Total Emissions Research Articles

Assessing uncertainty in building material emissions using scenario-aware Monte Carlo simulation

Global greenhouse gas emissions from the built environment remain high, driving innovative approaches to develop and adopt building materials that can mitigate some of those emissions. However, life-cycle assessment (LCA) practices still lack standardized quantitative uncertainty assessment frameworks, which are urgently needed to robustly assess mitigation efforts. Previous works emphasize the importance of accounting for the three types of uncertainties that may exist within any quantitative assessment: parameter, scenario, and model uncertainty. Herein, we develop a quantitative uncertainty assessment framework that distinguishes between different types of uncertainties and suggest how these uncertainties could be handled systematically through a scenario-aware Monte Carlo simulation (MCS). We demonstrate the framework’s decision-informing power through a case study of two multilevel ordinary Portland cement (OPC) manufacturing scenarios. The MCS utilizes a first-principles-based OPC life-cycle inventory, which mitigates some of the model uncertainty that may exist in other empirical-based cement models. Remaining uncertainties are handled by scenario specification or sampling from developed probability distribution functions. We also suggest a standardized method for fitting distributions to parameter data by enumerating through and implementing distributions based on the Kolmogorov–Smirnov test. The level of detail brought by the high-resolution parameter breakdown of the model allows for developing emission distributions for each process of OPC manufacturing. This approach highlights how specific parameters, along with scenario framing, can impact overall OPC emissions. Another key takeaway includes relating the uncertainty of each process to its contributions to total OPC emissions, which can guide LCA modelers in allocating data collection and refinement efforts to processes with the highest contribution to cumulative uncertainty. Ultimately, the aim of this work is to provide a standardized framework that can provide robust estimates of building material emissions and be readily integrated within any uncertainty assessment.

Climate change, public health, and animal welfare: towards a One Health approach to reducing animal agriculture’s climate footprint

Animal agriculture contributes significantly to global greenhouse gas (GHG) emissions—an estimated 12%-20% of total anthropogenic emissions. This has led both governmental and private actors to propose various ways to mitigate those climate impacts. This paper applies a One Health lens to the issue, arguing that the choice of solutions should not only consider the potential to reduce GHG emissions—which is not always a given—but also the implications for public health and animal welfare. With this perspective, we examine the potential public health and animal welfare impacts of three types of strategies that are often proposed: (1) “sustainable intensification” methods, aimed at maintaining or increasing production while limiting emissions and avoiding further land conversion; (2) “species shift” approaches, which focus on changing diets to consume meat from animals produced with lower GHG emissions instead of that of animals associated with higher emissions; and (3) “systemic dietary change” approaches that promote shifts towards whole plant-based foods or novel alternatives to conventional animal products. We discuss how some approaches—particularly those associated with sustainable intensification and species shift—could introduce new and significant risks to public health and animal welfare. Promoting systemic dietary change helps to overcome some of these challenges, but requires careful attention to equity to ensure that vulnerable populations still have access to the nutrients they need. We end with recommendations for a more holistic approach to reducing emissions from farmed animals that can help avoid trade-offs and increase synergies with other societal goals.

Spatiotemporal Effects and Optimization Strategies of Land-Use Carbon Emissions at the County Scale: A Case Study of Shaanxi Province, China

Land use, as one of the major sources of carbon emissions, has profound implications for global climate change. County-level land-use systems play a critical role in national carbon emission management and control. Consequently, it is essential to explore the spatiotemporal effects and optimization strategies of land-use carbon emissions at the county scale to promote the achievement of regional dual carbon targets. This study, focusing on Shaanxi Province, analyzed the spatiotemporal characteristics of land use from 2000 to 2020. By establishing a carbon emission evaluation model, the spatiotemporal effects of county-level carbon emissions were clarified. Utilizing Geodetector and K-means clustering methods, the driving mechanisms and clustering characteristics of county-level carbon emissions were elucidated, and optimization strategies for land use carbon emission were explored. The results showed that during 2000–2020, land use in Shaanxi Province underwent significant spatiotemporal changes, with constructed land increasing by 97.62%, while cultivated land and grassland were substantially reduced. The overall county-level carbon emissions exhibited a pattern of North > Central > South. The total carbon emissions within the province increased nearly fourfold over 20 years, reaching 1.00 × 108 tons. Constructed land was the primary source of emissions, while forest land contributed significantly to the carbon sink of the study area. Interactions among factors had significant impacts on the spatial differentiation of total county-level carbon emissions. For counties with different types of carbon emissions, differentiated optimization strategies were recommended. Low-carbon emission counties should intensify ecological protection and rational utilization, medium-carbon emission counties need to strike a balance between economic development and environmental protection, while high-carbon emission counties should prioritize profound emission reduction and structural transformation.

