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In the global ecosystem, wetlands are vital carbon sinks, playing a crucial role in absorbing greenhouse gases such as carbon dioxide and mitigating global warming. Accurate estimation of wetland carbon content is essential for research on wetland carbon sinks. However, the carbon cycle of wetlands is complex, and the carbon sinking of wetlands is affected by climate, topography, water level conditions, vegetation types, soil types, and other factors. This has caused significant challenges in the estimation of wetland carbon sinks. In current studies, most research has focused on the impact of individual factors on wetland carbon sinks, often ignoring the interaction between various factors, which further leads to uncertainty in wetland carbon measurements. This paper aims to elucidate the process of the wetland carbon cycle, summarize the factors affecting wetland carbon sinks, and explore the interplay between various factors and their influence on wetland carbon sinks, aiming to provide theoretical support for the study of wetland carbon sinks. Additionally, this paper reviews the advantages and disadvantages of current wetland carbon measurement methods, proposes research directions for combining machine learning methods, identifies existing difficulties in current wetland carbon measurement, and offers suggestions to serve as a reference for future wetland carbon sink estimation and wetland management.Highlights: The potential and significance of wetland carbon sinks are explained. The advantages and disadvantages of current wetland carbon measurement techniques are summarized. The prospective method for integrating machine learning into integrated wetland carbon measurement is proposed. [ABSTRACT FROM AUTHOR]

Coal-based power plants are largest emitter of CO as a single sector. To use fossil fuels (including coal), CO capture and storage is a visible option. But large energy requirement for this process and risk associated with storage of CO demand alternative solutions including recycling of captured CO. In this paper, a co-production of power and urea is proposed using coal with captured CO. Detailed ASPEN Plus model is developed for this plant. As shift reaction for producing H has significant effect on output parameters, analysis is done for two different values of shift reaction, i.e., 90 and 95 % conversion. Plant consumes substantial auxiliary power (~19 % for the base case). Auxiliary power becomes a minimum for about 25 % captured CO utilization for 95 % shift conversion. An economy factor is also defined to estimate the economic advantage of utilizing captured CO. Results show that economic advantage is obtained for CO utilization beyond ~5 % for 95 % water gas shift reaction and it is beyond ~10 % for a 90 % shift reaction. [ABSTRACT FROM AUTHOR]

According to the Intergovernmental Panel on Climate Change (IPCC) of the United Nations (UN), rise in atmospheric concentration of carbon dioxide (CO 2 ) due to anthropogenic factors is considered as the primary driver for global climate change. With almost every major corporation around the world working towards their "net-zero goals", it is becoming increasingly important to have more technologies that can help reduce carbon footprint. Achieving sequestration of CO 2 in the subsurface through Carbon Capture Utilization and Storage (CCUS) technologies like CO 2 -Enhanced Oil Recovery, CO 2 -Enhanced Geothermal Systems, CO 2 -Enhanced Coal Bed Methane, etc. is well accepted. We introduce yet another attractive CCUS opportunity through well rehabilitation. Aqua Freed® and Aqua Gard® are well-known well rehabilitation and preventive well maintenance technologies that utilize (inject underground) liquid CO 2 for the purpose. The goal of this study was to quantify the storage capacity of Aqua Freed® and Aqua Gard®, and establish their CCUS credentials. Depending on the well being serviced, these technologies can inject up to 40 US tons of CO 2 per well. Based on field data collection and statistical modeling, we estimated that 82–96% (median 90%) of the injected CO 2 remains in the subsurface post injection. Overall, our results and analysis of the US market suggest that using CO 2 for well rehabilitation and maintenance has a storage potential of several megatonnes of CO 2 annually in the US alone. [ABSTRACT FROM AUTHOR]

