Emission Control Technologies Research Articles

HISTORICAL EMISSIONS AND FUTURE MITIGATION OF PRIMARY AIR POLLUTANTS FROM INDUSTRIAL BOILER IN CHINA

Industrial boilers are recognized as a significant anthropogenic emission source of primary air pollutants in China. By using specific and detailed statistical data and comprehensive time-varying dynamic emission factors (EFs), we calculated the temporal-spatial emission characteristics of total suspended particulate (TSP), SO2 and NOx from industrial boilers during 1980 to 2016 for the first time. Further emission trends from 2016 to 2030 were also forecasted based on the current atmospheric action policy. Our results showed a generally decreasing trend of the annual EFs for TSP, SO2 and NOx due to implementation of stricter local emission standards, application of advanced emission control technologies, and elimination of small and inefficient boilers. In 2016, national TSP, SO2 and NOx emissions from industrial boilers were estimated at 5.43, 6.99 and 2.47 million tons (Mt), respectively. The higher emissions of primary air pollutants from coal-fired industrial boilers (CFIBs) were concentrated in northeast and eastern China, while NOx emissions from gas-fired industrial boilers (GFIBs) were mainly concentrated in the Beijing-Tianjin-Hebei region and its surrounding areas. Under a series of current action plans, it would be successful in abating emissions of TSP, SO2 and NOx by 95%, 94% and 71% in the year of 2030. More attention should be paid to the whole process control of industrial boilers in the future polices making, such as introducing clean fuels for persistent emission reduction at source, strengthening the operation, maintenance and management of pollution control technologies to ensure the best control effect.

Research on exhaust emission characteristics and technical route under CLTC cycle

In this paper, the light duty that meets the China 6 emission standard is selected to study the emission characteristics of different emission control technology routes under China light-duty vehicle test cycle (CLTC). The results show that the cold start stage of CLTC cycle is still the stage with the most pollutant emissions. The THC, CO and NOx emissions of vehicles on the supercharged direct injection technology are higher than those on the naturally aspirated port fuel injection technology. In terms of reducing the exhaust emission, PHEV technology route is the best, followed by naturally aspirated PFI technology route, and then turbocharged direct injection with GPF route.

A comprehensive study on emission of volatile organic compounds for light duty gasoline passenger vehicles in China: Illustration of impact factors and renewal emissions of major compounds

BackgroundMany volatile organic compounds (VOCs) are efficient precursors for both ozone and secondary organic aerosol (SOA) which are problematic to environmental controls in many global cities. Vehicle emission is one of the most important anthropogenic sources for VOCs. In between, light duty gasoline passenger vehicles (LDGPVs) contributed more than half of the on-road vehicles in China, demonstrating unique emission characteristics and also significant contributions in emission inventory. ObjectivesTo illustrate the variation of VOCs emissions from LDGPVs under different conditions, evaluate the sensitivity of the potential influencing factors, such as emission standards, displacement, cumulative mileage, and driving mode, on the VOCs emissions profiles, and to update the emission inventory by taking into account of the most influential factor. MethodsIn this study, seventy-four in-used LDGPVs were examined by the chassis dynamometer. A total of 25 VOCs in the emissions was quantified using an online time of flight mass spectrometer (TOF-MS). Fuel-based emission factors (EF) were calculated. ResultsThe results showed that the maximum ΣEF (260.4 ± 241.1 mg/L) was seen for LDGPVs at a high acceleration rate (0.9 m/s2). From the technical control emission standard aspect, the total emission factor of VOCs (expressed as ∑EF) was declined for China IV LDGPVs relative to China III vehicles, with the decreasing extent determined as 24.8%. Among LDGPVs with engine capacity of <1.5 L, 1.5–2.5 L and >2.5 L, it is for 1.5–2.5 L that the lowest ∑EF (101.2 ± 70.1 mg/L) was determined. Along with the increasing of cumulative mileage, the EF values of VOCs were uplift, and the ∑VOCs increased almost linearity, while the increasing trend became steady for ∑EF when the cumulative mileage more than 8 × 104 km. As for different driving conditions, the sequence of EFs from high to low are presented as acceleration (239.3 ± 203.5 mg/L) >idle (226.1 ± 195.6 mg/L) >deceleration (218.5 ± 193.1 mg/L)>uniform (218.2 ± 182.5 mg/L)>slide (176.1 ± 165.2 mg/L). While the cruising speeds increased between 15 and 50 km/h, the linearity between ΣEF declined; however, an opposite trend was seen when the acceleration rates increased. In the chemical speciation, the reactive aromatics contributed the largest fraction of the VOCs (>40%). The ratio of benzene to toluene (B/T) was loaded in high interval (0.94–1.33) in this paper. Larger fluctuation of coefficient of variation (CV) was found among different cumulative mileage and displacement. By taking into account the deterioration effect related to cumulative mileage, emissions of butene, pentene, benzene and toluene were 42.9 Gg, 49.7 Gg, 109.6 Gg and 51.9 Gg in respect for LDGPVs that composed of China III and China IV. ConclusionsOur results demonstrated the necessaries in upgrading the emission control technology. Cumulative mileages and displacements are the two most dominated factors that impacted on the EFs and chemical profiles of VOCs. The higher emission of benzene estimated demonstrated the possible elevation of VOCs in comparison with previous studies.

