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• Concentrations of atmospheric CO2 and tropospheric ozone (O3) are rising concurrently in the atmosphere, with potentially antagonistic effects on forest net primary production (NPP) and implications for terrestrial carbon sequestration. • Using free-air CO2 enrichment (FACE) technology, we exposed north-temperate forest communities to concentrations of CO2 and O3 predicted for the year 2050 for the first 7 yr of stand development. Site-specific allometric equations were applied to annual nondestructive growth measurements to estimate above- and below-ground biomass and NPP for each year of the experiment. • Relative to the control, elevated CO2 increased total biomass 25, 45 and 60% in the aspen, aspen–birch and aspen–maple communities, respectively. Tropospheric O3 caused 23, 13 and 14% reductions in total biomass relative to the control in the respective communities. Combined fumigation resulted in total biomass response of −7.8, +8.4 and +24.3% relative to the control in the aspen, aspen–birch and aspen–sugar maple communities, respectively. • These results indicate that exposure to even moderate levels of O3 significantly reduce the capacity of NPP to respond to elevated CO2 in some forests. [ABSTRACT FROM AUTHOR]

• Concentrations of atmospheric CO2 and tropospheric ozone (O3) are rising concurrently in the atmosphere, with potentially antagonistic effects on forest net primary production (NPP) and implications for terrestrial carbon sequestration. • Using free-air CO2 enrichment (FACE) technology, we exposed north-temperate forest communities to concentrations of CO2 and O3 predicted for the year 2050 for the first 7 yr of stand development. Site-specific allometric equations were applied to annual nondestructive growth measurements to estimate above- and below-ground biomass and NPP for each year of the experiment. • Relative to the control, elevated CO2 increased total biomass 25, 45 and 60% in the aspen, aspen–birch and aspen–maple communities, respectively. Tropospheric O3 caused 23, 13 and 14% reductions in total biomass relative to the control in the respective communities. Combined fumigation resulted in total biomass response of −7.8, +8.4 and +24.3% relative to the control in the aspen, aspen–birch and aspen–sugar maple communities, respectively. • These results indicate that exposure to even moderate levels of O3 significantly reduce the capacity of NPP to respond to elevated CO2 in some forests. [ABSTRACT FROM AUTHOR]

Biochar possesses unique characteristics, including a substantial surface area, a high carbon content, sufficient capacity for cation exchange, and a robust structure. However, biochar contains hazardous pollutants like volatile organic compounds that harm soil properties and functionality. Although several studies on biochar production from various feedstocks have been undertaken in recent years, several issues about feedstock preparation, economic feasibility, influencing factors, and the proper utilization of biochar production processes need to be addressed. This paper thus addresses these issues by providing potential solutions identified through a comprehensive review. Slow pyrolysis of lignocellulosic biomass and Acacia nilotica yields biochar from 20 to 52 wt% at various temperatures and residence times. Biochar yield varies from 29 to 48.3 wt% when waste tires and corn stalks are rapidly pyrolyzed at higher temperatures and for shorter periods. Torrefaction of algal biomass at moderate temperatures with different residence times can result in a substantial yield of 50–60 wt%. However, the variability and heterogeneity of waste feedstocks pose potential challenges affecting biochar's quality and properties. Given its widespread use in carbon sequestration, soil remediation, wastewater purification, and organic waste composting, the mechanisms of biochar production in environmental usage need to be investigated. [ABSTRACT FROM AUTHOR]

In their comment on our 2021 paper "How Green is Blue Hydrogen," Romano et al. purport to provide "a more balanced perspective on blue hydrogen, which is in line with current best available practices." We strongly disagree. First, we categorically dismiss their presentation on methane emissions. Methane dominates the greenhouse gas footprint of blue hydrogen in our analysis, and our estimates were based on very recent, peer‐reviewed science. Romano et al., in sharp contrast, use only three sources: (1) a 2015 non‐peer‐reviewed report (which gave reasonable values, although at the low end, since based on older science, but nonetheless compatible with our paper); (2) a 2018 report from the International Energy Agency (which also gave values consistent with ours, but has been updated by the Agency in a 2022 report to give much higher values that are very consistent with ours); and (3) a value from a cartoon on a web site from an oil and gas industry trade group (i.e., not supported by any data or references and is simply wrong based on peer‐reviewed science). We cannot stress enough that the Romano et al. criticism of our methane emission rates is based totally on this industry web‐site cartoon. Beyond the methane issue, our analysis used actual data for capture of carbon dioxide from real‐world operations. Romano et al. dismiss the use of real‐world data, and instead rely on presentations from theoretical studies. We find this fanciful. But even if one accepts their theoretical values for carbon capture, the greenhouse gas footprint of blue hydrogen remains unacceptably high because of methane. We unequivocally stand by our analyses and conclusions: There is no room for blue hydrogen in a decarbonized energy future. The Romano et al. result derives from a cartoon and hypothetical guesses, not scientific data. [ABSTRACT FROM AUTHOR]

This paper is written in response to the paper "How green is blue hydrogen?" by R. W. Howarth and M. Z. Jacobson. It aims at highlighting and discussing the method and assumptions of that paper, and thereby providing a more balanced perspective on blue hydrogen, which is in line with current best available practices and future plant specifications aiming at low CO2 emissions. More specifically, in this paper, we show that: (i) the simplified method that Howarth and Jacobson used to compute the energy balance of blue hydrogen plants leads to significant overestimation of CO2 emissions and natural gas (NG) consumption and (ii) the assumed methane leakage rate is at the high end of the estimated emissions from current NG production in the United States and cannot be considered representative of all‐NG and blue hydrogen value chains globally. By starting from the detailed and rigorously calculated mass and energy balances of two blue hydrogen plants in the literature, we show the impact that methane leakage rate has on the equivalent CO2 emissions of blue hydrogen. On the basis of our analysis, we show that it is possible for blue hydrogen to have significantly lower equivalent CO2 emissions than the direct use of NG, provided that hydrogen production processes and CO2 capture technologies are implemented that ensure a high CO2 capture rate, preferably above 90%, and a low‐emission NG supply chain. [ABSTRACT FROM AUTHOR]

Environmental issues are the most discussed in today's industrialized world, and this has always been associated with the emission of greenhouse gases. CO2 emissions, especially from power plants, are considered the major greenhouse gas source. Capturing CO2 from large emission sources is necessary to address the worst impacts of climate change, including more frequent and severe droughts, heat waves, and intermittent rainfall. Conventional post‐combustion CO2 capture has always been questioned because of its high impact on energy costs. Rotating packed bed technology has shown the potential to reduce the cost of CO2 capture. This paper presents an experimental study on an in‐house designed rotating packed bed absorber for the capture of CO2 from a flue gas stream. Effects of process parameters such as rotating speed, liquid‐to‐gas ratio, and monoethanolamine (MEA) concentration on CO2 capture efficiency and overall volumetric mass transfer coefficient were studied. The study showed that as rotor speed increased, the CO2 capture efficiency increased, this can be attributed to higher rotor speed, resulting in more droplet flow, indicating an increase in the area of contact between the flue gas and the MEA solvent. Also, as the concentration of MEA increased CO2 capture efficiency increased, since an increase in concentration results in an increase in the rate of reaction. Finally, the study showed that a rotating packed bed absorber is an efficient unit for CO2 capture since it enhances mass transfer performance. [ABSTRACT FROM AUTHOR]

Under the promotion of low‐carbon policies, the coordinated operation of integrated electricity‐gas distribution system (IEGDS) considering CO2 emission is of great significance to accelerate the process of energy conservation and could improve the economy of IEGDS. The paper proposes a low‐carbon coordinated operation of the IEGDS considering hybrid AC/DC distribution network, carbon capture and carbon storage. Firstly, the coordinated scheduling model of the IEGDS is discussed, with coupling constraints of gas turbines and power‐to‐gas. Secondly, the paper presents the model of hybrid AC/DC power distribution system, where non‐linear network constraints are relaxed into second‐order‐cone programming forms. Regarding carbon emission, the CO2 produced by fossil fuel burning can be partly captured by carbon capture plant, stored in carbon storage tank, and transported by trucks to carbon storage warehouse that trades with the carbon market. With the cooperation of various components, a comprehensive model considering carbon flow and trading in the distribution system is innovatively presented here. Numerical experiments validate the effectiveness of proposed low‐carbon coordinated scheduling model for the integrated electricity and natural gas distribution system. [ABSTRACT FROM AUTHOR]

