Pollutant Emission Characteristics Research Articles

Pollutant emission characteristics of the close-coupled selective catalytic reduction system for diesel engines under low exhaust temperature conditions

The selective catalyst reduction system is an effective method for reducing pollutant emissions from diesel engines. To meet the increasingly strict requirements of pollutant emission regulations and further reduce the pollutant emissions of heavy diesel engines at low exhaust gas temperatures, a close-coupled selective catalyst reduction (ccSCR) system based on a corrugated substrate was proposed. Based on the corrugated substrate with V2O5-WO3/TiO2 catalysts, the pollutant emission characteristics of the ccSCR system were compared with those of a conventional selective catalyst reduction (SCR) system under the World Harmonized Transient Cycle at the exhaust gas temperature of 165 °C. Additionally, the effects of the volume ratio of ammonia to nitrogen (α) and the catalyst volume to engine gas capacity ratio (γ) on pollutant emissions of the ccSCR system were investigated. Results showed that pollutant emissions exhausted from the ccSCR system were significantly lower than those from the conventional SCR system. With the increase of α from 0.3 to 0.7 and γ from 0.33 to 0.76 in the ccSCR module, the NOx emission and NH3 slip of the ccSCR system decreased, and α had a larger effect on reducing pollutant emissions from the ccSCR system. The minimum values of NOx emission and NH3 slip were 0.22 g/kW·h and 2.33 ppm, respectively, at α = 0.7 and γ = 0.76 of the ccSCR module. The proposed ccSCR system was conducive to reducing the pollutant emission of diesel engines and its pollutant emission characteristics outperformed the conventional SCR system.

Present and future emission characteristics of air pollutants and CO2 from the Beijing transport sector and their synergistic emission reduction benefits

Coordinated control of both carbon dioxide (CO2) and air pollutants from the urban transport sector will deliver the greatest benefit to climate and health. To calculate and assess the synergistic control effect on CO2 and air pollutants from various transport types in Beijing from 2021 to 2050, we built a quantitative analysis model based on the Long-range Energy Alternatives Planning framework. Results showed that passenger transport was the dominant contributor to CO2 and major air pollutants (fine particles, carbon monoxide, volatile organic compounds) emitted from the transport sector in 2021 in Beijing. An exception is for nitric oxide which was mostly from freight transport. Clean energy alternatives for road vehicles and aviation, and electrification of railways offer the best synergistic emission reduction potential for both CO2 and air pollutants, and are also the most important measure to realize carbon neutrality in transportation. A change in transport mode (e.g. from road to rail) and the early elimination of aging vehicles would lead to a greater synergistic effect than that achieved by improving fuel economy in the short-term, except for co-benefits for fine particles and CO2 for which the fine particle emission reduction was much lower than that of CO2. In general, the adoption of clean energy for motor vehicles and aviation (e.g., electric vehicles, hydrogen fuel cell vehicles, and bio-fuels), is the best way for Beijing to quickly pass the carbon peak and achieve neutrality in the transport sector and improve air quality in the future.

Nitrogen-containing malodorous gas pollutants emission characteristics and health risk assessment from an A/O wastewater treatment plant

Unpleasant odorous emitted from wastewater treatment plants (WWTPs) have been of great concern for many years, especially among local communities with high population density. Knowledge about characteristics of odorous gas release from WWTP can assist in developing gas pollution reduction technologies. This study investigated the emission and variation of NH3 and organic amines (CH3NH2, C2H6NH, and C3H9N) at the water-air interface and concentrations of ambient air exposure from different treatment units in a wastewater treatment plant in North China, which uses the anaerobic/oxic (A/O) treatment process. Results demonstrated that NH3 and C2H6NH emission fluxes had followed a descending order of aeration treatment units > non aeration treatment units. NH3 and C2H6NH achieved the highest release concentration throughout the whole wastewater treatment process, where 0.0023 g of NH3 and 0.0018 g of C2H6NH were emitted during the treatment of 1 m3 wastewater, while CH3NH2 and C3H9N had never been detected. The emission of NH3 and C2H6NH from biological aeration tanks account for 98 % and 95 % of the total discharge of wastewater treatment plant, respectively. The odor pollution of NH3 and C2H6NH in the ambient air of different treatment units of WWTP was the most serious in summer. At the sensory level, NH3 dominated the malodorous effect and its exposure concentration posed a certain non carcinogenic risk to workers in wastewater treatment plant.