Emission Control Technologies in Spark Ignition Engines

This paper extensively discusses a review of the latest technologies considered to control emissions in spark-ignition engines in addition to the background and history of the industry. Moreover, the paper discusses in detail the major pollutants affecting the environment negatively, which are Carbon Monoxide (CO), Hydrocarbons (HC), Oxides of Nitrogen (NOx), Sulfur Oxides (SOx), Carbon Dioxide (CO2), and Particulates. Furthermore, the crankcase emissions, the fuel system, and the exhaust system are discussed which are considered to be the main sources of pollution coming from a conventional spark-ignition engine. Also, the major emission control technologies in spark-ignition engines among numerous methods could be shortlisted in the following factors: modifications in the engine design and operating parameters, treatment of exhaust products of combustion, and modification of the fuels. Each technology has its branches and subcategories. In this paper, mainly the most prominent, up to date, and effective technologies were reviewed and discussed, which are lean combustion, design of a muffler, automatic hot air intake system, engine compression ratio, modification of combustion chamber, modification of the fuels, treatment of exhaust products of combustion, three-way, and four-way catalytic converters, exhaust gas recirculation (EGR), total emissions control packages, pre-combustion control; (Positive Crankcase Ventilation (PCV), and valve gear design. The points covered were related but not limited to the three main categories mentioned above. Finally, a conclusion and recommendations for future work are considered.

Implication of emission regulation on cost and tariffs of coal-based power plants in India: A system modelling approach

Coal-based thermal power plants (TPPs) are one of the major culprits contributing to the degrading ambient air quality globally. To address this issue, the Government of India revised the emission standards for coal TPPs in 2015. However, the high upfront cost for installing emission control technologies and ambiguity over their impact on electricity tariff and regulatory provisions have led to delays in the implementation of these technologies. In this study, the total investment—including capital, and operational and maintenance costs—required to meet the new emission standards for all existing and proposed TPPs by 2030 and their tariff implications are estimated. Moreover, the potential system-wide reduction in pollutant emissions by 2030 is also calculated.The detailed techno-economic analysis conducted in this study shows that a total investment of USD 59 billion (INR 3,906 billion) is required to meet the new emission standards across all Indian TPPs. In addition, levelized cost of electricity (LCoE) analysis showed that the electricity tariff would increase by 0.37–1.13 cents/kWh (0.25–0.75 INR/kWh) (around 9%–25% increase over the base electricity tariff), depending on the installation of suitable control technologies. Finally, the likely challenges in installing and operating the new controls are identified, and suitable policy recommendations are provided.

