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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]

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]

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]

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]

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]

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]

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]

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]

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]

This paper describes experiments comparing a commercial available R134a refrigeration plant subjected to a cold store and a prototype R744 (carbon dioxide) system working as a classical ‘split-systems’ to cool air in residential applications in a transcritical cycle. Both plants are able to develope a refrigeration power equal to 3000 W. The R744 system utilizes aluminium heat exchangers, a semi-hermetic compressor, a back-pressure valve and a thermostatic expansion valve. The R134a refrigeration plant operates using a semi-hermetic reciprocating compressor, an air condenser followed by a liquid receiver, a manifold with two expansion valves, a thermostatic one and a manual one mounted in parallel, and an air cooling evaporator inside the cold store. System performances are compared for two evaporation temperatures varying the temperature of the external air running over the gas-cooler and over the condenser. The refrigeration load in the cold store is simulated by means of some electrical resistances, whereas the air evaporator of the R744 plant is placed in a very large ambient. The results of the comparison are discussed in terms of temperature of the refrigerants at the compressor discharge line, of refrigerants mass flow rate and of coefficient of performance (COP). The performances measured in terms of COPs show a decrease with respect to the R134a plant working at the same external and internal conditions. Further improvements regarding the components of the cycle are necessary to use in a large-scale ‘split-systems’ working with the carbon dioxide. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The iron and steel industry is a large energy user in the manufacturing sector. Carbon dioxide from the steel industry accounts for about 5–7% of the total anthropogenic CO2 emission. Concerns about energy consumption and climate change have been growing on the sustainability agenda of the steel industry. The CO2 emission will be heavily influenced with increasing steel production in the world. It is of great interest to evaluate and decrease the specific CO2 emission and to find out feasible solutions for its reduction. In this work, a process integration method focusing on the integrated steel plant system has been applied. In this paper, an optimization model, which can be used to evaluate CO2 emission for the integrated steel plant system, is presented. Two application cases of analysing CO2 emission reduction possibilities are included in the paper. Furthermore, the possibility to apply the model for a specific integrated steel plant has been discussed. The research work on the optimization of energy and CO2 emission has shown that it is possible to create a combined optimization tool that is powerful to assess the system performance from several aspects for the steel plant. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Using carbon dioxide as working fluid receives increasing interest since the Kyoto Protocol. In this paper, thermodynamic analysis was conducted for proposed CO2-based Rankine cycle powered by solar energy. It can be used to provide power output, refrigeration and hot water. Carbon dioxide is used as working fluid with supercritical state in solar collector. Theoretical analysis was carried out to investigate performances of the CO2-based Rankine cycle. The interest was focused on comparison of the performance with that of solar cell and those when using other fluids as working fluids. In addition, the performance and characteristics of the thermodynamic cycle are studied for different seasons. The obtained results show that using CO2 as working fluid in the Rankine cycle owns maximal thermal efficiency when the working temperature is lower than 250.0°C. The power generation efficiency is about 8%, which is comparable with that of solar cells. But in addition to power generation, the CO2-based solar utilization system can also supply thermal energy. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Because of rapidly growing renewable power capacity, energy storage system is in urgent need to cope with the reliability and stability challenges. CO2 has already been selected as the working fluid, including thermo-electrical energy storage or electrothermal energy storage systems and compressed CO2 energy storage (CCES) systems. In this paper, a CCES system based on Brayton cycle with hot water as the heat storage medium is proposed and analyzed. Thermodynamic model of the system is established for energy and exergy analysis. Sensitivity analysis is then conducted to reveal effects of different parameters on system performances and pursue optimization potential. At a typical transcritical operation condition, round trip efficiency is 60% with energy density of 2.6 kWh/m3. And for the typical supercritical operation condition, the round trip efficiency can reach 71% with energy density of 23 kWh/m3. High round trip efficiency and energy density, which is comparable with those of compressed air energy storage systems, thermo-electrical energy storage (electrothermal energy storage) systems, and other CCES systems, lead to promising prospect of the proposed system. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Enhanced geothermal systems (EGS) technology is regarded as the future of geothermal energy and could become a major energy source in the future. However, EGS technology is not well developed. The challenges of EGS technology development, such as the small heat-recovery factors and water limitations, need to be addressed. A comprehensive understanding of heat transfer in the complex subsurface structures is crucial for energy management in the reservoir, and an accurate heat transfer model of the reservoir is a key tool to optimize heat extraction to improve the heat-recovery factor. The use of CO2 as the EGS working fluid is regarded as an emerging technology to address water limitations. The analytical solutions, lab-scale experiments, field-scale modeling methods of water/CO2 fluid flow and heat transfer in the reservoir, and a thermodynamic analysis of the energy conversion system at the surface are reviewed in this paper. Based on the existing literature, future research should focus on improving our knowledge and optimizing the heat transfer performance in the reservoir. Moreover, the emerging design of a heat exchange network in the reservoir and CO2-EGS could result from technology development. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Summary: Injecting carbon dioxide for shale gas recovery enhancement (CO2‐ESGR) is an effective method to improve gas production and also realize the CO2 geosequestration. In the CO2‐ESGR system, there are two‐component gases (TCG) coexisted. The gas transport and adsorption mechanisms are different from the single‐component gas system. However, most of current work is still focused on single‐component gas (ie, methane). Many mechanisms have not been considered in the study of CO2‐ESGR study. In order to conduct reliable numerical simulation for CO2‐ESGR, a clear understanding of the transport and adsorption mechanisms for TCG system is necessary. In this review, we focused on two key issues regarding CO2‐ESGR: the fluid transport and competitive adsorption. The fundamental mechanisms and models for pure gas and TCG transport have been comprehensively summarized. The adsorption models for TCG system have been reviewed and analyzed. Models such as extended Langmuir model, ideal adsorption solution model, and lattice density functional model have been compared. Also, the factors affecting the competitive adsorption of TCG in shale have been illustrated. The main factors include organic matter content, shale composition, pore structure, water content, and pressure. At last, the problems existed in current research of transport and adsorption models for TCG have been analyzed. The issues that are necessary to be considered in CO2‐ESGR technology have been proposed so that more accurate numerical simulation and more reliable production prediction can be achieved. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, a transcritical carbon dioxide heat pump system driven by solar-owered CO2 Rankine cycle is proposed for simultaneous heating and cooling applications. Based on the first and second laws of thermodynamics, a theoretical analysis on the performance characteristic is carried out for this solar-powered heat pump cycle using CO2 as working fluid. Further, the effects of the governing parameters on the performance such as coefficient of performance (COP) and the system exergy destruction rate are investigated numerically. With the simulation results, it is found that, the cooling COP for the transcritical CO2 heat pump syatem is somewhat above 0.3 and the heating COP is above 0.9. It is also concluded that, the performance of the combined transcritical CO2 heat pump system can be significantly improved based on the optimized governing parameters, such as solar radiation, solar collector efficient area, the heat transfer area and the inlet water temperature of heat exchange components, and the CO2 flow rate of two sub-cycles. Where, the cooling capacity, heating capacity, and exergy destruction rate are found to increase with solar radiation, but the COPs of combined system are decreased with it. Furthermore, in terms of improvement in COPs and reduction in system exergy destruction at the same time, it is more effective to employ a large heat transfer area of heat exchange components in the combined heat pump system. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, an experimental work is carried out to investigate the characteristics of solar thermal collection using supercritical CO2. This solar thermal conversion is based on supercritical CO2 natural convection, which is much easily induced because a small change in temperature can result in large change in density close to the critical point. In addition, its critical temperature is 31.1°C and low enough to be easily reached in the low-temperature solar thermal conversion system. The obtained results show that the supercritical CO2 flow rate is smooth curve and not affected by the sudden variation of the solar radiation. The solar thermal conversion operation process can be divided into three periods: starting-up, transition, and stable period. When the system reaches the stable period, the CO2 flow rate will keep at a high value even if the solar radiation stays at a low level. It is also found that the smaller local solar radiation variation is, the better ability of keeping the flow rate near the peak level the supercritical CO2 fluid owns. It is also found that a small pressure difference can drive a supercritical CO2 flow with high flow rate. Furthermore, high solar thermal conversion efficiency is found at a high mass flow rate and under operation pressure near the critical point. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY The assessment for realistic CO2-adsorption capacities of different rocks is important for understanding the processes associated with CO2 storage. This paper investigates the adsorption characteristics of rocks for CO2 (limestone, sandstone, marl, claystone, clay, siltstone and metamorphic rock) by using a gravimetric method. The measurements were performed at 21°C with pressures from 1 up to 4 MPa. Sandstone (and clay with sand/sandstone) showed the largest adsorption capacity at 21°C. The highest amount of in situ CO2 contents in measured samples was 21.4 kg/t. The CO2-adsorption capacities were lower than past results in different coal samples. The results indicate that adsorption of CO2 into rocks may play an important role in storing CO2 in subsurface rock. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY This work presents a non-conventional combined cycle comprising a topping supercritical Brayton cycle working with carbon dioxide (S-CO2) and a bottoming organic Rankine cycle (ORC). As shown by previous authors in the field of nuclear energy, carbon dioxide cycles are characterised by lower turbine inlet temperatures (around 1100 K) than conventional gas turbines, and they usually incorporate a highly efficient recuperative heat exchanger in order to increase system efficiency. Accordingly, temperatures of around 200 °C are achieved at the outlet of the recuperator, hence leaving a certain amount of heat at the disposal of a bottoming cycle. Presently, ORCs are the most appropriate commercially available technology for such low temperature heat recovery. In this paper, an analysis of ORCs with different organic fluids is presented. Initially, only pure substances are considered. Then, the performance of the same cycle working with mixtures of hydrocarbons is assessed finding a 7 percentage point improvement in global efficiency with respect to the stand-alone topping cycle when the bottoming system (heat recovery unit and ORC) is incorporated. Following this interesting result, the performance of a S-CO2-ORC, a conventional gas turbine and ORC and an ORC-ORC combined cycles are evaluated for a tower-type central receiver Concentrating Solar Plant. Isopentane (the optimum pure substance obtained in the analysis mentioned earlier) is used in all cases for the bottoming system, showing favourable results for the proposed combined cycle configuration. Additionally, a discussion about the most relevant techno-economic concerns is presented at the end of the work showing that complementary economic benefits must be expected because of the lower footprint of the heat transfer equipments when carbon dioxide is used. These positive features derive from the more interesting transport properties of carbon dioxide when it is used at very high pressure, what also contributes to reducing the size of turbomachinery by decreasing their volumetric flows. In summary, the work presents a very interesting proposal, both thermodynamically and economically, to be used in intermediate temperature systems even if this technology is not mature yet. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Carbon capture and storage from flue gases is the most common method to reduce greenhouse gas emissions. Using a primary amine as the solvent of CO2 capture unit is popular because of its high activity and ability to be used for streams with low concentration and low partial pressure of CO2. Monoethanolamine(MEA) and Diglycolamine(DGA) are the most common kinds of primary amines which have been traditionally used in many natural gas sweetening plants. In this research, the capture plant has been designed for these two solvents at various CO2 concentrations in the feed flue gas. This paper proposes different possible alters to overcome the high energy requirements of capture plant. It also presents the results of technical evaluation of different parameters, in order to design an actual plant with minimum energy requirement. The results of different parameters show that for DGA solvent, there will be an improvement in overall energy usage in the capture plant rather than MEA for some special cases. To gain the practical results, actual stages have been used for absorber and stripper instead of equilibrium stages. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, we evaluate the viability of a 9.5-kWe wooden pellet-fueled Stirling engine-based micro-cogeneration plant as a substitute for small-scale district heating. The district heating systems against which the micro-cogeneration plant is compared are based either on a pellet-fueled boiler or a ground-source heat pump. The micro-cogeneration and district heating plants are compared in terms of primary energy consumption, CO2 emissions, and feasibility of the investment. The comparison also considers an optimally operated individual 0.7-kWe pellet-fueled Stirling engine micro-cogeneration system with exhaust gas heat recovery. The study is conducted in two different climates and contributes to the knowledge base by addressing: (i) hourly changes in the Finnish electricity generation mix; and (ii) uncertainty related to what systems are used as reference and the treatment of displaced grid electricity. Our computational results suggest that when operated at constant power, the 9.5-kWe Stirling engine plant results in reduced annual primary energy use compared with any of the alternative systems. The results are not sensitive to climate or the energy efficiency or number of buildings. In comparison with the pellet-fueled district heating plant, the annual use of primary energy and CO2 emissions are reduced by a minimum of 25 and 19%, respectively. Owing to a significant displacement of grid electricity, the system's net primary energy consumption appears negative when the total built area served by the plant is less than 1200 m2. On the economic side, the maximum investment cost threshold of a CHP-based district heating system serving 10 houses or more can typically be positive when compared with oil and pellet systems, but negative when compared with a corresponding heat pump system. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The polymer electrolyte membrane fuel cell (PEMFC) using reformate gas as fuel is regarded as an attractive solution for the near-term introduction of fuel cells in stationary or mobile power generation market. With respect to hydrogen feeding, the reformate gas fuelling involves additional polarization losses because of the hydrogen dilution and the impurities contained in the gas. In this paper a one-dimensional model has been developed to investigate the behaviour of a PEMFC operating with reformate gas mixture. The model, based on a semi-empirical approach, considers the kinetic reactions in the anode side taking into account the effect of reverse water–gas shift (RWGS) due to the presence of CO2 in the fuel. As it is well known, the exhaust stream from fuel reformers can contain a high carbon dioxide concentration (>20%) that can have a detrimental effect on the fuel cell performance because of the combination of the dilution and the formation of CO by the RWGS reaction. The numerical simulation results have been compared with the experimental data, obtained in the test room of Industrial Engineering Department of Cassino University, and a good match has been observed. The model has been developed by using a simplified approach that, nevertheless, can allow to obtain a good numerical prediction of the fuel cell performance reducing the simulation time and computational efforts. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The use of fossil fuels has caused an increase in GHG concentration in the atmosphere, which has a direct effect on global warming. Among the possible technologies to mitigate GHG emissions, carbon capture and storage (CCS) can be applied to existing plants and now it is being accepted officially in order to gain emission reduction certificates. This paper presents a feasible solution for CO2 capture and storage network in Italy from sources that are included in the National Allocation Plan and that are forced to reduce carbon dioxide emissions in the second phase of the implementation of the Kyoto Protocol. The technical aspects of carbon sequestration are derived from industrial applications, while transportation and storage depend on local and geological characteristics. Since Italy has complex geological characteristics, the selection of the most convenient sites should include hydrocarbon reservoirs that are currently used or are depleted. To select these sites, all oil wells that are located in the Italian territory and are managed by UNMIG (National Mining Office for Hydrocarbons and Geothermy) were considered, and a short list was selected among those that have safety and lasting characteristics to ensure a long time permanence. The position of the selected storage sites is drawn on a GIS map containing all the plants included in the National Allocation Plan to be able to identify the optimal networks for carbon dioxide transportation. The case study is located in an area that includes Milan, Pavia and Lodi districts. Knowing the amount of CO2 produced by plants in the selected zone, it is possible to determine the tons of CO2 to capture and the size of transportation and storage systems. Pipelines are, in this case, the most appropriate transport technologies. From emission and sequestration points to storage sites it is necessary to build 122 km pipelines for 8 MtCO2 capacity. Using this CCS grid it is possible to avoid CO2 emission with economic feasibility close to the cost of carbon trading values. In fact, the market cost of a European Union Allowance (EUA) at the start of the first period of application of Directive 2003/87/CE was about 30 €/tCO2. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The aim of this paper is to simulate the performance of an air source heat pump water heater using carbon dioxide (CO2) as a working fluid. The heat pump water heating system consists of a compressor, a gas cooler, an expansion device and an evaporator. The computer simulation model has been developed by using the heat transfer data and the thermodynamic properties of CO2. The effects on the heat pump performance by the operating parameters such as the compressor rotational speed, the inlet water temperature at the gas cooler, the inlet air temperature at the evaporator and the mass flow rate ratio of water to refrigerant were presented. For rated capacities of a 4 kW compressor with a 10 kW gas cooler and a 6 kW evaporator, the coefficient of performance is found to be between 2.0 and 3.0. The mass flow rate ratio of water and CO2 between 1.2 and 2.2 is the most suitable value for generating hot water temperature above 60°C at 15–25°C ambient air temperature. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Hydrogen generation on a large scale will be required to power the emerging hydrogen economy without emitting large amounts of carbon dioxide into the atmosphere. All large-scale hydrogen production facilities currently in operation use processes such as steam–methane reforming or partial oxidation of heavy hydrocarbons, which emit large amounts of carbon dioxide. Atomic Energy of Canada Ltd. (AECL) is studying several process options for large-scale production of hydrogen without emitting carbon dioxide. One of these options is to produce hydrogen via steam electrolysis, where the heat and electricity are produced by nuclear reactors. This paper investigates the technical issues and economics of hydrogen production by integrating a steam electrolysis system with the Advanced CANDU Reactor ACR-1000. The overall thermal-to-hydrogen efficiency of the combined ACR-1000 and steam electrolysis process is 33–34% compared to about 27% for conventional water electrolysis. The heat recovered from the steam electrolysis loop is used to provide heat at appropriate locations in the electricity generation cycle. Copyright © 2007 Crown in the right of Canada. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, the performance of solar energy powered transcritical cycle using supercritical carbon dioxide for a combined electricity and heat generation, is studied experimentally. The experimental set-up consists of evacuated solar collectors, pressure relief valve, heat exchangers and CO2 feed pump. The pressure relief valve is used to simulate operation of a turbine and to complete the thermodynamic cycle. A complete effort was carried out to investigate the cycle performances not only in summer, but also in winter conditions. The results show that a reasonable thermodynamic efficiency can be obtained and COP for the overall outputs from the cycle is measured at 0.548 and 0.406, respectively, on a typical summer and winter day. The study shows the potential of the application of the solar energy powered cycle as a green power/heat generation system. Copyright © 2006 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Summary: CO2, a greenhouse gas, is continuously emitted by different sources due to the extensive use of fossil fuels. Hence various methods have been developed to mitigate CO2 gas from the environment. The capturing and storing of carbon is termed carbon capture and storage, a method of reducing the level of CO2 from the atmosphere emitted by industrial sites and power stations. The reduction of the atmospheric carbon or the stored carbon to different products by multiple techniques has been a current topic of research, taking the environmental concern into account. The reduction of CO2 is very challenging since the bond energy of C=O is very high. Additionally, the separation of the gas from the atmosphere or industrial flue gas is also technologically difficult. This review comprises a detailed discussion of the methods adopted for the conversion of CO2 into different carbon nano‐materials and hydrocarbons. The mechanisms associated with the conversion, along with the role of electrodes used for the conversion of the gas during electrolysis, have also been conferred extensively. [ABSTRACT FROM AUTHOR]

