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CO 2 sequestration has proven to be an attractive way to combat global warming. However, due to the corrosive nature of CO 2 , chemical reactions between CO 2 and the host rock can happen after the injection. This study reviews the current state of knowledge about chemical reactions and their effects on the mineralogy, structure, mechanical, deformation, and transport properties of different types of rocks from research papers published in 2004–2024. In addition to drawing a comprehensive picture of the research that has been done on the subject and the gaps that need to be filled, this review combined the data from the papers to introduce the relationships between exposure conditions (CO 2 pressure, exposure duration, and temperature) and mineralogy, strength, and elastic properties, and permeability of multiple types of rocks. Results showed that some minerals like quartz are not affected by CO 2 while others like carbonates can easily be dissolved. Datapoints from various papers showed a negative effect of CO 2 pressure and exposure duration, and a positive effect of temperature on the strength properties of rocks. An increase in permeability was another consequence of CO 2 treatment in most cases. This study is one of the first works to gather data from multiple sources in developing relationships between CO 2 treatment conditions and the strength properties of rocks. Results will potentially improve understanding and prediction of the effect of CO 2 on the properties and behavior of rocks. [Display omitted] • Quartz, unlike carbonates, is not impacted by CO 2. • Dissolution/precipitation of minerals leads to increase/decrease in pore volume. • The compressive strength mostly decreases with an increase in CO 2 pressure. • Bulk and elastic moduli of rocks decrease after CO 2 treatment. • CO 2 increases the permeability of most rocks. [ABSTRACT FROM AUTHOR]

Energy transition requires a high penetration of reliable and flexible renewable energy. To do so, low-cost, efficient, high capacity and environmentally friendly storage technologies to manage the mismatch between energy production and demand are required. Carnot Batteries are considered as promising energy storage solutions tackling these requirements and storing electrical energy as thermal energy and releasing it whenever necessary while operating on reversible thermodynamic cycles. In Carnot Batteries, power is managed through rotating machines, such as compressors and turbines, and energy is stored as heat in thermal energy storages. In recent years, thermal cycles exploiting Carbon Dioxide (CO 2) as operating fluid, in sub-critical, trans -critical and supercritical conditions, are gaining major interest, thanks to their versatility and high performance, especially for large scale applications. This paper provides an in-depth review on the state of the art of global R&D activities on the use of carbon dioxide for large scale Carnot Battery application, while providing preliminary market and technology maturity breakdown. Different studies on CO 2 -Carnot Batteries at industrial and academic levels are discussed in detail while highlighting the novelty and improvement methods. Detailed information on battery parameters of charging, discharging and storage have been listed and critically analysed, finally concluding with SWOT (Strength, Weakness, Opportunity, Threats) and TRL (Technology Readiness Level) analyses for future developments. [Display omitted] • Academic and industrial outlook on CO2-Carnot batteries. • Important design parameters of charging, storage and discharging are tabulated for each study • · Critical analysis of the design parameters and performance • Roadmap for future developments on CO2-Carnot batteries [ABSTRACT FROM AUTHOR]

Geological CO 2 storage is an emerging topic in energy and environmental community, which is, as a commonly-accepted sense, considered a powerful approach to mitigate the global carbon emissions during the transition to net-zero. The geological media initially considered cover the saline aquifers, oil and gas reservoirs, coal beds, and potentially basalts. Up to now only the first two choices have been proven to be the most capable storage sites and successfully implemented at pilot/commercial scales. Here, novel strategies were proposed for the first time, by synthesizing and utilizing new high-dryness CO 2 foam, to enhance geological CO 2 storage capacity in oil and gas reservoirs. As a major storage site, the oil and gas reservoirs ranked only second to the saline aquifer, due to their huge underground spaces, and more importantly, spontaneous economic benefits by injecting CO 2 for geological storage. However, at any development stage, particularly late stage with high water cut, CO 2 injection usually tends to cause gas channeling and therefore result in low-efficient storage. In this paper, a series of dynamic evaluation experiments are carried out to investigate the effect of newly-synthesized high-dryness CO 2 foam in oil and gas reservoirs. A comprehensive set of parameters, including the fluid production volume, rate, efficiency, pressure, porous media weight, water cut, mobility reduction factor, oil-gas-water ternary phase saturation, etc., are specifically analyzed. The lab results show that when the foam quality is 85 %, the oil recovery performance and gas phase saturation reach their highest values, of 82.68 % and 75.36 %, respectively; meanwhile, the water consumption is at the lowest level, 43.88 g/mol, for the CO 2 storage in oil and gas reservoirs. This indicates the synthesized high-dryness CO 2 foam, attributed to its superb stability, modifies the mobility ratio, suppresses the viscous fingering, and finally results in higher oil recovery and more CO 2 storage. Similar work has been done for the reservoirs with permeabilities from high to low levels. The study provides experimental evidences that suggest benefits from applying CO 2 flooding in oil and gas reservoirs. • Novel strategies for enhancing geological CO 2 storage capacity in hydrocarbon reservoirs. • In-depth properties of a newly-synthesized high-dryness CO 2 foam characterized. • A series fluid and pore parameters analyzed for enhancing geological CO 2 storage capacity. [ABSTRACT FROM AUTHOR]

Negative emission technologies driven by nature with less energy input, lower costs, and long carbon storage capacities are essential for meeting ambitious global carbon mitigation goals. This paper evaluates the carbon sequestration potential of bivalve shellfish farming because its sequestration process is driven by nature, and it is cost-effective and energy efficient. The carbon in shells and the carbon that enters sediments via bio-deposition are long-lived forms of carbon. Using China as a case study, a preliminary estimation suggests that the carbon sequestration efficiency and intensity of cultivated shellfishes are much higher than those of artificial forests. In China, approximately 6.23 Mt CO 2 -eq a−1 was fixed via net carbon sequestration during shellfish growth from 2015 to 2019. In addition, the farmed shellfishes provided 0.37 Mt of harvested protein, and approximately 37.39 Mt CO2-eq a-1 were reduced compared to the same amount of protein provided by beef, and thus, shellfish farming has the win-win benefits of carbon sequestration and high-quality food provision. More importantly, a total of 5.64 Gt CO 2 -eq, accounting for 17.63% of the total emissions in 2020, can be potentially sequestrated at the global scale under the world's largest farming area scenario. • A Negative Emission Technology via shellfish farming was introduced. • Carbon sequestration function and efficiency of shellfish farming were investigated. • Carbon sequestration potential for bivalve shellfish farming was evaluated globally. • Life cycle GHG emissions of shellfish farming in China was assessed. [ABSTRACT FROM AUTHOR]

The residential sector is one of the EU's priority sectors where carbon mitigation needs to be realised. In this paper, we carry out a review of the effectiveness of individual policies or policy packages in terms of the uptake of these carbon mitigation measures and/or energy savings realised as a result. The focus lies on the existing residential building stock. The literature reviewed in this paper covers panel data studies, applied behavioural research, and situated approaches. Most of the reviewed quantitative studies find that financial incentives and subsidies have a positive impact on the probability of energy efficiency improvements being undertaken. However, when evaluating the energy efficiency improvements or CO 2 reductions induced by the incentives and therefore their effectiveness, the presence of free riding turns out to be a problem. Energy and CO 2 taxation should play a larger role in encouraging people to save energy and reduce CO 2 emissions, since the reviewed studies indicate that people are responsive to savings in energy costs and expected price increases in the future. The evidence on the relative impact of regulation vs. financial incentives is inconclusive. For information policies the quantitative evidence is still limited. The reviewed panel data studies find no or a negative impact. This finding however does not necessarily imply that information policies are useless, as panel data do not allow for a detailed analysis of different types of informational approaches. Situated accounts provide further necessary qualitative findings on best practices for energy savings by households. [ABSTRACT FROM AUTHOR]

