Search

Due to its cost-effectiveness and high product selectivity, tin oxide has been regarded as a promising catalyst for the electrochemical conversion of CO2 to formate. However, formate production is hindered by the high overpotential; there is a need to reduce the overpotential to enhance energy efficiency and lower electricity cost for the implementation of carbon utilization technology. Here, we report a facile synthesis method for 1 nm-sized SnO2 cluster catalysts, which can be used for CO2-to-formate conversion. SnO2 clusters were prepared through impregnation of porous carbon with a tin precursor solution. The SnO2 clusters showed a low overpotential, generating a current density of 10 mA cm-2 at a potential of -0.34 V vs. RHE in 1 M KOH. They also achieved high Faradaic efficiencies of 90.5% and 81.5% at 200 and 300 mA cm−2, respectively. Their electrocatalytic performance was strongly dependent on the annealing conditions, which affected the particle size, electrochemical active surface area, and metal oxidation state. This paper presents a versatile method for synthesizing metal oxide cluster catalysts, apart from providing insights into the catalytic activity for the electrochemical conversion of CO2 to formate. [ABSTRACT FROM AUTHOR]

In order to study the performance of partially precast partially encased assembled composite beam (PPECB) in reducing costs and reducing carbon dioxide (CO2) emissions, this paper obtained the bearing capacity of PPECBs by a static test. Considering the load conditions and beam height conditions as constraints, the steel-concrete composite beam (SCCB) and reinforced concrete beam (RCB) were optimized and designed based on the principle of fully utilizing the advantages of steel and concrete. On the basis of investigating the quantity of different materials, the cost and CO2 emissions of the three different types of beams were analyzed. The cost and CO2 emission of the PPECB are the lowest, and SCCBs have the highest cost and CO2 emissions. This paper can provide reference for design choice and further research from the perspective of cost and CO2 emission and lay a solid foundation for the realization of economic and environment-friendly buildings. [ABSTRACT FROM AUTHOR]

The increasing carbon dioxide content is identified as the main cause of global warming. Capturing carbon dioxide in the atmosphere and transporting it to deep salt layer for storage have been proven and practiced in many aspects, which considered to be an effective way to reduce the content of carbon dioxide in the atmosphere. The sealing property of cap rocks is one of the key factors to determine whether CO2 can be effectively stored for a long time. In view of the disadvantages of tedious and time-consuming laboratory test methods for breakthrough pressure of cap rock, this paper explores the relationship between breakthrough pressure and other parameters such as porosity, permeability, density, specific surface area, maximum throat radius, and total organic carbon. The results show that the rock breakthrough pressure is closely related to the maximum throat radius and permeability determined by the mercury injection method, followed by the porosity and specific surface area, and less related to the density, depth, and TOC content of the rock itself. Then, with the selected parameters, a neural network model is established to predict the breakthrough pressure of cap rock, which can achieve good prediction results. [ABSTRACT FROM AUTHOR]

The year 2020 has seen the world gripped by the effects of the COVID‐19 pandemic. It is not the first time, nor will it be last, that our increasingly globalized world has been significantly affected by the emergence of a new disease. In much of the Northern Hemisphere, the academic year begins in September, and for many countries, September 2020 marked the return to full schooling after some period of enforced closure due to COVID‐19. In this paper, we focus on the airborne spread of disease and investigate the likelihood of transmission in school environments. It is crucial to understand the risk airborne infection from COVID‐19 might pose to pupils, teachers, and their wider social groups. We use monitored CO2 data from 45 classrooms in 11 different schools from within the UK to estimate the likelihood of infection occurring within classrooms regularly attended by the same staff and pupils. We determine estimates of the number of secondary infections arising via the airborne route over pre/asymptomatic periods on a rolling basis. Results show that, assuming relatively quiet desk‐based work, the number of secondary infections is likely to remain reassuringly below unity; however, it can vary widely between classrooms of the same school even when the same ventilation system is present. Crucially, the data highlight significant variation with the seasons with January being nearly twice as risky as July. We show that such seasonal variations in risk due to changes in ventilation rates are robust and our results hold for wide variations in disease parameterizations, suggesting our results may be applied to a number of different airborne diseases. [ABSTRACT FROM AUTHOR]

The scroll-type compressor is the core component of the refrigeration system using the natural refrigerant carbon dioxide. An accurate scroll geometric theoretical model is essential for evaluating and enhancing compressor performance. The present paper proposed and validated an improved geometric theoretical model of a scroll compressor. A vector triangle method-based general piecewise function describes precisely the volume variation of the working chambers, based on which the transient throughflow modeling and performance evaluation of a carbon dioxide scroll compressor were conducted. The mechanisms and influencing factors of the suction precompression and the asymmetry discharging were analyzed. The results indicate that the strength of the suction precompression is mainly influenced by the suction vacuum under different rotating speeds, partly associated with the tangential leakage under low rotating speeds. The increasing initial suction pressure contributes to the linear raising of the pressure difference between suction initial and ending pressures, decreasing the precompression extension slightly. The variation of the discharge throughflow areas of two symmetric discharge chambers dominates the pressure asymmetry, which is gradually eliminated by the overlapping throughflow area. Compared with the circular discharge structure, the waist-shape port reduces the pressure asymmetry degree and shortens its duration. [ABSTRACT FROM AUTHOR]

Summary: The greenhouse effect is exacerbated as greenhouse gas concentrations rise. Capturing and degrading methane in the atmosphere can effectively slow the trend of global temperature rise. The solar chimney power plant integrated with photocatalytic reactor (SCPP‐PCR) is a promising concept for both clean electricity generation and large‐scale atmospheric methane removal. In this paper, this concept was for the first time quantitatively verified by integrating a photocatalytic reactor in the collector of SCPP to realize the above two targets. A systematic numerical model was proposed to evaluate the performance of degradation of methane and the electricity generation of the SCPP‐PCR. The results revealed that the methane purification rate decreased with increasing turbine rotational speed, but the photocatalytic efficiency improved. In this research, the start of the PCR was set at the entrance of the collector, and it was cost‐effective to lay 40 m in the radial direction with an investment of $4587 (around 0.37% of the total investment of the system). The system could degrade 30 595.47 g of atmospheric methane and reduce CO2 emissions by 245.38 kg in the daytime in Wuhan. It was revealed that SCPP‐PCR could be crucial for reducing greenhouse gas and limiting climate change. [ABSTRACT FROM AUTHOR]

