Total Emission Level Research Articles

Response of Low Carbon Level to Transportation Efficiency in Megacities: A Case Study of Beijing, China

Global warming caused by massive carbon dioxide emissions can lead to a chain of ecological disasters. As one of the main sources of carbon emissions, transportation is of great significance, and the evaluation of its connections with carbon emissions is necessary to achieve “carbon neutrality”. Taking Beijing as an example, this study evaluated traffic efficiency (TE) by utilizing principal component analysis and fuzzy comprehensive evaluation. Using the Tapio decoupling model and coupling coordination degree model, the corresponding relationship between urban low carbon level (LCL) and TE was explored. The results showed the following: (1) The total carbon emission (CE) level exhibited fluctuating variation from increasing to decreasing. The carbon emission intensity (CEI) continued to slow down, and the rapid growth of population density played a key role in low-carbon development. (2) The traffic operations continually showed a positive trend in development. TE increased from a step-like to a slow shape, until it declined in 2020 due to the pandemic. (3) TE and LCL both developed from low coordination to an extreme level of coordination. Per capita carbon emission (CEP) and TE presented an inverted U-shaped curve; meanwhile, with increases in TE, the decline in CEI slowed. In addition, the weak decoupling of TE changed to become strong, due to CE and CEP, and maintained a strong decoupling state from CEI. (4) There is a necessity for the rational planning of land use for transportation infrastructure, the encouragement of a combination of public and private transportation, and the strengthening of the maintenance of the relative infrastructure and the management of traffic behaviors to attain a win–win situation. The results provide a reference for optimizing the traffic structure to achieve “carbon neutrality”.

Low carbon strategy and coordination for a two-echelon automotive supply chain considering dual credit policy

The dual-credit policy currently plays a crucial role in the automobile industry and significantly contributes to low-carbon operations in the automotive supply chain. This paper employs the game-theoretic approach to build a supply chain comprising a supplier (leader) and an automaker (follower), considers the impact of dual-credit policy, and incorporates vertical spillovers into the supply chain abatement. Both parties lower carbon emissions through vertical spillovers while maximizing profits, thereby studying the low-carbon strategy of the automobile supply chain. Our findings reveal that (1) increased vertical spillover rate reduces the prices of fuel vehicles (FVs) and new energy vehicles (NEVs), raises the low-carbon levels and profits of automakers and suppliers. (2) An increase in the NEV credit ratio under the centralized system raises both price and demand for NEVs, while the low-carbon levels of automotive enterprises are reduced. (3) The carbon emissions of each vehicle under the centralized system will be lower than those of the decentralized system, and the order of total carbon emission levels under both systems is closely related to the credit trading price and credits per NEV. Moreover, we explore the automotive supply chain coordination and find that the Nash bargaining model fully coordinates the supply chain, while the cost-sharing and revenue-sharing contracts do not. Also, numerical analysis shows that the optimal system profit under revenue-sharing is greater than cost-sharing.

A zero discharge, carbon-neutral bi-fuel production process for algal biodiesel and renewable hydrogen

This work proposes a novel zero discharge, carbon-neutral bioprocess for the simultaneous production of algal biodiesel and renewable hydrogen. This innovative bi-fuel production process (BiFPP) consists of five units connected in series for biodiesel production, biodiesel purification, glycerol separation, glycerol steam reforming and hydrogen purification. To assess the techno-economic feasibility, the genetic algorithm based multi-objective optimization strategy is developed to minimize the total annual cost and CO2 emission level, and maximize the fuel purity. The optimal BiFPP scheme yields 97.3 mol % biodiesel and 98.8 mol % hydrogen, and thereby meets the standard specifications, ASTM D6751 and EN 14214. A heat exchanger network is designed with thermal coupling to secure the energy savings of 79.5% (heating load) and 50% (cooling load), leading to 93% reduction in utility cost. To achieve carbon neutrality, a CO2 sink for algae cultivation is finally proposed to integrate with this industrial-scale BiFPP process that overall yields a novel zero discharge bi-fuel production technology.

