CO2 Capture And Sequestration Research Articles

CO2 Capture and Sequestration

CO2 capture and sequestration (CCS) aims to capture carbon dioxide (CO2) from CO2 sources (e [...]

Impacts of Permeability Heterogeneity and Background Flow on Supercritical CO2 Dissolution in the Deep Subsurface

AbstractMotivated by CO2 capture and sequestration (CCS) design considerations, we consider the coupled effects of permeability heterogeneity and background flow on the dissolution of a supercritical CO2 lens into an underlying deep, confined aquifer. We present the results of a large‐scale Monte Carlo simulation study examining the interaction of background flow rate and three parameters describing multi‐Gaussian log‐permeability fields: mean, variance, and correlation length. Hundreds of high‐resolution simulations were performed using the PFLOTRAN finite volume software to model CO2 dissolution in a kilometer‐scale aquifer over 1,000 years. Predictive dimensionless scaling relationships relating CO2 dissolution rate to heterogeneity statistics, Rayleigh (Ra) and Péclet (Pe) numbers were developed for both gravitationally dominated free convection to background flow‐dominated forced convection regimes. An empirical criterion, Pe = Ra3/4, was discovered for regime transition. All simulations converged quickly to a quasi‐steady, approximately linear dissolution rate. However, this rate displayed profound variability between permeability field realizations sharing the same heterogeneity statistics, even under mild permeability heterogeneity. In general, increased heterogeneity was associated with a lower mean and higher variance of dissolution rate, undesirable from a CCS design perspective. The relationship between dissolution rate and background flow was found to be complex and nonlinear. Dimensionless scaling relationships were uncovered for a number of special cases. Results call into question the validity of the Boussinesq approximation in the context of modest‐to‐high background flow rates and the general applicability of numerical simulations without background flow.

Photo-Responsive Signatures in a Porous Organic Polymer Enable Visible Light-Driven CO2 Photofixation

Porous organic polymers (POPs) continue to garner immense attention for CO2 capture and sequestration (CCS) as well as CO2 fixation to generate useful chemicals for alleviating global warming. Functionally engineered, visible light responsive organic photopolymers with extended π-conjugation and abundant heteroatoms enable photogenerated charge carriers, enhancement in visible light absorption, higher charge separation, and reduction in charge recombination during photocatalysis. In this work, we have explored the construction of a chemically stable, pyridine-equipped, and imine-linked porous organic polymer (Py-POP) by template-free Schiff base condensation of 1,3,5-tris(4-aminophenyl) benzene (APB) and 2,6-pyridinedicarboxaldehyde (PDC). This donor–acceptor Py-POP with extensive π-conjugations enables photocatalytic fixation of CO2 with styrene epoxide (STE) under visible light illumination. We have achieved an impressive conversion of STE to styrene carbonate (STC) (∼99%) under optimized reaction conditions using tert-butyl ammonium bromide (TBAB) as a promoter. Both the efficient CO2 adsorption and activation for photocatalytic fixation reaction are enabled by the existence of both imine and pyridine moieties in Py-POP. The interaction between Py-POP and CO2 is further illustrated by density functional theory (DFT) calculations that show that all the POP-CO2 interactions are favorable and exergonic. Using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) characterization techniques, we elucidate the mechanistic pathways of active key surface species in CO2 photofixation with Py-POP. Our results provide mechanistic insight into the effectiveness of efficient, sustainable porous organic photocatalysts in visible light-driven CO2 conversion for various energy applications.

Coal measure energy production and the reservoir space utilization in China under carbon neutral target

Coal measure energy production and reservoir space utilization are both important for energy security and can assist in achieving carbon neutrality. Coal measure energy production and reservoir utilization are therefore of scientific significance. This study focuses on the security of coal supply by discussing the possible technical approaches of combining low-carbon mining of coal measure resources and coal reservoir space utilization. Our study found that 1) the integration of underground coal gasification and carbon capture and sequestration (UCG-CCS) is an effective technology to improve energy efficiency and achieve the carbon neutral target in China; 2) CO2-enhanced coalbed methane (CO2-ECBM) recovery is an important way to reduce CO2 emissions during coalbed methane recovery; and 3) the integrated technology of solid waste filling (WF), coal bioconversion (CB), gas production (GP), and CO2 capture and sequestration (CCS) in coal goafs and abandoned coal mines can improve the energy production efficiency and reservoir space utilization and reduce geological disasters due to surface subsidence. These integrated technologies will become increasingly important for coal measure energy production and efficient reservoir space utilization as they will provide scientific theory and technical support to achieve carbon neutrality.