Emission characteristics of coal gasification fine slag direct combustion and co-firing with coal

Coal gasification is an effective way to use coal cleanly and efficiently, and coal gasification fine slag is a by-product of coal gasification with high carbon content, large specific surface area, developed pore structure and large output during production. At present, combustion has become an effective way to dispose of coal gasification fine slag on a large scale, and the coal gasification fine slag after combustion treatment can be further used for construction raw materials. In this paper, the emission characteristics of gas-phase pollutants and particulate matter under different combustion temperatures (900 °C, 1100 °C, 1300 °C) and combustion atmosphere (5%, 10%, 21% O2 concentration) are studied with the drop tube furnace experimental system. By co-firing different proportions of coal gasification fine slag (10%, 20%, 30%) and raw coal, the pollutants formation law under co-firing conditions is studied. Scanning electron microscopy-energy spectroscopy (SEM-EDS) is used to characterize the apparent morphology and elemental composition of particulate samples. The measurement results of gas-phase pollutants show that the increase of furnace temperature and O2 concentration can effectively promote combustion and improve burnout characteristics, but the emission of gas-phase pollutants increases. A certain proportion (10%–30%) of coal gasification fine slag is added to the raw coal, which reduces the total emission of gas-phase pollutants (NOx and SOx). Studies on the characteristics of particulate matter formation show that co-firing with coal gasification fine slag in raw coal can effectively reduce submicron particle emission, and the lower fine particle emission is also detected at lower furnace temperature and oxygen concentration. The element analysis of particulate matter formation shows that the Fe, Si and S elements content of submicron particle generated by YL (the coal gasification fine slag generated by water slurry furnace in of Shaanxi Extended China Coal Yulin Energy Chemical Co., Ltd) sample increases significantly with the increase of furnace temperature and O2 concentration, which is the main influencing factor for the increase of submicron particle. With the increase of the mixing ratio of YL sample, the content of major elements such as Fe, K and Mg of submicron particle decreases significantly, which is an important reason why the amount of the submicron particle decreases.

The impact of pollutant emissions from co-incineration of industrial waste in municipal solid waste incinerators

A large amount of industrial solid waste (including waste plastics, textiles, wood, etc., which are byproducts of industrial production) urgently needs to be treated. Incineration is undoubtedly the most efficient and convenient method. The existing municipal solid waste incineration plants can be transformed to burn such industrial wastes. However, the potential risks associated with high levels of heavy metals in industrial waste and the air pollution caused by co-incineration pose significant challenges to the co-incineration disposal of industrial solid waste. The change of physical and chemical properties of municipal solid waste and the emission characteristics of flue gas pollutants after co-incineration of industrial waste were studied by means of material flow simulation and experiment. In addition, experiments were designed to study the effects of temperature, calcium sulfur ratio and chlorine content on heavy metal emission during the incineration of industrial waste. The results showed that co-incineration of a certain proportion of industrial waste significantly increased the calorific value of municipal solid waste, but excessive mixing of plastic and paper industrial waste would increase the ash content. Co-incineration of plastic industrial waste can significantly increase HCl, and with the increase of temperature, the transformation of Cl to HCl is more thorough. The increase of temperature can promote the migration of Cr, Pb and Se elements to the gas phase. When Cr, Pb, and Se elements are present in the gas phase, they can combine with other gases and aerosols to form particulate matter and toxic substances, causing air pollution. When Ca/S is 1, Ba, Mn, Ni, Zn can effectively reduce the retention rate of elements in the ash. Under certain conditions, chlorine in industrial waste plastics will react with Zn to form tiny particles and low boiling point chlorides, which will increase its volatility. The mineral components in the ash can also be used for making ceramsite and building materials. These results will provide reference for the pollutants controlling during co-incineration of industrial waste and municipal solid waste process.