Effects of fuel injection system and exhaust gas catalytic treatments on PAH emissions from motorcycles.

The motorcycles are unignorable near-ground pollutant emission sources that increase the human exposure in the dense area. However, the information of the polycyclic aromatic hydrocarbons (PAHs) emissions under different scenarios of engine and emission control for motorcycle is limited. This study focused on the PAH emissions from two fuel-injection types of motorcycles, including the premixed fuel-injection (PFi) with carburetor and electronic fuel-injection (EFi). Specifically, the effects of throttle opening (TO), secondary air system (SAS), oxygen sensor (OS), oxidation catalytic converter (OCC), and three-way catalytic converter (TWC) on PAH emissions are investigated. Results show that the PAH emission concentrations increase 227-727%, 351-492%, and 155-408% by the increasing TO ratio, unworking SAS, and OS units in both motorcycles. For the PFi engine, the OCC unit is found to be more effective in PAH control (31-89%) than the SAS system (72-80%), especially under low TO operation. For the EFi engine which dominates the motorcycle market recently, the oxygen sensor for more accurate combustion control shows a better PAH reduction (36-76%) than TWC system (21-66%). The ultra-fine particulate phase PAHs, which is hardly removed by catalyst, needs to be further considered. Moreover, the total PAH emission level of the EFi engine is still about ten times higher than that of the PFi. By the annual emission calculation for three densely populated countries, the recent evolution significantly reduces the annual hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) emissions but have unignorable PAH emissions. These emissions continuously affect the human health in the near-ground urban air and need to be considered in the next generation of motorcycle design.

Revisiting Total Particle Number Measurements for Vehicle Exhaust Regulations

Road transport significantly contributes to air pollution in cities. Emission regulations have led to significantly reduced emissions in modern vehicles. Particle emissions are controlled by a particulate matter (PM) mass and a solid particle number (SPN) limit. There are concerns that the SPN limit does not effectively control all relevant particulate species and there are instances of semi-volatile particle emissions that are order of magnitudes higher than the SPN emission levels. This overview discusses whether a new metric (total particles, i.e., solids and volatiles) should be introduced for the effective regulation of vehicle emissions. Initially, it summarizes recent findings on the contribution of road transport to particle number concentration levels in cities. Then, both solid and total particle emission levels from modern vehicles are presented and the adverse health effects of solid and volatile particles are briefly discussed. Finally, the open issues regarding an appropriate methodology (sampling and instrumentation) in order to achieve representative and reproducible results are summarized. The main finding of this overview is that, even though total particle sampling and quantification is feasible, details for its realization in a regulatory context are lacking. It is important to define the methodology details (sampling and dilution, measurement instrumentation, relevant sizes, etc.) and conduct inter-laboratory exercises to determine the reproducibility of a proposed method. It is also necessary to monitor the vehicle emissions according to the new method to understand current and possible future levels. With better understanding of the instances of formation of nucleation mode particles it will be possible to identify its culprits (e.g., fuel, lubricant, combustion, or aftertreatment operation). Then the appropriate solutions can be enforced and the right decisions can be taken on the need for new regulatory initiatives, for example the addition of total particles in the tailpipe, decrease of specific organic precursors, better control of inorganic precursors (e.g., NH3, SOx), or revision of fuel and lubricant specifications.

A method for measuring the emissions of in situ agricultural plastic film microplastics by ultraviolet and mechanical abrasion