The integrated farming system (IFS) is a holistic farming approach specially designed for small/marginal farmers to enhance the system productivity, profitability, and employment generation of their farm, ultimately ensuring their food and nutrition security for their livelihood. The mechanism of IFS offers various ecosystem services making farms environment‐friendly, sustainable, and climate‐resilient. IFS is characterized by the allocation of different agricultural components systematically in a single farm performing synergistically among themselves making the farm more productive, healthy, biodiversity enriched, and eco‐friendly than simplified farms. Therefore, this review paper represents an extensive analysis of existing literature on IFS exploring its concept, components, and need, and emphasizing its potential for higher system productivity, profitability, and employment generation in a sustainable manner. Moreover, it develops a conceptualization of the relationship among different agricultural components in a single farm exploring its role in ecosystem services (reducing greenhouse gases, carbon sequestration, nutrient recycling, improving soil health, and biodiversity conservation). [ABSTRACT FROM AUTHOR]

Demand for sustainably produced biomass is expected to increase with the need to provide renewable commodities, improve resource security and reduce greenhouse gas emissions in line with COP26 commitments. Studies have demonstrated additional environmental benefits of using perennial biomass crops (PBCs), when produced appropriately, as a feedstock for the growing bioeconomy, including utilisation for bioenergy (with or without carbon capture and storage). PBCs can potentially contribute to Common Agricultural Policy (CAP) (2023–27) objectives provided they are carefully integrated into farming systems and landscapes. Despite significant research and development (R&D) investment over decades in herbaceous and coppiced woody PBCs, deployment has largely stagnated due to social, economic and policy uncertainties. This paper identifies the challenges in creating policies that are acceptable to all actors. Development will need to be informed by measurement, reporting and verification (MRV) of greenhouse gas emissions reductions and other environmental, economic and social metrics. It discusses interlinked issues that must be considered in the expansion of PBC production: (i) available land; (ii) yield potential; (iii) integration into farming systems; (iv) R&D requirements; (v) utilisation options; and (vi) market systems and the socio‐economic environment. It makes policy recommendations that would enable greater PBC deployment: (1) incentivise farmers and land managers through specific policy measures, including carbon pricing, to allocate their less productive and less profitable land for uses which deliver demonstrable greenhouse gas reductions; (2) enable greenhouse gas mitigation markets to develop and offer secure contracts for commercial developers of verifiable low‐carbon bioenergy and bioproducts; (3) support innovation in biomass utilisation value chains; and (4) continue long‐term, strategic R&D and education for positive environmental, economic and social sustainability impacts. Perennial biomass crops (PBCs) can potentially contribute to Common Agricultural Policy (2023–27) objectives provided they are carefully integrated into farming systems and landscapes. Despite significant research and development (R&D) investment over decades in herbaceous and coppiced woody PBCs, deployment has largely stagnated due to social, economic and policy uncertainties. This paper identifies the challenges in creating policies that are acceptable to all actors and discusses the interlinked issues: (i) available land; (ii) yield potential; (iii) integration into farming systems; (iv) R&D requirements; (v) utilisation options; and (vi) market systems and the socio‐economic environment. [ABSTRACT FROM AUTHOR]

Employing a time‐varying difference‐in‐differences model and a data set collected from 2,735 counties in China from 2003 to 2017, this study examines the causal relationship between Chinese government transfer payments to resource‐exhausted cities (TPREC) and carbon emissions for the first time. Our results show that TPREC could significantly reduce carbon emissions of resource‐exhausted cities in China. A variety of robustness tests supports our findings. Our further mechanism analysis shows that TPREC mainly affects carbon emissions through the following three channels: (a) promoting technological progress and industrial upgrades; (b) increasing vegetation carbon sequestration; (c) strengthening government environmental regulations. Finally, this paper analyzes the spatial heterogeneity of the carbon emission reduction effect of TPREC and finds that the most significant reduction effect of TPREC is in the western region and coal‐exhausted cities. This paper provides new empirical evidence for the role of transfer payments in promoting low‐carbon development using a unique set of data. Our findings provide new insights for decision‐makers to facilitate the low‐carbon development of resource‐exhausted cities. Plain Language Summary: By employing a time‐varying difference‐in‐differences model, we examine the causal relationship between central government transfer payments to resource‐exhausted cities and carbon emissions for the first time. We find China's TPREC can significantly reduce carbon emissions by promoting technological progress and industrial upgrades, increasing vegetation carbon sequestration, and strengthening government environmental regulations. Key Points: China's transfer payments to resource‐exhausted cities (TPREC) could significantly reduce carbon emissions, and this conclusion has also been supported by multiple robustness testsThe TPREC could achieve carbon emission reduction by promoting technological progress, industrial upgrading, and economic efficiencyThe most significant carbon emission reduction effect of TPREC is in the western region and coal‐exhausted cities [ABSTRACT FROM AUTHOR]

Produced through pyrolysis, biochars are used as a soil amendment. Differences in feedstock and processing result in differentiated products which impact their values in different soil conditions. Despite the enormous potential, biochars have not been widely used. This paper overviews the benefits and potential demand for biochar and features of supply chain, and identifies opportunities for viable introduction of biochars. The value of biochars should be evaluated as a part of the pyrolysis system that coproduces biochars and biofuels. Biochars can improve agricultural productivity and soil functioning and contribute to climate change mitigation through carbon sequestration. Furthermore, it can provide extra benefit by contributing to fire prevention. The cost of biochar system depends on the costs of feedstock acquisition, transportation, and processing. Biochar is most likely to be adopted in locations with marginal land and high‐value crop, and near low‐cost feedstock sources. The adoption of biochar can be enhanced by compensation for carbon sequestration, further investment in research, and learning of producers to enhance efficiency of the supply chain. Biochar is a charcoal that has been used to improve soil quality. It is obtained through heating organic materials such as crop and forest residues without oxygen. Diverse types of biochar can be coproduced with biofuels. The paper reviews the benefits and potential demand of biochar, and features of the supply chain that would be used to produce and market it. Biochar can improve agricultural productivity and mitigate climate change. Current adoption is low but will be improved with compensation for carbon sequestration, placing processing facilities closer to the biomass sources, and investment in research to reduce cost of production. [ABSTRACT FROM AUTHOR]

The even-aged northern hardwood forests of the Upper Great Lakes Region are undergoing an ecological transition during which structural and biotic complexity is increasing. Early-successional aspen (Populus spp.) and birch (Betula papyrifera) are senescing at an accelerating rate and are being replaced by middle-successional species including northern red oak (Quercus rubra), red maple (Acer rubrum), and white pine (Pinus sirobus). Canopy structural complexity may increase due to forest age, canopy disturbances, and changing species diversity. More structurally complex canopies may enhance carbon (C) sequestration in old forests. We hypothesize that these biotic and structural alterations will result in increased structural complexity of the maturing canopy with implications for forest C uptake. At the University of Michigan Biological Station (UMBS), we combined a decade of observations of net primary productivity (NPP), leaf area index (LAI), site index, canopy tree-species diversity, and stand age with canopy structure measurements made with portable canopy lidar (PCL) in 30 forested plots. We then evaluated the relative impact of stand characteristics on productivity through succession using data collected over a nine-year period. We found that effects of canopy structural complexity on wood NPP (NPPw) were similar in magnitude to the effects of total leaf area and site quality. Furthermore, our results suggest that the effect of stand age on NPPw is mediated primarily through its effect on canopy structural complexity. Stand-level diversity of canopy-tree. species was not significantly related to either canopy structure or NPPw. We conclude that increasing canopy structural complexity provides a mechanism for the potential maintenance of productivity in aging forests. [ABSTRACT FROM AUTHOR]