Fuel Effects on Regulated and Unregulated Emissions from Three Light-Duty Euro 5 and Euro 6 Diesel Passenger Cars

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Substantial advances in European road vehicle emissions have been achieved over the past 3 decades driven by strengthening revisions in emissions legislation and enabled by advances in fuel, vehicle engine and emissions control technologies. As both vehicle technology and emissions legislation in Europe continue to evolve, Concawe has conducted a study to examine the opportunities that fuels can provide to further reduce emissions from light-duty diesel passenger cars. Three European diesel cars spanning Euro 5, Euro 6b and Euro 6d-TEMP emissions certification levels have been tested over the cold-start WLTC (Worldwide harmonized Light-duty Test Cycle) with 6 fuels: an EN590-compliant B5 (petroleum diesel containing 5% biodiesel by volume), a bio-derived paraffinic diesel, a 50:50 blend of the aforementioned fuels, a low density petroleum-derived B5, a B30 and the same B30 additized with a high dose of cetane number improver. Results have shown that low density fuels with high hydrogen to carbon (H/C) ratio are capable of delivering benefits in tank-to-wheels CO&lt;sub&gt;2&lt;/sub&gt; (carbon dioxide), CO (carbon monoxide), HC (hydrocarbons), other greenhouse gases and NO&lt;sub&gt;x&lt;/sub&gt; (oxides of nitrogen), whereas no further benefits were measured in NH&lt;sub&gt;3&lt;/sub&gt; (ammonia) or in PN (particle number) at the low baseline levels produced by the vehicles. Compared to B5, B30 gave a significant increase in NO&lt;sub&gt;x&lt;/sub&gt; at the tailpipe from the Euro 5 car and engine-out from the Euro 6d-TEMP car but no tailpipe detriments in NOx were measurable in either of the Euro 6 cars, due to the good performance of their NOx aftertreatment devices. The latter results show that some fuel qualities previously important to control emissions such as PN or NOx have become less impactful with the latest engine technologies. The addition of cetane number improver to the B30 did not reduce NOx. The findings suggest that high H/C ratio diesel fuels could offer benefits to both emissions affecting local air quality and to greenhouse gas emissions on a tank-to-wheels basis. The addition of higher FAME (Fatty Acid Methyl Ester) levels to fuels can be used to increase renewable fuel contribution resulting in no penalty in NOx emissions from newer technology vehicles. Compatibility of these fuels with the existing vehicle fleet would require further specific consideration.&lt;/div&gt;&lt;/div&gt;

Approaches to design a surface with tunable wettability: a review on surface properties

Due to the wide application prospects in energy harvesting, conversion, and emission control technology, wettability has gathered momentum in recent years. Surface wettability alteration by nanomaterial fabrication and coating is of recent interest among researchers to attain desirable wetting surfaces. The wettability of liquid over a surface changes with surface properties such as roughness, surface energy, porosity, capillarity, and structure. Eventually, surface chemistry plays major role in changing surface energy which in turn leads to wettability alteration toward wetting and non-wetting extents. Herein, the dependence of surface properties in wettability alteration has been analyzed with the literature reports. Furthermore, surface pre- and post-treatments such as laser, ozone plasma, and UV irradiation contribute to change of surface energy inducing the liquid to encroach toward superhydrophilicity and superhydrophobicity. This review article analyzes the properties that induces wetting and non-wetting ability of liquids over surfaces. Theoretical models opted for wettability determination has been accounted to study the contribution of roughness, porosity, and surface energy. The article provides a clear idea of properties involved in wettability alteration with respect to wide range of applications in energy conversion, oil–water separation, self-cleaning, bio-adhesion, and bio-molecular immobilization.

An Overview on the Catalytic Materials Proposed for the Simultaneous Removal of NOx and Soot.

Vehicular pollution has become a major problem in urban areas due to the exponential increase in the number of automobiles. Typical exhaust emissions, which include nitrogen oxides (NOx), hydrocarbons (HC), carbon monoxide (CO), soot, and particulate matter (PM), doubtless have important negative effects on the environment and human health, including cardiovascular effects such as cardiac arrhythmias and heart attacks, and respiratory effects such as asthma attacks and bronchitis. The mitigation measures comprise either the use of clean alternative fuels or the use of innovative technologies. Several existing emission control technologies have proven effective at controlling emissions individually, such as selective catalytic reduction (SCR) and lean NOx trap (LNT) to reduce NOx and diesel particulate filter (DPF) specifically for PM abatement. These after-treatment devices are the most profitable means to reduce exhaust emissions to acceptable limits (EURO VI norms) with very little or no impact on the engine performances. Additionally, the relative lack of physical space in which to install emissions-control equipment is a key challenge for cars, especially those of small size. For this reason, to reduce both volume and cost of the after-treatment devices integrated catalytic systems (e.g., a sort of a “single brick”) have been proposed, reducing both NOx and PM simultaneously. This review will summarize the currently reported materials for the simultaneous removal of NOx and soot, with particular attention to their nature, properties, and performances.