Recently, ionic liquids (ILs) have been introduced as potential carbon dioxide (CO)-capturing solvents, as a substitute to conventional amine-based solvents. Conventional amine-based solvents that are used for CO capture show some drawbacks, such as high solvent loss, high regeneration energy requirement, and solvent degradation. These shortcomings can be potentially overcome if IL-based solvents are considered. ILs have negligible vapour pressure, high thermal stability, and wide range of thermophysical properties. Nonetheless, using experimentation to identify suitable ILs as CO-capturing solvents is a tedious and costly task, as there are more than a million possible combinations of cations and anions that make up the ILs. Computer-aided tools have been previously developed for targeted IL design, which often involve non-linear programming. However, non-linear programming sometimes fails to converge, due to enlarged search space for optimal solution and its complex formulations. In this paper, the authors present a simple yet systematic visual approach to design IL solvents for carbon capture. Property integration framework is employed in this approach to systematically design IL, where the design problem can be mapped from the property domain into a cluster domain through clustering technique. The advantage of the visual approach is the ability to enumerate novel IL candidates. Group contribution (GC) method is included in the framework to estimate the properties of designed ILs. By combining property integration framework and GC method, the proposed approach is able to provide a property-based platform to visualise the performance of designed ILs on a ternary diagram. A case study is presented to illustrate the validity of the proposed approach. [ABSTRACT FROM AUTHOR]

In this paper, we develop a model to analyze the economics of carbon capture, transport, and storage (CCTS) in the wake of expected rising CO prices. We present a scalable mixed integer, multiperiod, welfare-optimizing network model for Europe, called CCTS-Mod. The model incorporates endogenous decisions on carbon capture, pipeline and storage investments, as well as capture, flow and injection quantities based on given costs, CO prices, storage capacities, and point source emissions. Given full information about future costs of CCTS-technology, and CO prices, the model determines a cost minimizing strategy on whether to purchase CO certificates, or to abate the CO through investments into a CCTS-chain on a site by site basis. We apply the model to analyze different scenarios for the deployment of CCTS in Europe, e.g., under high and low CO prices, respectively. We find that beyond CO prices of €50 per t, CCTS can contribute to the decarbonization of Europe's industry sectors, as long as one assumes sufficient storage capacities (onshore and/or offshore). We find that CCTS is only viable for the power sector if the CO certificate price exceeds €75 per t. [ABSTRACT FROM AUTHOR]

The Climate Change Conference of Parties (COP) 21 in December 2015 established Nationally Determined Contributions toward reduction of greenhouse gas emissions. In the years since COP21, it has become increasingly evident that carbon dioxide removal (CDR) technologies must be deployed immediately to stabilize concentration of atmospheric greenhouse gases and avoid major climate change impacts. Biochar is a carbon-rich material formed by high-temperature conversion of biomass under reduced oxygen conditions, and its production is one of few established CDR methods that can be deployed at a scale large enough to counteract effects of climate change within the next decade. Here we provide a generalized framework for quantifying the potential contribution biochar can make toward achieving national carbon emissions reduction goals, assuming use of only sustainably supplied biomass, i.e., residues from existing agricultural, livestock, forestry and wastewater treatment operations. Our results illustrate the significant role biochar can play in world-wide CDR strategies, with carbon dioxide removal potential of 6.23 ± 0.24% of total GHG emissions in the 155 countries covered based on 2020 data over a 100-year timeframe, and more than 10% of national emissions in 28 countries. Concentrated regions of high biochar carbon dioxide removal potential relative to national emissions were identified in South America, northwestern Africa and eastern Europe. Highlights: Biochar production via biomass pyrolysis is one of few carbon dioxide removal (CDR) technologies that can be deployed at scale. Modeled biochar CDR potential of nearly every country, based on available biomass residues and national average soil temperature. Biochar can offset over 10% of national emissions in many countries, with concentrated impacts in three global regions. [ABSTRACT FROM AUTHOR]

Deployment of carbon capture, utilisation, and storage (CCUS) technologies to mitigate climate change and overturn CO2 emissions growth would require transformational changes comprehensively. The primary focus of this manuscript is on the impurities standards and limitation that can ensure project feasibility in the long run. There is a need in the industry for guidance on purity analysis prior to capture, shipment, and storage of carbon dioxide. This is because the cost to capture and separate the stream is proving to be very costly that can make the project to be unfeasible to operate. Following this further, this manuscript discusses the previous research and best practices that establish standards for acceptable impurities that might present in the stream and its effects towards the CCUS system. Consequently, this manuscript also provides better understanding on the impurities effects towards CCUS technology system in general. Understanding these limitations, may provide cost effective solution for CCUS problems that revolves around the impurities in CO2 stream. Impurities can affect some components of the carbon capture and storage process. It is clear that even a little number of impurities can cause the carbon dioxide stream properties to change. There are two primary factors discussed in this manuscript that affect how a CCUS system responds to a CO2 stream that contains impurities: a physical and chemical effects. [ABSTRACT FROM AUTHOR]