Feasibility of thermal disposal masks in domestic waste incinerators: a study on the combustion characteristics, gaseous pollutant emissions characteristics and control of masks

ABSTRACT Discarded disposable medical masks generated due to the COVID−19 epidemic are overwhelming the current medical waste disposal facilities. Thermal disposal masks in domestic waste incinerator can both utilize the heat energy released by their combustion and dispose of the headache-inducing masks in a harmless manner. The masks are divided into 6 parts: white inside (WI), filter (FI), blue outside (BO), bonding of 3 parts (BP), ear strap (ES) and nose wire (NW). The highest burnout temperature (Tb) of each part of the mask was only 481.2°C and had a high HHV of 40.47 MJ/kg, which has a high energy potential as an energy source. The NOx, SO2, and HCl emission characteristics of each part of the masks were evaluated in a fixed-bed reactor. BP, BO, and ES contradict SO2 and HCl emission limits in China. The SO2 and HCl emission peaks of the masks with the addition of 10 wt% Ca(OH)2 did not exceed 60 mg/m3, which made the combustion emissions of the masks comply with GB 18,485–2014. Considering subsidies for disposal of masks and power generation, blending masks with a 1%−5% ratio enhances the subsidy revenue of waste incineration power plants by 12.63%−63.13%.

Numerical study on pollutant emissions characteristics and chemical and physical exergy analysis in Mild combustion

This analytical study appraises the emission characteristics of different pollutants such as CO and NOX as well as conducting chemical and physical exergy analyses on conventional and Mild combustion regimes. The RANS turbulence approach and the k-ε RNG model were utilized in this study to simulate turbulence, whereas the eddy dissipation concept (EDC) model and the GRI–Mech 2.11 chemical mechanism were adopted to treat the turbulence-chemistry interaction. This study evaluated local and global pollutant emissions and exergy efficiency along the reacting jet and explored the effects of temperature and chemical species on the physical and chemical exergies in MILD combustion in comparison to conventional combustion. It is found that the overall exergy efficiency of MILD combustion rises by 1, 3, and 4% for oxygen mass fractions of 3, 6, and 9% in hot oxidizer coflow, with the NOx emissions are 81, 72, and 55% lower than conventional combustion, respectively. Chemical exergy is greater than physical exergy near the fuel nozzle due to high CH4 and H2 concentrations. Chemical exergy reduces along the burner due to chemical reactions, while physical exergy increases due to the increased temperature. However, owing to the trade-off between these two exergies along the flame jet, the total exergy approaches a constant value at large distances from the burner. The maximum total exergy occurs at a distance of 0.12 m from the fuel nozzle, with chemical exergy accounting for 83% of the total exergy. In the outlet (0.5 m from the fuel nozzle), chemical exergy accounts only for 30% of the total exergy. It can also be concluded that the exergy is stabilized at a distance of 0.3 m from the nozzle (60% of the domain length). Despite a higher local CO emission in conventional combustion than in MILD combustion, the CO emission substantially decreases at a smaller distance from the nozzle in conventional combustion due to the high O2 concentration.

Airborne Air Pollutant Emission Characteristics of Mobile Vehicles in Taiwan

This study examines the air pollutant emission characteristics, activity intensity, and trends of mobile sources from 2013 to 2021. The target pollutants include criteria pollutants (fine particulate matters, nitrogen oxides, and hydrocarbons) and hazardous air pollutants (benzene, formaldehyde, and BaP). The results indicated that the activity intensity levels of road mobile sources in Taiwan were148 × 109, 156 × 109, 159 × 109, and 155 × 109 km/year in 2013, 2016, 2019, and 2021, respectively, with the largest proportion attributed to gasoline passenger cars (42.6%), followed by four-stroke motorcycles (32.6%). An emission factor of PM2.5 was estimated by EPA’s MOVES (Motor Vehicle Emission Simulator) model, and the results showed that the emission sequence was diesel > gasoline > motorcycle; the NOx emission factor was estimated using the MOBILE6.2 model, and the results showed that the order was diesel > gasoline > motorcycle; the HC emission factor was compiled with the use of gasoline vehicle dynamometer data, and the results showed that motorcycle > gasoline vehicles. Further results showed that the emission sequence for benzene was motorcycle > gasoline ≥ diesel; the formaldehyde emission sequence was diesel > motorcycle ≥ gasoline. The BaP emission factors of different vehicle types were estimated using MOVES, and the emission factors of old heavy-duty diesel vehicles were the highest.