Storing CO 2 and H 2 in underground reservoirs represents an effective approach to sequester increasing amounts of captured CO 2 for carbon neutrality and to store H 2 to promote clean energy revolutions. However, commercial/pilot-scale CO 2 /H 2 storage sites are mainly restricted to conventional oil reservoirs or salt caverns – both capacity and geographic-location limited. This paper presents a systematic review of the feasibility and prospects of CO 2 and H 2 storage in fractured shale reservoirs as secure repositories. Both field pilot and laboratory studies of CO 2 injection in shales are cross-analyzed across various spatial and time scales, to provide a reliable and substantial basis to support new findings. The presence of suitable injectivity and adequate sealing capacity in shale are demonstrated. The fracture networks are shown to provide major storage space in shales, contrasting with the pore system in conventional reservoirs. This difference in storage mechanisms results in an overestimation in the storage capacity of shales when applying porous-medium-based methods. An underestimation in the mass of injection, however, is apparent from a single well for the reported cases due to unknown characteristics of underground fracture networks. The symbiotic storage of CO 2 and H 2 in shale is discussed in its feasibility and ability to improve both CO 2 storage but principally H 2 recovery – due to the presence of a gas cushion. A new equivalent-fracturing method is proposed as a supplement to recalibrate the over- and under-estimated prospects of CO 2 /H 2 storage in shales – a necessary component in reducing carbon emissions and accelerating the energy transition. [Display omitted] • Field pilots and laboratory studies are cross-analyzed and validated. • Fracture networks in shale reservoirs dominate CO 2 and H 2 storage. • Over- (in shales) and under- (in wells) estimations of CO 2 storage are revealed. • New estimation method is proposed for the technically achievable storage capacity. • Symbiotic storage of CO 2 and H 2 in shales is feasible and promising. [ABSTRACT FROM AUTHOR]

Capture and sequestration of CO 2 released by conventional fossil fuel combustion is an urgent need to mitigate global warming. In this work, main CO 2 capture and sequestration (CCS) systems are reviewed, with the focus on their integration with renewables in order to achieve power plants with nearly zero CO 2 emissions. Among these technologies under development, the Dry Carbonate Process shows several advantages. This manuscript analyses the integration of a CO 2 sorption-desorption cycle based on Na 2 CO 3 /NaHCO 3 into a coal fired power plant (CFPP) for CO 2 capture with solar support for sorbent regeneration. The Dry Carbonate Process relies on the use of a dry regenerable sorbent such as sodium carbonate (Na 2 CO 3 ) to remove CO 2 from flue gases. Na 2 CO 3 is converted to sodium bicarbonate (NaHCO 3 ) through reaction with CO 2 and water steam. Na 2 CO 3 is regenerated when NaHCO 3 is heated, which yields a gas stream mostly containing CO 2 and H 2 O. Condensation of H 2 O produces a pure CO 2 stream suitable for its subsequent use or compression and sequestration. In this paper, the application of the Dry Carbonate CO 2 capture process in a coal-based power plant is studied with the goal of optimizing CO 2 capture efficiency, heat and power requirements. Integration of this CO 2 capture process requires an additional heat supply which would reduce the global power plant efficiency by around 9–10%. Dry Carbonate Process has the advantage compared with other CCS technologies that requires a relatively low temperature for sorbent regeneration (< 200 °C). It allows an effective integration of medium temperature solar thermal power to assist NaHCO 3 decarbonation. This integration reduces the global system efficiency drop to the consumption associated with mechanical parasitic consumption, resulting in a fossil fuel energy penalty of 3–4% (including CO 2 compression). The paper shows the viability of the concept through economic analyses under different scenarios. The results suggest the interest of advancing in this Solar-CCS integrated concept, which shows favourable outputs compared to other CCS technologies. [ABSTRACT FROM AUTHOR]

The demand for biofuels is rising with the growing population and decreasing reserves of petroleum. Indeed the rising population and increasing level of greenhouse gases not only contribute for global warming, but also imparts serious effects on humans and the environment. There is a constant urge to find other alternatives to the petroleum-based products. Of the three generations of biofuel feed stocks i.e. food crops, non-food crops and microalgae-derived biofuels; it is discussed that microalgae can be the best source of feed stock in terms of food security and for reducing the harmful impact on the environment. This paper serves as base to discuss the benefits of using microalgae as a source of biomass for biofuels and the methods that can be used to enhance the microalgal biology in order to improve their production. It reviews how the use of optimized nutrient concentration and culture conditions increase the yield, cell density and lipid productivity. It further reviews the role of bacteria in enhancing/inhibiting the microbial biomass and lipid productivity in microalgal-bacterial biological associations. The final part of the paper lays emphasis on the importance of improving microalgal biology by the use of genetic engineering and metabolic engineering in order to obtain desired results. Overall stress is placed upon unfolding and unraveling the gaps present in producing microalgal biomass, such as inefficient and reduced production, poor penetration of light in dense cultures, low oil content and higher harvesting costs. Overcoming of these major bottlenecks by ecologically engineering species specific valuable microalgal-bacterial mini consortium might lead to specific and noteworthy breakthrough in the production of clean, green, renewable, sustainable and high yielding microalgal biofuel. [ABSTRACT FROM AUTHOR]

The diesel engine is being widely used in day to day life in both mobile and stationary applications. The main drawback is the release of harmful gasses like HC, CO, NO x and particulate matter into the atmosphere. This affects both human beings and environment to a great extent and should be controlled effectively. This paper reviews the works on the control of diesel particulate matter in both pre-combustion and post-combustion techniques employed in the past few decades. The initial part of this review will discuss particulate matter composition and its structure. Then the various physical processes involved in the formation of particulate matter are discussed. Effects of fuel composition and its structure on soot formation are reported. Hazardous effects of particulate matter on both human beings and the environment are reviewed. Use of biodiesel water emulsified fuel as a fuel to control soot formation is highlighted. This review also highlights control of particulate matter by varying injection parameters like injection pressure, injection timing and auxiliary air injection. Multiple fuel injections within the same cycle to control NOx and particulate matter are also discussed. The conventional control technique of particulate matter by using Diesel particulate filter and its types are also compared with the new technologies. Various regeneration concepts to burn the collected soot are also highlighted. The major part of this review focuses on pre-combustion techniques to control particulate matter. This review paper, it is hoped, will be very useful for the researchers working on the control of diesel particulate matter. [ABSTRACT FROM AUTHOR]

This paper presents a review of 32 Life Cycle Assessment studies on Power-to-X. Due to their multiplicity, different Power-to-X chains are compared and influencing factors on environmental impacts are identified. Besides technological specifications, methodological choices of the publications are assessed. The majority of studies consider Power-to-Gas or Power-to-Transport. Additionally, six publications assess Power-to-Power, Power-to-Liquids or Power-to-Chemicals. Climate change is the most analyzed environmental impact category. Further impacts are assessed in 14 publications. The electricity source and the methodological concept of carbon dioxide consideration are crucial drivers of environmental impacts. The review reveals a lack of transparency on technological as well as on methodological level. Specifications like the multi-functionality approach used or in case of Power-to-Transport chains the life time mileage of vehicles are missing in most publications and hinder their comparability. • Review of 32 Life Cycle Assessment studies on Power-to-X. • Electricity source and CO 2 supply for upgrading have an eminent environmental impact. • Power-to-Hydrogen and Power-to-Transport are most considered Power-to-X chains. • Climate change is the most analyzed environmental impact category. • A lack of LCA methodological specifications is evident. [ABSTRACT FROM AUTHOR]

The paper empirically examines the cointegrating relationship between carbon emissions, energy consumption, trade openness and financial development in Pakistan using ARDL bounds test for cointegration procedure. Annual time series data is used for the period 1971–2011. The results reveal an inverted U-shaped relationship between carbon emission and energy consumption with a maximum threshold value of energy consumption per capita 640 kg of oil equivalent. Currently, the economy is operating below this level and therefore it is expected that carbon emission will continue to rise gradually over some time until the threshold level is reached. The lower than threshold level of energy consumption implies that scale and composition effects dominate the technology effect in terms of energy use. Further, the long-run results indicate that one percent increase in trade openness and financial development will increase carbon emission by 0.247% and 0.165%, respectively. The short-run elasticities are 0.122% and 0.087% for trade openness and financial development, respectively. The Granger causality results indicate a unidirectional causality from energy consumption, trade openness and financial development to carbon emission; and a bi-directional causality between energy consumption and financial development. In line with the results and given the growing focus on climate change effects in Pakistan, the paper discusses some policy issues for consideration and highlights the need to interpret elasticities with caution. [ABSTRACT FROM AUTHOR]

