Geoscience for CO 2 storage collection available at: https://www.lyellcollection.org/cc/geoscience-for-co2-storage

Demonstration of a ceria membrane solar reactor promoted by dual perovskite coatings for continuous and isothermal redox splitting of CO2 and H2O

The direct one-step CO2 and H2O splitting using an oxygen-transport membrane (OTM) reactor was investigated as a potentially ideal way to generate renewable fuels from concentrated solar energy. The solar-driven thermolysis of CO2 (or H2O) was promoted by in-situ oxygen removal across nonstoichiometric ceria-based membranes. A new solar membrane reactor integrating a tubular densified membrane made of either pure ceria or perovskite-coated ceria was designed and operated under high-flux concentrated solar radiation. A continuous flow of inert gas on the permeate side was used to create the required oxygen partial pressure gradient (driving force) and ensure continuous oxygen permeation via oxygen ion diffusion across the densified ceria membrane. The continuous OTM solar operation at high temperature was demonstrated through testing under various operating conditions. The CO and O2 production rates were sharply enhanced by increasing the operating temperature (up to 1550 °C). The increase of CO2 concentration or oxidant gas flow rate also enhanced the process performance. Unprecedented fuel production rates (>0.07 μmol s−1 cm−2 at 1550 °C) were achieved with a pure CO2 stream on the feed side and flowing Ar on the sweep side of the reactive ceria membrane. An original composite membrane integrating two different perovskite coatings on each side of the ceria membrane, with a sandwich-like structure, was designed and tested under concentrated sunlight. Thin layers of La0.5Sr0.5Mn0.9Mg0.1O3 on the inner side and Ca0.5Sr0.5MnO3 on the outer side were added to enhance oxygen ion transfer. With such a membrane configuration, a remarkable production of CO (>0.13 μmol s−1 cm−2) and oxygen (with CO:O2 ratio of 2) was obtained simultaneously, respectively on the inner and outer sides of the OTM. These results outperform the production rates achieved with the uncoated ceria membranes, and demonstrate the benefits of using composite membranes composed of a densified core material coated with (or sandwiched in between) redox active perovskite materials.

Inside the reaction mechanism of direct CO2 conversion to DME over zeolite-based hybrid catalysts

This paper aims at shedding more light on the reaction mechanism behind the direct hydrogenation of CO2 streams into DME in presence of hybrid catalysts. Starting from the physico-chemical properties of an optimized CuO-ZnO-ZrO2/HZSM-5 catalytic system, whose synergy among active sites of different nature (i.e., metal/oxide and acid/base) was recently proposed as the key to overcome the typical limitations showed by random mixing of two preformed catalysts, new evidences are herewith reported about catalytic performance, conditions for activation of reactants, limiting steps and product formation. Likewise to other proposed mechanisms at the state of the art, the catalyst efficiency is resulted to be dependent on several catalyst features, related not only to the metal-oxide phase responsible for CO2 activation/hydrogenation, but also to specific characteristics of the zeolite (i.e., porosity, specific surface area, population, location and strength of acid sites, interaction with active metals, …), influencing the activity-selectivity pattern. The production of DME is conditioned by the rate of methanol formation in proximity of the metal-oxide interface, followed by a rapid transferring of methanol towards the neighboring acid sites of the zeolite. Operando spectroscopic investigations performed under simulated reaction conditions (30 bar, 200−260 °C) have shown that the intermediates formation strongly depends upon a concurrence of texture, structure and surface aspects; however, depending on the reaction conditions, methanol formation normally passes through the formation of formate species. From a technological point of view, a reaction pressure of 30 bar appears as the ideal compromise between CO2 conversion and limitation of operative costs, while, due to thermodynamic restrictions, a reaction temperature not higher than 200 °C is necessary to attain DME selectivity close to 90 %.