The water table depth (WTD) in peatlands determines the soil carbon decomposition rate and influences vegetation growth, hence the above‐ground carbon assimilation. Here, we used satellite‐observed Solar‐Induced chlorophyll Fluorescence (SIF) as a proxy of Gross Primary Production (GPP) to investigate water‐related vegetation stress over northern peatlands. A linear model with interaction effects was used to relate short‐ and long‐term anomalies in SIF with WTD anomalies and the absolute WTD. Most locations showed the occurrence of drought and waterlogging stress though regions with exclusively waterlogging or drought stress were also detected. As a spatial median, minimal water‐related vegetation stress was found for a WTD of −0.22 m (short‐term) and −0.20 m (long‐term) (±0.01 m, 95% confidence interval of statistical uncertainty). The stress response observed with SIF is supported by an analysis of in situ GPP data. Our findings provide insight into how changes in WTD of northern peatlands could affect GPP under climate change. Plain Language Summary: Water table depth is an important variable influencing the carbon cycle and vegetation growth in northern peatlands. In this paper, the impact of changing wetness conditions on vegetation growth over peatlands was studied through satellite measurements of solar‐induced fluorescence (SIF), which is a radiation signal emitted by vegetation during photosynthesis. Previous studies over ecosystems on mineral soil, that is, not over peatland, suggested a response of SIF to drought conditions. In our study, it was shown that peatland vegetation experiences moisture‐related growth stress under both very wet and very dry conditions, which might reduce the photosynthesis efficiency and the ability to capture and store CO2. Stress due to drought conditions was detected for peatlands in the south of the Western Siberian Lowlands and the Boreal Plains. Stress due to prolonged wet conditions occurred for example, in the north of the Western Siberian Lowlands and the north of the Hudson Bay Lowlands. Key Points: Spaceborne Solar‐Induced Fluorescence (SIF) data was used to analyze soil moisture‐related vegetation stress regimes in northern peatlandsFor most locations, waterlogging as well as drought stress regimes occurred and alternated depending on peatland water level dynamicsThe SIF‐based stress response observations are supported by in situ data of Gross Primary Production [ABSTRACT FROM AUTHOR]

Adsorption‐based carbon capture has been recognized as an attractive method for mitigating global warming. Metal–organic frameworks (MOFs) are promising candidate adsorbents for this purpose due to their high adsorption uptake and selectivity for carbon dioxide. However, in real‐world applications, such as direct air capture, the presence of moisture in the feed gas may pose a grand challenge for CO2 adsorption in MOFs. This paper aims to address the issue of water–CO2 co‐adsorption in MOFs and present screening criteria for selecting MOFs that preferentially adsorb CO2 under humid conditions. First, we uncover a comprehensive overview of CO2–water co‐adsorption characteristics of various MOFs. Then, the high‐throughput screening methods are summarized. Both computational and experimental efforts have been dedicated to identify the promising MOFs for humid CO2 capture. According to the screening results and adsorption mechanism, the optimal preparation strategies are proposed to modulate the effect of water on CO2 uptake in MOFs. Finally, current MOF‐based CO2 capture prototypes are presented to evaluate their practical feasibility and performance. This work could offer valuable guidance for the development and application of MOFs for CO2 capture in the presence of water and inspire further research in this field. [ABSTRACT FROM AUTHOR]

The increasing utilization of fossil fuels and industrial activities has resulted in a surge of CO2 emissions, which have significantly impacted global climate change. Carbon capture and utilization technologies offer a promising solution to decrease atmospheric CO2 concentrations and convert CO2 into valuable products. This study focuses on the capture and storage of CO2 through the mineralization of magnesium‐containing materials. The analysis encompasses the mineralization process of solid and liquid minerals, the various mineralization processes of magnesium‐containing minerals categorized as direct and indirect mineralization, and the latest research advancements in magnesium‐containing minerals. Brine and seawater from salt lakes are considered the most appropriate materials for mineralization due to their abundance and the simplicity of the process compared to solid mineralization. This paper analyzes the impact of temperature, impurity ions, additives, and microorganisms on the process of magnesium carbonate synthesis crystallization. The use of magnesium‐containing materials for carbon dioxide sequestration can effectively reduce carbon emission. The review offers guidance on carbon dioxide mineralization and explores the potential applications of magnesium mineralization. [ABSTRACT FROM AUTHOR]

The rising amount of greenhouse gases has been contributing to global warming and, subsequently, climate change. Industries such as refineries and power plants emit a significant amount of CO2 into the atmosphere. It is imperative to curb anthropogenic CO2 emissions, and hence, in this effort, we explore the utilization of a refinery emission stream to produce value‐added chemicals. The chosen emission stream for the said purpose is a typical flue gas stream from refineries. Following the capture step, this CO2 stream has been leveraged for subsequent valorization processes. Two strategies have been proposed in this paper to valorize the captured carbon dioxide. The first strategy employs the tri‐reforming process with a refinery‐specific fuel gas stream as the co‐reactant. The resulting syngas from tri‐reforming has been converted to chemicals such as methanol (MET) and ethanol. Furthermore, to improve the amount of CO2 valorized, another approach with green hydrogen has been considered. The second strategy aims at direct hydrogenation of the captured CO2 stream to produce MET and ethanol. The proposed strategies analyze the feasibility of valorizing captured CO2 from flue gas to MET and ethanol in terms of gross margin per feed and percentage of CO2 valorization. The performance assessment and analysis of the proposed processes have been carried out using simulations in Aspen Plus® that exhibited up to 74% valorization of CO2 into valuable chemicals. [ABSTRACT FROM AUTHOR]

As primary producers and ecosystem engineers, kelp (generally Order Laminariales) are ecologically important, and their decline could have far‐reaching consequences. Kelp are valuable in forming habitats for fish and invertebrates and are crucial for adaptation to climate change by creating coastal defenses and in providing key functions, such as carbon sequestration and food provision. Kelp are threatened by multiple stressors, such as climate change, over‐harvesting of predators, and pollution. In this opinion paper, we discuss how these stressors may interact to affect kelp, and how this varies under different contexts. We argue that more research that bridges kelp conservation and multiple stressor theory is needed and outline key questions that should be addressed as a priority. For instance, it is important to understand how previous exposure (either to earlier generations or life stages) determines responses to emerging stressors, and how responses in kelp scale up to alter food webs and ecosystem functioning. By increasing the temporal and biological complexity of kelp research in this way, we will improve our understanding allowing better predictions. This research is essential for the effective conservation and potential restoration of kelp in our rapidly changing world. [ABSTRACT FROM AUTHOR]

In order to achieve greenhouse gas neutrality, hydrogen generated from renewable sources will play an important role. Additionally, as underlined in the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), new technologies to remove greenhouse gases from the atmosphere are required on a large scale. A novel concept for hydrogen production with net negative emissions referred to as HyBECCS (Hydrogen Bioenergy with Carbon Capture and Storage) combines these two purposes in one technological approach. The HyBECCS concept combines biohydrogen production from biomass with the capture and storage of biogenic carbon dioxide. Various technology combinations of HyBECCS processes are possible, whose ecological effects and economic viability need to be analyzed in order to provide a basis for comparison and decision‐making. This paper presents fundamentals for the techno‐economic and environmental evaluation of HyBECCS approaches. Transferable frameworks on system boundaries as well as emission, cost, and revenue streams are defined and specifics for the application of existing assessment methods are elaborated. In addition, peculiarities concerning the HyBECCS approach with respect to political regulatory measures and interrelationships between economics and ecology are outlined. Based on these considerations, two key performance indicators (KPIs) are established, referred to as levelized cost of carbon‐negative hydrogen (LCCNH) and of negative emissions (LCNE). Both KPIs allow deciding whether a specific HyBECCS project is economically viable and allows its comparison with different hydrogen, energy provision, or negative emission technologies (NETs). Carbon‐negative hydrogen production referred to as HyBECCS (Hydrogen Bioenergy with Carbon Capture and Storage) combines hydrogen production from biomass with the capture and storage of biogenic carbon dioxide. Various technology combinations of HyBECCS processes are possible, whose ecological effects and economic viability need to be analysed. This paper presents fundamentals for the techno‐economic and environmental evaluation of HyBECCS approaches. Transferable frameworks on system boundaries as well as emission, cost and revenue streams are defined and specifics for the application of existing assessment methods are elaborated. [ABSTRACT FROM AUTHOR]

The results indicate a high capacity to recover from disturbance, with "released" vegetation supporting an increase in the forest carbon sequestration following the decline of aspen and paper birch. The Forest Accelerated Succession Experiment (FASET) was established in 2008 to examine the effects of a moderate severity disturbance on forest carbon cycling processes. Forest Carbon Sequestration Increases Following a Large-Scale Manipulation of Moderate Severity Disturbance. [Extracted from the article]