Environmental impacts of Australian pork in 2020 and 2022 determined using lifecycle assessments

Context The Australian pork industry is highly efficient, with a history of ongoing productivity and environmental improvement. The introduction of economy-wide environmental targets require delivering and tracking performance improvement. Aims This study determined carbon footprint (greenhouse gas [GHG] and land use [LU] and direct land use change [dLUC] emissions, reported as kg CO2-e), fossil energy (MJ), freshwater consumption (L), water stress (L H2O-e), land occupation (m2) and eutrophication potential (nitrogen and phosphorus) for Australian pork for 2020 and 2022. Variability between housing, manure management systems, and regions were identified, and systems analysed to determine new options for low-impact pork. Methods In the largest Australian study of its kind, data for ~70% of pigs produced were collected using a stratified design. Using attributional life cycle assessment, impacts were reported per kilogram of liveweight (LW), post-processed, retail, and boneless, fat-corrected pork. Results are presented as industry averages ± 2 × s.d. Key results Key results were 3.0 ± 0.1 and 3.0 ± 0.1 kg CO2-e GHG, 0.4 ± 0.07 and 0.3 ± 0.03 kg CO2-e LU and dLUC, 12.9 ± 0.5 and 13.4 ± 0.5 MJ, 93.8 ± 9.6 and 52.5 ± 3.6 L, 68.4 ± 6.7 and 43.2 ± 3.3 L H2O-e, and 12.0 ± 0.9 and 12.7 ± 0.9 m2/kg LW in 2020 and 2022, respectively. Due to industry growth, total emissions were higher in 2022. Eutrophication potential for Australian pork (2.2 × 10−4 ± 3.0 × 10−5 kg phosphorus and 8.7 × 10−3 ± 3.5 × 10−4 kg nitrogen/kg LW), reported for the first time, was low compared with grazing systems and European piggeries. Conclusions Industry has demonstrated long-term performance improvement, though the rate slowed between 2020 and 2022. Ongoing interventions are required to return to trend. Covered pond, deep litter, and outdoor systems produce lower carbon footprint pork and can provide other environmental benefits from renewable energy, and reduced fossil energy demand. Implications There is potential to further reduce environmental impacts through practice change. If industry is to meet formal targets, investment and proactive policy settings are required to overcome barriers to adoption of existing technology and support the techno-economic case for novel strategies.

Spatial distribution of CH4 emissions from livestock farming in Poland: a comparison of 2010 and 2020

ABSTRACT Among greenhouse gases (GHGs), methane (CH4) is a major contributor to global warming. Agriculture accounts for about 40% of CH4 emissions, with livestock being a crucial source. CH4 emissions from livestock primarily arise during enteric fermentation and manure management in livestock. This study aims to estimate Poland’s CH4 emissions from enteric fermentation and manure management in 2010 and 2020 at the municipal level (LAU-2). Data from the National Agricultural Census (NAC) and the UNFCCC National Inventory Report (NIR) for 2010 and 2020 were used for the analysis. The results reveal a slight overall increase in total CH4 emissions from livestock farming in Poland over the decade. The highest emissions were observed in regions where livestock farming was predominant, while significant changes in emissions occurred in regions experiencing considerable livestock production growth. Conversely, the lowest emissions were found in areas where the decrease in livestock population was most prominent. Understanding the spatial distribution of CH4 emissions from livestock farming at the municipal level is essential for effective climate change mitigation efforts. This study highlights the importance of continuous monitoring and analysis of livestock farming in Poland to assess its impact on GHG emissions and facilitate informed policy-making for sustainable agricultural practices.