A System Integration Analysis of a Molten Carbonate Electrolysis Cell as an Off-Gas Recovery System in a Steam-Reforming Process of an Oil Refinery

Technologies capable of efficiently exploiting unavoidable CO2 streams, have to be deeply investigated and deployed during the transition phase to achieve long-term climate neutrality targets. Among the technologies, Molten Carbonate Cells (MCC) Operating in Electrolysis Mode (MCEC) represents a promising facility to valorize CO2-rich waste streams, which are typically available in industrial plants, by their conversion into a high-value H2/CO syngas. These gaseous products can be reintegrated in a plant or reused in different applications. This study analyzes the integration of a system of the MCEC unit under different operating conditions in terms of composition, current density, and the utilization of fuels in a steam-reforming process of an Italian oil refinery via a mixed experimental-simulative approach. The aim of the current study is to assess the improvement in the overall product yield and further impacts of the MCEC unit on the plant efficiency. The results have shown that it is possible to obtain an electrochemical Specific Energy Consumption for the production of H2 of 3.24 kWh/NmH23 using the MCEC, whereby the possible integration of a 1-MWe module with a reformer of the proposed plant not only increases the hydrogen yield but also decreases the amount of fuel needed to assist the reforming reaction and separates a CO2 stream after additional purification via an oxy-fuel combustor, consequently determining lower greenhouse gases emissions.

Negative CO2 Emissions for Transportation

Negative emission technologies have recently received increasing attention due to climate change and global warming. One among them is bioenergy with carbon capture and storage (BECCS), but the capture process is very energy intensive. Here, a novel pathway is introduced, based on second-generation biofuels followed by carbon circulation in an indefinitely closed chain, effectively resulting in a sink. Instead of using an energy-intensive conventional CCS process, the application of an on-board solid oxide fuel cell (SOFC) running on biofuels in an electric vehicle (FCEV) could result in negative emissions by capturing a concentrated stream of CO2, which is readily stored in a second tank. A CO2 recovery system at the fuel station then takes the CO2 from the tank to be transported to storage locations or to be used for local applications such as CO2-based concrete curing and synthesis of e-fuels. Incorporating CO2 utilization technologies into the FCEVs-SOFC system can close the carbon loop, achieving carbon neutrality through feeding the CO2 in a reverse-logistic to a methanol plant. The methanol produced is also used in SOFCs, leading to an infinite repetition of this carbon cycle till a saturation stage is reached. It is determined this pathway will reach typical Cradle-to-Grave negative emissions of 0.515 ton CO2 per vehicle, and total negative CO2 emission of 138 Mt for all passenger cars in the EU is potentially achievable. All steps comprise known technologies with medium to high technology readiness level (TRL) levels, so principally this system can readily be applied in the mid-term.

Preventing Agglomeration of CuO-Based Oxygen Carriers for Chemical Looping Applications

Chemical looping combustion (CLC) is a promising alternative to the conventional combustion-based, fossil fuel conversion processes. In CLC, a solid oxygen carrier is used to transfer oxygen from air to a carbonaceous fuel. This indirect combustion route allows for effective CO2 capture because a sequestrable stream of CO2 is inherently produced without any need for energy-intensive CO2 separation. From a thermodynamic point of view, CuO is arguably one of the most promising oxygen carrier candidates for CLC. However, the main challenge associated with the use of CuO for CLC is its structural instability at the typical operating temperatures of chemical looping processes, leading to severe thermal sintering and agglomeration. To minimize the irreversible microstructural changes during CLC operation, CuO is commonly stabilized by a high Tammann temperature ceramic, for example, Al2O3, MgAl2O4, and so forth. However, it has been observed that a high Tammann temperature support does not always provide a high resistance to agglomeration. This work aims at identifying the descriptors that can be used to characterize accurately the agglomeration tendency of CuO-based oxygen carriers. CuO-based oxygen carriers supported on different metal oxides were synthesized using the Pechini method. The cyclic redox stability and agglomeration tendency of the synthesized materials were evaluated using both a thermo-gravimetric analyzer and a lab-scale fluidized bed reactor at 900 °C using 10 vol % H2 in N2 as the fuel and air for re-oxidation. In order to study the diffusion of Cu(O) during redox reactions, well-defined model surfaces comprising thin films of Cu/CuO and two different supports, namely, ZrO2 and MgO, were prepared via magnetron sputtering. Energy-dispersive X-ray spectroscopy on focused ion beam-cut cross-sections of the thin films revealed that Cu atoms have a tendency to diffuse outward through the support material under redox conditions. The support that inhibits the outward movement of Cu(O), that is, avoiding the presence of low melting Cu on the oxygen carrier surface, is found to provide the highest agglomeration resistance. The support MgO was found to possess such diffusion characteristics.