Agricultural plastic film (APF) is widely used in modern agriculture. Under natural environmental conditions, the structure, surface properties and mechanical properties of APFs change because of sunlight, wind and other factors and gradually break into debris, resulting in the generation of microplastics (MPs). Studies have reported that the MPs concentration in soil is positively correlated with the use intensity and duration of APFs. Unfortunately, to the best of our knowledge, no method to measure the emissions of in situ APFs has been developed. In this study, the effects of mechanical abrasion driven by wind on MPs fragmentation by polyethylene (PE) and polyvinyl chloride (PVC) APFs with the increase of exposure time were investigated. Meanwhile, based on the release rate model of PS fragmented MPs under natural sunlight, a modified model to quantify the effect of ultraviolet (UV) radiation exposure duration on the production of APF fragmented MPs was developed. Based on these models, the amount of MPs produced from APFs in farmland in China was estimated. The national annual MPs mass emissions from APFs in agricultural soil were approximately 5 × 104 to 6.8 × 104 tons in 2018 due to wind and 6.5 × 103 tons due to sunlight, and the total emission level due to both wind and sunlight was 5.1 × 104 to 7.0 × 104 tons. Compared with that of wind, the contribution of UV radiation to MPs emission is smaller. Our estimates are comparable to data reported in previous studies, indicating that our models have good practical applications and are of great significance for predicting MPs production from APFs in farmland.

Controlling non-point source pollution in Cournot oligopolies with hyperbolic demand

This paper constructs an n-firm Cournot oligopoly in which the price function is hyperbolic. It provides a game-theoretic approach to characterize the ambient charge’s impact on NPS pollution’s total and individual emission levels. The main findings are as follows: (1) the positivity of individual Cournot output depends on the marginal production cost, the average abatement technology and the number of firms in the industry; (2) the ambient charge is effective for controlling the total amount of NPS pollution when the average marginal production cost is less than the average emission coefficient; (3) the ambient charge is also effective for controlling the individual pollution when the tax rate and the average pollution level are sufficiently high; (4) assuming hyperbolic rather than linear demand, stronger parametric conditions are necessary for the effectiveness of the ambient charge.

Natural gas–ammonia dual-fuel combustion in spark-ignited engine with various air–fuel ratios and split ratios of ammonia under part load condition

Considering the revised standards pertaining to the regulations on the carbon dioxide emissions of marine engines by international maritime organizations, the use of low- or zero-carbon fuel is necessitated to reduce greenhouse gas emissions from the engine-out mixture. In this study, a natural gas–ammonia dual-fuel spark-ignited engine is experimentally investigated, focusing on its feasibility for marine engine operation. An 11 L 6-cylinder turbocharged spark-ignited engine is used to operate a dual-fuel combustion with various air–fuel ratios and split ratios of ammonia. A relatively low speed (840 rpm) with low-load operation is selected for this study because of its similarity with the operating point of typical marine engines. In addition, simulations are conducted to obtain the laminar flame speed of each point corresponding to the real experimental operating points. It is observed that increasing the air–fuel ratio and split ratio of ammonia retarded the laminar flame speed.By substituting natural gas with ammonia (by more than 50% of the volume fraction), specific carbon dioxide emissions reduced by approximately 28%. It is discovered that the air–fuel ratio is limited to a lambda value of 1.5, resulting in the deterioration of combustion efficiency and emission characteristics. As for nitrogen oxide emissions, the fuel-bound emissions dominated the total emission level of nitrogen oxides because combustion phasing retarded owing to the slow flame speed and large amount of minimum ignition energy when the ammonia fraction increased. The slow laminar flame speed of ammonia substantially affected the initial flame propagation.

Impact of international lobby groups on international environmental agreements

Economists have long argued over the political economy of tradable emission permits, especially the political pressure of lobby groups on international environmental agreements. However, little attention has been paid to the effects of cross-national lobbying on this market. Here, we examine how an international lobby group can affect national and international climate policies concerning international market for emission permits. It extends the common agency model of policy-making to multiple-agency relationships in the context of international environment agreements. The main questions are (1) to what extent are governments’ rent-seeking incentives affected through international lobbying? (2) how do domestic and global emissions change in the presence of an international lobby group? We present a three-stage non-cooperative game in which international and national lobbies try to influence governments both when the governments decide on the formation of the international market and when each country chooses the number of permits. We find the condition under which the formation of an international lobby group can raise the contributions of national lobbies which support an international market and hence bring more benefits to the government. We also show that domestic and total emission levels not only depend on the aggregate levels of organized stakes in all countries but also on the distribution of stakes among individual lobby groups that form an international lobby group.