Summary: Anthropogenic activities including the combustion of fossil fuels have led to a dramatic increase in the rate of carbon dioxide (CO2) emission in the last three decades. Since fossil‐based fuels are still the predominant energy source for this century, CO2 is a colossal problem. It is emitted as a consequence of combustion and human activities and is a major greenhouse gas (GHG) that significantly contributes to climate change and global warming, making CO2 emission a worldwide problem. The Intergovernmental Panel on Climate Change (IPCC) has proposed a 45% decrease in anthropogenic CO2 emissions by 2030, with a target of "net‐zero" CO2 emissions by 2050. Despite its harmful effects, CO2 has the potential to be used for a wide range of different industrial needs, after its capture. CO2 capture technologies are still in the early stage of development because of economic and technological issues. However, in the future, carbon capture and related application technologies and methods may become easier and more accessible due to the new developments in the materials synthesis, strategies and skills and inexpensive utilization, and functioning cost of the employed methods. Furthermore, carbon capture system (CCS) might improve the recent power plan system properties. Concerning climate change, carbon capture is deemed as a promising solution to prevent CO2 emissions. CO2 capture, storage, and utilization are garnering intensive interest from scientists worldwide. This review paper identifies and gave particular attention to the literature on the recent CO2 capture technologies, for example, adsorption, absorption, membrane, and algae‐based separation techniques for pre‐combustion, oxy‐fuel combustion, and post‐combustion periods. Aside from all of these capture technologies, the utilization and application of captured CO2 in various industrial fields such as solvents, chemicals, and fuels are evaluated. [ABSTRACT FROM AUTHOR]

Summary: In this paper, the effects of operating conditions on CO hydrogenation reactions were explored by statistical‐based selectivity models in the presence of a γ‐Al2O3 supported Fe‐Co bimetallic nanocatalyst. The temperature, pressure, and feed ratio varied in 1 to 7 bar, 573 to 663 K, 0.5 to 2, respectively; while the GHSV was 3000 h−1 in a fixed bed micro‐reactor. Response surface methodology indicated that optimum conditions for the production of maximum olefins and minimum CH4, paraffin, and carbon dioxide involved T = 579 K, H2/CO = 1, and P = 1 bar. The increase in H2/CO, pressure, and temperature reduced olefin selectivity and raised the selectivity of paraffin, CH4, and carbon dioxide. SEM and BET techniques were used to characterize the catalyst. [ABSTRACT FROM AUTHOR]

This paper proposes an oxygen and carbon dioxide concentration monitoring system for freshness management based on radio frequency identification (RFID). Freshness can be checked by various factors including humidity, temperature, oxygen, and carbon dioxide. This paper focuses on oxygen and carbon dioxide. The concentrations of these two gases are related to freshness and affect the food. We use a sensor for monitoring these gases and combine the sensor with an RFID tag. The RFID system is relatively easy to manage. With this combined system, we estimated the freshness of vegetables. [ABSTRACT FROM AUTHOR]

Under the situation of global low-carbon development, the contradiction among energy consumption, economic growth, and CO2 emissions is increasingly prominent. Considering the possible two-way feedback among the three, based on the panel data of 30 regions in China from 2000 to 2017, this paper establishes a spatial Durbin model including economic growth, energy consumption equation, and CO2 emissions and studies the dynamic relationship and spatial spillover among economic growth, energy consumption, and CO2 emissions effects. The results show that the economic growth can significantly improve carbon dioxide emissions, and China's economic growth level has become a positive driving force for carbon dioxide emissions. However, economic growth will not be significantly affected by the reduction of carbon dioxide emissions. There is a two-way relationship between energy consumption (ENC) and carbon dioxide emissions (CO2). Energy consumption and carbon emissions are interrelated, which has a negative spatial spillover effect on the carbon dioxide emissions of the surrounding provinces and cities. [ABSTRACT FROM AUTHOR]

In the field of condition-based maintenance, maintenance costs and system reliability criteria are the primary considerations for traditional maintenance management. These methods lack consideration of the environmental impact caused by equipment degradation, such as excessive emissions and energy consumption. In addition, because equipment degradation has various impacts on the ecological environment, companies with excessive emissions and energy consumption can receive huge fines, making it of great value to study ecoconscious maintenance strategies. In this paper, we propose a condition-based maintenance strategy considering energy consumption and carbon dioxide emissions. The major objective of the research is to extend a model which integrates ecological aspects with maintenance decision-making and optimization. The simulation and sensitivity analyses conducted verify that the model proposed can minimize total costs, as well as the environmental impact. [ABSTRACT FROM AUTHOR]

Indoor carbon dioxide ( CO2) concentrations have been used for decades to characterize building ventilation and indoor air quality. Many of these applications require rates of CO2 generation from the building occupants, which are currently based on approaches and data that are several decades old. However, CO2 generation rates can be derived from well-established concepts within the fields of human metabolism and exercise physiology, which relate these rates to body size and composition, diet, and level of physical activity. This paper reviews how CO2 generation rates have been estimated in the past and discusses how they can be characterized more accurately. Based on this information, a new approach to estimating CO2 generation rates is presented, which is based on the described concepts from the fields of human metabolism and exercise physiology. Using this approach and more recent data on body mass and physical activity, values of CO2 generation rates from building occupants are presented along with the variability that may occur based on body mass and activity data. [ABSTRACT FROM AUTHOR]

In this paper, the inerting effect and migration law of inert N2 and CO2 in large inclined goaf are studied using a physical simulation model. The differences in oxygen reduction and inert gas migration are analyzed and compared. The results show that as N2 and CO2 injection increased, the oxidation zone's range and width shrunk, and the end of the loose and oxidation zones moved closer to the working face. The migration profile of CO2 and N2 resembled a trumpet and an L shape, respectively, and under the same inerting flow rate, the effect of CO2 inerting on oxygen reduction was much less significant than that of N2. [ABSTRACT FROM AUTHOR]