The problematic of climatic changes and the respective consequences raises the need to discuss the problem and define measures to control and/or reverse them. Because one of the causes of climatic changes is the emission of greenhouse gases, the European Union defined the reduction of emissions as a main concern as well as increasing efficiency in the energy sector. With the objective of analysing the main conditions affecting the growth of per capita emissions, this paper uses a fuzzy-set qualitative comparative analysis (fsQCA). Based on a sample of data from 2010 to 2014, the conditions evaluated were: i) GDP growth; ii) change in the share of GDP relating to private consumption; iii) change in the share of GDP relating to public consumption; iv) change in the share of GDP on investment; v) and energy consumption growth. The main drivers contributing to reduced emissions were the crisis and energy consumption. Evaluation of the main factors affecting emissions growth is the main contribution of this study. Considering that economic growth is an obvious goal, the European Union must design measures encouraging investment in more efficient and less pollutant technologies, which is also in accordance with OECD sustainability goals. • Fuzzy-set qualitative comparative analysis is used to study emission growth in the European Union. • The main drivers of reduced emissions were the economic crisis and energy consumption. • The results are important for policy makers in order to redesign their strategies. • It is crucial to start investing in more efficient and less pollutant technologies. [ABSTRACT FROM AUTHOR]

Abstract Dual fluidized bed steam gasification is a well-known technology for the thermochemical conversion of biogenic fuels into a valuable product gas comprising hydrogen, carbon monoxide, carbon dioxide, and methane. Based on the dual fluidized bed gasification principle, further benefits can be obtained by considering the bed material: Limestone allows the removal of carbon dioxide from the gasification reactor and its release in the combustion reactor. Therefore, the gasification and combustion reactors must be operated at 650 °C and 830 °C, respectively. Moreover, this sorption enhanced reforming process affords hydrogen contents of ~70 vol.-% db and allows an adjustment of the hydrogen-to-carbon monoxide ratio in the range of 2–10. The circulating bed material undergoes carbonation and calcination cycles, that lead to a decrease in the carbon dioxide sorption capacity with time. This paper discusses the main reasons for this decrease as well as the positive or negative effects of steam and carbon dioxide. The major disadvantage of using limestone in the fluidized beds is its low attrition resistance. Thus, gentle separation units for the limestone as bed material are recommended to overcome this problem. Several process configurations have been published by different institutions, mainly by IFK Stuttgart and TU Wien. The most important experimental and theoretical results, including the dependence of the product gas composition on the gasification temperature and the bed material cycle rate, tar content in the product gas, and test runs in the industrial scale are summarized and discussed. Sorption enhanced reforming of different fuel types, sorption enhanced reforming with oxyfuel combustion, and performance indicating key figures of the process are also investigated. Highlights • Detailed description of SER process and influencing parameters on CO 2 sorption. • Existing plants and concepts are summarized and simplified schemes are displayed. • Results from different plants are summarized and presented in an unique way. • Equilibrium modelling of product gas based on results from different plants. [ABSTRACT FROM AUTHOR]

Abstract As investments and policies that promote renewable energy (RE) projects in electricity systems are most often grounded on the goal of reducing emissions of greenhouse gases, and actual investment and policy decisions are shaped by the estimates of the accrued emissions savings, it is crucial that these estimates are as accurate as possible. In this paper we compare different econometric models that estimate the amount of carbon abated due to RE in terms of their results and their inherent methodological benefits and drawbacks. Specifically, we use the British, French and Spanish grids as case studies for the application of a selection of econometric models and compare the resulting CO2 abatement estimates. We find that, across the three markets, estimates can vary substantially across the different models – this can lead to an over or underestimation of the emissions abated by RE. Overall, our results highlight the need for choosing econometric specifications that lead to results that are congruent with the operational framework of the examined power systems. Highlights • We compare three econometric models to estimate marginal emissions factors (MEF) in power systems. • Focus on CO2 reductions due to renewable electricity generation – wind and solar. • We use the British, French and Spanish grids as case studies. • In each country MEF estimates vary substantially according to the model that is used. [ABSTRACT FROM AUTHOR]

Abstract The recycling of carbon dioxide (CO 2) into synthetic fuels via Power-to-Gas (PtG) could represent an important instrument for achieving the complete decarbonization of the energy sector. To address such issue, this paper calculates the investments in PtG units, grid reinforcements and renewable installations that allow the almost complete recycling of the CO 2 emissions of a countrywide electric power system. Furthermore, this work evaluates the feasibility of gas and electric operations in the new system configuration. The analysis is enabled by coupled gas and electric network modelling. The necessary PtG station installations and overhead line reinforcements are identified via scenario-based cost optimization. Hourly operations of electric power plants are scheduled as a sequence of day-head security-constrained unit commitment problems. A transient gas flow model assesses the capability of the gas network to act as short- and long-term storage of synthetic gas. The developed framework is applied to the electric and gas transmission networks of Great Britain, whose investments and operations are investigated for increasing renewable capacity levels based on the 2030 Gone Green case. Results show that almost complete CO 2 recycling is achieved if the installed renewable capacity is approximately three times as large as the 2030 Gone Green estimates. The investments comprise 114 GW of PtG capacity and the construction of 23 electric parallel lines. Remarkably, gas network operations do not represent a limit to the storage of large amount of synthetic methane. Moreover, PtG stations are preferentially installed at locations with large RES capacity and foster large renewable penetration; only small curtailments occur even for large renewable capacity levels. These results support decision makers by quantifying the techno-economic implications of the presented extensive CO 2 recycling strategy. Highlights • We investigate the techno-economic implications of extensive CO 2 recycling. • Complete CO 2 recycling is achievable via PtG if enough RES power is available. • CO 2 recycling in the British system requires 114 GW of PtG and 23 new power lines. • Gas network operations do not limit the injection of synthetic methane. • The gas infrastructure can serve as long-term energy storage of RES. [ABSTRACT FROM AUTHOR]

Abstract Anaerobic digestion of organic wastes produces valuable biogas. The main constituents of biogas, methane (CH 4) and carbon dioxide (CO 2), although being greenhouse gases (GHGs) are versatile feedstock for production of valuable fuels and chemicals. This paper provided an overview on conversion technologies to produce syngas and methanol from CH 4 and CO 2. Two conversion routes are considered: (1) reforming of methane which is used to produce syngas from biogas and (2) CO 2 hydrogenation which directly converts CO 2 to methanol. An overview of the most significant factors to attain high conversion efficiency in both conversion processes is presented. The effect of operating parameters (including reaction temperature, gas hourly space velocity (GHSV), reduction temperature, etc.), catalyst preparation method and use of promoters in catalyst on conversion efficiency and product yield is reviewed and discussed. An overview on techno-economic analysis of biogas constituent conversion is presented based on the available literature. This survey of literature indicates that despite the high potential of biogas constituents to be converted to value added products, many problems in terms of technology maturity and economic feasibility need to be addressed before the process could be exploited at industrial scale. Issues such as catalyst deactivation, biogas purification and H 2 S removal from biogas need to be obviated. With further improvement of the process and also with the involvement of policy makers and private sectors, the conversion technologies can help to mitigate the GHG release and the products obtained from the conversion can be used as sources of renewable fuel and energy. Graphical abstract fx1 Highlights • The utilization of biogas as feed source for syngas and methanol production is discussed. • In order to achieve desired efficiency of conversion, some parameters must be chosen wisely. • Several methods to improve the catalytic conversion are suggested. [ABSTRACT FROM AUTHOR]

Abstract The Renewable energy power generation capacity has been rapidly increasing in China recently. Meanwhile, the contradiction between power supply and demand is becoming increasingly more prominent due to the intermittence of renewable energies. On the other hand, on the mitigation of carbon dioxide (CO 2) emissions in China needs immediate attention. Power-to-Gas (PtG), a chemical energy storage technology, can convert surplus electricity into combustible gases. Subsurface energy storage can meet the requirements of long term storage with its large capacity. This paper provides a discussion of the entire PtG energy storage technology process and the current research progress. Based on the comparative study of different geological storage schemes for synthetic methane, their respective research progress and limitations are noted. In addition, a full investigation of the distribution and implementation of global PtG and CO 2 capture and storage (CCS) demonstration projects is performed. Subsequently, the opportunities and challenges of the development of this technology in China are discussed based on techno-economic and ecological effects analysis. While PtG is expected to be a revolutionary technology that will replace traditional power systems, the main issues of site selection, energy efficiency and the economy still need to be adequately addressed. Additionally, based on the comprehensive discussion of the results of the analysis, power-to-gas and subsurface energy storage implementation strategies, as well as outlook in China are presented. Graphical abstract fx1 Highlights • The entire process of power-to-gas (PtG) and subsurface energy storage is reviewed in detail. • A comparative analysis of gas storage in the same or different formations. • Opportunities and challenges for China based on techno-economic and ecological effects analysis. • Power-to-gas implementation strategies and outlook for China. [ABSTRACT FROM AUTHOR]