The effectiveness of Carbon Capture and Storage (CCS) as an imperative decarbonization technology relies on the sealing capacity of a fine‐grained caprock to permanently store CO2 deep underground. Uncertainties in assessing the caprock sealing capacity increase with the spatial and temporal scales and may delay CCS deployment at the gigatonne scale. We have developed a computationally efficient transport model to capture the dynamics of basin‐wide upward CO2 migration in a multi‐layered setting over geological time scales. We find that massive capillary breakthrough and viscous flow of CO2, even through pervasively fractured caprocks, are unlikely to occur and compromise the storage security. Potential leakage from the injection reservoir is hampered by repetitive layering of overlying caprocks. This finding agrees with geologic intuition and should be understandable by the public, contributing to the development of climate policies around this technology with increased confidence that CO2 will be indefinitely contained in the subsurface. Plain Language Summary: Massive and timely deployment of Carbon Capture and Storage (CCS) at the gigatonne scale is a critical component of the majority of pathways toward reaching the Paris Agreement emissions abatement targets to mitigate climate change. Although CCS has been successfully deployed at multiple sites around the world, concerns about long‐term containment, especially for gigatonne‐scale storage, are causing uncertainty about the ability of geological layers to permanently store CO2 underground. This uncertainty is delaying the widespread deployment of CCS. This paper focuses on assessing the possibility of basin‐wide CO2 leakage through a typical multi‐layered geological setting with a sequence of aquifers and fine‐grained caprocks (e.g., shales). Numerical transport models, constrained by hydraulic properties of intact and pervasively fractured caprocks (as the best‐ and worst‐case scenarios, respectively), enable us to draw unambiguous limits on the CO2 leakage rates over previously unexplored temporal and spatial scales. We show that CO2 leakage to shallow sediments in both extreme scenarios is quite unlikely and the injected CO2 will be contained in the subsurface over millions of years. These findings should offer confidence to industrial developers, policy‐makers, investors, and most importantly, the public that CCS provides a secure and environmentally sound carbon removal option. Key Points: We develop a numerical transport model to understand the long‐term fate of CO2 in gigatonne‐scale geologic carbon storageCO2 leakage is dominated by molecular diffusion at inherently slow rates, hardly approaching a meter per several thousands of yearsThe long‐term potential for CO2 leakage from a multi‐layered system is low, making geologic storage a secure decarbonization technology [ABSTRACT FROM AUTHOR]

Aim: The accumulation of microbial necromass carbon has gained increasing attention due to its slow decomposition. However, it remains unclear what induces the accumulation of microbial necromass carbon via reiterated community turnover on large spatial scales. This study explores the characteristics of soil necromass carbon accumulation in terrestrial ecosystems. Location: Global. Time Period: Contemporary (1999–2022). Major Taxa Studied: Soil microorganisms. Methods: A dataset was compiled using 993 observations from 82 peer‐reviewed papers on the effects of coefficients of microbial necromass accumulation (hereafter NAC) in equilibrium. Linear mixed‐effect models and structural equation models were used to ascertain the controlling factors of the NAC. Results: The average NAC was higher in croplands (28.2) and forests (26.8) than in grasslands (21.1). Edaphic factors seemingly affected the NAC, which was lower in soils with high pH and clay content on a global scale. Biotic factors, particularly those related to living microorganism abundance and microbial biomass nitrogen content, were the pivotal drivers of NAC and accounted for approximately 43.6% of its geographic variability. More organic carbon was likely to be preserved in soil with a higher NAC, regardless of ecosystem type. Conclusions: Novel findings regarding the overriding controls for the living microorganism abundance and microbial biomass nitrogen that drive the NAC highlight an urgent need for viable strategies to manipulate microbial attributes for enhancing carbon sequestration. [ABSTRACT FROM AUTHOR]

Bioenergy will be one of the most important renewable energy sources in the conversion from fossil fuels to bio‐based products. Short rotation coppice Salix could be a key player in this conversion since Salix has rapid growth, positive energy balance, easy to manage cultivation system with vegetative propagation of plant material and multiple harvests from the same plantation. The aim of the present paper is to provide an overview of the main challenges and key issues in willow genetic improvement toward sustainable biofuel value chains. Primarily based on results from the research project "Optimized Utilization of Salix" (OPTUS), the influence of Salix wood quality on the potential for biofuel use is discussed, followed by issues related to the conversion of Salix biomass into liquid and gaseous transportation fuels. Thereafter, the studies address genotypic influence on soil carbon sequestration in Salix plantations, as well as on soil carbon dynamics and climate change impacts. Finally, the opportunities for plant breeding are discussed using willow as a resource for sustainable biofuel production. Substantial phenotypic and genotypic variation was reported for different wood quality traits important in biological (i.e., enzymatic and anaerobic) and thermochemical conversion processes, which is a prerequisite for plant breeding. Furthermore, different Salix genotypes can affect soil carbon sequestration variably, and life cycle assessment illustrates that these differences can result in different climate mitigation potential depending on genotype. Thus, the potential of Salix plantations for sustainable biomass production and its conversion into biofuels is shown. Large genetic variation in various wood and biomass traits, important for different conversion processes and carbon sequestration, provides opportunities to enhance the sustainability of the production system via plant breeding. This includes new breeding targets in addition to traditional targets for high yield to improve biomass quality and carbon sequestration potential. [ABSTRACT FROM AUTHOR]

Park integrated energy system (PIES) can utilize multiple energy resources complementarily and promote comprehensive energy efficiency. However, the uncertainty of renewable energy generation poses significant challenges to the optimal operation of PIES. This paper proposes a data‐driven distributionally robust optimization (DDRO) model for the day‐ahead scheduling of PIESs with coordination of carbon capture and storage devices (CCS) and combined heat and power plants (CHP). First, a deterministic economic dispatch model of PIES was presented with the aim at minimizing the total operating costs of PIES and promoting the photovoltaic (PV) power accommodation. Then, a DDRO model was developed based on the historical data to yield the optimal solution in the worst PV output scenario, where the confidence set is established with comprehensive consideration of norm‐1 and norm‐inf constraints. Furthermore, an efficient solving framework was proposed for the DDRO based on the combination of the column‐and‐constraint generation (C&CG) algorithm and a duality‐free decomposition method. Finally, case studies are carried out to demonstrate the effectiveness of the proposed model. [ABSTRACT FROM AUTHOR]

Carbon capture and utilization/storage is an integral part of a smooth transition to a net‐zero energy portfolio. The distinctive advantages of the calcium looping (CaL) process, including low‐cost and high‐theoretical uptake capacity, make it a promising approach for the decarbonization of fossil fuel power plants and carbon‐intensive industries, including cement and steel. CaL exploits the reversible reaction of CO2 with CaO to capture and release carbon dioxide in a cyclic process. This paper reviews the fundamentals of the CaL process, the kinetics of the carbonation reaction, and extensive research on the development of sorbent materials with high durability for use in the CaL process. Various optimizing strategies for the improvement of the stability and CO2 uptake capacity of materials are outlined. Lastly, an overview of bench‐ and pilot‐scale testing facilities around the world is provided. The characteristics, operating conditions, and the main experimental findings of the testing facilities are summarized. [ABSTRACT FROM AUTHOR]

A new technique for reinforced ammonia with a low carbonized ratio to be crystallized by means of antisolvent crystallization using ethanol as the antisolvent was put forward in this paper in view of existing problems of carbon capture by ammonia. Through the application of antisolvent crystallization to reinforce the crystallization process, low energy consumption of regeneration could be achieved easily due to saving the energy to heat the water of carbonized ammonia in the desorption process. Additionally, if the rate of rising temperature is 5 K/min, the crystal product will be totally decomposed, which has advantages over the process of rich carbonated ammonia. The percent conversion of crystal product can be 100 % when the temperature is 350 K, which can be achieved by the waste heat from the power plant that can be used as a heat source of the regeneration process. When the regenerated temperature is between 313 K and 353 K, the active energy can be 44 kJ/mol. When the rate of rising temperature is 5 K/min, 10 K/min, 15 K/min, and 25 K/min respectively, the rate of decomposition and active energy at different experimental conditions are studied in this paper. [ABSTRACT FROM AUTHOR]

Over the last decades, renewable and clean energy sources are being rigorously adopted along with carbon capture technologies to tackle the increasing carbon dioxide (CO2) concentration level in the environment. CO2 capture is a quintessential option for tackling global warming issues. In this context, the present paper has reviewed the process intensification equipment called a rotating packed bed (RPB), which is highly industry applicable due to high gravity (HiGee) force. This facilitates strong mass transfer characteristics, a compact design, and low energy consumption. In this review, the current research scenario of RPBs using numerical, computational fluid dynamics (CFD), and mathematical modelling, along with different machine learning approaches in the CO2 capture process, has been reviewed. The different geometry designs, hydrodynamic characteristics, performance parameters, research methods, and their effects on CO2 removal efficiency have been discussed. Furthermore, the latest experimental studies are also summarized, especially in the absorption and adsorption domain. Finally, recommendations have been given to support the RPBs in different industrial and commercial applications of CO2 removal. [ABSTRACT FROM AUTHOR]