Since China's reform and opening up, the social economy has achieved rapid development, followed by a sharp increase in carbon dioxide (CO2) emissions. Therefore, at the 75th United Nations General Assembly, China proposed to achieve carbon peaking by 2030 and carbon neutrality by 2060. The research work on advance forecasting of CO2 emissions is essential to achieve the above-mentioned carbon peaking and carbon neutrality goals in China. In order to achieve accurate prediction of CO2 emissions, this study establishes a hybrid intelligent algorithm model suitable for CO2 emissions prediction based on China's CO2 emissions and related socioeconomic indicator data from 1971 to 2017. The hyperparameters of Least Squares Support Vector Regression (LSSVR) are optimized by the Adaptive Artificial Bee Colony (AABC) algorithm to build a high-performance hybrid intelligence model. The research results show that the hybrid intelligent algorithm model designed in this paper has stronger robustness and accuracy with relative error almost within ±5% in the advance prediction of CO2 emissions. The modeling scheme proposed in this study can not only provide strong support for the Chinese government and industry departments to formulate policies related to the carbon peaking and carbon neutrality goals, but also can be extended to the research of other socioeconomic-related issues. [ABSTRACT FROM AUTHOR]

Summary: The use of CO2 as a refrigerant has become a trend in the development of the refrigeration industry. Refinement of new layout and improvement of cycle performance remains a major research direction, which coupling ejector and internal heat exchanger with the transcritical CO2 cycle is a popular method. In this paper, the issue of the effect of different positions of the internal heat exchanger on the dual‐ejector transcritical CO2 refrigeration cycle is discussed. The dual‐ejector cycle is evaluated both thermodynamically and economically by means of multi‐parameter optimization, which is compared with conventional two‐stage transcritical CO2 refrigeration cycle. The obtained results show that the COP of the dual‐ejector transcritical CO2 refrigeration cycle is on average about 42% higher than that of the conventional two‐stage transcritical CO2 refrigeration cycle. Adding internal heat exchanger at different locations cannot improve the performance of dual‐ejector transcritical CO2 refrigeration cycle system in low‐temperature refrigeration. In addition, the exergy and economic analysis shows that the dual‐ejector transcritical CO2 refrigeration cycle has better exergy efficiency, and the increase of internal heat exchanger is an unfavorable exergy efficiency. The exergy destruction rate and the total cost of the dual‐ejector system are on average 58% and 19% lower than that of the conventional cycle, respectively. At the same time, the addition of internal heat exchanger has very little impact on the total system cost. [ABSTRACT FROM AUTHOR]

Indoor carbon dioxide (CO2) concentrations have been considered for decades in evaluating indoor air quality (IAQ) and ventilation, and more recently in discussions of the risk of airborne infectious disease transmission. However, many of these applications reflect a lack of understanding of the connection between indoor CO2 levels, ventilation, and IAQ. For example, a single indoor concentration such as 1000 ppmv is often used as a metric of IAQ and ventilation without an understanding of the significance of this or any other value. CO2 concentrations are of limited value as IAQ metrics, and a single concentration will not serve as a ventilation indicator for spaces with different occupancies and ventilation requirements. An approach has been developed to estimate a space‐specific CO2 level that can serve as a metric of outdoor ventilation rates. The concept is to estimate the CO2 concentration that would be expected in a specific space given its intended or expected ventilation rate, the number of occupants, the rate at which they generate CO2, and the time that has transpired since the space was occupied. This paper describes the approach and presents example calculations for several commercial, institutional, and residential occupancies. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, the characteristics of the supercritical CO2-based Rankine cycle powered by solar energy are experimentally investigated. In order to study the controlling factors of system performances, in the experimental setups an electrical heating section as well as an evacuated solar collect is utilized. Also, corresponding heat transfer measurements of the supercritical CO2 fluid in the heating section are conducted. Results show that the collecting efficiency will increase with the CO2 mass flow rate. The increase in solar radiation and the decrease in condensation temperature in the cycle both can lead to the increase in CO2 mass flow. It is also found that the CO2 fluid flow in the heating section is not fully developed and the Local Nusselt number decreases along the flow direction of the testing pipe. The influences of pressure as well as other controlling factors on heat transfer are also analyzed in detail in this paper. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper applies the Rudnick and Milton method through the dynamic evaluation of the probability of airborne contagion, redefining all parameters and variables in discretized form. To adapt the calculation of the risk of contagion to real needs, scenarios are used to define the presence of people, infected subjects, the hourly production of the quanta of infection, and the calculation of the concentration of CO2 produced by exhalation in the air. Three case studies are discussed: a school, an office, a commercial activity. Complex scenarios include environmental sanitization, a variable number of people, and the possibility of simulating work shifts. The dynamic evaluation of the quanta of infection is also estimated, not foreseen by the Rudnick and Milton model, and involves updating the average values of the equivalent fraction of the indoor air with an improvement in the accuracy of the calculation due to the reduction of improper peaks of the stationary variables. [ABSTRACT FROM AUTHOR]

Summary: This paper explores an alternative method of ethanol production using a high‐temperature two‐step electrolytic cycle using carbon dioxide (CO2). The cycle comprises two steps namely; absorption step and electrolytic step. The proposed cycle uses CO2 and water as the feed stocks and produces methanol using electricity. The other chemicals in the cycles are recycled, which are used in the subsequent steps. To assess the performance, evaluation of the exergy and energy efficiencies of the complete cycle is done. Furthermore, the comparison with the traditional/conventional method of methanol production is also made by comparing various efficiencies. The simulation findings reveal the potential utilization of the proposed electrolytic methanol cycle, the exergy efficiency of 94.4% and the energy efficiency of 37.0% can be achieved. Furthermore, it is found that to produce 1 mole of methanol, ideally, 1.4 V of voltage is required by using the proposed cycle. In addition, a detailed parametric study is also conducted to observe the effects of significant parameters such as cycle temperature, supplied electricity, etc. on the cycle performance. [ABSTRACT FROM AUTHOR]

