Search Results (4,373)

A very important method of reducing carbon emissions is to make sure industrial plants are operated at optimal energy efficiency. The oil and petrochemical industries spend large amounts of energy in the transportation of petroleum and its various products that have high viscosities. A critical component in these plants is abrupt pipe contraction. Large amounts of energy are lost in pipe contractions. In this paper we investigate the energy losses in pipe contraction using the local entropy generation method after solving the detailed flow field around an abrupt pipe contraction. We have applied the method at various Reynolds numbers covering laminar and turbulent flow regimes. Furthermore, we have used an integral entropy analysis and found excellent agreement between the differential and integral entropy methods when the computational grid is well refined. The differential analysis was able to predict the local entropy generation and find where the large losses are located and therefore be able to minimize these losses effectively. Based on the detailed entropy generation field, it is recommended to use rounded contraction in order to reduce the losses. By introducing rounded contractions in laminar flow, the losses have been reduced by 22%. In the case of the turbulent flow regime, the losses were reduced by 96% by introducing a rounding radius to diameter ratio r/D₂ of 10%. The turbulent flow results for the case of pipe entrance, which is a special case of abrupt contraction (D₂/D₁ goes to zero) agree very well with the present results. This work addresses a large range of D₂/D₁ for laminar and turbulent flows. It is recommended that companies involved in designing petrochemical plants and installations take these findings into consideration to reduce carbon emissions. These recommendations also extend to the design of equipment and piping systems for the food industry and micro-device flows. Full article

Four biomass residues–rosemary pomace, rosemary cake, grape seed and apple pomace–were torrefied at 250, 350 and 450 °C, and the physical, chemical and structural changes were characterized. The mass and energy yield decreased with increasing torrefaction temperature; the lowest mass (~10.4%) and energy yield (~10.6%) were observed for rosemary cake torrefied at 450 °C. The HHV increased the most for all feedstocks at 350 °C, with rosemary cake reaching a peak value of 36.4 MJ/kg at 350 °C. Ash content increased with temperature due to organic mass loss, while volatiles decreased and fixed carbon increased in most samples. The FTIR spectra showed the progressive loss of hydroxyl, carbonyl and C–O functionalities and the appearance of aromatic C=C bonds, indicating the formation of the biochar. TGA and DTG analyses revealed that the torrefied samples exhibited higher initial and maximum temperatures for decomposition, confirming improved thermal stability. The TGA-FTIR analyses of gas emissions during pyrolysis and combustion showed that the emissions of CO₂, CH₄, NO_x and SO₂ decreased with increasing degree of torrefaction. Overall, 350 °C was optimal to maximize energy density. The results show that agro-industrial residues can be effectively converted into sustainable biofuels, which offer the dual benefit of reducing waste disposal problems and providing a renewable alternative. In practice, such residues could be used for decentralized power generation in rural areas, co-combustion in existing power plants, or as feedstock for advanced bioenergy systems. Full article

The strategic goal of the transition to a low-carbon economy in Russia requires the active integration of forest-climatic projects into regional sustainable development strategies, especially for areas with high agricultural pressure such as the central forest-steppe of the European part of the Russian Federation. The region contains over 18 million hectares of forest land, which is approximately 2.1% of the area of Russian forests, and intensive agricultural development increases the need for innovative approaches to restoring forest ecosystems. The work uses indicators of the state forest register, data on 18 reforestation projects and 22 afforestation projects, and the results of forecasting the dynamics of greenhouse gas absorption until 2030. It is estimated that by 2030, the sequestration potential of the forests of the central forest-steppe can be increased by 28–30%, which will neutralize up to 12% of emissions from industrial enterprises in the region. In the paper, to unify the assessment, it is proposed to use the carbon intensity factor of investment costs, which, in a number of implemented projects, ranged from 1.2 to 2.7 RUB/1 kg CO₂ eq., reflecting the cost of achieving one ton of absorbed CO₂ equivalent. At ratios above 1, the economic value of the carbon units created exceeds investment costs by at least 20%. Environmental–economic modeling showed that with an increase in the forest cover of the region by 1% (180 thousand hectares), the annual absorption of CO₂ increases by approximately 0.9–1.1 million tons, and the increase in potential income from the sale of carbon units could amount to 1.6–2.2 billion RUB per year at the current price of 1.8–2 RUB/kg CO₂-eq. The use of an integral criterion of environmental and economic efficiency helps increase the transparency and investment-attractiveness of forest-climatic projects, as well as the effective integration of natural and climatic solutions into long-term strategies for the sustainable development of the Central Forest-Steppe of Russia. Full article