Optimized Configuration to Reduce H2 Carbon Footprint in a Refinery

As hydrogen is increasingly being recognized as a critical energy vector in the energy transition, capturing CO2 from existing H2 production facilities plays a significant role towards decarbonisation. In a refinery, the H2 production process contains the most concentrated CO2 streams, namely the off-gas from the H2 PSA (containing 40-50%v CO2), and the flue gas from SMR burners (containing 20-25%v CO2). Air Liquide, as one of the leaders for H2 production, has industrialized Cryocap™ H2, combining membranes and cryogenic solutions to capture CO2 most efficiently, at the lowest cost, and at a very high purity. On top of capturing and liquefying the CO2 in one step, one of its salient features is the ability to boost the hydrogen production of a plant by ~10% to 20% further decreasing the SMR carbon footprint. This paper illustrates the impact of cost-effective partial capture technology choices (e.g. amine wash versus Cryocap™ H2) and optimization path on the CO2 emissions reduction rate for various scopes of emissions, power grid footprint, and network configuration within a refinery. It was found that the CO2 emissions reduction rate on Scope 1 for an Amine Wash is decreased to 56% (compared to the typical 60% reduction rate) due to additional steam consumption. On the contrary, it is increased to 62% with Cryocap™ H2, and further to 80% thanks to the additional hydrogen production allowing a reduced load on other H2 production on the network. All emission scopes considered, Cryocap™ H2 is significantly more efficient in terms of carbon footprint reduction than the solvent technology regardless of the power grid footprint and the way additional steam is produced (i.e. natural gas versus electric boiler).

Carbon Sequestration Through Syngas Biomethanation Coupled with H2 Supply for a Clean Production of Natural Gas Grade Biomethane

Biomass gasification generates a gas mixture (syngas) that constitutes a rich source of carbon and energy for the production of second-generation renewable fuels such as biomethane. However, the produced syngas composition (H2/CO/CO2) cannot be converted to natural gas grade biomethane due to stoichiometric limitations, and a waste stream of CO2 is released unexploited in the atmosphere. The present study introduces the concept of biomass gasification coupled to syngas biomethanation with in-situ exogenous H2 supply for the complete sequestration of the syngas carbon, the valorization of renewable excess electricity from wind and solar power and the production of biomethane satisfying the criteria for injection in the natural gas grid. Syngas biomethanation was executed by mixed microbial consortia in a trickle bed reactor at 37 °C and 60 °C. The assessment of the effects of the net inlet gas composition was performed according to a hereby proposed syngas quality index ( $$SQI$$ ), which is based on the syngas content in compounds able to act as carbon and electron donors and the stoichiometry of methane production. The SQI of the stoichiometrically ideal syngas composition is 4. Values below 4 correspond to a stoichiometric carbon-moles excess while values above 4 correspond to a stoichiometric electron-moles excess. It was demonstrated that switching the SQI of the supplied syngas from 1.44 to 3.67 increased the CH4 content in the outlet of the reactor from 30 to 72%, accompanied by an at least 1.2-fold increase of the CH4 productivity. A SQI of 4.78 (> 4) resulted in a significant deterioration of the quality of the produced biomethane due to a high content (52–54%) of unconverted H2 and because of thermodynamic limitations on carboxydotrophic hydrogenogenesis in thermophilic conditions. Maximal carbon sequestration and production of natural gas grade biomethane was shown to be feasible at a SQI = 3.98 in thermophilic conditions.