Sustainability analyses of CO2 sequestration and CO2 utilization as competing options for mitigating CO2 emissions

CO2 capture and sequestration (CCS) and CO2 capture and utilization (CCU) are potential alternatives to mitigate CO2 emissions. There have been concerns regarding long-term geological impact of CCS and CCU requires co-reactant(s) for converting CO2 into value-added products. In this work, sustainability of CCS and CCU are assessed by simulating three processes. Each of these processes used post-combustion amine technique to capture CO2 from flue gas stream coming out of natural gas-based power plant. In the first process (CCS), captured CO2 undergoes sequestration whereas in the other two processes (CCU) CO2 reacts with hydrogen to produce methanol and dimethyl ether. Based on our technoeconomic assessment, total annualized cost of CCS process is 7.57% and 6.55% lower than CCU-methanol and CCU-DME processes, respectively. Thus, CCS is economically favourable over CCU. DME is found to be a favourable CCU-product owing to its higher market price as compared to methanol. Our analysis suggests that hydrogen price significantly impacts the technoeconomics of CCU processes. We have also demonstrated that at current market prices of methanol and DME, CCU process can be economical compared to CCS provided hydrogen price reduces to $778.5/t and $942.6/t for CCU-methanol and CCU-DME processes, respectively.

Energy transition and green energy: the struggle for climate and for a new redivision of the world—and the proposal for a balanced Russia–EU solution

ABSTRACT The author argues that current energy transition is the seventh one in the long-term history of the mankind though different from the previous ones. He explains why Paris Agreement (the ‘no return point’ for current energy transition) has grown from the 1970s. He explains the role of hydrogen in current energy transition and three different paths for H2 production: water electrolysis; methane steam reforming with CO2 emissions and CO2 capture and sequestration (CCS); methane pyrolysis and similar technologies without CO2 emissions. He demonstrates their competitive advantages and disadvantages. He describes European Union (EU) vision of cooperation in H2 within EU hydrogen strategy and H2 section of Russian Energy Strategy. He argues why cooperation based on Russian gas supplies to the EU and H2 production in EU at end-use in ‘EU H2 valleys’ based on mostly pyrolysis technologies without CO2 emissions is the mutually beneficial one for both Russia and the EU: for the EU it helps to decrease low-carbon development costs and for Russia to further monetize its vast gas resources within export-oriented decarbonization. He presents his ‘win-win’ scenario for Russia–EU hydrogen cooperation.

Research on micro mechanism and influence of hydrate-based methane-carbon dioxide replacement for realizing simultaneous clean energy exploitation and carbon emission reduction

New energy development and carbon emission reduction are two important issues of sustainable development for human beings. Hydrate-based methane - carbon dioxide (CH4-CO2) replacement is the promising technology for it can realize CH4 production from natural gas hydrate (NGH) and CO2 capture and sequestration (CCS) in the strata simultaneously and stably. This work reported the micro mechanism and the influence of the hydrate-based CH4-CO2 replacement by differential scanning calorimetry (DSC) measurements and in situ Raman spectroscopy measurements. It was found the replacement is affected by the potential energy of destruction (Eped) and the binding energy (Eb). The replacement happens only when the Eped is larger than the Eb. The concentration of CO2 around the hydrate is the controlling influence on the replacement. The higher the concentration of CO2, the greater the Eped, and the higher CH4 production efficiency.

Options to reduce Carbon Dioxide in the atmosphere using advance technologies

Carbon dioxide, CO2, capture and storage or sequestration enable us to have a low carbon system. Human-made or anthropogenic CO2 is the primary source of GHG emission which causes global warming. This study begins with an overview of CO2 capture and sequestration(CCS) and discusses the importance of CCS, types of CCS processes and why we need to capture carbon dioxide from a point source. In this study, we have discussed the cyclic process of chemical absorption and desorption of CO2 using advanced solvents (alkanolamine-MEA, PZ etc.) A detailed description of the various CO2 absorption technologies to mitigate the ill effects of CO2 in the atmosphere, MOFs, membranes, Carbonate Based systems, enzyme-based like emerging technologies has been brought out. The potential scale of application, cost, risk assessment and emerging research issues has also been adequately covered.