Reaching net-zero greenhouse gas emissions will require broad deployment of carbon capture and storage (CCS), yet significant challenges remain. This paper reviews the main barriers that may hinder or delay widespread CCS adoption, drawing on current projects in various stages of planning, construction, and development. The discussion focuses on technical, economic, social, and regulatory aspects of CCS and identifies several key obstacles. These include the high financial burden on energy production, persistent uncertainties about the long-term behavior of stored CO₂, and the complexity of the regulatory framework governing CCS projects and CO₂ pipelines. Carbon capture, use, and storage (CCUS) remains a major focus of attention in the petroleum industry due to its potential to remove carbon dioxide from the atmosphere or prevent future emissions. Despite this potential, challenges and risks continue to limit progress. Full article

With the world facing the twin pressures of a warming climate and an ever-increasing amount of waste, it is becoming increasingly clear that we need to rethink the way we generate energy and use materials. Despite growing awareness, our energy systems are still largely dependent on fossil fuels and characterized by a linear ‘take-make-dispose’ model. This leaves us vulnerable to supply disruptions, rising greenhouse gas emissions, and the depletion of critical raw materials. Hydrogen is emerging as a potential carbon-free energy vector that can overcome both challenges if it is produced sustainably from renewable sources. This study reviews hydrogen production from a circular economy perspective, considering industrial, agricultural, and municipal solid waste as a resource rather than a burden. The focus is on the reuse of waste as a catalyst or catalyst support for hydrogen production. Firstly, the role of hydrogen as a new energy carrier is explored along with possible routes of waste valorization in the process of hydrogen production. This is followed by an analysis of where and how catalysts from waste can be utilized within various hydrogen production processes, namely those based on using fossil fuels as a source, biomass as a source, and electrocatalytic applications. Full article

The civil construction and infrastructure sectors are known for their high environmental impact. Most of this impact is related to the carbon dioxide (CO₂) emissions from Portland cement. As a sustainable alternative, alkali-activated binders (AABs) are explored for their potential to replace traditional binders. This research focused on AAB formulations using steel industry byproducts, such as Baosteel’s slag short flow (BSSF), coke oven ash (CA), blast furnace sludge (BFS), and centrifuge sludge (CS), as well as fly ash (FA) from a thermoelectric plant. Byproducts were characterized through laser granulometry, Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM), followed by the formulation of AABs with different precursor ratios. After 28 days, the compressive strength was obtained for each formulation. Based on the compressive strength tests, two binary mixtures were selected for microstructural and chemical analyses through XRF, FTIR, and SEM. CA demonstrated the greatest potential for use in binary AABs based on BSSF, as it presented a higher source of aluminosilicates and smaller particle sizes. The formulations containing BSSF and CA achieved compressive strengths of up to 9.8 MPa, while the formulations with BSSF and FA reached 23.5 MPa. SEM images revealed a denser, more cohesive matrix in the FA-based AAB, whereas CA-based AABs showed incomplete precursor dissolution and higher porosity, which contributed to the lower mechanical strength of CA-based AABs. These findings highlight the critical role of precursor selection in developing sustainable AABs from industrial byproducts and demonstrate how different formulations can be tailored for specific applications. Full article