Study on combustion performance of microgas turbine combustor with different fuels

AbstractA low‐pollution single‐tube microgas turbine combustor using different gas fuels was studied. The combustion performance of two kinds of landfill gas and natural gas was tested in a single‐head combustor. The effects of fuel nozzle position, and the fuel distribution ratio between pilot and main combustion stage on pollutant emission were investigated under rated load condition. The flow field, temperature field, and pollutant generation characteristics with different fuel nozzle diameters and nozzle positions were analyzed by numerical simulation. The results show that: the combustor can form an obvious central recirculation zone, which is convenient for ignition and stable flame propagation; in the case of limited premixed length, the influence of fuel nozzle position on fuel–air mixing uniformity is less obvious than that of fuel nozzle diameter. The fuel–air mixing uniformity plays a decisive role in the temperature field and the generation of pollutants in the combustor. The combustor has good pollutant emission characteristics, and the NOx emission can be reduced to about 10 ppmv (15% O2 concentration) under the appropriate combination of fuel nozzle diameter and position, which provides a reference for the further optimization of low‐emission combustor.

Big data-driven carbon emission traceability list and characteristics of ships in maritime transportation-a case study of Tianjin Port.

As China's shipping industry continues to develop, ship emissions have become a significant source of pollutants. Consequently, it has become imperative to comprehend accurately the nature and attributes of ship pollutant emissions and understand their causation and effect as a crucial aspect of pollution control and legislation. This paper employs high-precision automatic identification system (AIS) dynamic and static data, along with pollutant emission parameters, to estimate the pollutant emissions from a ship's main engine, auxiliary engine, and boiler using a dynamic approach. Additionally, the study considers the sailing state and trajectory of the vessel and analyzes the characteristics of ship carbon emissions. Taking Tianjin Port as an example, this study conducts a multi-dimensional analysis of pollutant emissions to gain insight into the causation and effect of pollutants based on the collected big AIS data. The results show that the pollutant emissions in this region are mainly concentrated in the vicinity of Tianjin Port land port area, Dagusha Channel, and the Main Shipping Channel of Tianjin Xingang Fairway. Carbon emissions peak in September and are lower in June and December. Through accurate analysis of pollutant emission sources and emission characteristics in the region, this paper establishes the regular relationship between pollutant emissions and possible influencing factors and provides data support for China to formulate accurate pollutant emission reduction policies and regulate ship construction technology and carbon trading.

Comparative study on pollutant emission characteristics of rural solid waste and its typical components during different combustion processes

ABSTRACT Rural solid waste (RSW) treatment is a key part in waste management. Current research on pollutant emissions from the thermal treatment of RSW is scarce. This study aimed to investigate the effects of different thermal treatments on the pollutant emission characteristics of RSW in Guangdong, China. Rubber, polyvinyl chloride (PVC), and food waste (FW) were selected as the source enriched materials for SO2, HCl, and NOx, respectively. Firstly, the impact of combustion and gasification-combustion on pollutant formation characteristics was compared. With the application of gasification-combustion, total NO and NO2 emissions from FW reduced by 60.3% and 40%, respectively. In contrast, SO2 and HCl emissions increased slightly by 1.67% and 5.49% for rubber and PVC, respectively. Besides, the reaction temperature and atmosphere of gasification-combustion were investigated. When the temperature exceeded 700°C with proportion of air (PA) fixed at 0.5 no NO2 was detected. The synergy among the components and the catalytic contribution of ash had been identified as important factors influencing the pollutant emission characteristics, and the application of gasification-combustion can effectively improve NOx emission characteristic.

Study on the spatio-temporal patterns of urban air pollution and its spatial mismatch with air pollutant emissions in the Yellow River Basin, China

In order to promote the precise governance of air pollution in the Yellow River Basin(YRB), it is of great significance to reveal the spatio-temporal patterns of urban air pollution in the basin and its spatial mismatch characteristics with air pollutant emissions. Based on spatial autocorrelation model and spatial mismatch model, this paper selected air pollution-related monitoring data from 69 cities in YRB from 2015 to 2020 as samples, and used ArcGIS, Stata, GeoDa and other softwares to analyze the spatio-temporal patterns of urban air pollution and its spatial mismatch characteristics with air pollutant emissions in YRB. The results showed that: (1) Temporally, the average annual Air Quality Index (AQI) values of cities in YRB ranged from 78.22 to 97.08 in 2015–2020, among which, the average annual AQI values of cities in the upper, middle and lower reaches of the basin decreased from 79.86, 89.23 and 122.14 in 2015 to 66.87,82.98 and 98.43 in 2020. (2) Spatially, there were obvious spatial differences in urban air pollution in YRB, and the AQI was roughly distributed in a geographical gradient of upper reaches < middle reaches < lower reaches, and there were significant spatial correlations in urban air pollution, mainly showing ‘high-high’ and ‘low-low’ aggregating characteristics. Among them, the lower reaches of YRB had formed a concentrated ‘high pollution zone’. (3) There was an obvious spatial mismatch between urban air pollution and air pollutant emissions in YRB, among which the spatial mismatch was obvious in cities such as Wuhai, Zibo, Shizuishan, Yangquan, Taiyuan, Datong, Jiyuan, Kaifeng, Puyang and Xi’an. (4) To improve the overall situation of air pollution in the cities of YRB, this paper proposed that the geographical gradient difference of air pollution in the upper, middle and lower reaches of YRB needs to be fully considered, following the principle of ‘focused treatment, gradual progress, enhanced prevention’, and according to the spatial mismatch characteristics of urban air pollution and air pollutant emissions, it is necessary to build a ‘differentiated’ governance strategy system for urban air pollution in the basin, which is ‘tailored to local conditions and categorized measures’.