Characterizing Spatial and Temporal Variations in N2O Emissions from Dairy Manure Management in China Based on IPCC Methodology

The emission factor method (Tier 1) recommended by the Intergovernmental Panel on Climate Change (IPCC) is commonly used to estimate greenhouse gas (GHG) emissions from livestock and poultry farms. However, the estimation accuracy may vary due to practical differences in manure management across China. The objectives of this study were to estimate the direct and indirect nitrous oxide (N2O) emissions from dairy manure management between 1990 and 2021 in China and characterize its spatial and temporal variations following IPCC guideline Tier 2. The N2O emission factor (EF) of dairy cow manure management systems was determined at the national level and regional level as well. The results showed that the national cumulative N2O emission of manure management from 1990 to 2021 was 113.1million tons of CO2 equivalent, ranging from 90.3 to 135.9 million tons with an uncertainty of ±20.2%. The annual EF was 0.021 kg N2O-N (kg N)−1 for total emissions, while it was 0.014 kg N2O-N (kg N)−1 for direct emissions. The proportions of N2O emissions in North China, Northeast China, East China, Central and Southern China, Southwest China and Northwest China were 32.3%, 18.6%, 11.4%, 5.8%, 6.1% and 25.8%, respectively. In addition, N2O emissions varied among farms in different scales. The respective proportions of total N2O emissions from small-scale and large-scale farms were 64.8% and 35.2% in the past three decades. With the improvement in farm management and milk production efficiency, the N2O emissions per unit mass of milk decreased from 0.77 × 10−3 kg to 0.48 × 10−3 kg in 1990–2021. This study may provide important insights into compiling a GHG emission inventory and developing GHG emission reduction strategies for the dairy farming system in China.

Differential Analysis of Carbon Emissions between Growing and Shrinking Cities: A Case of Three Northeastern Provinces in China

Carbon emission issues are becoming increasingly severe, and the carbon emissions in shrinking cities, primarily characterized by population loss, are often overlooked and insufficiently studied. This paper focuses on the carbon emissions from county-level administrative units in China’s three northeastern provinces from 2001 to 2017. The study scientifically identified shrinking cities and measured the differences in carbon emission characteristics between growing and shrinking cities using the Theil index. Ultimately, the paper constructs a panel spatial econometric model to analyze the factors influencing them and explore their spatial effects. (1) The total carbon emissions in the Three Northeastern Provinces exhibited an inverted U-shaped trend, increasing from 734.21 million tons in 2001 to 1731.73 million tons in 2017, with the Mann–Kendall trend test showing a significant increase; spatially, this manifests as a significant positive spatial autocorrelation. (2) The region has 138 shrinking cities, accounting for over 50%; regarding carbon emission characteristics, the Theil index has consistently remained above 0.18, indicating significant differences between the carbon emissions of growing and shrinking cities. (3) The panel spatial econometric model results show that the influencing factors of carbon emissions in shrinking cities have unique directions, intensities, and spatial effects. In shrinking cities, aside from localized GDP effects and per-capita GDP acting as a suppressant, the population size has a pronounced inhibitory effect on local and surrounding carbon emissions. The analysis reveals significant differences in the carbon emission patterns and mechanisms between growing and shrinking cities; based on these results, the paper proposes differentiated carbon control strategies.

High carbon dioxide emissions from Australian estuaries driven by geomorphology and climate

Estuaries play an important role in connecting the global carbon cycle across the land-to-ocean continuum, but little is known about Australia’s contribution to global CO2 emissions. Here we present an Australia-wide assessment, based on CO2 concentrations for 47 estuaries upscaled to 971 assessed Australian estuaries. We estimate total mean (±SE) estuary CO2 emissions of 8.67 ± 0.54 Tg CO2-C yr−1, with tidal systems, lagoons, and small deltas contributing 94.4%, 3.1%, and 2.5%, respectively. Although higher disturbance increased water-air CO2 fluxes, its effect on total Australian estuarine CO2 emissions was small due to the large surface areas of low and moderately disturbed tidal systems. Mean water-air CO2 fluxes from Australian small deltas and tidal systems were higher than from global estuaries because of the dominance of macrotidal subtropical and tropical systems in Australia, which have higher emissions due to lateral inputs. We suggest that global estuarine CO2 emissions should be upscaled based on geomorphology, but should also consider land-use disturbance, and climate.

High-Resolution Estimates of N2O Emissions from Inland Waters and Wetlands in China.