Assessment of the Redox Characteristics of Iron Ore by Introducing Biomass Ash in the Chemical Looping Combustion Process: Biomass Ash Type, Constituent, and Operating Parameters.

Chemical looping combustion (CLC) is a potential CO2 capture and sequestration (CCS) technology that can easily separate CO2 and H2O without energy loss and greatly improve the efficiency of carbon capture. Due to the inherent defects of natural iron ore, such as low reactivity and poor oxygen carrying capacity, four kinds of biomass ashes (rape stalk ash, rice stalk ash, platane wood ash, and U. lactuca ash) that have different constituents of K, Na, Ca, and Si were applied to modify the redox performance of natural iron ore. The effects of biomass ash type, constituent, reaction temperature, H2O vapor flow rate, and redox cycle on the CLC process were assessed experimentally in a batch fluidized bed reactor system. Oxygen carrier physicochemical characteristics were determined by several analytical techniques. The results showed that rape stalk ash, platane wood ash, and U. lactuca ash with a high K content and high K/Si ratio significantly improved the reactivity and cycle stability of iron ore, even after 10 redox cycles, while rice straw ash with a low K/Si ratio showed an inhibitory effect due to the formation of bridge eutectics, which enhanced agglomeration. In a range from 800 to 950 °C, higher temperatures led to a much better ability to promote the CLC process than lower temperatures. A higher flow rate of H2O had little effect on the further promotion of the CLC process due to hydrogen inhibition. It is believed that the application of BA-modified iron ore oxygen carriers is an effective strategy to improve the CLC process.

Technoeconomic analysis of a waste tire to liquefied synthetic natural gas (SNG) energy system

Thermochemical conversion of solid wastes through gasification offers the dual benefit of production of high-value fuels and environmentally friendly waste disposal. In this paper, we propose a novel process for production of liquefied synthetic natural gas (SNG) from waste tires via a rotary kiln gasification process. We use a combination of experimental data available in the open literature, first principles mathematical models and empirical models to study three design cases (without CO2 Capture and Sequestration (CCS), with precombustion CCS and with pre- and postcombustion CCS) in two locations (USA and Norway). The thermodynamic, economic and environmental performance of the concept is studied. The results show that minimum selling prices of 16.7, 17.5 and 19.9 $/GJLHV,SNG are required for USA and 20.9, 21.8 and 24.9 $/GJLHV,SNG for Norway. We note that these prices may become competitive under certain regulatory conditions (such as recent public policy movement in British Columbia, Canada requiring public utilities to purchase natural gas made from renewables at prices up to 30 $/GJLHV,SNG). The minimum selling price reduces substantially with process scale and with levying tipping fees. The design situated in Norway with both pre- and post-combustion CCS has near zero direct and indirect CO2 emissions.

Molten Carbonate Fuel Cell Performance for CO2 Capture from Natural Gas Combined Cycle Flue Gas

CO2 capture and sequestration (CCS) from stationary flue gas sources is one of the critical technologies needed as the future energy landscape shifts to low carbon intensity energy systems. Molten carbonate fuel cells (MCFCs) have the potential to capture CO2 from flue gas at higher thermal efficiency than traditional CCS technologies while simultaneously producing electricity. Herein, we present an investigation of molten carbonate fuel cell behavior at carbon capture conditions using simulated natural gas combined cycle flue gas. Measurements at these low CO2 and high current conditions reveal a lower than expected cathodic consumption of CO2 Based on the strong dependence of this deviation on water partial pressure as well as mass balances revealing a net consumption of water at the cathode, a parallel oxygen reduction mechanism is proposed. In this mechanism, water and oxygen are consumed at the cathode to produce hydroxide ions which migrate through the electrolyte to the anode. This parallel mechanism contributes to power generation but not to CO2 capture. Mass transport limitations in the molten carbonate fuel cell cathode were identified as the primary driver for this alternative mechanism which were heavily influenced by the design of the current collector and cathode interface.