DNS study on reactivity stratification with prechamber H[formula omitted]/air turbulent jet flame to enhance NH[formula omitted]/air combustion in gas engines

The present study investigates turbulent flame dynamics and pollutant emission characteristics in a prechamber/main chamber system. A H2/air turbulent jet flame issued from the prechamber penetrates into the NH3/air mixture found in the main chamber. Recent experimental studies have demonstrated that this configuration is very promising for future NH3 combustion in gas engines. In the present work, 3D direct numerical simulations (DNS) with detailed chemistry have been carried out in the above configuration. The dynamics of the turbulent premixed flame in the prechamber (flame thickness, flame propagation speed) and the structure of the turbulent stratified flame in the main chamber are investigated. It is found that the stratified flame thickness is becoming thicker as the flame propagates within the NH3/air mixture. The flame displacement speed is slowing down in a first phase, before becoming faster again after jet-induced turbulence starts to decay. A chemical explosive mode analysis (CEMA) has been done to distinguish between ignition, flame propagation, and local extinction events both for the premixed flame in the prechamber and the stratified flame in the main chamber. The temporal evolution of the identified modes are consistent with the flame dynamics and help to explain the later increase in flame displacement speed. NO emission characteristics in the main chamber have also been investigated. The NO production speed first increases, reaches a plateau, before being reduced during later flame propagation; stratification is important to explain the NO emission characteristics. Compared to the laminar NH3/air flame, the NO production speed is obviously larger in the present configuration, mainly due to the reduced contribution of the NO destruction reactions in the fuel pathway. Compared to premixed NH3/H2/air flames with H2 volume ratios found in practical systems (typically ≥ 0.4), the NO production speed is lower in the present configuration, demonstrating its superiority for practical applications. Finally, conventional heat release rate (HRR) markers are evaluated for the stratified flame. They approximate quite well the general structure of the flame front, but lead to noticeable quantitative errors.

Hydrogen production and pollutants emission characteristics by co-gasified of paper-mill sludge and automobile shredder residues in a commercial scale fluidized bed gasifier

This research investigated the hydrogen production and energy conversion from automobile shredder residues (ASRs) and paper mill sludge (PMS) co-gasified in a full-scale fluidized bed gasification plant. The results obtained from full-scale tests provided important information on the feasible assessment of ASRs-to-energy and the selection of alternative technologies for ASRs. Based on the analysis results of produced gas composition, H2, CO, and CH4 composition produced from paper-mill sludge gasified were 4.17%–6.01%, 3.08%–4.32%, 1.71%–2.4%, respectively. Another C2 gas composition ranged from 2.9% to 3.59%. The heating value of produced gas ranged between 1.64 MJ/Nm3 and 2.18 MJ/Nm3. In the case of 10% ASR addition, the heating value of produced gas was slightly increased to 1.84 MJ/Nm3-2.34 MJ/Nm3. The dioxin emission concentration of flue gas was approximately 0.064 ng I-TEQ/Nm3. It can comply with Taiwan regulation thresholds. The dioxin leaching concentrations of residues derived from gasification were also in compliance with regulation limits by the TCLP test. Meanwhile, in the case of 10% ASRs addition, the dioxin equivalence concentration of gasified residue was nearly 0.002 ng I-TEQ/Nm3. It was far below the current regulation standard limit. In summary, the results of this research have proved the performance of ASRs-to-energy by co-gasified with paper mill sludge using a full-scale gasification plant. The results obtained from this research also provided the information for selecting ASRs alternative technologies and operating full-scale gasifiers in the future.