Inland waters (rivers, lakes, and reservoirs) and wetlands (marshes and coastal wetlands) represent large and continuous sources of nitrous oxide (N2O) emissions, in view of adequate biomass and anaerobic conditions. Considerable uncertainties remain in quantifying spatially explicit N2O emissions from aquatic systems, attributable to the limitations of models and a lack of comprehensive data sets. Herein, we conducted a synthesis of 1659 observations of N2O emission rates to determine the major environmental drivers across five aquatic systems. A framework for spatially explicit estimates of N2O emissions in China was established, employing a data-driven approach that upscaled from site-specific N2O fluxes to robust multiple-regression models. Results revealed the effectiveness of models incorporating soil organic carbon and water content for marshes and coastal wetlands, as well as water nitrate concentration and dissolved organic carbon for lakes, rivers, and reservoirs for predicting emissions. Total national N2O emissions from inland waters and wetlands were 1.02 × 105 t N2O yr-1, with contributions from marshes (36.33%), rivers (27.77%), lakes (25.27%), reservoirs (6.47%), and coastal wetlands (4.16%). Spatially, larger emissions occurred in the Songliao River Basin and Continental River Basin, primarily due to their substantial terrestrial biomass. This study offers a vital national inventory of N2O emissions from inland waters and wetlands in China, providing paradigms for the inventorying work in other countries and insights to formulate effective mitigation strategies for climate change.

Decomposition of China’s Carbon Emissions Responsibility from the Perspective of Technological Heterogeneity

A global agreement has been reached on the reduction in greenhouse gas emissions. Worldwide, countries have implemented measures to tackle carbon emission issues by establishing aggregate targets and decomposing responsibilities. This study aims to decompose carbon emissions by creating an input–output model that incorporates multivariate factors like energy consumption and water consumption, together with a ZSG-DEA (zero-sum data envelopment analysis) model considering technological heterogeneity (Tech-ZSG-DEA). Based on the total carbon emission data predicted using the STIRPAT (Stochastic Impacts by Regression on Population, Affluence, and Technology) model, the carbon emission efficiency of 30 provinces in China is evaluated according to multiple principles. This is achieved by considering variations in population, economy, energy consumption, and water consumption across different locations. The efficiency findings indicate a discrepancy between the initial allocation and the highest efficiency value of 1. The traditional ZSG-DEA model overlooks regional disparities and may worsen carbon emission pressures in less developed areas. In contrast, the Tech-ZSG-DEA model, which considers regional technological diversity, allows more efficient regions to help alleviate some of the carbon emission burden and considers economic and social benefits. There is a large difference in the emission responsibility of the provinces based on the different decomposition principles. Finally, relevant policy recommendations are provided, such as the formulation of differentiated and inclusively coordinated emission plans. In addition, there are also mechanisms for coordinating interests and joint prevention among different regions.

Effects of Controlled-release Blended Fertilizer on Crop Yield and Greenhouse Gas Emissions in Wheat-maize Rotation System

The increasing use of nitrogen fertilizers exerts extreme pressure on the environment (e.g., greenhouse gas emissions, GHGs) for winter wheat-summer maize rotation systems in the North China Plain. The application of controlled-release fertilizers is considered as an effective measure to improve crop yield and nitrogen fertilizer utilization efficiency. To explore the impact of one-time fertilization of controlled-release blended fertilizer on crop yield and GHGs of a wheat-maize rotation system, field experiments were carried out in Dezhou Modern Agricultural Science and Technology Park from 2020 to 2022. Five treatments were established for both winter wheat and summer maize, including no nitrogen control (CK), farmers' conventional nitrogen application (FFP), optimized nitrogen application (OPT), CRU1 (the blending ratio of coated urea and traditional urea on winter wheat and summer maize was 5:5 and 3:7, respectively), and CRU2 (the blending ratio of coated urea and traditional urea on winter wheat and summer maize was 7:3 and 5:5, respectively). The differences in yield, nitrogen fertilizer utilization efficiency, fertilization economic benefits, and GHGs among different treatments were compared and analyzed. The results showed that nitrogen application significantly increased the single season and annual crop yields of the wheat-maize rotation system (P < 0.05). Compared with those of FFP, the CRU1 and CRU2 treatments increased the yields of summer maize by 0.4% to 5.6%, winter wheat by -5.4% to 4.1%, and annual yields by -1.1% to 3.9% (P > 0.05). N recovery efficiency (NRE), N agronomic efficiency (NAE), and N partial factor productivity (NPFP) were increased by -8.6%-43.4%, 2.05-6.24 kg·kg-1, and 4.24-10.13 kg·kg-1, respectively. Annual net income increased by 0.2% to 6.3%. Nitrogen application significantly increased the annual emissions of soil N2O and CO2 in the rotation system (P < 0.05) but had no effect on the annual emissions of CH4 (except for in the FFP treatment in the first year). The annual total N2O emissions under the CRU1 and CRU2 treatments were significantly reduced by 23.4% to 30.2% compared to those under the FFP treatment (P < 0.05). Additionally, nitrogen application significantly increased the annual global warming potential (GWP) of the rotation system (P < 0.05), but the intensity of greenhouse gas emissions was reduced due to the increase in crop yields. Compared with that under FFP, the annual GWP under the CRU1 and CRU2 treatments decreased by 9.6% to 11.5% (P < 0.05), and the annual GHGs decreased by 11.2% to 13.8% (P > 0.05). In summary, the one-time application of controlled-release blended fertilizer had a positive role in improving crop yield and economic benefits, reducing nitrogen fertilizer input and labor costs, and GHGs, which is an effective nitrogen fertilizer management measure to promote cleaner production of food crops in the North China Plain.