Carbon dioxide phase transition fracturing is a novel physical blasting technique, which is gradually used in mining and underground space engineering. The improvement of its rock breaking efficiency is the key concern in the application. In this paper, field experiments of CO2 phase transition fracturing were conducted. Based on the strain monitoring and fracturing crater volume measuring, the variation of CO2 filling amount and shear sheet thickness on rock fragmentation of CO2 phase transition fracturing was investigated. The experimental results indicated that the fracturing crater is shaped as an elliptical cone that is longer in the jet direction and shorter in the vertical jet direction. With the increase of the CO2 filling amount, the excavated crater volume gradually increases, but the growth rate gradually decreases. The powder factor is constant within a certain charge amount, and after exceeding this charge amount, the powder factor of CO2 increases significantly. As the shear sheet thickness increases, although the consultant peak stress gradually increases, its growth rate is still unchanged. The crater volume and its growth rate gradually increase in the same situation. Moreover, with the shear sheet thickness increase, the CO2 powder factor decreases continuously, and the decline rate remains unchanged. [ABSTRACT FROM AUTHOR]

Summary: Process intensification (PI) is devoted to obtaining safer, smaller, cost‐effective, environmentally friendly, energy‐efficient and sustainable technologies, playing a major role in chemical process industries. Conventional technologies applied in the adsorptive separations may suffer from low selectivities, conversions and energy efficiencies; higher costs, kinetic and thermodynamic limitations related to the specific separation systems. Suitable PI techniques based on material, equipment and process development methodologies can play a major role in the proper organization of the adsorption separations. This article provides an overview of the concept of PI, starting from the history and its evolution over the years. Recent advances on the adsorptive separation applications through chemical PI are discussed with illustrative examples. Type of adsorption technology, intensification technique in terms of various intensification parameters are illustrated for a variety of adsorption separation systems. Product purity, productivity, gas uptake, recovery, separation efficiency, adsorbent property, bed volume, production yield, selectivity, energy efficiency, process cost and environmental sustainability are among the intensification parameters involved depending on the type of the separation system. The significant process enhancements achieved through PI in the examples are given. Conclusions, perspectives and future approaches are proposed with the aim for further contribution to the development of adsorption separations. Novelty statement: Since the concept of process intensification (PI) has been introduced in the early 80s, a quite diverse range of definitions have been offered for PI during the years, which do not involve an exact standard definition that has been accepted commonly. Since then, PI has been a rapidly growing field in chemical process industries and generated many innovative processes, resulting in higher production yields, higher recovery, high‐purity products, energy‐efficient, cost competitive and environmental‐friendly sustainable clean technologies. The paper aims to compile the concepts and definitions of PI proposed by different researchers starting from the first limited definitions until the more extensive recent ones. Then the recent advances on the various adsorptive separation applications through chemical PI are presented with illustrative examples. The type of adsorption technology, the specific adsorbate/adsorbent system and the applied intensification technique in terms of various intensification parameters involved in each study are given. The benefits of PI, the role of applying PI in all these recent works on adsorptive separations are emphasized. Conclusions and perspectives with future approaches are presented with the aim to contribute to future development. [ABSTRACT FROM AUTHOR]

This field study aimed to investigate naturally ventilated bedroom environment and its effects on subjective perception and sleep quality. Totally, 104 healthy subjects living in urban areas of Beijing participated in the study for one night during transition seasons. Bedroom environment parameters, including temperature, relative humidity, and CO2 concentration, were recorded before and during sleep. Objective sleep quality was measured by Fitbit Alta 2, a wrist‐type actigraphy sensor. Subjective assessments were collected by paper‐based questionnaires on sleep quality and environmental perceptions. The results showed that neutral temperature for waking state (before sleep) was estimated to be 23.8°C while for sleep state it was 26.5°C. Furthermore, pre‐sleep thermal sensation vote was found to be positively correlated with deep sleep percentage. Indoor air quality was correlated with sleep quality as indicated by statistically significant correlations between odor intensity assessment, air quality acceptability, average nightly CO2 concentration, and measures of sleep quality. For naturally ventilated bedrooms during transition seasons with a mild outdoor climate, present findings suggest that a bedroom with slightly warm pre‐sleep environment than neutral, and with high ventilation as indicated by low indoor CO2 concentration, could be beneficial for sleep quality of residents. [ABSTRACT FROM AUTHOR]

Acid gases, such as CO2, H2S, and/or sulfur in oil industry’s production fluids, can be responsible for both general and localized corrosion, acting with different mechanisms, which depend on chemical and physical properties of the produced fluids. Materials selection for handling such fluids is performed by combining experience with suggestions from standards and regulations. A good deal of knowledge is available to predict corrosion rates for CO2-containing hydrocarbons, but the effect of high H2S pressure is less understood, mainly due to the difficulty of performing laboratory tests in such challenging conditions. For instance, the so-called NACE solution to assess SSC (Sulfide Stress Cracking) susceptibility of steels is a water-based solution simulating production fluids in equilibrium with one bar bubbling H2S gas. This solution does not represent environments where high gas pressure is present. Moreover, it does not take into account the corrosive properties of sulfur and its compounds that may deposit in such conditions. Besides, properties of high pressure gases are intermediate between those of a gas and those of a liquid: high pressure gases have superior wetting properties and better penetration in small pores, with respect to liquids. These features could enhance and accelerate damage, and nowadays such conditions are likely to be present in many production fields. This paper is aimed to point out a few challenges in dealing with high pressure gases and to suggest that, for materials selection in sour service, a better correspondence of test conditions with the actual field conditions shall be pursued. [ABSTRACT FROM AUTHOR]

Summary: Photocatalytic conversion of CO2 into value‐added hydrocarbon fuels and/or useful chemical products, using solar energy, has been the focus of active research, owing to its tremendous potential to provide a green fuel (eg, methanol) and simultaneously mitigate global warming by reducing CO2 levels in the atmosphere. CO2 photocatalytic reduction yields various hydrocarbon products. In this paper, we focus on methanol as it is an easily transportable energy‐dense fuel with multifarious applications in the automobile, industrial, and petrochemical sector. The photocatalytic conversion rate of CO2 to methanol depends on 3 factors: the photocatalyst used, photoreactor design, and experimental parameters (or variables). The last factor—experimental parameters—forms the basis of this review paper. These parameters include the reaction temperature, CO2 pressure, solvent used, intensity, wavelength, and duration of the incident light, concentration of organic impurities adsorbed on catalytic surface, addition of hole scavengers, type of reductant used, catalyst loading method, catalyst concentration, and the dissolved oxygen concentration. There have been numerous published works aiming to improve the methanol formation rate by optimizing these experimental parameters. In this paper, we consolidate and review these parameters, and investigate how optimizing them can enhance the photocatalytic conversion rate of CO2 into methanol, thus ushering in the era of a green methanol‐based economy. [ABSTRACT FROM AUTHOR]