Searching for materials and technologies of efficient CO capture is of the utmost importance to reduce the CO impact on the environment. Therefore, the (AlN) clusters ( n = 3-5) are researched using density functional theoretical calculations. The results of the optimization show that the most stable structures of (AlN) clusters all display planar configurations at B3LYP and G3B3 methods, which are consistent with the reported results. For these planar clusters, we further systematically studied their interactions with carbon dioxide molecules to understand their adsorption behavior at the B3LYP/6-311+G(d,p) level, including geometric optimization, binding energy, bond index, and electrostatic. We found that the planar structures of (AlN) ( n = 3-5) can capture 3-5 CO molecules. The result indicates that (AlN) (n = 3-5) clusters binding with CO is an exothermic process (the capture of every CO molecule on (AlN) clusters releases at least 30 kcal mol in relative free energy values). These analysis results are expected to further motivate the applications of clusters to be efficient CO capture materials. [ABSTRACT FROM AUTHOR]

Rising CO2 emissions call for actions to urgently address climate change and its impacts. To avoid the harmful consequences of climate change, limiting anthropogenic emissions of CO2 are a sensible response recognized by the global scientific community. Carbon capture and storage technologies are an integral part of the climate change mitigation portfolio. Among the various technologies, mineral carbonation shows promising potential as it is safer and offers a permanent solution for carbon capture and storage in the form of solid carbonates. In this regard, direct mineral carbonation of alkaline solid residues is viewed with global interest as they offer permanent and leakage-free storage of CO2. In this research work, CO2 sequestration using Indian coal fly ash (class F type- CaO < 10%) has been studied through the direct mineral carbonation process using flue gas concentration of CO2. Response surface methodology was used to design the carbonation experiments through gas–solid and aqueous routes. Aqueous carbonation of coal fly ash at optimum conditions (temperature-61.6 °C, pressure-48.7 bar, liquid/solid ratio-13.35, reaction time-50 min) resulted in a reduction of about 23% in the concentration of CO2. The waste exhibited a maximum sequestration capacity of 50.72 g of CO2/kg under aqueous carbonation and 20.03 g of CO2/kg under gas–solid carbonation. Both temperature and pressure were found to be significant factors impacting the gas–solid carbonation process. In aqueous carbonation, temperature and liquid/solid ratio were the significant factors. The carbonation process was evidenced using Fourier-transform-infrared spectroscopy, X-ray diffraction, and scanning electron microscope studies. The results suggest that Indian coal fly ash could be considered a potential feedstock for sequestration of CO2 with flue gas and requires further improvement for large-scale implementations. [ABSTRACT FROM AUTHOR]

Carbon capture and sequestration technology has been a ground-breaking tool in tackling carbon dioxide (CO2) emissions worldwide but has limitedly been researched and practised in Africa at present. Considering the vast growth and developmental level in the continent, there is a need to consider this option of mitigating global climate change. In this study, a systematic and process-based incorporation of seismic and well logs datasets was used to characterize the structural and stratigraphic framework of sandstone reservoirs within the field in order to determine their capacities for effective CO2 sequestration. Petrophysical analysis, fault modelling as well as geostatistical techniques were used to build facies and property models which enabled a qualitative assessment of the sealing potential of faults associated with the reservoirs based on prediction of key properties such as shale gouge ratio, lithological juxtaposition, fault permeability and fault transmissibility across the fault faces. Nine water-bearing sandstone reservoirs (reservoirs A–J) with varying reservoir quality were identified in the field. The dominance of high SGR, low permeability, higher fault throws and low fault transmissibility values at the lower parts of the faults indicates the deeper structural traps of the field are low-risk zones and might serve as good storage areas for CO2. [ABSTRACT FROM AUTHOR]