The inharmonious mechanism of CO2, NOx, SO2, and PM2.5 electric vehicle emission reductions in Northern China

Beijing benefits from the promotion of electric vehicles (EVs) in the improvement of road tailpipe emissions; these emissions are caused by internal combustion engine vehicles (ICEVs) and reduce the surrounding environmental quality. When analyzing the electricity grid, upstream emissions of EVs in Beijing can be tracked back to Shanxi and Inner Mongolia. This study investigates the inharmonious mechanism of emission reduction to promote EVs in Beijing and Northern China based on 6 scenarios and 42 real EVs. Because there is a neighbor effect, Beijing only accounts for 34%, 34%, 41%, and 35% of the total CO2, NOx, SO2 and PM2.5 emissions, respectively. Although the local CO2, NOx, and PM2.5 emissions can be easily reduced (as long as the conversion of “coal to gas” plan is realized), it is difficult to achieve emission reductions of NOx and SO2 without increasing the clean electricity generation mix in Shanxi and Inner Mongolia at the total emission level. However, there is still a large reduction potential of EVs themselves due to an increasingly clean electricity mix in Beijing, Shanxi and Inner Mongolia. Beijing local CO2, NOx, SO2 and PM2.5 emissions can be reduced by 86.92%, 98.79%, 99.98% and 99.94%, respectively, and a total reduction of 78.43% of CO2, 93.83% of NOx, 97.85% of SO2 and 99.26% of PM2.5 emissions is possible. Compared with the corresponding ICEV, an EV of 18 kWh/100 km starts to reduce Beijing local CO2, NOx and PM2.5 emissions in scenario 1, 3 and 1, respectively, while the SO2 emissions cannot be reduced. However, the total CO2, NOx, SO2 and PM2.5 emissions can be reduced in scenario 2, 5, 5, and 1, respectively. A sensitivity analysis shows that the promotion of EVs can reduce Beijing local CO2, NOx, SO2 and PM2.5 emissions by 125.568–238.960 g/km, 0.059–0.113 g/km, −0.00003 - - 0.00007 g/km and 0.034–0.065 g/km, respectively. In addition, the total CO2, NOx, SO2 and PM2.5 reduction in emissions can be 132.883–253.757 g/km, 0.189–0.361 g/km, 0.299–0.569 g/km and 0.053–0.101 g/km, respectively.

Dynamic Models of Pollution Penalties and Rewards with Time Delays

In cases of nonpoint pollution sources, the regulator can observe the total emission but unable to distinguish between the firms. The regulator then selects an environmental standard. If the total emission level is higher than the standard, then the firms are uniformly punished, and if lower, then uniformly awarded. This environmental regulation is added to n-firm dynamic oligopolies, and the asymptotical behavior of the corresponding dynamic systems is examined. Two particular models are considered with linear and hyperbolic price functions. Without delays, the equilibrium is always (locally) asymptotically stable. It is shown how the stability can be lost if time delays are introduced in the output quantities of the competitors as well as in the firms’ own output levels. Complete stability analysis is presented for the resulting one- and two-delay models including the derivations of stability thresholds, stability switching curves, and directions of the stability switches.

Influence of flame quenching and crevice gas on hydrocarbon emission formation in an enriched biogas dual-fuel engine – An experimental and theoretical investigation

Enriched biogas is a promising alternate fuel candidate for compression ignition engines which are used in transportation sector. However, utilization of enriched biogas in compression ignition engines under dual-fuel mode suffer a major problem of high hydrocarbon emission particularly at part load operations. Main causes for this problem are inadequately understood which foils for active penetration of dual-fuel technology in the automotive market. To address this research gap, the current work is focused to investigate the effects of flame quenching and crevice gas (i.e., trapped between cylinder barrel and piston rings) on hydrocarbon emission formation. Investigation was carried out on enriched biogas dual-fuel engine of 3.7 kW rated power at 1500 rpm at part load of 50%. It was explored that both quench and crevice hydrocarbon emissions together are in the range of 60% to 92% of total hydrocarbons. Total hydrocarbon emission level increased from 2 g/kWh with base diesel operation to 56 g/kWh with 77% enriched biogas energy share. Overall, it is emerged that the crevice mechanism plays a dominant role for high hydrocarbon emission levels in enriched biogas dual-fuel engines.