Summary: The production of CO via electrochemical CO2 reduction has been recognised as a promising technology that overcomes the environmental issues caused by global warming. It also facilitates the conversion of CO2 into energy sources. Earth‐abundant Zn is a well‐known alternative to noble metal catalysts such as Au and Ag for the electrochemical CO2 reduction to CO. In particular, Zn‐based materials in the form of nanowires are potentially applicable as electrocatalysts in the electrochemical CO2 reduction. However, the conventional methods for manufacturing the nanowire structure are difficult as they require harsh conditions such as high temperatures and excess energy. In this study, Zn‐based nanowire catalysts are prepared by the facile electrodeposition of Zn nanostructures on a substrate followed by their energy‐free solution‐phase reconstitution. Further, their electrochemical performance in the CO2 reduction is investigated in a CO2‐purged 0.5 M KHCO3 electrolyte. By optimising the deposition conditions, hexagonal Zn (h‐Zn) plates with dominant Zn(101) facets, the favoured crystal structure for CO2 reduction, are fabricated on carbon paper. Furthermore, it is found that, during the solution‐phase reconstruction over 16 hours, the h‐Zn plate transforms to a nanowire owing to the differences between the oxidation rates of different crystal facets and the formation of a hydroxide complex. The activity of the reconstructed Zn‐based nanowire catalyst is enhanced further by forming an oxide layer via thermal treatment in a H2 atmosphere. This treatment boosted the reaction kinetics, thereby enhancing the catalyst performance in the CO2 reduction. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, a method that utilizes CO2 vapor compression thermodynamic cycle to recover low-temperature heat from exhausted water steam of fossil fuel thermal power plants is reported. Experimental investigation was carried out to study the characteristics of low-temperature heat recovery by liquid CO2 evaporation process from vacuum exhausted steam condensation occurring at the turbine exit. Furthermore, measured heat recovery performances over one whole year are presented and discussed. Experimental results show that the present heat recovery process by CO2 vapor compression cycle is able to operate stably. The yearly averaged water temperature at the CO2 condenser outlet was measured at 87.5 °C with a COP value above 5.0. This high energy efficiency ratio is found to be mainly due to two factors: the transcritical CO2 vapor compression and steam condensation phase change occurring on the CO2 evaporator. The findings from this paper provide helpful guidelines for low-temperature heat recovery system design and improving fossil fuel utilization efficiency. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY This paper compares different energy-related investment options that can be implemented in a kraft pulp mill with a potential steam surplus. The options investigated include lignin extraction, electricity production, capturing of CO2 and black liquor gasification with production of electricity or biofuels, here DME. The investment options are compared with respect to annual net profit and global CO2 emissions for different future energy market scenarios. A further analysis of how different parameters such as policy instruments and investment costs affect the different technologies also is included. The results show that, generally, for reasonable levels of biofuel support, the best economic performance among the studied technologies is achieved by extraction of lignin valued as oil. However, if the level of support for biofuels is high, black liquor gasification with DME production generally has the best economic performance among the studied options. All the investment options investigated decrease global CO2 emissions significantly. Capturing and storing CO2 from the recovery boiler flue gases result in the highest CO2 emissions reduction and also is an economically attractive option in scenarios with a high CO2 emissions charge. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

High‐pressure carbon dioxide and thermosonication technologies were applied to cloudy apple juice to determine their effect on polyphenol oxidase (PPO) and pectin methylesterase (PME) activity and other quality parameters right after the treatment and during storage at 4ºC for 28 days. Treatment conditions were 20 MPa, 45ºC, for 60 min and 20 kHz, 62ºC, 100% amplitude for 20 min, for pressurized CO2 and thermosonication treatments, respectively. Both treatments showed a great impact on PPO activity and its residual activity steadily decreased during storage at 4ºC. In contrast, PME was found to be more resistant to the treatments. After both treatments, a homogenization effect was observed, which was also reflected in an increase in the cloud value of the juices after the treatments, kept during storage. Antioxidant capacity and total polyphenol content kept high levels during storage after both treatments. Practical applications: The paper is focused on one of the major challenges of the food industry to replace traditional thermal treatments for alternative non‐thermal technologies. Two non‐thermal technologies, high‐pressure carbon dioxide and thermosonication, have been applied to cloudy apple juice for the inactivation of two of the enzymes that cause deleterious effects on the quality of cloudy apple juice. Results obtained in this work are of interest in the research field of new non‐thermal technologies. Quality parameters of cloudy apple juice treated by these technologies were compared right after treatment and along refrigerated storage to help to understand the evolution of the treated juice in terms of enzyme activity and other quality properties during a period of 28 days. [ABSTRACT FROM AUTHOR]

Summary: Research projects on new electrical energy storage (EES) systems are underway because of the role of EES in balancing the electric grid and smoothing out the instability of renewable energy. In this paper, a novel compressed carbon dioxide energy storage with low‐temperature thermal storage was proposed. Liquid CO2 storage was employed to increase the storage density of the system and avoid its dependence on geological formations. Low‐temperature thermal energy storage technology was utilized to recycle the heat of compression and reduce the challenges to system components. The system configuration was introduced in detail. Four evaluation criteria, the round trip efficiency (RTE), exergy efficiency (ηEx), thermal efficiency (ηTE), and energy density (ρE) were defined to show the system performance. Parametric analysis was carried out to examine the effects of some key parameters on system performance and the genetic algorithm was adopted for system optimization. The calculated results show that, for the novel EES under the basic working condition, its RTE is 41.4%, ηTE is 59.7%, ηEx is 45.4%, and ρE is 15 kWh m−3. The value of ρE increases with the increasing pump outlet pressure for a fixed value of pressure ratio, and the changes of RTE, ηTE, and the total exergy destruction of the system (ED,total) with pump outlet pressure are complicated for different values of pressure ratio. When both pressure ratio and pump outlet pressure are high, the values of RTE and ρE can be maximized whereas the value of ED,total can be minimized. Besides, no matter how pump outlet pressure and pressure ratio change, the exergy destruction of the system mainly come from compressors and regenerators, which accounts for about 50% of the total exergy destruction. [ABSTRACT FROM AUTHOR]