A Ca-Cu Chemical Loop Process for CO2 Capture in Steel Mills: System Performance Analysis

The conceptual design and modelling of the Calcium Assisted Steel-mill Off-gas Hydrogen (CASOH) process for the conversion of blast furnace gas (BFG) into H2-rich stream and CO2-rich stream at a large scale is discussed in this work. High temperature reactors packed with CaO- and Cu-based materials are used to remove CO2 from the gaseous phase and simultaneously shifting the WGS equilibrium towards H2-rich products. The incorporation of a Cu/CuO chemical loop to such sorption process allows an efficient regeneration of the CO2 sorbent. In this case, the heat needed for the calcination of the CaCO3 is supplied in situ by the exothermic reduction of CuO to Cu with a gaseous fuel (e.g. CH4, CO or H2). The Cu-based solid is firstly converted to CuO(s) during the oxidation step with air and later reduced during the regeneration step, which involves the combination of the endothermic reaction of CaCO3(s) calcination and the exothermic gas-solid reduction of CuO(s) to Cu(s) using a gaseous fuel (typically BFG or natural gas producing a highly concentrated stream of CO2 and H2O(v)). In this paper, the three reaction stages of the CASOH process are modelled with a new 1-D reactor model that integrates state of the art kinetic information on the gas solid reactions, predicting the molar composition of the product gases (dry basis) at the outlet of the packed-bed reactor and maximum temperature achieved in each stage. The 1-D reactor modelling results confirm that process allows the conversion of up to 99% of the inlet CO to H2 at intermediate temperatures (about 650 °C), because of the efficient and continuous removal of CO2 from the gas phase. The high pressure (10 bar) during the Cu-oxidation step causes a very low leakage of CO2 (1.1 vol. %) due to the partial calcination of CaCO3, i.e. only 8 wt. % of the CaCO3 is calcined in this stage. Finally, the feed of BFG as reducing gas during the regeneration stage leads to a maximum temperature of 850 °C in the bed, which allows the complete calcination of the sorbent and gives as a result a CO2-rich stream ready for purification and subsequent use or storage.

CO2 EPOC project: effect of CO2 on the polymeric materials within the CO2 transport chain

Sustainable and efficient deployment of carbon capture and storage (CCS) requires suitable and reliable solutions that can be ensured at all levels of the value chain. Demonstrations of capture and storage technologies developed in the last decades have already realized a TRL able to support a quick CCS deployment, but knowledge gaps still exist regarding which polymer materials may be safely and effectively used in the CO2 transport infrastructure (e.g., elastomeric seals, gaskets, pipe liners, etc.). Transport of supercritical CO2 by pipeline or cryo-compressed CO2 by ship create very different, but highly demanding environments. These environments have different effects on polymeric materials, which up to now have not been systematically investigated. This raises concerns for long-term deployment of such materials in the CO2 value chain. The CO2-EPOC project aims to create knowledge on the compatibility between polymeric materials and CO2 streams to aid proper selection of polymer-based materials across the CO2 transport infrastructure (pipelines- and ship-mode) to avoid leakage and failure across the CCS chain which greatly undermines the efforts spent on CO2 capture.

Impact of Hydrogen as Impurity in the Physical and Transport Properties of CO2 Streams in CCS/CCUS Transport Systems: A Technical Discussion

One of the challenging aspects in CO2 pipeline transportation is an accurate understanding of the thermo-physical and transport properties of carbon dioxide and relevant impurities. H2 is a contaminant in the waste CO2 stream from pre-combustion capture processes as well as from hydrogen manufacturing. The design of a CCUS transport and injection network must consider all possible sources of CO2 and the impurities that can be collected from those sources. The objective of this paper is to review and discuss the impact of H2 in the physical and transport properties of CO2 with H2. The physical and transport properties that we considered were, vapor-liquid equilibria including critical point, Joule-Thomson coefficient, viscosity, density, and speed of sound. Hydrogen has the strongest effect on CO2 properties, when compared to other impurities at similar concentration. This is due to H2 having vastly different physical properties when compared to CO2 such as a low molecular weight and low critical properties. In this study, we assess the effect of H2 as an impurity on CO2 properties, allowing main pipeline issues in CCUS applications to be highlighted. In terms of modelling, we have optimised some of the departure parameters of the GERG-2008, for the improved prediction of the VLE of CO2-H2 mixtures.