An intelligent alternating current-optimal power flow for reduction of pollutant gases with incorporation of variable generation resources

Frequent escalations in fuel costs, environmental concerns, and the depletion of non-renewable fuel reserves have driven the power industry to significant utilisation of renewable energy resources. These resources cannot satisfy the entire system load demand because of the intermittent nature of variable generation resources (VGRs) such as wind and solar. Therefore, there is a need to optimally schedule the generating units (thermal and VGRs) to reduce the amount of fuel used and the level of emissions produced. In this study, an AC-power flow in conjunction with combined economic and environmental dispatch approach through the implementation of a modified constricted coefficient particle swarm optimisation was used to minimise the fuel cost and the level of emission gases produced. The approach was applied to the Institute of Electric and Electronic Engineers 30 bus test system through three different load conditions: base-load, increase-load and critical-load. The results showed the practicality of the proposed approach for the simultaneous reduction of the total generation cost and emission levels on a large electrical power grid while maintaining all the physical and operational constraints of the system.

Effects of primary energy consumption on CO2 emissions under optimal thresholds: Evidence from sixty countries over the last half century

We examine how different types of primary energy consumption (i.e. oil, coal, gas, hydroelectric and other renewables) contribute to carbon dioxide emissions (CO2) in the world. We allow the effects of each energy source on emissions to vary according to countries' real income or total emission levels. To achieve this, we use a panel breaking regression with four endogenously determined break points, employing time series (1965–2016) data across 60 major pollutant countries with over 2600 observations. Our analysis distinguishes between five optimally-determined country groupings at differing stages of industrialization, technology and scale, in terms of how they generate emissions from different fossil fuels. Our findings suggest that there exist different trade-offs from switching from one primary fuel source to another at different income levels and highlight how significant fuel-specific gains can be made by using other comparable economies as benchmarks.

Multi-area dynamic economic emission dispatch of hydro-wind-thermal power system

Multi-area dynamic economic emission dispatch (MADEED) is a significant chore of hydro-wind-thermal power system. This system comprises multi-reservoir cascaded hydro plant with time delay, thermal plants with nonsmooth fuel cost and emission level functions, wind power generating units with the effect of reserve coefficient, penalty coefficient and wind power uncertainty. This paper suggests nondominated genetic algorithm–II (NSGA-II) for solving multi-area dynamic economic emission dispatch (MADEED) of hydro-wind-thermal power system where power generations are allocated among the on line units in such a manner that total cost and emission level are optimized simultaneously while fulfilling all operational constraints. Test results of a four-area system acquired from the suggested technique have been fit to that acquired from strength pareto evolutionary algorithm 2 (SPEA 2).

General equilibrium economy-wide impacts of the increased energy taxes in Vietnam

The Vietnamese Government is proposing a new tax levy on either petroleum products or coal, or both. That is, the Government expects to increase the current tax rates to the maximum levels set previously. In this instance, the tax on coal is intended to increase by 50%, while the tax on petroleum products is intended to increase by 33.33%. This study employs a computable general equilibrium model to assess the effects of these increases in taxes on the Vietnamese economy, focusing on energy, transportation, and the private sectors. Results show that an increase in tax on petroleum products will considerably affect the country with a reduction of real GDP by 1.99%. Exports and imports are also highly unfavorably affected. In this instance, the total emission level will be reduced by 7.12%. The increased tax on coal, however, will allow Vietnam to experience much lower unfavorable effects, while being able to cut a substantial amount of the emission level. For example, real GDP would only decline by 0.51%, while total emission level will be reduced by 10.25%. If these taxes are increased together, Vietnam will experience considerable contractions in the economy, but it is able to reduce a substantial emission level.