Modification of a model for mixed hydrates to represent double cage occupancy

Gas hydrates are subject of current research work and are also important for several industrial applications. When transporting natural gases or oil through pipelines, the formation of gas hydrates and thus a blockage of the pipeline must be avoided. There is also a great interest to understand the thermophysical properties and the phase change behavior of hydrates during liquefaction processes of natural gases, for CO2 capture and sequestration (CCS) processes, and for CH4 and C2H6 hydrates, which can be found on the seabed or in permafrost soils as a potential energy source. In this work, the model for mixed gas hydrates (mixtures of water with more than one hydrate former), which has been introduced in a previous work [Fluid Phase Equilib. 459 (2018) 170–185] and is intended for the use in CCS relevant applications, is modified to take double cage occupancy into account. The three-phase equilibrium data can be reproduced up to high pressures at which N2, O2, and Ar are known to double occupy the hydrate cavities. The influence of double occupied hydrate cages and the improved reproduction of experimental phase equilibrium data at pressures at which double cage occupancy occurs are shown for pure hydrate and for mixed hydrate phase equilibrium and composition data. In case of mixed hydrates, comparisons are shown for synthetic air (N2+O2).

Land uplift induced by injection: a feasible method to evaluate the security of CO2 capture and sequestration projects

Technology of CO2 capture and sequestration (CCS) is one of the many solutions to reduce greenhouse gases and alleviate the current global warming, but its security is important and needs to be evaluated. A simulator which links TOUGHREACT and FLAC3D was used to simulate the process of coupled temperature-hydrologic-mechanics (THM) in CCS. A test on laboratory scale was set up and water was injected into compacted sand covered by low permeability clay to study the land uplift displacement. The results were used to verify the accuracy of the simulator for calculating the THM coupling. The effects of injection quantity, injection time, and injection mode on land uplift were also studied on the constructed model. At last, a land uplift evaluation system was built to quantify the CO2 escape if any. The evaluation process can be divided into five steps: model generalization, acquisition of model parameters, numerical modeling, simulation and analysis, monitor comparison, and evaluation of model results. The major output of this study will provide a feasible method for quantitative analysis of CO2 leakage in CCS projects.

Competitive Adsorption of CO2 over N2 in Asphaltene Slit Nanopores Studied by Molecular Simulation

CO2 capture and sequestration (CCS) is recognized as one of the most promising alternatives to weaken the greenhouse effect, and nanoporous materials are regarded as the promising candidates; therefore, developing a new cost-effective sorbent to achieve CCS is crucial. In this study, asphaltene-based slit nanopores were used to simulate capturing of CO2 from flue gas. The grand canonical Monte Carlo and molecular dynamics simulation methods were employed to examine the microscopic behaviors of CO2 and N2 in asphaltene slit nanopores. The isosteric heat of CO2 and N2 molecules adsorbed in asphaltene slit nanopores, the adsorption energy of a single molecule of CO2 and N2 adsorbed on the surface of asphaltene fragments, and the self-diffusion of CO2 and N2 molecules adsorbed in asphaltene slit nanopores were examined. Strong competitive adsorption of CO2 over N2 is found in a broad range of temperatures and pressures, and it was found that the temperature plays an important role on the competitive adsorptio...

The PVTx properties of aqueous electrolyte solutions containing Li+, Na+, K+, Mg2+, Ca2+, Cl− and SO42− under conditions of CO2 capture and sequestration

Based on the Pitzer electrolyte theory, an accurate density model of binary sulfate-water systems (Li2SO4-H2O, Na2SO4-H2O, K2SO4-H2O and MgSO4-H2O) has been established. Corresponding model parameters are obtained by the least square method. Compared with reliable experimental data of the Li2SO4-H2O, Na2SO4-H2O, K2SO4-H2O and MgSO4-H2O systems, the average density deviations are 0.046%, 0.036%, 0.051%, 0.038%, respectively, which are within or close to experimental uncertainties. Combined a simple mixing rule with the density models of binary sulfate-water systems and previous chloride-water systems (LiCl-H2O, NaCl-H2O, KCl-H2O, MgCl2-H2O and CaCl2-H2O), a predictive density model is proposed for aqueous mixed electrolyte solutions containing Li+, Na+, K+, Mg2+, Ca2+, Cl− and SO42− under conditions of CO2 capture and sequestration (CCS) (generally less than 473 K and 300 bar). Compared to experimental density data of multi-component water-salt systems, the average density deviation of each system is usually less than 0.1%. The model can be used to calculate the apparent molar volume at infinite dilution and the volumetric properties of CO2-bearing multi-component electrolyte solutions under the CCS conditions. A computer code for the volumetric properties of multi-component aqueous electrolyte solutions can be obtained from the corresponding author.