Mitigating CO2 emissions from industries and other sectors of our economy is a critical component of building a sustainable economy. This paper investigates two different methanol synthesis routes based on CO2 utilization (CO2 capture and utilization [CCU], and tri‐reforming of methane [TRM]), and compares the results with the conventional methanol production using natural gas as the feedstock (NG‐MeOH). A comprehensive techno‐economic analysis (TEA) model that includes the findings of the life cycle assessment (LCA) models of methanol production using various CO2 utilization pathways is conducted. Economic analysis is conducted by developing a cost model that is connected to the simulation models for each production route. Compared to the conventional process (with a GHG emission of 0.6 kg CO2/kg MeOH), the lifecycle GHG reduction of 1.75 and 0.41 kg CO2/kg MeOH are achievable in the CCU and TRM pathways, respectively. Furthermore, the results indicate that, under current market conditions and hydrogen production costs, methanol production via CO2 hydrogenation will result in a cost approximately three times higher than that of the conventional process. The integrated TEA–LCA model shows that this increased cost of production equates to a required life cycle GHG reduction credit of $279 to $422 per tonne of CO2 utilized, depending on construction material and selected pathway. Additionally, when compared to the CO2 hydrogenation route, the tri‐reforming process (TRM‐MeOH) can result in a 42% cost savings. Furthermore, a minimum financial support of $56 per tonne utilized CO2 will be required to make the TRM‐MeOH process economically viable. [ABSTRACT FROM AUTHOR]

An approach for preparing and applying micropatterned alumina tubular membranes was developed for improved gas‐liquid contact at low air pressure drop in direct air capture application. The paper demonstrated that the laser carving of micropatterns on the outer surface of the alumina tubular membranes could greatly increase their outer surface area and enhance gas‐liquid turbulence for a reduced diffusion mass transfer resistance. Six kinds of micropattern configurations were fabricated and studied, including random and regular micropatterns. By introducing a 500‐µm solid grid micropattern, the outer surface area doubles and enhances carbon dioxide capture efficiency from 61% to 97% after the membrane was hydrophobically modified with fluoroalkylsilane. The air pressure drop through the tube lumen remained low even when the packing density increased from 382 to 906 m2/m3. The liquid entry pressure of this micropatterned membrane was the same after testing for 220 h running with the help of periodic drying. [ABSTRACT FROM AUTHOR]

Coastal offshore currents transport terrestrial materials from coastal areas to continental shelf areas in the upper layer; these currents are regarded as unimportant in winter when wind‐driven onshore currents are dominant. In this paper, both long‐term observations and high‐resolution simulations in the East China Sea reveal unique wintertime offshore currents in the upper layer that are widespread in the 30–70‐m isobath area and even overcome the wind‐driven onshore currents at the 50–70‐m isobaths. The mixed layer instabilities, frontogenesis and turbulent thermal wind, which constitute a mechanism in the generation of submesoscale offshore currents, have a growth rate that is fast enough to compete with the wind‐driven dynamics when the winter monsoon is relatively weak (<10 m/s). The alternation of the weak‐wind and strong‐wind modes during the winter monsoons provides a general condition for the repeated occurrence of remarkable submesoscale cross‐shore transport and carbon sequestration in coastal seas. Plain Language Summary: The mechanism by which wintertime cross‐shore currents occur in coastal seas is re‐examined together with wind‐driven mesoscale currents and submesoscale processes. Submesoscale currents, which is shaped like filaments or eddies with a horizontal scale of approximately O(1) km, have frequently been reported in the upper ocean. These submesoscale currents are dynamically defined by conditions where the relative vertical vorticity equals or exceeds the planetary vorticity, where the Rossby number is O(1). Both long‐term observations and high‐resolution simulations in the East China Sea reveal unique wintertime offshore currents in the upper layer that can prevail over wind‐driven onshore currents. The synoptic winter monsoons provide the general conditions for the repeated occurrence of remarkable submesoscale cross‐shore transport and carbon sequestration in coastal seas. Key Points: Significant wintertime offshore currents that overcome wind‐driven onshore currents are investigated in the East China SeaThe submesoscale dynamics are fast enough to compete with the wind‐driven dynamicsThe synoptic winter monsoon provides a general condition for submesoscale cross‐shore events in coastal seas [ABSTRACT FROM AUTHOR]

Carbon capture and storage (CCS) is an important low‐carbon management technology used to reduce CO2 emissions with the captured anthropogenic CO2 for enhanced oil recovery (EOR). This paper provides an overview and analysis of current issues related to CCS projects and CCS technologies. The paper also assesses risks and costs as well as policy, legal, and regulatory frameworks relevant for CCS and the major countries with CCS deployment. Currently, the few CCS projects in operation are mostly for EOR purposes. However, miscible CO2‐EOR in depleted oil and gas reservoirs appears to be the industry's first choice for CO2 sequestration and increasing oil production. Potential CO2 leakage is a major risk for pipelines and geological storage and a comprehensive monitoring program needs to be developed to ascertain its impact on pipeline material integrity, humans, and the environment. The cost of the CCS chain largely depends on the compression solvent for the synthesis gas or flue gas treatment for separation, heat rate, energy required for capture, capital costs of capture equipment, pipeline diameter, and flow capacity, and the homogeneity and permeability of the geological formations. An effective carbon pricing and cap‐and‐trade system as a part of national carbon policy is needed to achieve the goal of CCS. This paper finally discusses China's carbon capture utilization and storage (CCUS) systems and proposes a new CCUS‐LNG transportation process system for the coastal areas of China. Special attention was focused on CO2 transportation, CCUS‐EOR, and a new CCUS‐LNG process system for China. [ABSTRACT FROM AUTHOR]

Hydrogen is often viewed as an important energy carrier in a future decarbonized world. Currently, most hydrogen is produced by steam reforming of methane in natural gas ("gray hydrogen"), with high carbon dioxide emissions. Increasingly, many propose using carbon capture and storage to reduce these emissions, producing so‐called "blue hydrogen," frequently promoted as low emissions. We undertake the first effort in a peer‐reviewed paper to examine the lifecycle greenhouse gas emissions of blue hydrogen accounting for emissions of both carbon dioxide and unburned fugitive methane. Far from being low carbon, greenhouse gas emissions from the production of blue hydrogen are quite high, particularly due to the release of fugitive methane. For our default assumptions (3.5% emission rate of methane from natural gas and a 20‐year global warming potential), total carbon dioxide equivalent emissions for blue hydrogen are only 9%‐12% less than for gray hydrogen. While carbon dioxide emissions are lower, fugitive methane emissions for blue hydrogen are higher than for gray hydrogen because of an increased use of natural gas to power the carbon capture. Perhaps surprisingly, the greenhouse gas footprint of blue hydrogen is more than 20% greater than burning natural gas or coal for heat and some 60% greater than burning diesel oil for heat, again with our default assumptions. In a sensitivity analysis in which the methane emission rate from natural gas is reduced to a low value of 1.54%, greenhouse gas emissions from blue hydrogen are still greater than from simply burning natural gas, and are only 18%‐25% less than for gray hydrogen. Our analysis assumes that captured carbon dioxide can be stored indefinitely, an optimistic and unproven assumption. Even if true though, the use of blue hydrogen appears difficult to justify on climate grounds. [ABSTRACT FROM AUTHOR]

The forest sector can play a significant role in climate change mitigation. We evaluated forest sector carbon trends and potential mitigation scenarios in Vermont using a systems‐based modeling framework that accounts for net emissions from all forest sector components. These components comprise (1) the forest ecosystem, including land‐use change, (2) harvested wood products (HWP), and (3) substitution effects associated with using renewable wood‐based products and fuels in place of more emission‐intensive materials and fossil fuel‐based energy. We assessed baseline carbon trends from 1995 through 2050 using a business as usual (BAU) scenario. Emission reductions associated with different forest management and HWP scenarios were evaluated relative to the BAU scenario from 2020 to 2050. We estimated uncertainty for each forest sector component and used a Monte Carlo approach to estimate the distribution of cumulative total mitigation for each scenario relative to baseline. Our analysis indicates that the strength of the forest sector carbon sink in Vermont has been declining and will continue to decline over coming decades under the BAU scenario. However, several scenarios evaluated here could be effective in reducing emissions and enhancing carbon uptake. Shifting HWP to longer‐lived commodities resulted in a 14% reduction in net cumulative emissions by 2050, the largest reduction of all scenarios. A scenario that combined extending harvest rotations, utilizing additional harvest residues for bioenergy, and increasing forest productivity resulted in a 12% reduction in net cumulative emissions. Shifting commodities from pulp and paper to bioenergy showed a 7.3% reduction in emissions. In contrast, shortening rotations to increase harvests for bioenergy use resulted in a 5.5% increase in emissions. In summary, model simulations suggest that net emissions could be reduced by up to 14% relative to BAU, depending on the management and HWP‐use scenario. Combining multiple scenarios could further enhance reductions. However, realizing the full climate mitigation potential of these forests may be challenging due to socioeconomic barriers to implementation, as well as alternative management objectives that must be considered along with carbon sequestration. [ABSTRACT FROM AUTHOR]