Summary: To alleviate the overloads in the power system and to reduce the exponential growth in carbon dioxide (CO2) emissions, deployment of the renewable energy sources (RES) into the power system is the need of the hour. However, injecting these RES into the current power system network causes large voltage and power overshoots hence deteriorate the transient response and power quality of the overall power system. In this paper, an efficient solution of the above‐mentioned issues is explored by developing an optimal microgrid (MG) controller using one of the most modern and intelligent artificial intelligence (AI) techniques named the salp swarm optimization algorithm (SSA). The intelligence of the SSA is exploited to select the optimal controller gains and dc‐link capacitance value by minimizing a time integrating error fitness function (FF) which in‐turn enhances the dynamic response and power quality of the studied MG system. The proposed grid‐tied MG controller is designed to achieve the preset active and reactive power sharing ratio between distributed generator (DG) and utility grid during DG and load switching conditions. To validate the superiority of the proposed controller, its performance is compared with that of its precedent grasshopper optimization algorithm (GOA)‐based controller for the identical operating conditions and system configuration. The outcomes of the study show that the proposed MG controller outperforms its competitor in terms of transient response and quality of power. [ABSTRACT FROM AUTHOR]

In order to solve the problem of hydrate reservoir collapse and hydrate regenerated in the process of solid fluidization of natural gas hydrate, a new method of natural gas hydrate exploit by high‐polymer additive (low viscosity carboxymethyl cellulose LV‐CMC) carbon dioxide jet was proposed. The wellbore temperature and pressure changes during this process are analyzed, and the wellbore temperature and pressure model are established and solved by the state space method. This paper also analyzed the effects of relevant parameters on hydrate decomposition, such as injection flow, temperature, and pressure. The results show that increasing the injection pressure allows the hydrate decomposition site to be closer to the annulus outlet. Compared with water, with polymer additive CO2 fluid as the drilling fluid, the intersection point of phase equilibrium curve and annular pressure curve is closer to annular outlet, which is obviously more conducive to well control. In order to avoid phase changes, the injection pressure of the carbon dioxide fluid of the high‐polymer additive should not be lower than 10 MPa, and the injection temperature should not be higher than 285 K. [ABSTRACT FROM AUTHOR]

Injecting CO2 into a reservoir disturbs the geostress field, which leads to variations in the permeability of caprock and affects its sealing performance. In this paper, the evolution characteristics of the permeability of Yingcheng mudstone were experimentally studied during deviatoric compression under different confining pressures. As the confining pressure increased, the strength of the mudstone increased bilinearly, the angle between the fault and the maximum principle stress increased, and the fault became flatter. During compression, the permeability of mudstone first decreased and then increased and the turning point of the permeability was between the onset of dilatancy and the turning point of volumetric strain; when the fault formed, the permeability increased sharply and the fault-induced increment was reduced exponentially with increasing confining pressure. In addition, the mudstone transformed to the ductile failure mode when the effective confining pressure was greater than 35 MPa, which means that the permeability did not jump within a small strain. Finally, a practical strain-based model of permeability evolution that separately considers compaction and dilatancy was proposed, and the predicted permeability values were in good agreement with the experimental results. This study revealed the effect of confining pressure on permeability evolution during compression and can help evaluate the sealing ability of mudstone caprock. [ABSTRACT FROM AUTHOR]

In order to ensure high-quality and on-time delivery in logistic distribution processes, it is necessary to efficiently manage the delivery fleet. Nowadays, due to the new policies and regulations related to greenhouse gas emission in the transport sector, logistic companies are paying higher penalties for each emission gram of CO2/km. With electric vehicle market penetration, many companies are evaluating the integration of electric vehicles in their fleet, as they do not have local greenhouse gas emissions, produce minimal noise, and are independent of the fluctuating oil price. The well-researched vehicle routing problem (VRP) is extended to the electric vehicle routing problem (E-VRP), which takes into account specific characteristics of electric vehicles. In this paper, a literature review on recent developments regarding the E-VRP is presented. The challenges that emerged with the integration of electric vehicles in the delivery processes are described, together with electric vehicle characteristics and recent energy consumption models. Several variants of the E-VRP and related problems are observed. To cope with the new routing challenges in E-VRP, efficient VRP heuristics and metaheuristics had to be adapted. An overview of the state-of-the-art procedures for solving the E-VRP and related problems is presented. [ABSTRACT FROM AUTHOR]

This paper presents the results of an evaluation study of gas drainability in the Bulli seam in the Southern Coalfield of the Sydney Basin, NSW, Australia, where the coal seam gas (CSG) contains a high proportion of carbon dioxide (CO2). Historically the gas drainability in some particular areas of this coal seam was found to be particularly poor, which posed a significant challenge to gas predrainage. As a result, a large volume of greenhouse gases were released to the atmosphere during mining of the coal seam. Furthermore, the high gas content associated with the CO2-rich composition also increased the risks of coal and gas outburst incidents, affecting the safety of mining. After systematic literature review of evaluation factors affecting gas drainability, this evaluation study comprehensively analyzed the main critical factors, including the geology of the area, the coal cleat system, coal microstructure, coal permeability, coal sorption capacity, gas content, and gas composition. Field geology analysis showed geological variations that affected the variations of the coal cleat system and CO2 content in the coal seam. Scanning Electron Microscope (SEM) tests showed the tight and less-porous features in hard-to-drain coal samples. The colliery gas database analysis was carried out to assess the impact of gas content and gas composition on the drainability of the coal seam. Laboratory tests showed that the coal seam had a permeability of less than 1 mD and also showed that the coal seam was highly undersaturated, especially with high CO2 content. [ABSTRACT FROM AUTHOR]