Summary: The energy storage device is indispensable in future power system due to the high share of renewable energies. Compressed gas energy storage (CGES) technology, including the compressed air energy storage (CAES), has been widely recognized as one of the most promising solutions in energy storage domain. Among multiple CAES forms, the isothermal CAES is a potential type in which the ideal round trip efficiency (RTE) can be 100%. On the other hand, carbon dioxide (CO2) as an excellent working medium in CGES system owing to its favorable properties. However, the existing isothermal type CGES systems just employ the air as working medium, the potential of CO2 in such system is not evaluated yet. Therefore, an 800 kW pumped hydro assisted near‐isothermal compressed carbon dioxide energy storage system with gas/liquid phase change process is proposed. In detail, the hydraulic machineries, the flexible rubber diaphragm and the helical coils are employed to realize the near‐isothermal process and high RTE. The transient models are built and system performance is thus investigated. The results show that the system possesses 68.36% in RTE and 1.0914 kWh/m3 in energy density (ED) under the design condition. Meanwhile, the water temperature in helical coil, the initial and maximum pressures of vessel and the vessel volume are sensitive for system behavior. [ABSTRACT FROM AUTHOR]

Summary: In the present work, the purification of hydrogen from a hydrogen/carbon dioxide/carbon monoxide (H2:CO2:CO) mixture by a high‐temperature electrochemical purification (HT‐ECHP) system is examined. Electrochemical H2 purification experiments were carried out in the temperature range of 140‐180°C. The effects of the molar ratio of the gases in the mixture (H2:CO2:CO‐75:25:0, H2:CO2:CO‐72:26:2,0 H2:CO2:CO‐75:22:3, H2:CO2:CO‐75:20:5, H2:CO2:CO‐97:0:3, H2:CO2:CO‐95:0:5) and the operating temperature on the electrochemical H2 separation were investigated. As a result of the electrochemical H2 purification experiments, it was determined that the operating temperature is the most important parameter affecting the performance. According to the results obtained, H2 purity of 99.999% was achieved at 160°C with the reformate gas mixture containing 72% H2, 26% CO2, and 2% CO by volume. According to the polarization curves of the gas mixtures containing CO, high current densities at low voltage were reached at 180°C, and it was observed that the performance increased as the temperature increased, whereas the gas mixture without CO gave the best performance at 160°C. [ABSTRACT FROM AUTHOR]