Electrochemical glycerol oxidation presents a sustainable and environmentally friendly pathway for formic acid production, addressing the significant carbon emissions and resource dependency associated with conventional industrial processes. However, the development of advanced electrocatalysts with high formic acid selectivity and durability remains challenging due to the polyhydroxy structure and carbon chain complexity of glycerol, which lead to intricate oxidation pathways and a wide variety of products. To tackle this issue, we report a AuCu-Ag/AgBr catalyst with a multiphase interface, referring to the integrated boundaries among AuCu, Ag, and AgBr phases that interact with the liquid electrolyte, for high-rate and high-efficiency glycerol oxidation. Comprehensive characterizations reveal that the multiphase interface may effectively modulate the adsorption configurations of glycerol molecules and enhance charge transfer efficiency. Under ambient conditions, glycerol electro-oxidation at 1.43 V for 8 h yielded a conversion of 38% and a formic acid selectivity of 81%, and recycling tests confirmed its high stability under prolonged electrolysis. This synergistic catalytic effect provides a kinetically favorable pathway for formic acid production, demonstrating the potential of AuCu-Ag/AgBr catalysts in advancing sustainable glycerol valorization. Full article

This study employs a systems theory approach to investigate the coupling coordination and driving mechanisms within the economic–social–environmental (ESE) system in China’s ethnic regions. It analyzes 67 ethnic counties in Sichuan Province, using an integrated framework that combines dynamic Shannon entropy, coupling coordination modeling, and GeoDetector. Based on data from 2005 to 2024, the study reveals the spatiotemporal patterns of ESE coupling coordination. The key findings are as follows: (1) The coupling coordination degree has gone through four stages: moderate imbalance → mild imbalance → primary coordination → moderate coordination. By 2024, 81.8% of counties had achieved coordinated development, and “highly coordinated” counties emerged for the first time. (2) The Western Sichuan Plateau has formed a high–high agglomeration zone by monetizing ecological assets and utilizing ethnic cultural resources. In contrast, the hilly and parallel ridge–valley regions in central and eastern Sichuan remain in low–low agglomerations due to their dependency on traditional industrialization paths. The decrease in high–low and low–high outliers indicates the recent policy polarization effects. (3) The interaction between habitat quality and per capita GDP has the strongest explanatory power. The rising marginal contributions of energy and carbon emission intensity suggest that green industrialization is crucial to breaking the “poverty–pollution” trap. Full article

Environmental emissions from the maritime sector, including CO₂, NO_x, and SO_x, contribute significantly to global air pollution and climate change. The International Maritime Organization (IMO) has set a target to reduce greenhouse gas emissions from international shipping to reach zero GHG by 2050 compared to 2008 levels. To meet these goals, the IMO strongly encourages the transition to alternative fuels, such as hydrogen, ammonia, and biofuels, as part of a broader decarbonization strategy. This study presents a comparative analysis of converting conventional diesel engines to dual-fuel systems utilizing alternative fuels such as methanol or natural gas. The methodology of this research is based on theoretical calculations to estimate various types of emissions produced by conventional marine fuels. These results are then compared with the emissions generated when using methanol and natural gas in dual-fuel engines. The analysis is conducted using the EVER ALOT container ship as a case study. The evaluation focuses on both environmental and economic aspects of engines operating in natural gas–diesel and methanol–diesel dual-fuel modes. The results show that using 89% natural gas in a dual fuel engine reduces nitrogen oxides (NO_x), sulfur oxides (SO_x), carbon dioxide (CO₂), particulate matter (PM), and carbon monoxide (CO) pollutions by 77.69%, 89.00%, 18.17%, 89.00%, and 30.51%, respectively, while the emissions percentage will be 77.78%, 91.00%, 54.67%, 91.00%, and 55.90%, in order, when using methanol as a dual fuel with percentage 91.00% Methanol. This study is significant as it highlights the potential of natural gas and methanol as viable alternative fuels for reducing harmful emissions in the maritime sector. The shift toward these cleaner fuels could play a crucial role in supporting the maritime industry’s transition to low-emission operations, aligning with global environmental regulations and sustainability goals. Full article