Porous Carbon Materials Based on Graphdiyne Basis Units by the Incorporation of the Functional Groups and Li Atoms for Superior CO2 Capture and Sequestration.

The graphdiyne family has attracted a high degree of concern because of its intriguing and promising properties. However, graphdiyne materials reported to date represent only a tiny fraction of the possible combinations. In this work, we demonstrate a computational approach to generate a series of conceivable graphdiyne-based frameworks (GDY-Rs and Li@GDY-Rs) by introducing a variety of functional groups (R = -NH2, -OH, -COOH, and -F) and doping metal (Li) in the molecular building blocks of graphdiyne without restriction of experimental conditions and rapidly screen the best candidates for the application of CO2 capture and sequestration (CCS). The pore topology and morphology and CO2 adsorption and separation properties of these frameworks are systematically investigated by combining density functional theory (DFT) and grand canonical Monte Carlo (GCMC) simulations. On the basis of our computer simulations, combining Li-doping and hydroxyl groups strategies offer an unexpected synergistic effect for efficient CO2 capture with an extremely CO2 uptake of 4.83 mmol/g at 298 K and 1 bar. Combined with its superior selectivity (13 at 298 K and 1 bar) for CO2 over CH4, Li@GDY-OH is verified to be one of the most promising materials for CO2 capture and separation.

An improved tri-reforming based methanol production process for enhanced CO2 valorization

The consistent rise of CO2 concentration in the atmosphere is known to be significantly detrimental to the environment. Thus, mitigating CO2 has become an urgent necessity. Current methods involving CO2 mitigation can be broadly divided into two major categories which involve (i) CO2 capture and sequestration (CCS) and (ii) CO2 capture and valorization. Since, production of fuels/chemicals is an added feature along with mitigation in CO2 valorization based methods, they could be economically favorable. An energy intensive CO2 capture step is a common drawback of most CO2 valorization methods that aim to mitigate CO2 from major CO2 emission sources (such as industrial flue gases). In this paper we employ and analyze a relatively new process called tri-reforming [1,2] which was developed to directly convert power plant based flue gases to synthesis gas, while avoiding the capture step. This paper is presented as an improvement over a tri-reforming coupled methanol production process as developed by Zhang et al. [3]. The process in Zhang et al. [3] involves utilizing tri-reforming process using flue gas and methane to produce synthesis gas which is then converted to methanol in the next step. The main contributions of this paper to the tri-reforming coupled methanol production process are: (i) proposition of a high pressure tri-reforming step to limit capital costs of the process (ii) establishment of steam input coupled with water separation step as a process improvement whose impact is shown to further amplify at higher tri-reformer pressures. The paper evaluates the process in terms of the profit generating and CO2 valorization potential of the process as reflected by two parameters, gross margin (GM) and NPCV (net percentage of CO2 valorized) respectively. In the proposed approach, higher pressures were utilized in the tri-reforming process to ensure economic feasibility of the process by limiting the reactor volume. The process improvements for the flowsheet containing the steam input combined with water separation (SWS) step over the one without these steps (termed as WSWS) are demonstrated in terms of an increase in GM/NPCV values at various pressures. The results indicate substantial improvements in GM and NPCV values (especially at higher tri-reformer pressures) ranging from 24.30 to 84.96% and 28.80–78.44% respectively in SWS cases over WSWS cases at various pressures. The simulations have been carried out in Aspen Plus V8.4 and are optimized using sensitivity analysis.