Blended cements are preferred to Ordinary Portland Cement (OPC) in construction industry due to costs and technological and environmental benefits associated with them. Prevalence of significant quantities of carbon dioxide (CO2) in the atmosphere due to increased industrial emission is deleterious to hydrated cement materials due to carbonation. Recent research has shown that blended cements are more susceptible to degradation due to carbonation than OPC. The ingress of CO2 within the porous mortar matrix is a diffusion controlled process. Subsequent chemical reaction between CO2 and cement hydration products (mostly calcium hydroxide [CH] and calcium silicate hydrate [CSH]) results in degradation of cement based materials. CH offers the buffering capacity against carbonation in hydrated cements. Partial substitution of OPC with pozzolanic materials however decreases the amount of CH in hydrated blended cements. Therefore, low amounts of CH in hydrated blended cements make them more susceptible to degradation as a result of carbonation compared to OPC. The magnitude of carbonation affects the service life of cement based structures significantly. It is therefore apparent that sufficient attention is given to carbonation process in order to ensure resilient cementitious structures. In this paper, an indepth review of the recent advances on carbonation process, factors affecting carbonation resistance, and the effects of carbonation on hardened cement materials have been discussed. In conclusion, carbonation process is influenced by internal and external factors, and it has also been found to have both beneficial and deleterious effects on hardened cement matrix. [ABSTRACT FROM AUTHOR]

The role of nuclear energy is to supply electric power on a stable basis to meet increasing demands, reduce carbon dioxide emissions, and maintain stable electric power costs while ensuring safety. The Fukushima accident taught us many lessons for creating safer nuclear power plants. Considering the design of systems, the areas of weakness at the Fukushima nuclear power plants can be divided into three categories: plant protection, electricity supply, and cooling of the nuclear fuel. In this paper, focusing on these three areas, the lessons learned are proposed and applied for pressurized heavy water reactors. Firstly, hard protection against external risks ensures the integrity of components and systems such that they can perform their original functions. Secondly, additional emergency power supply systems for electrical redundancy and diversity can improve the response capabilities for an accident by increasing the availability of active components. Thirdly, cooling for removing decay heat can be augmented by adopting diverse safety systems derived from other types of reactors. This study is expected to contribute to the safety enhancement of pressurized heavy water reactors by applying design changes based on the lessons learned from the Fukushima accident. [ABSTRACT FROM AUTHOR]

Microalgae are one of the most promising feedstocks for biodiesel production due to their high lipid content and easy farming. However, the extraction of lipids from microalgae is energy intensive and costly and involves the use of toxic organic solvents. Compared with organic solvent extraction, supercritical CO2 (SCCO2) has demonstrated advantages through lower toxicity and no solvent-liquid separation. Due to the nonpolar nature of SCCO2, polar organic solvents such as methanol may need to be added as a modifier in order to increase the extraction ability of SCCO2. In this paper, pilot scale lipid extraction using SCCO2 was studied on two microalgae species: Spirulina sp. and Schizochytrium sp. For each species, SCCO2 extraction was conducted on 200 g of biomass for 6 h. Methanol was added as a cosolvent in the extraction process based on a volume ratio of 4%. The results showed that adding methanol in SCCO2 increased the lipid extraction yield significantly for both species. Under an operating pressure of 4000 psi, the lipid extraction yields for Spirulina sp. and Schizochytrium sp. were increased by 80% and 72%, respectively. It was also found that a stepwise addition of methanol was more effective than a one-time addition. In comparison with Soxhlet extraction using methylene chloride/methanol (2:1, v/v), the methanol-SCCO2 extraction demonstrated its high effectiveness for lipid extraction. In addition, the methanol-SCCO2 system showed a high lipid extraction yield after increasing biomass loading fivefold, indicating good potential for scaling up this method. Finally, a kinetic study of the SCCO2 extraction process was conducted, and the results showed that methanol concentration in SCCO2 has the strongest influence on the lipid extraction yield. [ABSTRACT FROM AUTHOR]

We introduce different ways to solve the actual fragility problem of the epoxy-amine polymers by curing epoxidian oligomers with aliphatic amines without additional heat input. The pathways are the oligomer-oligomeric modification of epoxy resins-epoxy oligomers (EO), with their conversion to oligoethercyclocarbonates (OECC) by carbonization with carbon dioxide. The cocuring of these oligomers as a result of aminolysis competing reactions is “epoxide-amine” (forming a network polymer) and “cyclocarbonate-amine” (forming the linear hydroxyurethane, extending the internodal chains). Formation of internal and intermolecular hydrogen bonds was established on hydroxycarbonates (HA) and linear polyhydroxyurethanes (PHU) model compounds by IR and NMR spectroscopy. The results of the hydrogen bond system formation processes explain the change in the relaxation and physicomechanical properties of hard polymers modified by the epoxy-amine compositions (OECC), containing aromatic and aliphatic links. This paper presents a possible OECC modificator, the optimal EO:OECC ratio and its influence on the cross-link frequency, the polarity, the fragment and chain flexibilities and, as a consequence, the possible stiffness regulation for selected epoxy polymers. Thus, the causes of the increase in deformation-strength and adhesion characteristics were established by a factor of 1.5 to 3.0 due to an increase in cohesive strength (as a result of the combined network operation with covalent and physical bonds), as well as reduction of residual stresses (by adding the aliphatic fragments as additional relaxants), and reducing the defectiveness of the boundary layers (polymer-substrate). [ABSTRACT FROM AUTHOR]

Abstract: This paper reviews studies of the relationships between ventilation rates (VRs) in homes and occupant health, primarily respiratory health. Five cross‐sectional studies, seven case‐control studies, and eight intervention studies met inclusion criteria. Nearly all studies controlled for a range of potential confounders and most intervention studies included placebo conditions. Just over half of studies reported one or more statistically significant (SS) health benefits of increased VRs. Wheeze was most clearly associated with VR. No health outcomes had SS associations with VRs in the majority of statistical tests. Most studies that reported SS health benefits from increased VRs also had additional health outcomes that did not improve with increased VRs. Overall, the number of SS improvements in health with increased VRs exceeded the anticipated chance improvements by approximately a factor of seven. The magnitude of the improvements in health outcomes with increased VRs ranged from 20% to several‐fold improvements. In summary, the available research indicates a tendency for improvements in respiratory health with increased home VRs; however, health benefits do not occur consistently and other exposure control measures should be used together with ventilation. The research did not enable identification of a threshold VR below which adverse health effects occur. [ABSTRACT FROM AUTHOR]