Porous media gas bearings utilize gas as a lubricating medium to achieve non-contact support technology. Compared with traditional liquid-lubricated bearings or rolling bearings, they are more efficient and environmentally friendly. With the uniform gas film pressure of gas bearings, the rotating shaft can achieve mechanical motion with low friction, high rotational speed, and long service life. They have significant potential in improving energy efficiency and reducing carbon emissions, enabling oil-free lubrication. By eliminating the friction losses of traditional oil-lubricated bearings, porous media gas bearings can reduce the energy consumption of industrial rotating machinery by 15–25%, directly reducing fossil energy consumption, which is of great significance for promoting carbon neutrality goals. They have excellent prospects for future applications in the civil and military aviation fields. Based on the three-dimensional flow characteristics of the bearing’s fluid domain, this paper considers the influences of the transient flow field in the variable fluid domain of the gas film and the radial pressure gradient of the gas film, establishes a theoretical model and a three-dimensional simulation model for porous media gas bearings, and studies the static–dynamic pressure coupling mechanism of porous media gas bearings. Furthermore, through the trial production of bearings and performance tests, the static characteristics are verified, and the steady-state characteristics are studied through simulation, providing a basis for the application of gas bearings made from porous media materials in the civil and military aviation fields. Full article

The C₄F₇N eco-friendly switchgear shows significant application potential, and quantifying its carbon footprint can accelerate the low-carbon transition in the power industry. A life cycle assessment (LCA) model for a 12 kV C₄F₇N eco-friendly switchgear is established in this study, and the carbon footprint across four stages—raw material acquisition, transportation, operation, and recycling—is accurately quantified. Sensitivity analysis of key raw material parameters and Monte Carlo simulation are used to further quantify the impact of uncertainty in these key sensitive parameters. Results indicate that the operational stage contributes the most to the switchgear’s carbon footprint, amounting to 24,794.77 kgCO₂e, mainly due to electricity consumption. Within this stage, C₄F₇N gas leakage contributes minimally at 2.21 kgCO₂e. The raw material acquisition stage follows with 3005.57 kgCO₂e, where C₄F₇N gas, aluminum, and stainless steel are identified as the primary contributing materials. Sensitivity analysis shows that electricity, C₄F₇N, aluminum, and stainless steel are the resources that have the greatest impact on the switchgear’s carbon footprint. Compared with traditional SF₆ switchgear, the C₄F₇N switchgear has a 23.8% lower total carbon footprint, with its total carbon footprint reaching 26,771.58 kgCO₂e compared to 35,136.48 kgCO₂e for SF₆ switchgear. This advantage stems largely from C₄F₇N’s much lower global warming potential—2090 versus 25,200 for SF₆—which reduces gas-related emissions by 96.6%. These findings substantiate the practical viability of C₄F₇N-based eco-friendly switchgear and provide strategies for the power sector to achieve a low-carbon transition. Full article

Ecosystem services play a vital role in human well-being, with land-use changes exerting substantial influence on ecosystem service value (ESV) and land-use carbon emissions (LUCEs). Understanding the spatio-temporal relationship and transition dynamics between ESV and LUCEs is essential for promoting high-quality ecological development aligned with the “dual carbon” objective. This study takes the Loess Plateau as the research object. Based on five-phase land-use data from 2000 to 2020, the ESV and LUCEs are calculated. Exploratory spatio-temporal data analysis is used to explore their spatio-temporal relationship and transition paths, and the quadrant model is introduced to analyze the transition patterns from the perspective of ecological quality. The results indicate the following: (1) From 2000 to 2020, the ESV of the Loess Plateau increased from CNY 579.032 billion to CNY 582.470 billion, with an overall increase of only 0.15%. Among the changes in land use, changes in forest and grassland significantly affected the ESV. (2) The LUCEs from land use on the Loess Plateau increased from 137.15 Mt to 458.43 Mt, with an average annual growth rate of 6.22%. Affected by industrialization and urbanization, the LUCEs showed significant spatial differences at the provincial and county scales. (3) There was a certain positive spatial correlation between ESV and LUCEs. The distribution of significantly correlated areas did not change significantly from 2000 to 2020, and the relationship characteristics were mainly characterized by Type IV transitions. (4) At the county scale, ESV and LUCEs exhibited temporal stability, with most counties situated in the general ecological category, indicating substantial potential for enhancing regional ecological quality. These research outcomes offer a foundational framework for devising tailored regional carbon emission reduction strategies. Full article