Summary: The separation of carbon dioxide (CO2) from the flue gas is a challenging one in terms of the energy penalty. The development of a cryogenic or low‐temperature CO2 separation method helps to overcome the energy penalty associated with CO2 separation. In this study, a preliminary investigation is carried out in a theoretically modified Linde process which can be used for CO2 separation from a gas mixture containing CO2 and N2. A cryogenic cooling process is also studied for CO2 separation of the same quality of the gas mixture. The compression work and cooling loads in each case are analyzed using Aspen Plus software. The effect of CO2 volume in the mixture, compressor efficiency, and compressor discharge pressure on the energy consumption is studied for both the theoretically modified Linde and the cryogenic cooling processes, and the results are compared between them. The results indicated in the CO2 separation by the cooling process are better than the modified Linde process. The energy penalty shows for 20% CO2 composition of separation by the cooling process with the single‐stage compression is lower by around 123.9% and 128.8% in terms of compression work and compressor cooling load, respectively, than those of the modified Linde process working in a single‐stage compression. The separation by the cooling process refrigeration effect is 15.9% more than in the modified Linde process. [ABSTRACT FROM AUTHOR]

SUMMARY A novel solid oxide fuel cell (SOFC)/gas turbine (GT) hybrid cycle system with CO2 capture is proposed based on a typical topping cycle SOFC/GT hybrid system. The H2 gas is separated from the outlet mixture gas of SOFC1 anode by employing the advanced ceramic proton membrane technology, and then, it is injected into SOFC2 to continue a new electrochemical reaction. The outlet gas of SOFC1 cathode and the exhaust gas from SOFC2 burn in the afterburner 1. The combustion gas production of the afterburner1 expands in the turbine 1. The outlet gas of SOFC1 anode employs the oxy-fuel combustion mode in the afterburner 2 after H2 gas is separated. Then, the combustion gas production expands in the turbine 2. To ensure that the flue gas temperature does not exceed the maximum allowed turbine inlet temperature, steam is injected into the afterburner 2. The outlet gas of the afterburner 2 contains all the CO2 gas of the system. When the steam is removed by condensation, the CO2 gas can be captured. The steam generated by the waste heat boiler is used to drive a refrigerator and make CO2 gas liquefied at a lower temperature. The performance of the novel quasi-zero CO2 emission SOFC/GT hybrid cycle system is analyzed with a case study. The effects of key parameters, such as CO2 liquefaction temperature, hydrogen separation rate, and the unit oxygen production energy consumption on the new system performance, are investigated. Compared with the other quasi-zero CO2 emission power systems, the new system has the highest efficiency of around 64.13%. The research achievements will provide the valuable reference for further study of quasi-zero CO2 emission power system with high efficiency. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Methodologies to assess the effects of energy projects on global carbon dioxide emissions will be an important feature of a future international carbon dioxide trading system. In this paper, we present and discuss four different models for assessing the net carbon dioxide emissions resulting from a certain energy project. These models are applied to different district heating technologies. To judge the mitigation performance of a project, the amount of carbon dioxide released in kilograms is expressed per megawatt-hour of useful district heating produced. All the models consider the marginal change caused by the project on the electric power system. The different model perspectives are discussed, and it is shown that the choice of model is very critical for assessing the net carbon dioxide emissions from an energy project. Copyright © 2003 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents a capacity planning model for the Indian aluminium industry based on a linear dynamic programming technique. The model has been used to analyse energy demand and CO2 emission for the period 1992–2021. Copyright © 2000 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Summary: A prediction model for hydrogen loss rate (HLR) of coating zirconium hydride at 873 K based on Wagner's model was established using gas chromatograph. A continuous and dense coating of zirconium hydride with bilayer structure was prepared by phosphation‐oxidation method. The oxidation weight gain of coating zirconium hydride specimens at 873 K in a mixture atmosphere of CO2 and He was investigated. The oxidation weight gain law was obtained by fitting Wagner's model, and the release equation of CO were further deduced. The concentration of H2 and CO in the gas phase was measured by gas chromatograph in the closed system under the same conditions. The optimized HLR of coating zirconium hydride was obtained by deducting the amount of CO generated by the reaction of zirconium and CO2 using the release equation of CO. Fitted by Wagner's model, the dependence between optimized HLR and reaction time was obtained, and the loss amount of hydrogen at any moment can be calculated by extrapolated and integrated, thus a prediction model was established. Based on the model, the HLR of coating zirconium hydride is 0.97% in 1 year. Highlights: A prediction model for hydrogen loss rate of coating ZrHx at 873 K was established using gas chromatograph.A continuous and dense coating of ZrHx with bilayer structure was prepared by phosphation‐oxidation method.Fitted by Wagner's model, the equation of hydrogen permeability rate was obtained.The prediction model was further optimized by deducting the amount of CO produced by the reaction of Zr in CO2. [ABSTRACT FROM AUTHOR]