Exploring Corn Cob Gasification as a Low-Carbon Technology in the Corn Flour Industry in Mexico

In 2021, Mexico produced approximately 24.2 million tons of white corn, generating 3.6 million tons of corn cob residue. The final disposal of corn cob poses an environmental challenge in certain regions. This study examines the technical–economic feasibility and the greenhouse gas (GHG) mitigation potential of integrating a small-scale cogenerating gasifier fueled by corn cob into a nixtamalized corn flour manufacturing small and medium-sized enterprise (SME). This integration enables the generation of heat and electricity from the produced synthesis gas. Moreover, the process yields residual carbon, which can be used as biochar for soil restoration and removing atmospheric CO2. This option holds significance for the corn flour agroindustry in Mexico, as, in 2021, it consumed approximately 601.9 GWh of electrical energy and 938,279 GJ of thermal energy from LP Gas in its manufacturing processes to produce 2.6 million tons of nixtamalized white corn flour. These processes contributed to a total emission of 410,232 tons of CO2 into the atmosphere. The findings of this study demonstrate a cumulative reduction of 51.7% in CO2 emissions, resulting in economic benefits of USD 85,401 in 2017 for a case study SME that annually produces 1039 tons of corn flour. This study reveals the integration of a gasifier–cogenerator system fueled by corn cob as an economically viable low-carbon technology in the corn flour manufacturing industry.

Towards carbon neutrality: Transition pathways for the Chinese ethylene industry

Ethylene is one of the most important products in the emissions-intensive petrochemical industry. Decarbonizing the ethylene industry is thus important for achieving global carbon neutrality. This study is the first to explore future long-term zero-emissions production pathways for the ethylene industry in China, the world's biggest ethylene producer. An optimization model was built in the context of China's carbon neutrality target of 2060. Four scenarios were developed where the policy ambitions for climate mitigation and for plastic management including waste were varied. Based on this, authors assessed the cumulative total emissions, technology options, future geographical location of ethylene production, and policy challenges associated with each scenario. This is also the first time that scope 3 emissions from waste incineration are included, motivated by the short lifetime of most ethylene products. Results show the cumulative CO2 emissions for the scenarios differ considerably, ranging from 4.3 to 7.8 Gt, even if carbon neutrality by 2060 is achieved in all scenarios. The results suggest that ambitious plastic focused policies can result in lower costs and less cumulative emissions compared to ambitious climate focused policies. The results demonstrate the importance of adopting CCS for waste incineration. This reduces cumulative CO2 emissions by up to 2 Gt. However, reduced overall demand and increased recycling rates should be priority options due to CCS challenges. Results suggest Chinese ethylene industry should adopt a mixed portfolio of production technologies, where the share of emission-intensive coal-based methanol-to-olefins is limited. These findings on decarbonization pathways can contribute to achieving the Paris agreement.