Aiming at the demands for low-carbon transformation in multi-energy-coupled industrial parks, a model is proposed that incorporates a carbon trading system incorporating incentives and penalties. This model includes joint combined heat and power (CHP) units, carbon capture technologies, and power-to-gas (P2G) conversion equipment. Firstly, we develop a modeling framework for the joint operation of cogeneration units to establish a comprehensive energy system within the industrial park that integrates electricity, heat, gas, and cold energy sources. Subsequently, we introduce a reward and punishment carbon trading mechanism into an industrial park to regulate carbon emissions effectively. With an optimization objective focused on minimizing the overall operating costs of the system while considering relevant constraints, we formulate an optimization model. The Gurobi solver is employed through the Yalmip toolkit to address this optimization problem. Finally, four operational scenarios are established to compare and validate the feasibility of our proposed optimization strategy. The results from our computational example demonstrate that integrating combined heat and power along with carbon capture and P2G technologies—coupled with a tiered reward and punishment carbon trading mechanism—can significantly enhance the energy consumption structure of the system. Under this model, the overall expenses are decreased by 12.36%, CO₂ emissions decrease by 33.37%, and renewable energy utilization increases by 36.7%. This approach has effectively improved both wind power consumption capacity and low-carbon economic benefits within the system while ensuring sustainable economic development in alignment with “dual carbon” goals. Full article

This study investigates the impact of key economic variables on carbon dioxide (CO₂) emissions in Ecuador within the broader context of sustainable development. Annual data from 1990 to 2022 are analyzed using an Autoregressive Distributed Lag (ARDL) model in first logarithmic differences, estimated via Ordinary Least Squares (OLS). The model examines both short- and long-term relationships between CO₂ emissions and three core macroeconomic indicators: gross fixed capital formation (GFCF), GDP per capita, and oil consumption. Descriptive analysis reveals substantial variation in investment and fossil fuel use across the study period. Empirical findings indicate that oil consumption has a positive and statistically significant effect on emissions, while GFCF exhibits a significant negative association in the current period, suggesting the role of cleaner or more efficient investment. Lagged GDP per capita shows a negative effect on emissions, partially supporting the Environmental Kuznets Curve hypothesis. Although renewable energy is discussed in the conceptual framework, it is not included in the current empirical specification—a limitation that will be addressed in future model extensions. The results provide empirical support for directing investments toward low-carbon sectors and accelerating the energy transition, particularly in transport and industry. Full article

With CO₂ generation and emissions requirements, the cement industry faces huge pressure for reducing carbon emissions. Choosing alternative fuels instead of coal is a promising approach. However, the fuel properties of the alternative fuels have not been comprehensively studied. In this work, the fifty typical alternative fuels were selected based on the compositions for different classifications, and the basic fuel properties including proximate analysis, ultimate analysis, and low calorific values were analyzed. Most fuels from plastics and clothes have relatively low moisture; the values of as-received basis moisture (M_ar) and air-dry basis moisture (M_ad) of the others are all lower than 30 wt%. However, the alternative fuels of plastic and cloth all have relatively high contents of air-dry basis volatile compounds (V_ad) (>60 wt%), and they all have low contents of air-dry basis fixed carbon (FC_ad) (commonly <20 wt%) and air-dry basis ash (A_ad) (<30 wt%). The air-dry basis carbon contents (C_ad) of plastics are higher than 40 wt%, while the C_ad values of biomass are lower than 50 wt%. As for air-dry basis hydrogen (H_ad), the contents are all lower than 14 wt% and relatively stable for different kinds of alternative fuels. As for air-dry basis nitrogen (N_ad), the contents are all lower than 9 wt%, and most of them are lower than 3 wt%. In addition, the contents of air-dry basis sulfur (S_ad) of different alternative fuels are also lower than 3 wt%, while plastics, biomass, and clothes are all lower than 1 wt%. Also, the low calorific values (Q_net,ar) for the alternative fuels of plastic are commonly high, and the values for biomass are commonly between 500 and 1500 kJ/kg, while Q_net,ar values for the alternative fuels of cloth and others vary. The fuel properties of the fifty typical alternative fuels can guide fuel selection and optimization when they are mixed for combustion with coals in cement decomposition furnaces. Full article