Summary: Mevastatin is one of the common pharmaceuticals found in wastewaters, and its biodegradation is still an environmental problem due to its recalcitrant properties. Although various biological, chemical and physical methods have been investigated for the removal of mevastin, microbial electrolysis cells (MECs) have not been examined, yet. MECs are new generation biotechnological tools used in hydrogen energy production. In this study, the effects of mevastatin on hydrogen production in MECs were investigated for the first time. MECs produced hydrogen gas in the presence of mevastatin, and an increase in hydrogen production was observed. Over 90% of the mevastatin were removed in MECs. These results also showed that the fermentation process associated with carbon dioxide production can favor hydrogen production with mevastatin. In conclusion, the efficiency of hydrogen production in microbial cells can be increased by the use of wastewaters contaminated with mevastatin. [ABSTRACT FROM AUTHOR]

Summary: Modified graphene oxide (GO) nanosheets as fillers within poly(ether‐b‐amid) (PEBA) copolymer as matrix were used for mixed matrix membranes (MMMs) fabrication to improve CO2 capture. The GO nanosheets were modified by polypyrrole (PPy) and zinc cations. The former that have conjugated N‐containing groups provided a high degree of affinity toward CO2, and the latter has facilitated the gas molecules transport through the gas channel passages. The different modified GO nanosheets were characterized by HRTEM, FT‐IR, FESEM, XRD, and XPS analyses. Also, the FT‐IR, XRD, AFM, and SEM methods were used for the structural and morphological characterizations of the prepared MMMs with 0.1 wt% of the nanofiller. Gas permeation tests for CH4, N2, and CO2 were then performed for all prepared membranes. Compared to the neat PEBA membrane, the selectivity of both CO2/CH4 and CO2/N2 for PEBA‐GO‐PPy membrane increased up to 62% and 51% and for the PEBA‐GO‐PPy‐Zn membrane increased up to 58% and 56%, respectively. Furthermore, the PEBA‐GO‐PPy‐Zn disclosed a 10% increase in permeability of CO2 than the neat membrane. For PEBA‐GO‐PPy MMM, the permeability of CO2 was 122.4 Barrer, and the selectivity of CO2/CH4 and CO2/N2 was 29.8 and 122.5, respectively. Moreover, the gas separation results for PEBA‐GO‐PPy‐Zn MMM were about 131.8 Barrer for CO2 permeability and 30.7 and 119.2 for CO2/CH4 and CO2/N2 selectivities, respectively. Besides, the CO2/N2 selectivity of PEBA‐GO‐PPy and PEBA‐GO‐PPy‐Zn overcomes the Robeson's upper bound. [ABSTRACT FROM AUTHOR]