Impact of business strategy on carbon emissions: Empirical evidence from U.S. firms

AbstractThis study examines the nexus between business strategy and carbon emissions by utilising a dataset of U.S. firms from 2007 to 2020. It focuses on two broad types of firms, that is, prospectors and defenders. Regarding carbon emissions, we consider total emissions (Scope 1 & 2), direct emissions (Scope 1) and indirect emissions (Scope 2). The results reveal a significant association between business strategy and total carbon emissions as well as direct carbon emissions. Notably, the results suggest that prospectors, compared to defenders, display higher levels of total and direct carbon emissions. Our findings contribute to the debate on whether prospectors in developed countries mismanage sustainability issues. The study offers valuable insights into the interplay between business strategy and carbon emissions and provides empirical evidence that business strategy is an important determinant of total and direct carbon emissions.

Embodied carbon optimisation of concrete pile foundations and comparison of the performance of different pile geometries

Concrete production and construction are responsible for a considerable share of the total carbon emissions annually. With the emerging need to cut carbon emissions from the construction sector, there has been a big interest in optimising the embodied carbon of superstructures. However, limited attention is given to optimising the embodied carbon of foundations as most designers are more interested in addressing the optimal foundations cost instead. For the first time in the open literature, this paper presents a generic genetic-algorithm-based tool to optimise the design of reinforced concrete piles. The algorithm is capable of allocating the optimal design parameters and geometry for reinforced concrete piles at any given soil conditions and required pile capacities. The algorithm is used to compare the environmental impact of different concrete pile types; solid cylindrical piles, hollow cylindrical piles, solid tapered piles and hollow tapered piles at different load capacities, the optimisation results are then compared to common industrial pile designs to quantify the possible carbon and material savings. Results show that a significant cut of more than 70% of the embodied carbon values can be achieved if the optimal pile type is used compared to common industrial design. Moreover, a finite element model built and validated over ABAQUS is used to compare the geotechnical performance of the different pile geometries. Finite element analysis results show a negligible difference between the stiffness of the different pile types when tested in the same soil conditions highlighting an outstanding optimisation efficiency of the proposed optimisation tool.

Spatiotemporal variations and influencing factors of methane emissions from livestock in China: A spatial econometric analysis

In recent years, China has been implementing policies to improve the livestock industry in response to the global trend toward green and low-carbon development. These policies include the establishment of demonstration zones for high-standard agriculture, the relocation of farms to the north, etc. This study aims to investigate the impact of changes in the spatial structure of the livestock industry on methane emissions. It used panel data from 31 provinces in China from 2001 to 2021 and applied the IPCC methodology to quantify methane emissions at both the national and provincial levels. In addition, a spatial econometric model was used to analyze the impact of changes in the spatial structure of the livestock industry on methane emissions. The results show that methane from livestock in China decreased from 13.85 million tons in 2001 to 11.82 million tons in 2021. In addition, methane emissions from livestock in China show a significant spatial gradient and correlation. The Southwest has the highest methane emissions, accounting for 24 % of the total emissions. After controlling for spatial correlation and other factors in the model, it was found that the spatial structure of the livestock industry has a different influence on methane emissions both in the province and in neighboring provinces. To improve methane emission efficiency in the future, policies such as establishing functional zones for livestock farming, strengthening technological innovation and sharing for green development in agriculture, and promoting the optimization of agricultural and rural management structures should be implemented.

Sustainable steel production: Evaluating the reduction kinetics of iron ore self-reducing briquettes with eucalyptus charcoal

The steel industry in Brazil is responsible for around 5% of total carbon dioxide emissions, releasing around 1.85 tons of CO2 for every ton of steel produced. The use of charcoal in self-reducing iron ore briquettes can be an alternative to reduce fossil fuel consumption and reduce carbon emissions in the primary steelmaking industry, however, the particle size can affect the reduction process. This study aims to analyze the reduction kinetics of charcoal briquettes in three particle size ranges. To this end, the charcoal was characterized using thermogravimetric analysis to determine the contents of fixed carbon, ash and volatiles, analysis of sulphur in the charcoal by combustion in a tube furnace, determination of particle size by laser granulometer, elemental chemical analysis of the charcoal ash by X-ray fluorescence spectrometry. The briquettes were reduced in a thermogravimetric balance to 1100 °C with heating rates between 10 and 40 °C/min. They were characterized by X-ray diffraction. Finally, a kinetic study was carried out using the Coats-Redfern method. In all the briquettes, the controlling mechanism was diffusion. In the mixture with fines, the activation energy ranged from 31.95 to 33.72 kJ/mol and 120.29–137.17 kJ/mol. For the mixture with medium grain size, the activation energy ranged from 58.1 to 89.42 kJ/mol and 107.83–153.50 kJ/mol. X-ray diffraction revealed phases of hematite and magnetite at 800 °C, while at 900 °C phases of wustite and faialite and metallic iron were identified.