Societal Impact Statement: Globally, the conservation value of big trees is linked to biodiversity and carbon sequestration. We studied trees, greater than 80 cm in diameter, in a forest in the Republic of Congo. We found that more than 100 species reach this size and the most abundant species is Sapele (Entandrophragma cylindricum), which is exploited for global timber markets. More than 40% of the large tree species are used by local people for food. Our results show that big trees are important to local people in the Congo Basin in addition to being the focus of industrial logging and in many areas the basis for the formal economy. Summary: The main aim of this paper is to establish standard techniques for surveying the biggest trees in tropical rain forests.One hundred and thirty hectares (13 plots of 10 ha) of unlogged mixed species terra firma forest in the Republic of Congo were surveyed for trees greater than 80 cm in diameter.More than 100 species of tree exceed 80 cm in diameter and one species, Entandrophragma cylindricum (Sapele or Sapelli), dominates this size class.Obtaining comparable data of big trees from different sites across the tropics is a priority. We propose a standardised plot size of 10 ha, replicated 10 times for each forest type at different study sites and a minimum trunk diameter of 70 cm at breast height or above buttresses. [ABSTRACT FROM AUTHOR]

The article presents discussion on papers related to climate change policy design. The author states the first paper is on the incidence of the carbon tax in climate policy and examine the extent to which the indexing of government transfers makes carbon taxes progressive. He states the second covers unaddressed issues in agricultural soil carbon sequestration while the third concerns the impact of border carbon adjustments (BCAs) under different producer responses.

Biochar is considered to sequester C and deliver other soil ecosystem services, but an overview that synthesizes the current knowledge of biochar implications on all essential soil ecosystem services is difficult to find in the ample biochar literature. Most previous research and review articles on this topic focused on a single ecosystem service and did not integrate all essential soil ecosystem services. This overview paper (1) synthesizes the impacts of biochar on water and wind erosion, C sequestration, soil water, nutrient leaching, soil fertility, crop yields, and other soil ecosystem services based on published literature and (2) highlights remaining research areas. Literature indicates that, in addition to sequestering C, biochar can reduce N2O emissions, nitrate leaching, and runoff; increase soil microbial biomass, plant available water, and crop yields (particularly in tropical regions), and CO2 emissions; and have small or no effects on water and wind erosion. Biochar benefits can be in this order: C sequestration > N2O emissions > Nitrate leaching > Available water > Soil biology > Soil fertility > Crop yields > Runoff. However, literature also indicates that biochar does not always improve all ecosystem services. Its benefits depend on biochar feedstock, pyrolysis temperature, application rate, biochar properties, soil properties, climate, and other factors. For example, biochar can enhance crop yields more in degraded and low fertility soils than in highly fertile and fine‐textured soils. Long‐term (>3 years) field‐scale studies under different soil types, management conditions, and climates are needed for a determination of optimum levels of application, comprehensive life‐cycle analysis, and assessment of agronomic and environmental tradeoffs. Overall, biochar can improve most soil ecosystem services, but the extent of such improvement is highly dependent on biochar properties and soil and climatic conditions. [ABSTRACT FROM AUTHOR]

The targets of limiting global warming levels below 2°C or even 1.5°C set by Paris Agreement heavily rely on bioenergy with carbon capture and storage (BECCS), which can remove carbon dioxide in the atmosphere and achieve net zero greenhouse gas (GHG) emission. Biomass and coal co‐firing with CCS is one of BECCS technologies, as well as a pathway to achieve low carbon transformation and upgrading through retrofitting coal power plants. However, few studies have considered co‐firing ratio of biomass to coal based on each specific coal power plant's characteristic information such as location, installed capacity, resources allocation, and logistic transportation. Therefore, there is a need to understand whether it is worth retrofitting any individual coal power plant for the benefit of GHG emission reduction. It is also important to understand which power plant is suitable for retrofit and the associated co‐firing ratio. In order to fulfill this gap, this paper develops a framework to solve these questions, which mainly include three steps. First, biomass resources are assessed at 1 km spatial resolution with the help of the Geography Information Science method. Second, by setting biomass collection points and linear program model, resource allocation and supply chain for each power plants are complete. Third, is by assessing the life‐cycle emission for each power plant. In this study, Hubei Province in China is taken as the research area and study case. The main conclusions are as follows: (a) biomass co‐firing ratio for each CCS coal power plant to achieve carbon neutral is between 40% and 50%; (b) lower co‐firing ratio sometimes may obtain better carbon emission reduction benefits; (c) even the same installed capacity power plants should consider differentiated retrofit strategy according to their own characteristic. Based on the results and analysis above, retrofit suggestions for each power plant are made in the discussion. [ABSTRACT FROM AUTHOR]

Grasslands occupy almost half of the world's land area. Soil organic carbon (SOC) is a key indicator of soil fertility and grassland productivity. Increasing SOC stocks (so‐called SOC sequestration) improves soil fertility and contributes to climate change mitigation by binding atmospheric carbon dioxide (CO2). Grasslands constitute about 70% of all agricultural land, but their potential for SOC sequestration is largely unknown. This review paper quantitatively summarizes observation‐based studies on the SOC sequestration potential of grasslands in six East African countries (Burundi, Ethiopia, Kenya, Rwanda, Tanzania and Uganda) and seeks to identify knowledge gaps related to SOC sequestration potential in the region. In the studies reviewed, SOC stocks in grasslands range from 3 to 93 Mg C/ha in the upper 0.3 m of the soil profile, while SOC sequestration rate ranges from 0.1 to 3.1 Mg C ha‐1 year‐1 under different management strategies. Grazing management is reported to have a considerable impact on SOC sequestration rates, and grassland regeneration and protection are recommended as options to stimulate SOC sequestration. However, a very limited number of relevant studies are available (n = 23) and there is a need for fundamental information on SOC sequestration potential in the region. The effectiveness of potential incentive mechanisms, such as payments for environmental services, to foster uptake of SOC‐enhancing practices should also be assessed. [ABSTRACT FROM AUTHOR]

India has the second largest population in the world and is characterized by a broad diversity in climate, topography, flora, fauna, land use, and socioeconomic conditions. To help ensure food security in the future, agricultural systems will have to respond to global change drivers such as population growth, changing dietary habits, and climate change. However, alterations of how food is produced in the future may conflict with other UN Sustainable Development Goals (SDGs), such as the protection of land resources and climate change mitigation. It is crucial for decision‐makers to understand potential trade‐offs between these goals to find a balance of human needs and environmental impacts. In this paper, we analyze pathways of agricultural productivity, land use, and land‐cover changes in India until 2030 and their impacts on terrestrial biodiversity and carbon storage. The results show that in order to meet future food production demands, agricultural lands are likely to expand, and existing farmlands need to be intensified. However, both processes will result in biodiversity losses. At the same time, the projections reveal carbon stock increases due to intensification processes and decreases due to conversions of natural land into agriculture. On balance, we find that carbon stocks increase with the scenarios of future agricultural productivity as modeled here. In conclusion, we regard further agricultural intensification as a crucial element to help ensure food security and to slow down the expansion of cropland and pasture. At the same time, policies are required to implement this intensification in a way that minimizes biodiversity losses. Key Points: There are trade‐offs between SDGs related to food provision, climate change mitigation, and preservation of biodiversity in IndiaFurther agricultural intensification is required to help ensure food security and to slow the expansion of cropland and pasture in IndiaIntensification efforts for agricultural production should be joined with specific measures to minimize biodiversity losses [ABSTRACT FROM AUTHOR]