The residential sector is the third largest end-use energy consumer in Canada. With the increasing pressure on Canada to reduce its energy consumption and the associated carbon dioxide emissions, reducing energy consumption in the residential sector is very important. To quantitatively assess the impact of the large number of measures that can be adopted to reduce the residential energy consumption, a residential energy model for Canada (Canadian Residential Energy End-use Model—CREEM) was developed. This paper presents the model, the characteristics of the residential energy consumption in Canada, and impact of various energy consumption reduction scenarios. © 1998 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Summary: A facile method is developed to fabricate nanoporous, structured, Sn‐based catalyst electrodes. Sn, Zn, and multiwalled carbon nanotubes (MWCNTs) are co‐electrodeposited on a copper substrate, followed by chemical dezincification in NaOH aqueous solution to remove Zn. By controlling variables such as the contents of Zn and MWCNTs, a series of Sn‐MWCNT/Cu (SZMC) electrodes are fabricated. Experimental results show that using such novel SZMC electrodes can achieve a HCOO− Faradaic efficiency of over 91% at −0.99 V versus RHE for 10 hours in CO2‐saturated 0.5 M KHCO3 aqueous solution. The high performance is attributed to the addition of MWCNTs and Zn, followed by chemical dezincification to remove Zn and then create vacancies in the catalyst structure, which results in a special porous structure of SZMC with large surface area. Then ECSA is used for enhancing the catalytic activity and selectivity of HCOO− production, as well as promoting intermediate adsorption and mass transfer. [ABSTRACT FROM AUTHOR]

Summary: The safety issues are a major restriction on coal mining and growing efforts are being made in the search for solutions that will guarantee sustainable use of energy resources. Liquid carbon dioxide is attracting particular interest of coal fire‐fighting due to the promising efficiency of cooling and asphyxia. Our objective is to develop a valid model to simulate the dispersion and thermal behaviors of liquid carbon dioxide under crushed coal condition and assessment of liquid carbon dioxide injection for coal fire‐fighting. For this purpose, a numerical approach which requires an accurate state equation for calculating physical parameters of carbon dioxide, also accounts for appropriate description of energy transformation during the injection is presented. The validation of such a model against three experimental tests on temperature variation is proposed, and the model has proved capable of accurately predicting the heat and mass transfer process when liquid carbon dioxide is injected into crushed coal. Furthermore, the impact of nozzle diameter on the dispersion and thermal behaviors of liquid carbon dioxide is extensively investigated. [ABSTRACT FROM AUTHOR]

Summary: In the present study, the reaction kinetics of carbon dioxide (CO2) with two blends of N‐methyldiethanolamine; potassium salts of taurine and potassium salts of glycine were investigated. The experiments were performed using a stopped flow apparatus over a range of temperature varying from 293 to 313 K. The concentration of solution was varied from 0.2 to 0.8M in different proportions of potassium salts of taurine and glycine. For both cases, the overall reaction rate constant (kov) increased with increased temperature and amino acid salts proportions in the blends. Results also indicated that addition amino acid salts (AAS) could improve the overall reaction rate of methyldiethanolamine (MDEA) with CO2 by more than 100 times. The kinetics data were interpreted using the widely accepted mechanisms namely; zwitterion and termolecular mechanisms. An average absolute deviation of 8.8% was observed for both mechanisms applied to MDEA‐KTau blend, while an AAD% of 7.4 and 7.2 were observed for the case of MDEA‐KGly system when applying the zwitterion and termolecular mechanisms, respectively. The results showed that blends of MDEA and potassium salts amino acids react faster with CO2 compared to conventional amine systems. Hence, the use of both potassium salts of taurine and glycine as rate promotors can significantly enhance the reactivity of MDEA toward CO2. [ABSTRACT FROM AUTHOR]