Mercury flow network and its emission reduction in the steelworks

The steel industry is an important source of anthropogenic mercury (Hg) emissions. Hg is harmful to human health, causing symptoms such as dizziness, pneumonia, and renal failure. So, how do we reduce Hg emissions from the steelworks? What possibilities exist for Hg emission reduction? Firstly, in this study, the flow paths of Hg in the steelworks were described quantitatively using the substance flow analysis method, and the characteristics of the input and output of Hg-containing subjects were analyzed. Secondly, based on the Hg flow network, the circulation characteristics of Hg and the emission characteristics of Hg-containing pollutants were analyzed in the steelworks. Finally, according to the distribution of Hg in the steelworks, the emission reduction potential was examined at the source and end-of-pipe. The results showed that Hg, which mostly originated from coal, limestone, and iron ore concentrate in the steel production process, was mostly exported with waste gas and wastewater, primarily in the form of waste gas. The input, circulation, and output of Hg were 362.77, 3.25, and 392.55 mg/t crude steel (CS), respectively. Through source reduction and end-of-pipe treatment, the reduction rates of pollutants in the steelworks were 28.74% and 75.37%, respectively.

Pilot experimental study on pollutant emission characteristics from co-combustion of coal and spent cathode carbon block

Spent cathode carbon block (SCCB) is a hazardous waste produced by the electrolytic aluminum industry. Collaborative treatment of the SCCB in pulverized coal boilers is a potentially valuable technology. Pilot experiments were carried out on a 240 t/h pulverized coal boiler and its supporting flue gas treatment measures as a function of the mixing ratio of SCCB to verify the feasibility of coal collaborative disposal of SCCB. The thermal conversion characteristics of fluoride after mixing SCCB with coal were studied. A continuous emission monitoring system was used to monitor the impact on SO2, NOx and particulate matter in real time. The effectiveness of existing flue gas control measures was evaluated, and optimization suggestions of the flue gas control measures were postulated. The content of heavy metals (Hg, Cd, Ni, Pb, As, Se) in solid waste from co-combustion and the physical phase of solid waste were investigated. In addition, the transformation of heavy metals such as Hg, Cd, Ni, Pb, Cr, As and fluoride in defluorination wastewater during flue gas treatment were analyzed. The results show that it is feasible to use a pulverized coal boiler to dispose SCCB. The existing flue gas treatment measures proved to be appropriate, and desulfurization wastewater can achieve the discharge standards. Defluorination gypsum, fly ash and slag are not hazardous waste. When the mixing ratio of SCCB is increased, the existing neutralization and flocculation precipitation processes of the desulfurization wastewater are affected. It is suggested to add Al2O3 for the defluorination process before the desulfurization tower.

Port-owned Mobile Source Air Pollutant Emission Inventory

Based on the comprehensive development of the emission inventory of air pollution sources, the emission inventory of self-owned mobile sources of Tianjin coastal ports was researched and formulated. In this study, a gridded emission inventory with a resolution of 3 km×3 km was established for six types of air pollutants from road and non-road mobile sources. The spatial and temporal distribution characteristics of pollutant emissions were analyzed, and the uncertainty of the inventory was analyzed using the Monte Carlo method. The results showed that in 2020, the self-owned mobile sources of coastal ports emitted 148.22 t PM10, 135.34 t PM2.5, 1061.04 t SO2, 4027.16 t NOx, 756.60 t CO, and 237.07 t VOCs, of which the total emissions of road and non-road mobile sources accounted for 6.66% and 93.34% of the mobile source emissions, respectively. The main contributors to motor vehicle pollutant emissions from road mobile sources in the whole port area were small, medium, and large passenger vehicles (gasoline) and heavy trucks (diesel). The main contributors to the pollutants emitted by non-road mobile sources were ships and construction machinery. Uncertainty analysis results showed that the overall uncertainty of mobile sources ranged from -13.3% to 16.53%.