Carbon dioxide removal (CDR) will be essential to meet the climate targets, so enabling its deployment at the right time will be decisive. Here, we investigate the still poorly understood implications of delaying CDR actions, focusing on integrating direct air capture and bioenergy with carbon capture and storage (DACCS and BECCS) into the European Union power mix. Under an indicative target of −50 Gt of net CO2 by 2100, delayed CDR would cost an extra of 0.12−0.19 trillion EUR per year of inaction. Moreover, postponing CDR beyond mid-century would substantially reduce the removal potential to almost half (−35.60 Gt CO2) due to the underused biomass and land resources and the maximum technology diffusion speed. The effective design of BECCS and DACCS systems calls for long-term planning starting from now and aligned with the evolving power systems. Our quantitative analysis of the consequences of inaction on CDR—with climate targets at risk and fair CDR contributions at stake—should help to break the current impasse and incentivize early actions worldwide. The implications of delaying carbon dioxide removal (CDR) are poorly understood. Here the authors highlight the potential extra costs and reduced removal potential of delayed CDR action, with a special focus on direct air capture and bioenergy with carbon capture and storage (DACCS and BECCS). [ABSTRACT FROM AUTHOR]

Nanoscale open spaces formed by partial overlap of two-dimensional nanosheets in clays, abundantly and ubiquitously available, possess reactive molecular sites such as nanosheet edges in their interior. Here, the capture and storage of CO2 molecules in open spaces within saponite clay are explored by solid-state nuclear magnetic resonance coupled with open space analysis using positronium. CO2 physisorption occurs on the nanosheet surfaces inside the open spaces under ambient conditions. Thereby, CO2 molecules are activated by picking off weakly-bound oxygen from octahedral sites at the nanosheet edges and carbonate species are stabilized on the nanosheet surfaces. This instantaneous mineral carbonation and CO2 physisorption occurs in the absence of an energy-consumption process or chemical solution enhancement. This finding is of potential significance for CO2 capture and storage and presents an approach of environmentally friendly recycling of low contaminated soil in Fukushima. Sequestration of CO2 in geological reservoirs holds great potential, but ex situ mineral carbonation generally requires harsh, energy-intense conditions. Here the authors study CO2 physisorption at open nanospaces within overlapping nanosheets in saponite clay under ambient conditions. [ABSTRACT FROM AUTHOR]

The increasing demand for energy makes it difficult to replace fossil fuels with low-carbon energy sources in the short term, and the large amount of CO2 emitted by fossil fuel combustion increases global warming. Carbon capture and storage (CCS) technologies for reducing CO2 emissions in power plants and industrial processes have been developed. High costs and security issues limit industrial applications of these technologies, so an alternative for carbon reduction is needed, i.e., CO2 as a working fluid for coupled carbon storage and geothermal extraction in an Enhanced Geothermal System (EGS). We describe the status of global carbon emissions, CCS technologies, and their challenges. The characteristics of CO2 as a working fluid are compared from thermophysical and thermodynamic perspectives, and the solubility of CO2 in reservoir fluids with different ionic strengths, pressures, and temperatures is analyzed. The influence of artificial stimulation on the permeability of an EGS reservoir is described. Through heat extraction experiment of water alternating supercritical CO2 (SCCO2) cycle injection, the effects of CO2–fluid–rock interactions on the reservoir's structure and of mineral dissolution and precipitation on geological CO2 storage are analyzed. We summarize the application prospects for this alternative and the challenges of future application. [ABSTRACT FROM AUTHOR]

Ventilation of carbon stored in the deep ocean is thought to play an important role in atmospheric CO2 increases associated with Pleistocene deglaciations. The presence of this respired carbon has been recorded by an array of paleoceanographic proxies from various locations across the global ocean. Here we present a new sediment core from the Eastern Equatorial Pacific (EEP) Ocean spanning the last 180,000 years and reconstruct high-resolution 230Th-derived fluxes of 232Th and excess barium, along with redox-sensitive uranium concentrations to examine past variations in dust delivery, export productivity, and bottom-water oxygenation, respectively. Our bottom-water oxygenation record is compared to other similar high-resolution records from across the Pacific and in the Southern Ocean. We suggest that the deep Pacific is a site of respired carbon storage associated with periods of decreased global atmospheric CO2 concentration during the LGM, confirming the conclusions from a wealth of previous studies. However, our study is the first to show a similar relationship beyond the last glacial, extending to at least 70,000 years. [ABSTRACT FROM AUTHOR]