Effect of the exoplanet magnetic field topology on its magnetospheric radio emission

Context. The magnetized wind from stars that impact exoplanets should lead to radio emissions. According to the scaling laws derived in the solar system, the radio emission should depend on the stellar wind, interplanetary magnetic field, and topology of the exoplanet magnetosphere. Aims. The aim of this study is to calculate the dissipated power and subsequent radio emission from exoplanet magnetospheres with different topologies perturbed by the interplanetary magnetic field and stellar wind, to refine the predictions from scaling laws, and to prepare the interpretation of future radio detections. Methods. We use the magnetohydrodynamic (MHD) code PLUTO in spherical coordinates to analyze the total radio emission level resulting from the dissipation of the kinetic and magnetic (Poynting flux) energies inside the exoplanet’s magnetospheres. We apply a formalism to infer the detailed contribution in the exoplanet radio emission on the exoplanet’s day side and magnetotail. The model is based on Mercury-like conditions, although the study results are extrapolated to exoplanets with stronger magnetic fields, providing the lower bound of the radio emission. Results. The predicted dissipated powers and resulting radio emissions depend critically on the exoplanet magnetosphere topology and interplanetary magnetic field (IMF) orientation. The radio emission on the exoplanet’s night and day sides should thus contain information on the exoplanet magnetic field topology. In addition, if the topology of an exoplanet magnetosphere is known, the radio emission measurements can be used as a proxy of the instantaneous dynamic pressure of the stellar wind, IMF orientation, and intensity.

Extended Oligopolies with Pollution Penalties and Rewards

An extended n-firm oligopoly with product differentiation is considered. It is assumed that the government selects an emission standard for the industry and based on the output and technology of each firm it selects a maximum allowed amount of emission for each firm. If the actual amount is higher than the allowed maximum, then the firm has to pay a constant multiple of the excess to the government; otherwise it is rewarded similarly based on the saved emission amount. The existence of the unique interior equilibrium is first proved, and then the effect of the level of penalty or reward and that of the emission standard on the industry output and therefore on the total emission level is also examined. Time delay is introduced into the penalties the firms have to pay and into the rewards the firms receive. In analyzing the stability of the equilibrium both discrete and continuous time scales are considered. For mathematical simplicity the case of symmetric firms is analyzed. In the discrete case the various values of the delay length are examined. The equilibrium is stable if either the total industry output is sufficiently large or the common speed of adjustment of the firms is sufficiently small. In the continuous case, either the equilibrium is always stable or stability occurs if the delay is sufficiently small and at the critical value Hopf bifurcation occurs.

A Modified Artificial Bee Colony Algorithm Application for Economic Environmental Dispatch

In conventional fossil-fuel power systems, the economic environmental dispatch (EED) problem is a major problem that optimally determines the output power of generating units in a way that cost of total production and emission level be minimized simultaneously, and at the same time all the constraints of units and system are satisfied properly. To solve EED problem which is a non-convex optimization problem, a modified artificial bee colony (MABC) algorithm is proposed in this paper. This algorithm by implementing weighted sum method is applied on two test systems, and eventually, obtained results are compared with other reported results. Comparison of results confirms superiority and efficiency of proposed method clearly.

Economic and Emission Load Dispatch Solution via Artificial Bee Colony Algorithm

The Economic Load Dispatch (ELD) is considered to minimize the only fuel cost in power system planning and operation. Due to environmental issues, the emission amount released by thermal power generation should be considered in minimizing the total cost generation as well. This make the power dispatch problem become multi-objective problem that called Economic and Emission Load Dispatch (EELD). This paper investigates the performances of Artificial Bee colony (ABC) algorithm for determining optimal solution for EELD problem. In this paper, the EELD problem is formulated as a single objective problem by taking minimization of total cost and emission level as separated objective. The cost characteristic of thermal generator considered the effect of opening and closing of the valve for practical application. The ABC algorithm has been tested on standard test systems which is 10-generating unit test system in order to validate the effectiveness of proposed ABC algorithm. The results obtained have been compared with reported result by other methods in literature. From the result, it found that ABC algorithm is better than other methods for minimizing fuel cost of thermal power generation and obtained comparative results in reducing the emission level.