Attached microalgae cultivation could simplify the microalgae harvest process and reduce its associated cost, which has attracted much attention recently. In this paper, the reactor patterns, advantages, microalgae biomass productivity, influencing factors and the microalgae physicochemical properties in the attached microalgae cultivation was summarized to show the sketch of this novel microalgae cultivation. It was concluded that the attached microalgae cultivation is advantageous in achieving less water and space consumption, higher water treatment potential and higher biomass productivity compared with the traditional suspended microalgae cultivation. The accumulation of the attached microalgae biomass showed a linear increase with culture time with the largest productivity up to 20.7 g m −2 d −1 . Chlorella and Scenedesmus were the top two species that have been studied in attached culture system. Cellulose acetate/nitrate membrane, polycarbonate membrane and cotton were the most popular materials used owing to their high hydrophilicity and wide availability. Flow rate, nutrients, light, CO 2 and other factors could affect the attached microalgae productivity and the physicochemical property in a way different from the suspended microalgae, which were described in detail in this review. At last, some technical bottlenecks and the corresponding solvents in the attached microalgae were suggested. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have received special attention in recent years as a result of their attractive and unique properties such as structure flexibility, high surface area, tunable pore size and functionalizable organic linkers and metal centres which have led to vast array of promising applications. Their properties can be improved to further enhance their performance by functionalization of the organic linkers, postsyntheic modification, and doping of nanomaterials into their frameworks. In this review, some recent synthetic methods for the preparation of MOFs are discussed, especially those that are applicable to CO 2 adsorption. The second part of this paper discusses the applications of MOFs as heterogeneous catalyst for various CO 2 conversion processes, with a view to address some of the challenges faced by the current technology of CO 2 conversion which tend to be very energy intensive processes with high level of waste emission and cost. The current state of MOF commercialization for niche markets is also discussed. [ABSTRACT FROM AUTHOR]

Thermal power plants in India emit around 500 Mt of CO 2 annually. All of it is released into the atmosphere untreated. Microalgae, a third generation feedstock for bio-fuel emerges as a viable option for partly sequestering the emissions. Moreover, its carbon capture capacity of 4.8 kg CO 2 /kg biomass, which is very much as compared to terrestrial substitutes like Jhatropa curcas , enables to produce bio fuel hence adding value to the entire process. This paper intends to build upon this idea and come up with strategies to integrate bio fuel production and CO 2 sequestration with the existing thermal power plants. The raw materials needed for algal growth are available in the plant as elaborated in the paper. Thus the bio fuel produced can be routed back to power the plant consequently lowering the dependence on coal. This would help in putting a check on the carbon emissions thus making the existing systems more environmentally benign and suitable for long haul. This paper reviews currently employed carbon capture technologies and methods and comes up with a strategy to subsume carbon capture through microalgae with power plants of a certain capacity. 3 t/day is taken as the basis for calculations in the proposed flow sheet. An alternative of the above is also provided which substitutes the biofuel production with co-firing. This escalates the nitrogen content of flue gas but deescalates the investment. This brings down the capital investment in the plant but enhances N 2 content of flue gas. Carbon leakage is accounted for in a table of atomic balance. It takes care of input and output of carbon. The paper is inclined towards the conclusion that the Microalgae possess incredible potential and if tapped efficaciously could prove to be extremely helpful in these days of power and environmental crisis. [ABSTRACT FROM AUTHOR]

China is the top CO 2 emitter with enormous regional variation in economic development, resource endowment, and consumption patterns, which leads to great variations in regional CO 2 emissions and embodied CO 2 transfer among provinces. Analyzing the mechanisms responsible for carbon footprint (CF) and embodied CO 2 transfer among provinces via trade could help policy makers allocate emission responsibilities and reduction targets. Based on a multi-regional input–output model, this paper investigates the CFs and embodied CO 2 transfer in/among 30 provinces of China in 2007 and 2010, and analyzes emissions from different perspectives. Results indicate that China's CF grew from 5230 Mt in 2007 to 6922 Mt in 2010, with an annual growth rate of 9.8%. The provinces with the large CFs and per capita CF were mainly those locate in eastern, developed regions along the coast and several highly populated ones. CO 2 emissions due to capital formation contributes the most to the CFs and the increment in this period, and this was followed by urban consumption. Significant embodied CO 2 transfer were observed to drift from the developing and energy-abundant provinces like Hebei and Inner Mongolia, to the developed coastal provinces. Total embodied CO 2 transfer account for 43.9% of the national CF in 2007, and decreased to 41.0% in 2010. In order to control CO 2 emissions and make reduction allocations for provinces, interprovincial embodied CO 2 transfer and practical capacities need to be taken into account. [ABSTRACT FROM AUTHOR]

Investing in energy efficiency is considered to be an effective way to reduce the carbon emissions. However, the resulting CO 2 savings may be partially or totally offset by the rebound effect (RE). This paper goes beyond the traditional energy RE to investigate the rebound effect as related to CO 2 emissions, aims to explore the direct CO 2 rebound effect (CRE) in urban households at the provincial level. To achieve the objective, this study uses IPCC carbon emissions accounting method, then proposes an elasticity approach and constructs an individual fixed-effect variable coefficient panel data model. The results show that the total CO 2 emissions from household energy consumption were rising in most provinces during 2002–2017. The purchased electricity and heat CO 2 emissions are growing faster than combustion CO 2 emissions. Regarding the magnitude of the CRE, there are three types of direct CRE among urban households in China: the backfire effect, partial rebound effect and super conservation effect. Overall, the average direct CRE in urban households is 59.90%; specifically, the western region has the highest direct CRE (90.92%), compared with the eastern region (52.84%) and central region (24.88%). The government should take into account the CRE of households, in order to avoid overestimating the carbon reduction. Attention should also be paid to the differences between provinces when formulating energy policies. The analysis above helps local governments to formulate effective energy policies to promote households' carbon emission reduction. • This paper proposes an elasticity method for estimating CO 2 rebound effect. • The carbon emissions from household energy consumption are calculated. • There are three types of direct CO 2 rebound effect among urban households in China. • The average direct CO 2 rebound effect in urban households is 59.9%. [ABSTRACT FROM AUTHOR]

Abstract: Many renewable energy policies are looking into new incentives to absorb investments by targeting abating CO2 emission and fixing energy price fluctuation. Feed in Tariff (FIT) is a policy for rebating the amount of generated renewable electricity to investor. FIT is also defined as a CO2 mitigation policy in electricity generation from renewable sources. This paper presents a cost benefit survey that estimates the real produced carbon dioxide for electricity generation in selected countries. This study introduces the substitute price of avoiding CO2 emission as an indicator. The new indicator shows how much is paid for avoiding CO2 by each selected countries through the FIT policy for renewable technologies. The amount calculated for solar energy is taken as a case in this paper. The result confirms that the FIT policy reasonably works for solar energy in absorbing investment. However the FIT policy claims a large portion of liquidity compared with other approaches. Hence makes this mechanism inept as a CO2 mitigation policy. [Copyright &y& Elsevier]

Abstract: Microalgae are considered as a promising biofuel resource to fix carbon dioxide (CO2) in the future. Modelling microalgae growth is an effective method of studying the performance of microalgae growth manifested by the parameters including light distribution, pigment dynamics, nitrogen uptake, growth rate, respiration rate, temperature dependence, and depth dependence, and helping to control the culture of microalgae in artificial bioreactors. In this paper, the models of microalgae growth in nitrogen-limited and light-limited culture system for estimating biomass productivity are investigated by comparing different expressions and coefficients used in several main models. The results show that there are some differences among the results of numerical modelling due to different expressions and coefficients. This paper will lay a foundation for the selective use of microalgae growth models for researchers. [Copyright &y& Elsevier]

The objective of this paper is to assess carbon dioxide emissions and energy consumption for the production of road pavements by means of a literature review. The construction of the main types of pavements requires energy and generates greenhouse gas emissions that impact the environment. Different types of asphalt mixtures such as cold mixtures, warm mixtures, asphalt rubber mixtures and mixtures with reclaimed asphalt pavement were assessed. The fuel used in the burners that heat and dry the aggregates is the main source of emissions. Also, the aggregates moisture content is an important parameter that influences the energy consumption. On the other hand, the energy consumption and emissions to produce Portland cement mixtures are related to the process of cement production. For both asphalt and Portland cement mixtures, the extraction, manufacturing and placement were also evaluated. Moreover, the energy consumption of the pavements structures was evaluated. Pavements composed of Portland cement concrete consume more energy than hot mix asphalt. But, warm mix asphalt technologies can save 20-70% of the energy consumption when compared to hot mix asphalt, mainly due to the temperature reduction in the warm mix processes. In addition, the emissions caused by different fuels used to produce pavement mixtures were compared. Asphalt mixtures and their alternative technologies consumed less energy and emitted fewer gases than Portland cement mixtures. Carbon dioxide emissions for hot mix asphalt and asphalt rubber mixtures can be 70% lower than emissions for Portland cement concrete. Some alternatives to reduce energy consumption and greenhouse gas emissions in asphalt mixtures production are the decrease of aggregates moisture content, reduction of the asphalt mixtures production temperature and use of waste materials in pavement construction. Switching from hot mix to warm mix technologies would reduce the carbon footprint generated by the asphalt industry. [ABSTRACT FROM AUTHOR]