Effects of CO2 binary mixtures on pipeline performance for Carbon Capture and Storage

Captured CO2 from the manufacturing industries and power generation sources are not pure and may contain usually some amount of impure components, which affect the flow dynamics of the CO2 in the pipelines. Major component of impure components includes N2, H2, H2S, O2, Ar etc., depending on the capture technology used for the removal of CO2 streams. To design efficient CO2 pipeline transportation systems, it is imperative to understand the effect of these impure components on the flow behaviour. The simulation of the effect of CO2 binary mixture on pipeline performance is carried out in this study. The steady-state flow in pipeline is described by a set of parabolic mass, momentum and energy conservation equations. To solve the set of equations subject to the boundary and the inlet conditions of the pipeline, the non-linear algebraic solver library DNSQE in Fortran is used to study the behaviour of 90 vol% CO2, and 10 vol% single impure component (N2, H2, H2S, O2 and Ar). The phase diagram and pertinent fluid properties are calculated using the Peng-Robinson (PR) equation of state implemented in NIST Reference Fluid Thermodynamics and Transport Properties database program REFPROP. The results reveal that the bubble point curves were lifted up to higher pressures by impure components. The changes in the bubble point would affect the operating conditions of CO2 pipeline. The presence of impure components also changed the properties of the flowing fluid. From the results, H2 shows the most significant impact on the performance of CO2 pipeline as the highest pressure drop by ca. 0.18 bar/km which has smaller density and greater flow velocity against other CO2 streams. The results also show that Ar had the mildest effect followed by O2, N2 and CO. In the case of H2S, the flow parameters are found to be nearly identical to those for pure CO2. The pressure drop for binary mixture contains H2S shows the same value with pure CO2 stream by ca. 0.13 bar/km.

Assessment of CO2 capture technologies for CO2 utilization in enhanced oil recovery

AbstractCO2 capture is considered to be a viable means of reducing the harmful environmental impacts of the fossil fuel usage. The net cost of CO2 capture can be reduced and, consequently, the adoption of CO2 capture methods can be enhanced by developing revenue streams for the captured CO2. Enhanced oil recovery (EOR), which is the process of withdrawing crude from oil reservoirs after primary and secondary withdrawal, is viewed as an attractive means of CO2 utilization. The EOR process has the capacity to take large volumes of CO2 captured from power plants and use them for the production of incremental oil. The process which is known as CO2‐EOR has synergistic benefits for the oil and gas and power generation industries. Different CO2 capture technologies are currently being used and their suitability of supplying captured CO2 for utilization in EOR may not be similar. This study analyzes the ease of utilization of CO2 captured from power plants in EOR applications. The analysis is done by comparing different capture technologies in terms of cost and purity of CO2 captured and their suitability of integration with the EOR. The results determine that the post‐combustion CO2 capture is the most EOR friendly technique in terms of CO2 stream purity, while the chemical looping combustion (CLC) is the most EOR amenable in terms of the capture cost. The results show that the CO2 capture efforts from power plants using CLC can be fully covered by additional oil revenue at oil prices above $27.9 per barrel ($175.5/m3). © 2021 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons, Ltd.

A Pressure Swing Approach to Selective CO2 Sequestration Using Functionalized Hypercrosslinked Polymers.

Functionalized hypercrosslinked polymers (HCPs) with surface areas between 213 and 1124 m2/g based on a range of monomers containing different chemical moieties were evaluated for CO2 capture using a pressure swing adsorption (PSA) methodology under humid conditions and elevated temperatures. The networks demonstrated rapid CO2 uptake reaching maximum uptakes in under 60 s. The most promising networks demonstrating the best selectivity and highest uptakes were applied to a pressure swing setup using simulated flue gas streams. The carbazole, triphenylmethanol and triphenylamine networks were found to be capable of converting a dilute CO2 stream (>20%) into a concentrated stream (>85%) after only two pressure swing cycles from 20 bar (adsorption) to 1 bar (desorption). This work demonstrates the ease with which readily synthesized functional porous materials can be successfully applied to a pressure swing methodology and used to separate CO2 from N2 from industrially applicable simulated gas streams under more realistic conditions.

The Challenge of Monitoring Impurity Content of CO2 Streams

Carbon capture and storage has gained increased attention during the last decade, and several full-scale projects are currently being planned. From economic and public acceptance point of view it is important to ensure that the transportation system is operated in a safe manner, avoiding threats such as corrosion or formation of solid matters. Thus, routine chemical analyses are required to ensure that the CO2 stream complies with the required specifications. The CO2 will usually be transported in the liquid or supercritical state (high pressure), which makes the practicalities around chemical analyses difficult. Phase transition from liquid or supercritical state to gaseous state may also introduce several physiochemical effects that may affect the analyses. This paper discusses technical and practical challenges with CO2 stream analyses experienced in a joint industry project that studied corrosion and chemical reactions in a simulated CO2 transport system.