Miscible carbon dioxide (CO2) flooding has been recognized as a promising approach to enhance the recovery of oil reservoirs. However, depending on the injection strategy and rock/fluid characteristics, efficiency of the miscible CO2 flooding varies from reservoir to reservoir. Although, many studies have been carried out to evaluate the performance of the miscible CO2 flooding, a specific strategy which can be strictly followed for a hydrocarbon reservoir has not been established yet. The aim of this study is to assess one of Pakistan's oil reservoirs for miscible CO2 flooding by applying a modified screening criterion and numerical modeling. As such, the most recent miscible CO2 screening criteria were modified, and a numerical modeling was applied on the prospective reservoir. Based on the results obtained, South oil reservoir (S3) is chosen for a detailed assessment of miscible CO2 flooding. It was also found that implementation of CO2 water-alternating gas (CO2-WAG) injection at early stages of production can increase the production life of the reservoir. [ABSTRACT FROM AUTHOR]

Sequestering carbon dioxide (CO2) with enhanced coalbed methane recovery (ECBM) is a promising clean coal technology in Indonesia, which can reduce CO2 emissions and potentially lower-cost alternative for fulfilling of future Indonesia’s gas demand. Coal seams in South Sumatera Basin, Indonesia, are well placed to take advantage of CO2 sequestration based on economical and regulatory criteria. From technical criteria assessment, there are very limited studies undertaken in this area, especially for identification of coal seams suitability for CO2-ECBM in South Sumatera Basin. This study has therefore aimed to propose the technical criteria of coal seams suitability for CO2-ECBM recovery as well as predicting CO2 storage capacity by developing a novel numerical model based on the characteristics of coal seams in South Sumatera Basin. The comparison of primary and CO2-ECBM recovery was analysed by performing production forecasting for 30 year of simulation. A sensitivity study was then conducted in order to examine the performance of CO2-ECBM under the influences of permeability, a determining factor in the viability of a CO2 storage in coal seams. A simplified method for estimating CO2 storage capacity in coal seams has been proposed which was validated with the novel numerical model through parametric studies. From this study, one can screen the suitable coal seams for CO2 storage with enhanced coalbed methane recovery and can quickly quantify the CO2 storage capacity in the coal seams with general available data. [ABSTRACT FROM AUTHOR]

Less than 10% of oil is usually recovered from liquid-rich shales and this leaves much room for improvement, while water injection into shale formation is virtually impossible because of the extremely low permeability of the formation matrix. Injecting carbon dioxide (CO2) into oil shale formations can potentially improve oil recovery. Furthermore, the large surface area in organicrich shale could permanently store CO2 without jeopardizing the formation integrity. This work is a mechanism study of evaluating the effectiveness of CO2-enhanced oil shale recovery and shale formation CO2 sequestration capacity using numerical simulation. Petrophysical and fluid properties similar to the Bakken Formation are used to set up the base model for simulation. Result shows that the CO2 injection could increase the oil recovery factor from 7.4% to 53%. In addition, petrophysical characteristics such as in situ stress changes and presence of a natural fracture network in the shale formation are proven to have impacts on subsurface CO2 flow. A response surface modeling approach was applied to investigate the interaction between parameters and generate a proxy model for optimizing oil recovery and CO2 injectivity. [ABSTRACT FROM AUTHOR]

In this work we propose the transformation of CO into calcium carbonate utilizing steel slag and the waste heat generated in the steel industry. The necessary chemicals, aqueous NHCl and solid NaHCO, were obtained as products of a bench scale Solvay process. Our approach is divided into four steps: (i) CO capture using ammoniated brine, (ii) Ca lixiviation from steel slag, through the reaction with NHCl, (iii) CaCO precipitation by reacting the leachate with NaHCO, and (iv) NaCl and NH reclamation. Steel slag is utilized as the source of calcium. A small amount of heat is required by the overall process, which could be also provided by waste heat from the steel industry. Laboratory scale experiments showed that nearly 95 wt% of NaCl and NH necessary for the mineral carbonation can be regenerated, therefore minimizing costs. At the end of this process, 98 wt% pure CaCO is obtained, and up to 94 wt% of the extracted Ca was precipitated with no need for pH adjustments. Finally, we observed that, depending on the source of the steel slag, 86 kg of high purity CaCO could be obtained from 38 kg of CO and 1000 kg of steel slag. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