This paper explores the validity of the Environmental Kuznets Curve (EKC) using two different environment indicators: the carbon dioxide emissions (CO2) and the ecological footprint (EF) in Qatar over the 1980–2011 period. To this end, we investigate the impact of real gross domestic product (RGDP), the square of RGDP, the energy use, the financial development and the trade openness on the CO2 emissions and the EF. We employ the autoregressive distributed lag (ARDL) model with the presence of unknown structural breaks in order to study short-run and long-run elasticity between the variables. The findings infer that there is a long-run relationship among the selected variables with a shift in the cointegration vector in 1991 and 2000. The empirical result indicates that the inverted U-shaped hypothesis is not valid in Qatar when we use the CO2 emissions, whereas the inverted U-shaped held when using the EF. Furthermore, the error correction results confirm that the convergence towards the long-run equilibrium will mostly occur within one year after a short run shock. Generally, the findings suggest that Qatar should invest more in efficient energy and continue sustained its growth. Moreover, more efforts are needed for diversification particularly in technology-intensive and environment-friendly industries to improve environmental quality. [ABSTRACT FROM AUTHOR]

This study investigates the dynamic causal relationships among carbon emissions, financial development, economic growth, and energy consumption for Gulf Cooperation Council (GCC) countries from 1980 through 2011. Annual time series data and an autoregressive distributed lag (ARDL) model are used. The main contribution of this paper is that it has investigated the causes of carbon emissions by taking into account the role of financial development and economic growth in GCC countries. The results suggest long-run and causal relationships among carbon emissions, financial development, gross domestic product (GDP), and energy use in all GCC countries except United Arab Emirates (UAE). Moreover, there is long-run unidirectional causality running from carbon emissions to energy use in the case of Saudi Arabia, UAE, and Qatar. Furthermore, a one-way causal relationship from financial development to carbon emissions in the context of UAE, Oman, and Kuwait is found. The evidence suggests that financial systems should take into account environmental aspects in their current operations in these countries. The results of this study may be of great importance for policy and decision makers in developing energy policies for GCC countries that contribute to curbing carbon emissions while preserving economic growth. [ABSTRACT FROM AUTHOR]

A major portion of the total primary energy consumed by today’s buildings is used in heating, ventilating, and air-conditioning (HVAC). Conventional heating and cooling systems are having an impact on operational cost, energy requirement and carbon dioxide emission. In this regard, Trombe walls are receiving considerable attention because of their potential ability for addressing the environmental and energy crisis. This paper reviews the most pertinent contents of studies on Trombe walls that have been carried out in the recent 15 years. According to utilizing functions of Trombe walls, they are divided into two major types: a heating-based type and a cooling-based type. In terms of content, we emphasize the introduction of three groups of parameters that be considered when designing Trombe walls: the ‘Trombe wall’ parameters, the ‘building’ parameters and the ‘site’ parameters. Then different evaluation indicators on Trombe walls have been summarized from three points of view: energy, environment and economic. We hope that this review is useful to academic researchers and can provide a reference for architects or related engineering designers in the field of passive design. [ABSTRACT FROM AUTHOR]

The carbonation technology, which is promising in carbon capture and storage, is an emerging soil treatment method adopted in geotechnical engineering and geo-environmental engineering to enhance mechanical properties or mitigate environmental risks. The advantage of utilising CO 2 in solving engineering problems shows a large potential for the technology to be widely used to alleviate the greenhouse emission problems; Nevertheless, the changes in soil characteristics, including physical, chemical, mechanical, deformation, and durability characteristics, caused by carbonation are complicated, which brings challenges to possible engineering applications. This paper reviews the recent development of carbonation technology in geotechnical engineering and provides a systematic analysis of the effect of carbonation on soil properties, from the macro behaviours to the micro mechanism. The "double-edged sword" effect of carbonation on the mechanical properties of soils is proposed, together with the micro-scale mechanisms illustrated. A qualitative theoretical model for the prediction of the mechanical strength of carbonated soils is established. The prospective future and important insights of the carbonation technology to be utilized in geotechnical engineering can be concluded from the review, although some potential technical issues, including possible carbonation crack, heavy metal leaching, durability issues, and lack of construction techniques, require further study. [Display omitted] • Natural and artificial carbonation process in soils. • Carbonation technology for ground improvement and contaminated soil treatment. • Physical, chemical, and mechanical characteristics of carbonated soils. • Microscopic structures and chemical reactions of the carbonation process. • Positive and negative influences of carbonation on soil properties. [ABSTRACT FROM AUTHOR]

Commonly, carbon dioxide (CO 2 ) capture and resource utilization (CCRU) covers a broad area of research with different technical challenges. Thus, more exploratory technological investigations are needed to discover new applications and reactions. In this paper, an innovative method for CO 2 absorption by sodium borohydride (NaBH 4 ) from coal-fired flue gas was developed under atmospheric pressure and moderate temperature. The effects of influencing factors, such as volume ratio of ethanol to water, NaBH 4 concentration, reaction temperature, solution pH, and concentrations of sulfur dioxide, nitric oxide and oxygen on CO 2 absorption were investigated. The average absorption efficiency of CO 2 was 54.06% under optimal experimental conditions, in which volume ratio of ethanol to water was 80%, NaBH 4 concentration was 0.439 mol L −1 , reaction temperature was 318 K and solution pH was 9.0. The coexisting gases of sulfur dioxide, nitric oxide and oxygen in flue gas had no significant competition or inhibition effect on CO 2 absorption. Ion Chromatography and Fourier Transform Infrared Spectroscopy analyses of products proved that the main reaction product was formate with 41.52% of the selectivity. Combined with the analysis of the electrode potentials, the mechanism of CO 2 reaction with NaBH 4 was proposed. Meanwhile, a comparative research of CO 2 resource utilization can provide a useful reference for developing new CCRU technologies. [ABSTRACT FROM AUTHOR]

This paper estimates the short- and long-run effects of Internet usage and economic growth on carbon dioxide (CO 2 ) emissions using OECD panel data for the period 1991–2012. The Pedroni panel cointegration test confirms that the variables are cointegrated. Although Pooled Mean Group (PMG) estimates indicate a positive significant long-run relationship between Internet usage and CO 2 emissions, the coefficient is very small and no causality exists between them, which both imply that the rapid growth in Internet usage is still not an environmental threat for the region. The study further indicates that economic growth has no significant short-run and long-run effects on CO 2 emissions. Internet use stimulates both financial development and trade openness. The findings offer support in favor of the argument that OECD countries can promote their Internet usage without being significantly concerned about its environmental consequences. But the future emissions effect of Internet usage cannot be ruled out, as is evident from the variance decomposition analysis. Therefore, this study recommends that in addition to boosting the existing measures for combating CO 2 emissions, OECD countries need to use ICT equipment not to simply reduce its own carbon footprint but also to exploit ICT-enabled emissions abatement potential to reduce emissions in other sectors, such as the power, energy, agricultural, transport and service sectors. [ABSTRACT FROM AUTHOR]

Carbon dioxide hydrate has been paid growing attention due to its application potentials like being used as a secondary refrigerant and sequestration in the deep ocean. Therefore, there has been a lot of research on various gas hydrates, including methane hydrate, ethane hydrate, methane–CO 2 mixture hydrate and so on. However, there is no review especially on the CO 2 hydrate and its cooling application. In this paper, the review provides the comprehensive understanding of the CO 2 hydrate with focus on the formation and dissociation models, including the kinetic and thermodynamic ones, as well as its applications. It is proposed that more experimental and modeling work should be carried out on CO 2 hydrate dissociation, and the kinetic models should be developed by considering the effect of additives. It is also proposed that the cooling application of CO 2 hydrate will become popular in the very near future and therefore, the experimental data at low pressure are needed. Finding the effective additives which can reduce the equilibrium conditions and increase the kinetic formation/dissociation rate is recommended. [ABSTRACT FROM AUTHOR]