CO2 Reutilization in the Residential Sector Through Power to Gas and Oxyfuel Combustion

A novel concept of Power-to-gas (PtG) has been investigated as a versatile technology for storage and utilization of carbon dioxide coming from energy installations. The proposed PtG solution takes advantage of the synergies of different processes to integrate energy storage efficiently with carbon utilization to produce a ‘CO2 neutral’ natural gas. PtG converts surplus electricity into synthetic natural gas by combining H2 from water electrolysis and CO2 through methanation reaction and oxyfuel combustion. This carbon capture option releases thermal energy from the synthetic fuel producing a near-pure stream of CO2 that close the carbon loop used for methanation. Under this framework, the present work proposes to study and validate the hybridization between Power-to-Gas energy storage technology and CO2 oxyfuel combustion in the residential sector. This combination is a novel strategy focused on solving: (i) the intermittent and seasonal electricity generation from renewable resources; (ii) the large energy and economic penalties associated with CO2 capture and utilization (especially at small scale); (iii) and the development of energy storage systems of small-medium size and high flexibility. This hybridization allows managing the excess of renewable electricity in the Power-to-Gas installation and producing hydrogen (stored energy) and oxygen (by-product). Subsequently, oxygen is used to meet the needs of the oxyfuel combustion process, in this case, in the residential sector, with two important advantages: a high concentration CO2 flow is obtained, and the oxygen production neither requires an air separation unit (ASU) nor additional energy requirements. The stored hydrogen and the captured carbon dioxide are combined by methanation to produce synthetic natural gas stored for future uses. From CO2 capture point of view, the proposed hybrid system presents an additional advantage: there would also be no penalty associated with the compression and underground storage of captured CO2, since it is reused in the oxyfuel burner along with the oxygen, obtained in the electrolyzer, closing the carbon cycle. A PtG installation with recycled CO2 utilization has been designed to fully supply the thermal heating demand and partially the electrical demand of a single-family house located in the northeast of Germany, from a photovoltaic generator. The PtG system's characteristics, the CO2 storage and utilization strategy, the equipment necessary and energy balances are presented and illustrated with a case study. The proposed design can supply the 87% of the energy consumed by a single-family home and avoid the emissions of 2.8 tons of CO2 every year.

Carbon Utilization Through Power to Gas and Oxyfuel Combustion Hybridization with Recycled CO2: Design and Preliminary Results

Power-to-gas (PtG) is one of the most promising energy storage technologies. PtG converts surplus (renewable) electricity into synthetic natural gas by combining H2 from water electrolysis with CO2 through methanation reaction. This technology has been proposed for carbon utilization using captured CO2 to produce a ‘CO2 neutral’ natural gas. It allows the temporal displacement (storage) in the use of renewable energy. In theory, the interconnection between the electric and gas grids leads to higher flexibility of the global energy supply. This work presents the design, construction and testing of a methanation reactor at laboratory scale (1-5 kW of hydrogen input) to make use of the CO2 produced in oxy-fuel combustion. Experimental installation includes a mixer of CO2 and H2 flows coming from bottles, an electrical heater to obtain the temperature needed for the reactor catalyst operation, around 350oC, a fixed bed tubular reactor filled with Ruthenium based catalyst, an air-cooling jacket for the reactor, a flue gas cooler and water condenser, and several points for the gas analyser, thermocouples and pressure difference devices. In the next set of experimental tests a second catalytic reactor, after the flue gases water condensation, will be included to increase the extent of methanation reaction. The objective is to characterize the experimental production of synthetic methane under different temperatures, ranging 300-400oC, and pressures, ranging 1 bara-2bara. The work also includes the evaluation of the methane conversion rates under different CO2 stream impurities (CO and H2O). These impurities are related to the expected flue gas composition that comes from a burner working under oxy-fuel conditions. First results to be presented comprise the design of the lab-scale system together with the economic itemization of the installation and preliminary experimental results of methanation reactor.