Carbon footprint is one of the most widely used tools for assessing the environmental impacts of the production and utilization of concrete as well as of the components derived from it, representing the amount of carbon dioxide and other greenhouse gases associated with this product, expressed as CO2 equivalents. In this paper, carbon footprint was used to compare the environmental performance in the production phase of a concrete made with both recycled and crushed virgin limestone aggregates, using a life cycle analysis methodological approach. Research outcomes revealed, as expected, that carbon dioxide equivalent emissions decreased slightly as the use of recycled aggregates increased. Emissions for concrete with 0.5 w/c were between 347 and 351 kg of CO2-e/m3. It was also corroborated that cement is the material with the greatest influence on greenhouse gas emission generation in the concrete’s production phase, regardless of the use of recycled or virgin aggregates. [ABSTRACT FROM AUTHOR]

The CO2 formation during food storage can often be correlated with the increase in yeast population. Yogurt and other dairy products are susceptible to yeast contamination. Accumulation of CO2 in the headspace of yogurt packages can lead to the eventual blowing off of the package. Therefore, determination of CO2 in the yogurt packages can indicate eventual unsafety of the product. The aim of this paper was to determine CO2 concentration in the headspace of different yogurt containers contaminated with yeast at the levels of 1 and 5 CFU/ml. Yeast Candida kefyr, previously isolated from spoiled yogurt, was used for contamination. Contaminated and control samples of yogurt were incubated at 30°C. A device based on tunable diode laser absorption spectroscopy was used for the measurement of CO2 concentration. The CO2 content in all analysed samples changed in a similar manner with slow increase to the value of 6% during the first 30 h and, after that, rapid accumulation to 17–20%. The initial level of yeast contamination did not have significant influence to the CO2 content trend. The increase in the number of yeast was observed after 10 h of incubation, and the final value of 6-7 log·CFU/cm3 was reached after 40 h of incubation. The significant increase in the yeast number can be correlated with the CO2 content in a way that CO2 concentration of 6% can be considered as critical for microbial spoilage. Since the TDLAS technique is simple and nondestructive, it can be a promising possibility for detection of the microbial spoilage in food. [ABSTRACT FROM AUTHOR]

During catalytic cracking of methane reaction, different carbon nanostructures can be formed. This paper shows the results of a characteristic nanostructured carbon deposit obtained during cracking of methane reaction over nanocrystalline iron catalysts with or without cobalt addition. The properties of the carbon deposit were determined by X-ray diffraction, scanning electron microscope with energy dispersive spectrometer equipment, thermogravimetry-differential thermal analysis coupled with mass spectrometry, time-of-flight secondary ion mass spectrometry analysis and surface area analysis (Brunauer-Emmett-Teller isotherm [BET]). Significant differences in the morphology and properties of the obtained carbon were found. The mechanism of the formation of carbon nanostructures for both iron catalysts is proposed. [ABSTRACT FROM AUTHOR]

The increasing emission of carbon dioxide worldwide has emerged as a major global concern in the context of addressing climate change. Converting CO2 to high-value carbon materials is a promising solution to capture emitted carbon for achieving carbon neutrality. Furthermore, such conversion can provide carbon nanomaterials for key industries, including the lithium battery and fuel cell industries. Here, it is shown that sub-50 nm tangled carbon nanotubes (CNTs) can be synthesized by adjusting the metaborate concentration and the current density through the electrochemical conversion of carbon dioxide in a molten carbonate salt. The metaborate ion concentration affects the product selectivity and carbon morphology, and the current density is strongly related to the particle size of in situ seed catalysts supplied by the dissolution of an Ni-Fe-Cr alloy anode. The optimized process conditions control the nucleation and growth of carbon via a tip-growth mechanism, thereby promoting the formation of sub-50 nm CNTs rather than bulky irregular carbon particles. The Raman and Brunauer–Emmett–Teller analyses showed that the properties of the prepared CNTs depended on the synthetic parameters. This study provides deep insights into the mechanism underlying carbon synthesis through the electrochemical reduction of a molten carbonate salt. [ABSTRACT FROM AUTHOR]

SUMMARY Use of thermoelectric subcooler is one of the techniques to improve the performance of transcritical CO2 cycle. Thermodynamic analyses and optimizations of transcritical CO2 refrigeration cycle with thermoelectric subcooler are presented in this paper. Further, the effects of various operating parameters on cycle performances are studied. It is possible to optimize current supply, discharge pressure, and CO2 subcooling simultaneously based on maximum cooling COP for thermoelectrically enhanced transcritical CO2 refrigeration cycle to get best performance. Results show that thermoelectric current supply, COP improvement, and discharge pressure reduction increase with increase in cycle temperature lift, with maximum values of 11 A, 25.6%, and 15.4%, respectively, for studied ranges. Use of thermoelectric subcooler in CO2 refrigeration system not only improves the cooling COP, also reduces the system high-side pressure, compressor pressure ratio, and compressor discharge temperature, and enhances the volumetric cooling capacity. Component-wise irreversibility distribution shows similar trend with basic CO2 cycle, although values are lower leading to higher second law efficiency. Cooling capacity may be enhanced by increasing the current supply for the same thermoelectric configuration with penalty of COP. Study reveals that thermoelectrically enhanced CO2 refrigeration cycle yields significant performance improvement especially for higher-cycle temperature lift. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the present paper, an attempt has been made to review the performance of new refrigerant mixtures employed in vapour compression-based refrigeration, air-conditioning and heat pump units. The studies reported with refrigerant mixtures are categorized into six groups as follows: (i) hydrocarbon (HC), (ii) hydroflurocarbons (HFC), (iii) HFC/HC, (iv) hydrochloroflurocarbons (HCFC), (v) carbon dioxide (R744) and (vi) ammonia (R717). This paper explores the studies reported with new refrigerant mixtures in domestic refrigerators, commercial refrigeration systems, air conditioners, heat pumps, chillers and in automobile air conditioners. In addition, the technical difficulties faced with new refrigerant mixtures, further research needs in this field and future refrigerant options for new upcoming systems have been discussed in detail. This paper concludes that HC based refrigerant mixtures are identified as a long-term alternative to phase out the existing halogenated refrigerants in the vapour compression-based systems. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]