Railway Emission Trends in China Based on Fuel Life Cycle Analysis

Railway transportation is one of the main modes of modern transportation. Under the dual constraints of air quality improvement and carbon neutrality achievement, clarifying the emission trend of CO2 and pollutants in railway transportation is of great significance for pollution and carbon reduction in the transport sector. In this study, the CO2 and pollutant emission characteristics of Chinese railways from 2001 to 2018 were analyzed based on the fuel life cycle method. Then, railway emission trends from 2019-2030 were assessed combined with scenario analysis. The results showed that with the advancement of railway electrification, the use of new diesel locomotives, and the continuous upgrading of fuel standards, the total CO2 and pollutant emissions in the fuel life cycle of railway transportation showed an upward and downward trend, respectively. In 2018, the total emissions of CO2, NOx, CO, BC, and SOx from railway transportation were 3780.29×104t, 11.98×104t, 3.94×104t, 0.20×104t, and 3.08×104t, respectively. Accelerating the improvement of power structure and reducing unit energy consumption were the best single control strategies to reduce railway emissions of CO2, SOx, NOx, BC, and CO, respectively. Under the comprehensive scenario of actively responding to railway pollution and carbon reduction, the emission reduction rates of CO2, NOx, CO, BC, and SOx could reach 35%, 37%, 39%, 32%, and 45%, respectively. The stagnation of power structure reform or the railway electrification process will lead to a significant increase in total emissions of railway transportation. Therefore, the pollution and carbon reduction of railway transportation requires continuous attention.

Analysis of port pollutant emission characteristics in United States based on multiscale geographically weighted regression

The huge fuel consumption of shipping activities has a great impact on the ecological environment, port city environment, air quality, and residents’ health. This paper uses Automatic Identification System (AIS) data records and ship-related data in 2021 coastal waters of the United States to calculate pollutant emissions from ships in 30 ports of the United States in 2021. After calculating the pollutant emissions from ships at each port, the multiscale geographically weighted regression (MGWR) model is used to analyze the factors affecting the ship pollutant emissions. Geographically weighted regression (GWR) model is used to investigate the spatial heterogeneity of various factors affecting the characteristics of ship pollutant emissions at different scales. This paper mainly compares the effect of models of GWR and MGWR. MGWR may truly reveal the scale difference between different variables. While controlling the social and economic attributes, the coastline length, container throughput, and population are used to describe the spatial effects of ship pollutant emissions in the United States. The results denote that the distribution trend of ship pollutant emissions has a gap based on various ship types and ports. NOx accounts for the highest proportion of pollutant emissions from port ships, followed by SO₂ and CO. The impact coefficients of coastline length and population on pollutant emissions in port areas are mostly positive, indicating that the growth of coastline length and population will increase pollutant emissions in port areas, while the effect of container throughput is opposite. Relevant departments should put forward effective measures to curb NOx emission. Port managers should reasonably plan the number of ship transactions according to the coastline length of the port.

High Spatial Resolution Emission Inventory of Air Pollutants and Carbon in China’s Independent Coking Industry

China is the largest producer and exporter of coke globally, which means that it is very important to understand the characteristics of air pollutants and carbon emissions from China’s independent coking industry. This study was the first to establish a bottom-up inventory of the air pollutants and carbon emissions of China’s independent coking industry during 2001–2018 based on continuous emission monitoring system online monitoring data and unit-based corporate information. Based on the developed emission inventory, four scenarios were established to analyze potential emissions reduction of air pollutants and carbon dioxide (CO2) in future. The emissions of particulate matter (PM10 and PM2.5), sulfur dioxide (SO2), black carbon (BC) and organic carbon (OC) decreased by 62.11%, 63.41%, 72.85%, 63.41% and 63.41%, respectively. CO2, carbon monoxide (CO), volatile organic compounds (VOCs) and nitrogen oxides (NOX) emissions increased by 355.51%, 355.51%, 355.51% and 99.74%, respectively. In 2018, PM10, PM2.5, SO2, NOx, BC, OC, CO, VOCs and CO2 emissions were, respectively. 45.20, 16.91, 63.84, 117.71, 5.07, 5.92, 554.91, 1026.58 Gg, and 176.88 Tg. Shanxi province made the greatest contributions to the total emissions of air pollutants and CO2 from this industry by 25.01%. The emission source that contributed most to PM2.5 (SO2 and NOX) emissions was coke pushing (quenching and the coke oven chimney respectively) in 2018. Under the ULE scenario (2018–2035), PM2.5 and SO2 emissions will reduce by more than 30%. Under the PCP scenario, PM2.5 and SO2 emissions will reduce by more than 55%. Under the CBP scenario, CO2 emissions will peak at 197.99 Tg in 2025 and decrease to 70% of the peak in 2035. The results showed the emission characteristics of air pollutants and CO2, future emission with several scenarios and cooperative reduction potential in China’s independent coking industry, which provides scientific support for the development of pollution control strategies.