Spontaneous imbibition—the process of a wetting fluid displacing a nonwetting fluid purely by capillary forces—is a ubiquitous phenomenon in porous and fibrous materials. Here we present a new experimental method for quantification of spontaneous imbibition in geologic materials. This method makes it possible to perform spontaneous imbibition under elevated pressure conditions relevant to environmental and energy resource applications. Computed tomography imaging reveals a new time‐independent scaling relationship that describes local imbibition rates as a function of water saturation. Imbibition capillary pressure curves are calculated with this wetting‐phase pressure and flow rate characterization, with no assumptions about the functional form, end point behavior, or scaling factors. Calculated end point capillary pressure is nonzero, in agreement with recent pore‐scale measurements of capillary pressure of trapped nonwetting phase. This work provides a new approach and insights into trapping and remobilization of nonwetting fluids in CO2 storage reservoirs and contaminated groundwater aquifers. Plain Language Summary: Spontaneous flow of fluids in porous and fibrous materials is a common process that causes fluids to soak clothing, diapers, and paper and is an important process controlling the long‐term movement of slow‐moving fluids below the surface of the Earth. In this study, we describe a new experimental method for understanding this spontaneous fluid flow in porous rocks and map the fluid movement with a medical imaging system. We present new experimental observations of this type of flow behavior and explain the results with a mathematical model. The results of this work have important implications for how fluids interact and become trapped in carbon sequestration reservoirs, fractured geothermal reservoirs, and contaminated aquifers. Key Points: A new experimental method is described for performing cocurrent spontaneous imbibition under elevated pressure conditionsSpontaneous imbibition front roughening and local flow rate are described by t−1/4 saturation‐dependent scalingNumerically calculated capillary pressure is found to be nonzero at the residual gas saturation [ABSTRACT FROM AUTHOR]

Carbon sequestration can also occur as alkalinity, dissolved inorganic and organic carbon (DIC and DOC) as well as detritus export beyond the habitat where carbon is fixed. Aquatic carbon sequestration refers to the long-term (century-scale) storage of atmospheric carbon in sediments, biomass and/or water. GLO:4D9/02nov22:lno12268-fig-0001.jpg PHOTO (COLOR): 1 Blue carbon ecosystems (mangroves, saltmarshes, seagrass meadows, and kelp forests) are carbon sequestration hotspots. A faster turnover of contemporary autochthonous organic carbon ("fast carbon") than old allochthonous organic carbon ("slow carbon") revealed a decoupling between carbon burial and anthropogenic CO SB 2 sb emissions. [Extracted from the article]

The article looks at the future modes of transportation and the development of new types of fuel that are not derived from crude oil. Topics discussed include government intervention aimed at decreasing petrol-powered cars, expected increase in demand for electric cars, and innovative chemistries that are helping to create new fuels.

To celebrate the 100th volume of The Canadian Journal of Chemical Engineering (CJCE) in 2022, we briefly narrate its history and accomplishments. The CJCE's journey began in 1929 with the launch of the Canadian Journal of Research (CJR), which transformed to the Canadian Journal of Technology (CJT) in 1951, and finally to its present name in 1957 as the flagship publication of the Canadian Society for Chemical Engineering (CSChE). Using statistical data and keywords mined from Clarivate's Web of Science (WoS) together with manual searches of the articles published in the CJR and CJT, we describe how the scope of chemical engineering has continued to evolve, over the past 90+ years, in becoming ever more multifaceted. Chemical engineering encompasses traditional areas, such as polymers, thermodynamics, transport phenomena, transfer and separation processes, reactor design, energy conversion, process simulation and control, and environmental science; however, it has been expanding to include biotechnology, biomedical, food processing, novel composite materials, nanotechnology, renewable/green energy, CO2 capture and transformation, and numerical techniques like neural networks, artificial intelligence, discrete element methods, etc. Like all scientific journals, the growth and success of the CJCE are attributed to the commitment of its contributing authors. We recognize and celebrate the contributions of several prominent Canadian and international researchers, who published their articles in the CJCE. With a number of new initiatives launched in the last decade, we foresee continued improvements in the stature of the CJCE as a top‐ranked journal for publishing impactful research, leading to advancements in chemical sciences and engineering. [ABSTRACT FROM AUTHOR]

Biological productivity in the Southern Ocean is modulated by iron availability. Every summer, a large phytoplankton bloom forms northwest of the Ross Sea, above the Antarctic Australian Ridge (AAR), due to a plume of iron‐rich waters. Here, we investigate the origin and trajectories of these iron‐rich waters by analyzing water mass observations and Lagrangian experiments. Output from the Southern Ocean State Estimate (SOSE) and in situ measurements reveal that iron‐rich AAR bloom waters share properties with Modified Circumpolar Deep Water (MCDW), which forms on the Antarctic shelf‐slope. The Lagrangian experiments are conducted using SOSE velocities. Bloom waters tracked with virtual Lagrangian particles highlight an along isopycnal pathway of MCDW from Antarctica's shelf‐slope to the AAR bloom site, illustrating advection of these waters by the Balleny Gyre. These results are supported by temperature‐salinity analyses, which show a correlation between waters advected northwards; MCDW properties; and high iron concentrations. Plain Language Summary: The biological productivity in the Southern Ocean is limited by the availability of iron and light. During the summer, when light is abundant, a current of iron‐rich waters allows the formation of a phytoplankton bloom on the Pacific sector of the Southern Ocean, above the Australian Antarctic Ridge (AAR). The AAR bloom has an average area of 266,000 km2 and has been observed by satellites for more than 20 years. The temporal and spatial consistency of this bloom has important ecological implications. For example, it is a persistent feeding ground for humpback whales. In this work, we use observations and model output to characterize the properties of these iron‐rich waters and their origin. Our analyses suggest that these iron‐rich waters form near the Antarctic shelf and are transported to the AAR bloom area by the local circulation. Quantifying the connectivity between iron sources and the surface is crucial to better monitor Southern Ocean ecosystems as well as their impact on carbon sequestration. Key Points: The Antarctic Australian Ridge phytoplankton bloom's cooler, iron‐rich waters share properties with Modified Circumpolar Deep WaterLagrangian simulations reveal pathways for iron supply from the Antarctic shelf‐slope to the bloom site following the Balleny GyreThe cooler, iron‐rich waters at the bloom site are correlated with northward Lagrangian displacements after a year of advection [ABSTRACT FROM AUTHOR]

Rechargeable Li‐CO2 batteries are considered as a promising carbon‐neutral energy storage technology owing to their ultra‐high energy density and efficient CO2 capture capability. However, the sluggish CO2 reduction/evolution kinetics impedes their practical application, which leads to huge overpotentials and poor cyclability. Multi‐element transit metal oxides (TMOs) are demonstrated as effective cathodic catalysts for Li‐CO2 batteries. But there are no reports on the integration of defect engineering on multi‐element TMOs. Herein, the oxygen vacancy‐bearing Li‐Ni‐Co‐Mn multi‐oxide (Re‐NCM‐H3) catalyst with the α‐NaFeO2‐type structure is first fabricated by annealing the NiCoMn precursor that derived from spent ternary LiNi0.8Co0.1Mn0.1O2 cathode, in H2 at 300 °C. As demonstrated by experimental results and theory calculations, the introduction of moderate oxygen vacancy has optimized electronic state near the Fermi level (Ef), eventually improving CO2 adsorption and charge transfer. Therefore, the Li‐CO2 batteries with Re‐NCM‐H3 catalyst deliver a high capacity (11808.9 mAh g−1), a lower overpotential (1.54 V), as well as excellent stability over 216 cycles at 100 mA g−1 and 165 cycles at 400 mA g−1. This study not only opens up a sustainable application of spent ternary cathode, but also validates the potential of multi‐element TMO catalysts with oxygen defects for high‐efficiency Li‐CO2 batteries. [ABSTRACT FROM AUTHOR]

Quantifying the carbon budget in rice paddy ecosystems is fundamental to understanding the role of paddy fields as carbon sinks or sources and to mitigating global climate change. This study used a process‐based model of the denitrification‐decomposition (DNDC) model to estimate greenhouse gas (GHG) emissions and carbon sinks in the paddy ecosystem across China. The simulation results showed that the GHG emissions were 0.147 Pg C‐equivalent year−1 and that the carbon sequestration in rice plants and soils reached 0.253 Pg C year−1 in 2016, indicating high carbon sequestration potential of the Chinese paddy ecosystem. Land management had a great influence on carbon budgets, among which straw residue incorporation rate and nitrogen fertilizer applications had a stronger influence on carbon budgets, particularly for double cropping rice. These results indicate that appropriate tillage practices can reduce GHG emissions and increase carbon sequestration of rice ecosystems while ensuring rice yields. [ABSTRACT FROM AUTHOR]