For decades, ecosystem scientists have used global warming potentials (GWPs) to compare the radiative forcing of various greenhouse gases to determine if ecosystems have a net warming or cooling effect on climate. On a conceptual basis, the continued use of GWPs by the ecological community may be untenable because the use of GWPs requires the implicit assumption that greenhouse gas emissions occur as a single pulse; this assumption is rarely justified in ecosystem studies. We present two alternate metrics-the sustained-flux global warming potential (SGWP, for gas emissions) and the sustained-flux global cooling potential (SGCP, for gas uptake)-for use when gas fluxes persist over time. The SGWP is generally larger than the GWP (by up to ~40%) for both methane and nitrous oxide emissions, creating situations where the GWP and SGWP metrics could provide opposing interpretations about the climatic role of an ecosystem. Further, there is an asymmetry in methane and nitrous oxide dynamics between persistent emission and uptake situations, producing very different values for the SGWP vs. SGCP and leading to the conclusion that ecosystems that take up these gases are very effective at reducing radiative forcing. Although the new metrics are more realistic than the GWP for ecosystem fluxes, we further argue that even these metrics may be insufficient in the context of trying to understand the lifetime climatic role of an ecosystem. A dynamic modeling approach that has the flexibility to account for temporally variable rates of greenhouse gas exchange, and is not limited by a fixed time frame, may be more informative than the SGWP, SGCP, or GWP. Ultimately, we hope this article will stimulate discussion within the ecosystem science community about the most appropriate way(s) of assessing the role of ecosystems as regulators of global climate. [ABSTRACT FROM AUTHOR]

Mesocellular siliceous foams (MCFs) with and without remaining template were prepared and modified by polyethylenimine (PEI) or mixed amines [Diethylenetriamine and PEI or 3-aminopropyltrimethoxysilane (APTMS) and PEI]. These samples were evaluated for their adsorption capacities for CO at different temperatures. With the increase of PEI loading, the optimal adsorption temperature shifts to higher temperature for samples prepared in our study. The remaining template in MCF materials plays an important role in promoting CO adsorption capacity, which could be 3.24 mmol/g when the amount of PEI loading is 70 % at 85 °C. Meanwhile, the remaining template contributes greatly to the dispersion of PEI, resulting in higher adsorption capacity at low temperature. The effect of the amount of remaining template was studied, and it was found that CO adsorption capacity decreases with increasing template. The CO adsorption capacities for mixed-amine-modified MCFs are higher than those of the samples modified by PEI only, which was ascribed to the better dispersion of PEI. MCF modified with the mixing of APTMS and PEI exhibited highest adsorption capacity of 2.67 mmol/g at 50 °C. These findings reveal that pore structure, PEI loading, PEI dispersion, and remaining template work together to influence the CO adsorption performance. [ABSTRACT FROM AUTHOR]

Direct structural information of confined CO2 in a micropore is important for elucidating its specific binding or activation mechanism. However, weak gas-binding ability and/or poor sample crystallinity after guest exchange hindered the development of efficient materials for CO2 incorporation, activation and conversion. Here, we present a dynamic porous coordination polymer (PCP) material with local flexibility, in which the propeller-like ligands rotate to permit CO2 trapping. This process can be characterized by X-ray structural analysis. Owing to its high affinity towards CO2 and the confinement effect, the PCP exhibits high catalytic activity, rapid transformation dynamics, even high size selectivity to different substrates. Together with an excellent stability with turnover numbers (TON) of up to 39,000 per Zn1.5 cluster of catalyst after 10 cycles for CO2 cycloaddition to form value-added cyclic carbonates, these results demonstrate that such distinctive structure is responsible for visual CO2 capture and size-selective conversion. Porous coordination polymers that possess structural flexibility show great promise for gas adsorption and catalysis. Here the authors synthesize a dynamic porous coordination polymer with rotating ligands that permit effective CO2 trapping, and demonstrate subsequent CO2 cycloaddition to epoxides. [ABSTRACT FROM AUTHOR]