How effective is the reduction of major pollutants in thermal power plants under the ultra-low emission policy?

In 2015, the Chinese government set ultra-low emission standards for thermal power to alleviate the pressure of increasing total pollutants from energy demand. This paper analyzes the policy effect of ultra-low emission in different regions based on panel data of 1202 thermal power enterprises, and the results of hierarchical linear model show that the total amount of air pollutants emitted by thermal power enterprises showed a decreasing trend during 2017–2021, realizing the dual control of concentration and total amount. Due to the differences in primary energy structure, industrial structure and economic development level of different regions, the total emission reduction of thermal power pollutants is affected differently. First, the proportion of the region's secondary industry in the region's GDP is negatively correlated with the decrease of the total pollutant emission of local thermal power enterprises. Second, the higher the per capita GDP of the region, the more significant the decrease in the total amount of pollutants, economic development is conducive to pollutant emission reduction. Third, the higher the proportion of thermal power in local energy, the more obvious the reduction of total pollutant emissions of thermal power enterprises, indicating that the implementation of ultra-low emission policies in these regions is more thorough. In addition, the environmental protection tax plays a positive role in the total emission reduction, and the higher the sulfur dioxide tax rate, the more significant the reduction of total pollutants of thermal power enterprises. To further reduce the total amount of pollutants in thermal power, more coordinated efforts of environmental and economic policies are needed.

Prospective Life Cycle Assessment of Biological Methanation in a Trickle-Bed Pilot Plant and a Potential Scale-Up

The fluctuating nature of renewable energies results in the need for sustainable storage technologies to defossilize the energy system without other negative consequences for humans and the environment. In this study, a pilot-scale trickle-bed reactor for biological methanation and various scale-up scenarios for 2024 and 2050 were investigated using life cycle assessment. A best- and worst-case scenario for technology development until 2050 was evolved using cross-consistency analysis and a morphological field, based on which the data for the ecological models were determined. The results show that the plant scale-up has a very positive effect on the ecological consequences of methanation. In the best-case scenario, the values are a factor of 23–780 lower than those of the actual plant today. A hot-spot analysis showed that electrolysis operation has an especially large impact on total emissions. The final Monte Carlo simulation shows that the technology is likely to achieve a low global warming potential with a median of 104.0 kg CO2-eq/MWh CH4 and thus can contribute to decarbonization.

Multi-timescale optimization of integrated energy system with diversified utilization of hydrogen energy under the coupling of green certificate and carbon trading

Promoting renewable energy and developing low-carbon integrated energy systems are noteworthy in the energy sector. However, in existing works on the integrated energy system, the coupling of green certificate and carbon trading mechanism under diversified utilization of hydrogen energy has not been fully considered to provide an incentive effect for uncertain renewable energy resources. Based on these considerations, a multi-timescale optimization of an integrated energy system with diversified utilization of hydrogen energy is studied under the coupling of green certificate and carbon trading mechanism. First, the coupled interaction mechanism of green certificate trading-stepped carbon trading is proposed by linking stepped carbon trading to green certificate trading through green certificates. Furthermore, the establishment of the diversified utilization unit of hydrogen energy addresses carbon emissions from the perspective of energy application and offers fresh concepts for a low-carbon economy. Then, an optimized scheduling model for multiple time scales of day-ahead/intraday/real-time is developed to reduce the impact of renewable energy prediction errors on system operation. Results acquired from case studies demonstrate the effectiveness in terms of achieving economic and low carbon. The accommodation level of renewable energy with a coupling mechanism improves by 3.08% compared to that without considering coupling. In addition, the diversified utilization of the hydrogen energy model enables the reduction in total cost and carbon emission by 5.14% and 2.4927 tonnes in comparison to the traditional power-to-gas mode.