Progress in inorganic cathode catalysts for electrochemical conversion of carbon dioxide into formate or formic acid

As a greenhouse gas, carbon dioxide in the atmosphere is one of the key contributors to climate change. Many strategies have been proposed to address this issue, such as CO2 capture and sequestration (CCS) and CO2 utilization (CCU). Electroreduction of CO2 into useful fuels is proving to be a promising technology as it not only consumes CO2 but can also store the redundant electrical energy generated from renewable energy sources (e.g., solar, wind, geothermal, wave, etc.) as chemical energy in the produced chemicals. Among all of products from CO2 electroconversion, formic acid is one of the highest value-added chemicals, which is economically feasible for large-scale applications. This paper summarizes the work on inorganic cathode catalysts for the electrochemical reduction of CO2 to formic acid or formate. The reported metal and oxide cathode catalysts are discussed in detail according to their performance including current density, Faradaic efficiency, and working potentials. In addition, the effects of electrolyte, temperature, and pressure are also analyzed. The electroreduction of CO2 to formic acid or formate is still at an early stage with several key challenges that need to be addressed before commercialization. The major challenges and the future directions for developing new electrocatalysts for the reduction of CO2 to formic acid are discussed in this review.

Selective CO2 Sequestration with Monolithic Bimodal Micro/Macroporous Carbon Aerogels Derived from Stepwise Pyrolytic Decomposition of Polyamide-Polyimide-Polyurea Random Copolymers.

Polymeric aerogels (PA-xx) were synthesized via room-temperature reaction of an aromatic triisocyanate (tris(4-isocyanatophenyl) methane) with pyromellitic acid. Using solid-state CPMAS 13C and 15N NMR, it was found that the skeletal framework of PA-xx was a statistical copolymer of polyamide, polyurea, polyimide, and of the primary condensation product of the two reactants, a carbamic-anhydride adduct. Stepwise pyrolytic decomposition of those components yielded carbon aerogels with both open and closed microporosity. The open micropore surface area increased from <15 m2 g-1 in PA-xx to 340 m2 g-1 in the carbons. Next, reactive etching at 1,000 °C with CO2 opened access to the closed pores and the micropore area increased by almost 4× to 1150 m2 g-1 (out of 1750 m2 g-1 of a total BET surface area). At 0 °C, etched carbon aerogels demonstrated a good balance of adsorption capacity for CO2 (up to 4.9 mmol g-1), and selectivity toward other gases (via Henry's law). The selectivity for CO2 versus H2 (up to 928:1) is suitable for precombustion fuel purification. Relevant to postcombustion CO2 capture and sequestration (CCS), the selectivity for CO2 versus N2 was in the 17:1 to 31:1 range. In addition to typical factors involved in gas sorption (kinetic diameters, quadrupole moments and polarizabilities of the adsorbates), it is also suggested that CO2 is preferentially engaged by surface pyridinic and pyridonic N on carbon (identified with XPS) in an energy-neutral surface reaction. Relatively high uptake of CH4 (2.16 mmol g-1 at 0 °C/1 bar) was attributed to its low polarizability, and that finding paves the way for further studies on adsorption of higher (i.e., more polarizable) hydrocarbons. Overall, high CO2 selectivities, in combination with attractive CO2 adsorption capacities, low monomer cost, and the innate physicochemical stability of carbon render the materials of this study reasonable candidates for further practical consideration.

Investigation of Two Hematites as Oxygen Carrier and Two Low-Rank Coals as Fuel in Chemical Looping Combustion

Chemical looping combustion (CLC) is a novel technique, which exhibits the merit of CO2 inherent separation and has been proposed as one of the most promising routes for CO2 capture and sequestration (CCS). The economically feasible and environmentally benign oxygen carrier (OC) is of critical importance for the successful implementation of CLC processes for industrial application. Natural iron ore, known as a kind of particularly cheap mineral material, has been verified as an appropriate OC candidate. However, there are differences among the iron ores with variable contents of active and inert phases, which may eventually result in diverse performance in CLC processes. In this work, CLC performance of hematite from Australia (AH) and China (CH) were systematically compared in a batch fluidized bed reactor, using two low-rank coals: Victorian brown coal (VC) from Australia and Inner Mongolia coal from China as fuels. The results showed that the maximum CO2 yield was 0.92 at 1000 °C under the match of CH ...