Miscanthus × giganteus (miscanthus) is considered a beneficial biomass energy crop because of its carbon (C) sequestration potential and low fertilizer requirements, but few studies in the United States have measured long‐term C sequestration of miscanthus on suboptimal agricultural lands over a decadal scale, and none have been conducted in southeast Ohio. The objective of this study was to measure the soil C sequestration on abandoned agricultural land with a miscanthus crop that is harvested annually, the long‐term changes in plant and soil nitrogen (N), and the photosynthetic capacity in the tenth year of growth. This study was conducted over a 10‐year period from 2013 through 2023. A significant amount of C was accumulated in the soil (p < 0.05) and the mean C sequestration rates were 0.83 and 1.37 Mg C ha−1 year−1 at two different sites. The amount of C accumulated in the miscanthus plots by the tenth year was also greater than soil C in unmanaged grassland soils, but the difference was not statistically significant (p > 0.05). There was no statistically significant change in the amount of N found in soil and plants over 10 years (p > 0.05), but the variability in plant N was greater in some years relative to others. Even though miscanthus was grown without N fertilizers in this study, soil N at 0–30 cm depth was not depleted over 10 years of crop management. The photosynthetic capacity of miscanthus measured in this study indicated that the plants were thriving after 10 years, and C assimilation for growth was consistent with the findings of prior work that evaluated the maximum photosynthetic rates of this species. The combination of significant soil C sequestration, sustained soil N, and high photosynthetic rates has important implications for the sustainability of miscanthus as a biomass crop. [ABSTRACT FROM AUTHOR]

Biofuel can be used to abate greenhouse gas emissions in the transport sector, by replacing fossil fuel. To avoid the problem of competition with food production, the use of abandoned agricultural land (AAL) for production of the feedstock for biofuel has been proposed. AAL has generally low productivity but has also low opportunity costs, and production of perennial bioenergy crops on it can lead to carbon sequestration. A spatially explicit optimization model of biofuel production and transport fuel consumption, applied to Sweden, was used for an analysis of how AAL can alter costs for greenhouse gas emissions abatement. Results show that, compared to the case without AAL, AAL could decrease the costs of reducing greenhouse gas emissions by 29%, for emissions reductions equivalent to 50% of current emissions from gasoline in Sweden. The carbon sequestration from establishing perennial bioenergy crops on AAL is the main driver of the positive results. High carbon sequestration on AAL implies larger emissions reduction for a given volume of biofuel, and the results show that the total biofuel production can be both smaller and larger with AAL. The use of arable land for biofuel production is generally smaller with AAL, but larger at some of the highest analyzed target levels. The low AAL feedstock costs contribute to lower costs of the total biofuel production, which pushes for more total biofuel production and less fuel use reduction and therefore counteracts the reduced use of arable land. [ABSTRACT FROM AUTHOR]

Existing estimates of the climate mitigation potential from cropland carbon sequestration (C‐sequestration) are limited because they tend to assume constant rates of soil organic carbon change over all available cropland area, use relatively coarse land delineations, and often fail to adequately consider the agronomic and socioeconomic dimensions of agricultural land use. This results in an inflated estimate of the C‐sequestration potential. We address this gap by defining a more appropriate land base for cover cropping in the United States for C‐sequestration purposes: stable croplands in annual production systems that can integrate cover cropping without irrigation. Our baseline estimate of this suitable stable cropland area is 32% of current U.S. cropland extent. Even an alternative, less restrictive definition of stability results in a large reduction in area (44% of current U.S. croplands). Focusing cover crop implementation to this constrained land base would increase durability of associated C‐sequestration and limit soil carbon loss from land conversion to qualify for carbon‐specific incentives. Applying spatially‐variable C‐sequestration rates from the literature to our baseline area yields a technical potential of 19.4 Tg CO2e yr−1 annually, about one‐fifth of previous estimates. We also find the cost of realizing about half (10 Tg CO2e yr−1) of this potential could exceed 100 USD Mg CO2e−1, an order of magnitude higher than previously thought. While our economic analyses suggest that financial incentives are necessary for large‐scale adoption of cover cropping in the U.S., they also imply any C‐sequestration realized under such incentives is likely to be additional. Plain Language Summary: As a "Nature‐based Climate Solution" (NCS), the practice of cover cropping has received widespread attention and investment recently. Through cover cropping, croplands may be able to absorb and hold more carbon in soil, drawing down CO2 in the atmosphere (i.e., sequester carbon). However, the sequestration that is feasible, which reflects socioeconomic and land use considerations, remains unquantified. We estimate this feasible potential for carbon sequestration in the U.S. croplands from cover cropping and find it to be a fraction of previous estimates. A large portion of the reduction is due to our use of a more realistic and rigorous definition of the land area suitable for cover cropping for climate mitigation purposes. This land area comprises "croplands remaining croplands" (or stable croplands) that are planted to annual crops, like corn and soybeans, because they can more easily integrate the practice. We exclude irrigated croplands to conserve water resources. At just under 44 million ha, our baseline area estimate is 32% of the current U.S. cropland extent. The rest of the reduction is associated with our use of more conservative rates of increase in soil carbon from cover cropping than earlier studies that are more realistic for assessing soil carbon sequestration potential over large areas. Our economic analyses suggests that without financial incentives, implementing cover cropping could be expensive for most U.S. farmers. This high cost hurdle needs to be evaluated against the cost‐effectiveness of alternatives that compete for the same limited resources for climate mitigation. Key Points: For U.S. croplands, the feasible potential of carbon sequestration from cover cropping is a fraction of previous estimatesDefining the land base suitable for mitigation practices more realistically and rigorously is critical to estimating the feasible potentialCover cropping, though beneficial for soil health, may not be a low‐cost pathway for climate mitigation at scale in the U.S. [ABSTRACT FROM AUTHOR]

Ongoing concern over climate change has led to interest in replacing fossil energy with bioenergy. There are different approaches to quantitatively estimate the climate change effects of bioenergy systems. In the present work, we have focused on a range of published impact assessment methods that vary due to conceptual differences in the treatment of biogenic carbon fluxes, the type of climate change impacts they address and differences in time horizon and time preference. Specifically, this paper reviews fifteen different methods and applies these to three hypothetical bioenergy case studies: (a) woody biomass grown on previously forested land; (b) woody biomass grown on previous pasture land; and (b) annual energy crop grown on previously cropped land. Our analysis shows that the choice of method can have an important influence on the quantification of climate change effects of bioenergy, particularly when a mature forest is converted to bioenergy use as it involves a substantial reduction in biomass carbon stocks. Results are more uniform in other case studies. In general, results are more sensitive to specific impact assessment methods when they involve both emissions and removals at different points in time, such as for forest bioenergy, but have a much smaller influence on agricultural bioenergy systems grown on land previously used for pasture or annual cropping. The development of effective policies for climate change mitigation through renewable energy use requires consistent and accurate approaches to identification of bioenergy systems that can result in climate change mitigation. The use of different methods for the same purpose: estimating the climate change effects of bioenergy systems, can lead to confusing and contradictory conclusions. A full interpretation of the results generated with different methods must be based on an understanding that the different methods focus on different aspects of climate change and represent different time preferences. There are different approaches to quantitatively estimate the climate change effects of bioenergy systems. In the present work, we review fifteen different methods and apply these to three hypothetical bioenergy case studies. Our analysis shows that the choice of method can have an important influence on the quantification of climate change effects of bioenergy. The use of different methods for the same purpose can lead to confusing and contradictory conclusions. [ABSTRACT FROM AUTHOR]

Chemical looping air separation (CLAS) is a novel and promising technology for oxygen production. This paper presents the application of CLAS to the supercritical power plant for MILD oxy‐combustion. Compared with the reference conventional supercritical power plant, the power generation efficiency of the CLAS integrated MILD oxy‐combustion plant is only reduced by about ~1.37% points at the baseline case. CO2 compression process imposes additional ~3.97% points efficiency penalty, which is inevitable to all of the CO2 capture technologies. The net power efficiency of the CLAS integrated MILD oxy‐combustion plant is ~37.37%. Even though a higher reduction reactor temperature could boost the power efficiency and a higher oxidization reactor temperature reversely decreases the power efficiency, the influence of reactor temperature is marginal. The performance of CLAS integrated MILD oxy‐combustion plant is not sensitive to excess CO2 and O2 ratio. Different oxygen carriers have different suitable operating region, but possess similar power efficiency. The carbon capture rate of the CLAS integrated MILD oxy‐combustion plant is up to ~100%, resulting in a virtually carbon‐free fossil power plant. Chemical looping air separation is integrated with MILD oxy‐combustion. Net power efficiency of the plant is 37.37% including CO2 compression. Sensitivity analysis is conducted. [ABSTRACT FROM AUTHOR]