Abstract: Nuclear power and carbon capture and storage (CCS) are key greenhouse gas mitigation options under consideration across the world. Both technologies imply long-term waste management challenge. Geological storage of carbon dioxide (CO2) and nuclear waste has much in common, and valuable lessons can be learnt from a comparison. Seeking to compare these technologies economic, social and environmental criteria need to be selected and expressed in terms of indicators. Very important issue is costs and economics of geological storage of carbon dioxide and nuclear waste. The costs of storage are one of the main indicators for assessment of technologies in terms of economic criteria. The paper defines the costs of the geological storage of CO2 and nuclear waste in Lithuania, drawing also on insights from other parts of the world. The costs of carbon dioxide and nuclear waste storage are evaluated in UScnt/kWh and compared. The paper critically compares the characteristics and location of the both sources of and storage options for CO2 and nuclear waste in Lithuania. It discusses the main costs categories for carbon dioxide and nuclear waste storage. The full range of potential geological storage options is considered and the most reliable options for carbon dioxide and nuclear waste are selected for the comparative costs assessment. [Copyright &y& Elsevier]

Abstract: Carbon dioxide is a safe, economic and environmentally sustainable refrigerant which can be used in heat pump and refrigeration systems. Research into the performance and benefits of a transcritical heat pump cycle using carbon dioxide began in the early 1990s. Theoretical and experimental research, as well as commercial system development, has improved transcritical system performance to a level similar to that of conventional heat pump systems. This paper presents an overview of transcritical carbon dioxide heat pump systems. The paper begins with a summary of carbon dioxide''s use as a refrigerant and the distinctions of the transcritical cycle, followed by a numerical analysis of transcritical cycle performance. The study will then present a review of research on transcritical carbon dioxide heat pump systems, which covers system components, configurations and modifications and how these factors affect overall system performance. [Copyright &y& Elsevier]

Abstract: The paper investigates the causality relationships among energy consumption, carbon dioxide (CO2) emissions and income in India using a dynamic modeling approach. The paper also utilises an innovation accounting method to investigate profiles of the macroeconomic variables persisting from an unanticipated shock in innovation. Our results provide evidence of the existence of bi-directional Granger causality between energy consumption and CO2 emissions in the long-run but neither CO2 emissions nor energy consumption causes movements in real income. There is no causality relationship between energy consumption and income in any direction in the long-run implying that India could follow energy conservation and efficiency improvement policies without impeding economic growth. This will allow India to reduce CO2 emissions without affecting its economic growth and contribute significantly towards combating global warming as well. [Copyright &y& Elsevier]

Abstract: The cement sub-sector consumes approximately 12–15% of total industrial energy use. Therefore, a state of art review on the energy use and savings is necessary to identify energy wastage so that necessary measures could be implemented to reduce energy consumption in this sub-sector. In this paper energy use at different sections of cement industries, specific energy consumption, types of energy use, details of cement manufacturing processes, various energy savings measures were reviewed and presented. Various energy savings measures were critically analyzed considering amount of energy that can be saved along with the implementation cost. Amount of CO2 reduction has been presented along with the payback period for different energy savings measures as well. This study complied a comprehensive literature on the cement industries in terms of Thesis (MS and PhD), peer reviewed journals papers, conference proceedings, books, reports, websites. It has been observed that China producing major share of global cement production. Coal contribute major share of fuel used in cement industries. However, along with conventional fuels, industries are moving towards the use of alternative fuels to reduce environmental pollution. It was reported that cement industries are moving from wet process to dry process as it consume less energy compared to wet process. [Copyright &y& Elsevier]

Abstract: Petroleum resources are finite and, therefore, search for their alternative non-petroleum fuels for internal combustion engines is continuing all over the world. Moreover gases emitted by petroleum fuel driven vehicles have an adverse effect on the environment and human health. There is universal acceptance of the need to reduce such emissions. Towards this, scientists have proposed various solutions for diesel engines, one of which is the use of gaseous fuels as a supplement for liquid diesel fuel. These engines, which use conventional diesel fuel and gaseous fuel, are referred to as ‘dual-fuel engines’. Natural gas and bio-derived gas appear more attractive alternative fuels for dual-fuel engines in view of their friendly environmental nature. In the gas-fumigated dual-fuel engine, the primary fuel is mixed outside the cylinder before it is inducted into the cylinder. A pilot quantity of liquid fuel is injected towards the end of the compression stroke to initiate combustion. When considering a gaseous fuel for use in existing diesel engines, a number of issues which include, the effects of engine operating and design parameters, and type of gaseous fuel, on the performance of the dual-fuel engines, are important. This paper reviews the research on above issues carried out by various scientists in different diesel engines. This paper touches upon performance, combustion and emission characteristics of dual-fuel engines which use natural gas, biogas, producer gas, methane, liquefied petroleum gas, propane, etc. as gaseous fuel. It reveals that ‘dual-fuel concept’ is a promising technique for controlling both NO x and soot emissions even on existing diesel engine. But, HC, CO emissions and ‘bsfc’ are higher for part load gas diesel engine operations. Thermal efficiency of dual-fuel engines improve either with increased engine speed, or with advanced injection timings, or with increased amount of pilot fuel. The ignition characteristics of the gaseous fuels need more research for a long-term use in a dual-fuel engine. It is found that, the selection of engine operating and design parameters play a vital role in minimizing the performance divergences between an existing diesel engine and a ‘gas diesel engine’. [Copyright &y& Elsevier]

Biodiesel is typically produced from a wide variety of edible vegetable oils. The cost of biofuels is projected to rise in the future as an alternative and ecologically suitable replacement to traditional fuel. Reliable and inexpensive raw materials, including meat processing by-products or waste animal fats, have rapidly attracted interest in biodiesel production. The operational and reaction parameters play an important role in the conversion of processes and biodiesel yield. Kinetic models explain the reaction rate and process optimization to improve the biodiesel conversion process. The process intensification approaches applied by different researchers are illustrated in the current study. This paper proposes a groundbreaking solution to stepping up biodiesel development by utilizing a coalescer reactor and a preliminary review to justify the solution's potential for further analysis. Optimization techniques and kinetics studies used to enhance biodiesel production from renewable sources are explored in the current review paper. • Biodiesel is projected to rise in the future as an alternative and ecologically suitable replacement to traditional fuel. • The effect of operational and reaction parameters on the conversion/yield of processes are reviewed. • To avoid these biodiesel development problems, the process intensification approaches applied by different researchers are also illustrated. • Method optimization, kinetics, and enhancing biodiesel output from renewable sources are explored in detail. [ABSTRACT FROM AUTHOR]

Meeting the Paris Agreement will most likely require the combination of CO 2 capture and biomass in the industrial sector, resulting in net negative emissions. CO 2 capture within the industry has been extensively investigated. However, biomass options have been poorly explored, with literature alluding to technical and economic barriers. In addition, a lack of consistency among studies makes comparing the performance of CO 2 capture and/or biomass use between studies and sectors difficult. These inconsistencies include differences in methodology, system boundaries, level of integration, costs, greenhouse gas intensity of feedstock and energy carriers, and capital cost estimations. Therefore, an integrated evaluation of the techno-economic performance regarding CO 2 capture and biomass use was performed for five energy-intensive industrial sub-sectors. Harmonization results indicate that CO 2 mitigation potentials vary for each sub-sector, resulting in reductions of 1.4–2.7 t CO 2 /t steel (77%–149%), 0.7 t CO 2 /t cement (92%), 0.2 t CO 2 /t crude oil (68%), 1.9 t CO 2 /t pulp (1663%–2548%), and 34.9 t CO 2 /t H 2 (313%). Negative emissions can be reached in the steel, paper and H 2 sectors. Novel bio-based production routes might enable net negative emissions in the cement and (petro)chemical sectors as well. All the above-mentioned potentials can be reached for 100 €/t CO 2 or less. Implementing mitigation options could reduce industrial CO 2 emissions by 10 Gt CO 2 /y by 2050, easily meeting the targets of the 2 °C scenario by the International Energy Agency (1.8 Gt CO 2 /y reduction) for the industrial sector and even the Beyond 2 °C scenario (4.2 Gt CO 2 /y reduction). • Literature review on CO 2 mitigation in steel, cement, chemical, H 2 and paper sectors. • Introduction harmonized methodology to allow comparison between industrial sectors. • All investigated sectors have large reduction potentials for <100 €/t CO 2 avoided. • Negative emissions possible in iron/steel, H 2 and paper sectors. • Potential CO 2 emission reduction of 10 Gt/yr in 2050, easily meeting climate target. [ABSTRACT FROM AUTHOR]

Global steel production is currently dependent on coal and capital-intensive production facilities with long economic lifetimes. While the Paris Agreement means carbon neutrality must be reached globally by 2050–2070, with negative emissions thereafter, coal-based steel production today accounts for around 8% of global energy-related CO 2 emissions. Its production may stabilize or even decline in industrialized countries, but it will increase significantly in the emerging economies. In the past, the focus of CO 2 reduction for steel has been on moderate emissions reductions through energy efficiency measures and on exploring carbon capture and storage. However, as (1) the cost of renewable electricity is declining rapidly, (2) carbon capture and storage has not materialized yet, and (3) and more and more countries set deep emission reduction targets, electricity- and hydrogen-based steelmaking has gathered substantial momentum over the past half-decade. Given the short time frame and the sector's deep carbon lock-in, there is an urgent need to understand the national climate and energy policy as well as the current implementation of low-CO 2 and renewable electricity that would enable a shift from coal-based to electricity-based steelmaking. In this paper, we first identify the countries that are likely to be major steel producers in the future and thus major CO 2 -emitters. Then we map medium- and long-term CO 2 reduction and renewable targets as well as the current share of low-CO 2 and renewable electricity by country. Based on these data, we develop a set of indicators that map the readiness of steel-producing countries for a sustainable transition. Our findings show that although binding long-term CO 2 reduction targets are being implemented, medium-term CO 2 reduction do not yet affect coal based steel production. Overall, the global steel industry seems not be on track yet, though differences between steel producing countries are large. Common shortcomings across countries are a lack of access to renewable electricity and a lack of demanding medium-term CO 2 reduction targets. The paper ends with recommendations on how to enable a low-carbon transition of the global steel industry in line with the Paris Agreement. • Four major steel producing countries have committed to carbon neutrality by mid-century. • 2030 CO 2 reduction targets do not affect coal-based steelmaking. • Access to renewable electricity is limited in most countries. • One third of the steelmaking countries strongly rely on coal for their economy. [ABSTRACT FROM AUTHOR]

Metal–organic framework (MOF) and gas hydrate synergy is a potential technology for CH 4 storage and CO 2 separation. This review introduces the structural characteristics of MOFs and gas hydrates and highlights their limitations in gas storage and separation. Herein, the crystal types, pore structures, and wettability of all the MOFs used for CH 4 and CO 2 hydrate formation to date are summarized. The effects of different MOFs on hydrate thermodynamics, kinetics, and gas storage capacity are analyzed, along with the changes in MOF structures. Confined and bulk phase hydrates are formed in MOFs, and the CH 4 hydrate phase equilibrium in MOFs show only negligible changes. Generally, the confined phase equilibrium is more severe than those in the bulk phase. In most studies on the effect of MOFs on hydrate kinetics, only the induction time has been explored, and it can be shortened by adding MOFs. Additionally, the synergistic effect of MOFs and hydrates on CH 4 storage capacity forms a majority of research in this field. Hydrophobic MOFs, synergistic with hydrates, can enhance the CH 4 storage capacity of MOF–hydrate systems. The MOF structure is not influenced by hydrate formation and dissociation. In the case of CO 2 hydrate formation by MOFs, the number of studies is relatively few, although the corresponding results and conclusions are similar to those of CH 4 hydrates. This paper highlights the research progress and challenges associated with MOF–hydrate synergy and their impact on CH 4 storage and CO 2 separation, unveiling new avenues for research in this direction. • Both confined and bulk phase CH 4 hydrates can form in hydrophilic MOFs. • Hydrophobic MOFs enhanced the storage capacity of CH 4 storage capacity. • CH 4 hydrate formation induction time was reduced by HKUST-1, ZIF-67 and ZIF-8. • MOFs structure remained unchanged after CH 4 and CO 2 hydrate dissociation. [ABSTRACT FROM AUTHOR]

Hydropower, which contributes to around 16% of global electricity and more than 72% of renewable electricity, is expected to play an important role in the deep decarbonization of the energy sector. However, the idea that hydropower is a carbon-neutral energy alternative on par with solar and wind is controversial. Research, mainly from limnology and climate modeling, shows that depending on the characteristics of the hydro project, it could be a significant source of GHG emissions. This aspect has been ignored in most life cycle assessment (LCA) studies, affecting the effective use of LCA results, especially in comparative assessments. This paper aims to provide a comprehensive and critical review on this topic by conducting a systematic literature review on hydropower LCA studies published since 2010. We found that there is inconsistency in how LCA is used for hydropower projects. While the emissions associated with the engineering work are well addressed, efforts to accurately estimate and model reservoir GHG emissions are constrained by limited data availability, difficulties in accurately quantifying highly variable carbon fluxes, and inconsistent modeling approaches. A huge range of emissions values is reported in the reviewed literature, from 1.5 to 3747.8 g CO 2 eq per kWh. Reservoir-based hydropower shows high variability, which is mainly dictated by reservoir-related GHG emissions. Reservoir GHG emissions could be more than 90% of the life cycle emissions, especially for hydropower in a tropical region. The regionalized aspect is a key factor to be considered in extrapolating reservoir GHG emissions. • There is inconsistency in how LCA is used for hydropower projects. • A wide range of emission intensities has been reported (1.5–3747.8 g CO 2 eq/kWh). • The high variability in the emissions is due to major differences in key reservoir characteristics. • Data limitations are the main cause for over- or underestimation of hydropower emissions. • Harmonization of data is vital to effectively conduct LCA and to generate useful results. [ABSTRACT FROM AUTHOR]

Oxy-fired fluidized bed combustion technique combines the advantages of both the fluidized bed combustion and oxy-fired technology. In oxy-fired condition, a mixture of oxygen with CO 2 or recycled flue gas (RFG) is used for the combustion. This paper is divided into two parts; First part covers a technical review of the oxy-fired fluidized bed units, including the studies performed on bubbling fluidized bed, circulating fluidized bed and pressurized fluidized bed. Work presented, identifies and illustrates the trends and challenges related to oxy-fired fluidized bed in the current scenario. It is found that it would take many years to utilize the benefit of this technology fully. The second part explores the possibility of this technology for co-firing cases. Rice husk (RH), plant litter (PL), and coal are co-fired inside a 20 kW lab scale bubbling fluidized bed combustor under O 2 /N 2 /RFG mode. The experimental results show that the blends of coal-PL and coal-RH have been burnt successfully. Carbon dioxide is increased found as a result of increasing oxygen. The measured percentage of NOx and other gasses are found within permissible limit. [ABSTRACT FROM AUTHOR]

This paper applies the autoregressive distributed lag (ARDL) bounds testing approach to cointegration to investigate the dynamic causal relationships between CO 2 emissions per capita, real GDP per capita, per capita non-renewable electricity production and per-capita renewable electricity production, and international trade in the case of Italy from 1960 to 2011. We find cointegration among these variables in the presence of possible structural breaks and we overcome the problem of multicollinearity in the research design. The environmental Kuznets curve (EKC) hypothesis is validated analytically because the estimated pollution model indicates that economic growth leads to less pollution over time. Per capita renewable electricity production reduces the level of CO 2 emissions per capita in the short-run and in the long-run, whereas international trade only impacts positively upon carbon dioxide emissions per capita in the long-run. International trade Granger causes CO 2 emissions per capita and non-renewable electricity production per capita. Moreover the results depict the existence of the long-run unidirectional Granger causality relation running from output per capita to renewable electricity production per capita, and from non-renewable electricity production per capita to renewable electricity production per capita. The findings indicate that renewable electricity production is a key solution in reducing pollutant emissions over time. This result should be of concern to policy makers. [ABSTRACT FROM AUTHOR]

Buildings significantly contribute to global environmental pollution due to consumption of both natural and primary-energy resources as well as to emission of carbon dioxide in their life-cycles. Therefore, to enable construction of more sustainable buildings, it is important and urgent that new low-environmental impact materials are developed, mainly by reducing the use of non-renewable resources. In this regard, the recent advances in the development of natural fibres represent a significant opportunity to produce improved-materials and energy from renewable resources. For this purpose, assessments of energy and environmental performances are needed to support both the design and the production of the aforementioned materials so as to identify solutions for enhanced contribution to global sustainability. In this context, this study presented a review of the papers published up to February 2015 that have been focussed upon the assessment of the environmental and energy impacts related to the use of hemp-based materials for building applications. The reviewed studies aimed at testing and improving hygro-thermal properties and eco-friendliness of these materials for reduction of both embodied and operational energy, whilst preserving both indoor air quality and comfort. Doing so would enable limiting the use of energy resources and, as a consequence, their impacts to human health and to the environment, so contributing to making buildings healthier and more environmentally sustainable throughout their life-cycles. Based upon the findings of the studies reviewed, these materials have strengths and weaknesses and their use is strictly dependent upon the given structural situation as well as upon specific requirements of thermal, moisture, fire and sound protection. In particular, all studies concluded that the main strength in the use of hemp-based materials comes from the production phase because of the “green” origin of these materials, mainly associated with the carbon sequestration during plantation growth. [ABSTRACT FROM AUTHOR]

This paper presents an estimation of the European (EU28) industrial heat pump market potential in terms of magnitude, sizing and number of units. This study is carried out in order to provide technology suppliers and manufacturers of industrial heat pumps perspectives for the technology. Potential heat pump applications in the food, paper, chemical and refining sectors are identified considering a maximum sink temperature of 200°C. This is achieved utilising a bottom-up methodology that uses detailed information from individual processes in the aforementioned sectors. Combining individual process data with typical plant capacities provides information on the heating capacities of heat pumps. The data is upscaled to European level, using production statistics relevant to the individual processes analysed. Since the database of processes is generic in nature and not fully covering the whole industrial sector, the results of this analysis provide a conservative estimate of the heat pump market potential. The results show a potential cumulative heating capacity of industrial heat pumps in EU28 of 23.0 GW, consisting of 4174 heat pump units which are able to cover 641 PJ/a of process heat demand. The largest number of heat pump units (%) can be found for heating capacities <10 MW, making up about 50% of the total market cumulative heating capacity. Clearly, there is a large market ahead for industrial heat pump manufacturers and suppliers. • Individual process data from food, paper, chemical and refinery sectors collated. • Heat pump integration options in processes in various sectors identified. • Methodology presented to upscale individual applications to European level. • Heat pump market potential characterised by heating capacity and number of units. • Energy and CO 2 emission reduction of the industrial heat pump market are estimated. [ABSTRACT FROM AUTHOR]

Nanoabsorbents manufactured by dispersing nanomaterials in liquid absorbents have attracted considerable attention from researchers and exhibit various promising applications because of their excellent heat- and mass-transfer characteristics. Therefore, many experimental and theoretical studies have been conducted recently to investigate the mass-transfer performance enhancement of nanoabsorbents in different fields. This paper reviews the mass-transfer characteristics and enhancement mechanisms of nanoabsorbents for CO 2 capture. The proposed enhancement mechanisms are discussed in terms of both absorption (bubble breaking, shuttle, and interfacial mixing effects) and regeneration (activation energy, thermal, and surface effects) processes using nanoabsorbents. The results of laboratory-scale experiments and parametrical analysis indicate that the CO 2 absorption performance of nanomaterials is maximized when they exhibit a high surface area, high thermal conductivity, small cluster size, and magnetic properties, which can be explained using the proposed theoretical models. Based on this, the following selection criteria for nanomaterials to maximize the CO 2 absorption/regeneration performance are proposed: thermophysical properties, powder/cluster size, concentration, and addition of nanoabsorbents. In the future, mass-transfer studies need to be conducted for real-life applications and should account for dispersion stability and integrated absorption/regeneration processes. Moreover, optimum geometric conditions and gas–liquid contact modes need to be achieved in the reactor for real-life applications. Finally, this paper suggests future research directions for the absorption and regeneration of CO 2 for industrial applications, including the scale-up method, numerical approach, and life cycle analysis. • Mass-transfer enhancement mechanisms of nanoabsorbents for CO 2 capture are proposed. • Selection criteria for nanomaterials to maximize the CO 2 capture performance are proposed. • Optimum gas–liquid contact modes need to be developed for the reactor design. • Strategy for industrial applications of nanoabsorbents is proposed. [ABSTRACT FROM AUTHOR]

Small hydropower plants, which are one of most important means for producing clean energy, have a high prestige in the carbon trade market. In this paper, a method for accounting the carbon dioxide emission of small hydropower plants is proposed. Twenty-six small hydropower plants (SHPs) in southwest China are chosen as a case study. The following results were found: (1) the carbon dioxide emission during the construction period (COE c ) per installed capacity ranged between 0.01957 t/kW and 0.1926 t/kW, with its average value 0.04592 t/kw; (2) the carbon dioxide emission during the construction period is classified into two groups; for each group, there is a reciprocal relationship between the installed capacity and the annual COE c per installed capacity, and (3) the annual CEO o (carbon dioxide emission during the operation period) declines with increasing installed capacity, the two related by a straight line. Specifically, when the installed capacity increases by 1 kW carbon emissions are reduced by 16.33 t. COE o is directly determined by hydropower. In addition, (4) the trend of carbon dioxide emission during the system lifecycle of SHPs is determined by COE o . The most important factor in determining the carbon dioxide emission of SHPs is to ensure the precise hydropower of SHPs. [ABSTRACT FROM AUTHOR]

Energy is a commodity which impacts heavily upon the competitiveness of a country in the global scale. Thus, nations have begun to understand that utilization of energy affects its economic performance. In recent times, there has been a drive for global awareness on Low Carbon Society (LCS) measures, where carbon mitigation is at the forefront. Thus, this paper analyses the LCS measures for the Thai industrial sector. Thai industrial sector is the second highest CO 2 emitting end-use sector and contributes approximately 30% to the national income of Thailand. The total CO 2 emission from end use sectors in 2010 was 119 Mton-CO 2 and approximately 38% constituted industrial sector emissions. The primary objective of this research study is to quantitatively analyse the carbon mitigation possible in the Thai industrial sector and the co-benefits which accrue along with mitigation in various policy pathway scenarios. Thai industrial sector was modeled using Asia-Pacific Integrated Model (AIM)/Enduse. Three groups of scenarios under LCS, emission tax and reduction target principles were modeled along with the BAU case. Results show that LCS scenarios are capable of cumulative mitigation of approximately 35% by 2050 in comparison to the BAU case and the predominant technologies are the 2nd generation biomass and the CCS technology. The emission tax scenarios, where tax rates of 50, 100, 200 and 500 USD/t-CO 2 were enforced show a maximum of 55% cumulative mitigation by 2050. Even though this reduction is higher than the LCS scenarios, there is no shift to long term renewable or sustainable technologies in the emission tax scenarios. The same applies to reduction target scenarios as well. The co-benefits, which were measured along the themes of energy security and local air pollutant mitigation show maximum benefits accruing to the LCS scenarios, where renewable fuel share increases, whilst primary energy intensity and carbon intensity decreases. The LCS scenarios also show a mitigation of local air pollutants such as SO 2 and Particulate Matter. [ABSTRACT FROM AUTHOR]

Climate change and global warming as the main human societies’ threats are fundamentally associated with energy consumption and GHG emissions. The residential sector, representing 27% and 17% of global energy consumption and CO 2 emissions, respectively, has a considerable role to mitigate global climate change. Ten countries, including China, the US, India, Russia, Japan, Germany, South Korea, Canada, Iran, and the UK, account for two-thirds of global CO 2 emissions. Thus, these countries’ residential energy consumption and GHG emissions have direct, significant effects on the world environment. The aim of this paper is to review the status and current trends of energy consumption, CO 2 emissions and energy policies in the residential sector, both globally and in those ten countries. It was found that global residential energy consumption grew by 14% from 2000 to 2011. Most of this increase has occurred in developing countries, where population, urbanization and economic growth have been the main driving factors. Among the ten studied countries, all of the developed ones have shown a promising trend of reduction in CO 2 emissions, apart from the US and Japan, which showed a 4% rise. Globally, the residential energy market is dominated by traditional biomass (40% of the total) followed by electricity (21%) and natural gas (20%), but the total proportion of fossil fuels has decreased over the past decade. Energy policy plays a significant role in controlling energy consumption. Different energy policies, such as building energy codes, incentives, energy labels have been employed by countries. Those policies can be successful if they are enhanced by making them mandatory, targeting net-zero energy building, and increasing public awareness about new technologies. However, developing countries, such as China, India and Iran, still encounter with considerable growth in GHG emissions and energy consumption, which are mostly related to the absence of strong, efficient policy. [ABSTRACT FROM AUTHOR]