Real-world gaseous and particulate emissions from Euro IV to VI medium duty diesel trucks

This study offers emission factors for earlier and late technology medium duty diesel particulate filter (DPF) -equipped trucks, operating on real-world conditions. The analysis includes levels of nitrous oxide (N2O) emissions as well as the impacts of DPF regenerations on emission levels. The real-driving gaseous and particulate emissions, as well as fuel consumption of 14 Euro IV, Euro V, and Euro VI medium duty diesel trucks were analysed and the efficiency of different emission control technologies were assessed. Measurements were conducted using portable emission measurement systems (PEMS) over a wide range of driving and operating conditions. Distance-based integration of emission rates over 500 m sections was considered for statistical analysis, providing a large dataset of emission factors to be used for network link-based traffic and emissions modelling. In terms of emissions performance, nitrogen oxides (NOx) levels were in general above the corresponding Euro standard limits, while carbon monoxide (CO), total hydrocarbons (THC) and particulate matter (PM) levels were within limits. Selective catalytic reduction (SCR) -equipped Euro V vehicles were seen to emit more than their non-SCR-equipped counterparts. NOx and fuel consumption were positively correlated with road gradient over the −6% to 6% gradient range. The emission levels of ammonia (NH3) were measured significantly lower than the respective Euro VI provisions for heavy duty engines, while the N2O levels were found to contribute approximately 1% to the respective total greenhouse gases levels. DPF regeneration events in real world seem to have a measurable impact mostly on THC and PM emissions, increasing baseline levels by 8.1% and 29%, respectively, for Euro VI vehicles.

Mechanism of accelerating soot oxidation by NO2 from diesel engine exhaust

NO2 oxidation of soot exhausted from engines is more efficient than O2 under low-temperature conditions, and is crucial for diesel particulate filter to control soot pollution. To explore the principle behind accelerating soot oxidation by NO2, this paper uses density functional theory to reveal soot oxidation process by NO2. This study contributes to understanding rules of soot oxidation by NO2 and perfecting soot oxidation models to develop soot emission control technologies. Results show that NO2 oxidation of pyrene radical involves three steps. Firstly, NO2 attacks the C∗ atom to form –C (NO2) with reaction energy of 306.3 kJ/mol, which decomposes to produce a –C (O) compound. Secondly, another NO2 molecule climbs over an energy barrier of 8.8 kJ/mol, and changes into a –C (ONO2) intermediate on –C (O). Finally, the N or O atom of NO2 attacks –C (O) for a second time to help open aromatic ring for releasing CO or CO2. Further decomposition of –C (NO2) and –C (ONO2) requires activation energies of 81.6 kJ/mol, 75.7 kJ/mol, and 53.5 kJ/mol, respectively, on preferential pathways. Calculations prove that attacks of O atom from NO2 on C∗ help open the aromatic ring more efficiently than N atom.

Transformation of selenium during coal thermal conversion: Effects of atmosphere and inorganic content

Study on selenium (Se) transformation during coal combustion will facilitate the development of emission–control technologies. A fixed–bed reactor was used to conduct pyrolysis and combustion experiments involving three types of coal at 600–1000 °C. In an inert atmosphere, the release ratios of Se increased slowly as temperature increased, varying between 56% and 74% for different coals at 1000 °C. All forms of Se in coal were thermally unstable and the conversion of Se in other forms into residual and organic–bound Se occurred. In an oxidizing atmosphere, the release ratios of Se differed significantly for different coals at low temperatures, but approached 100% at 1000 °C. Each form of Se in coal was released in different ratios. The water–soluble and ion–exchangeable Se, and carbonate– and oxide–bound Se were produced in the solid products. The oxidizing atmosphere was more conducive to the release of Se because the sulfide– and organic–bound Se was fully oxidized. Se could be converted into water–soluble and ion–exchangeable form and released less in Ca–rich coal. Sulfur (S) prohibited Ca from adsorbing Se by forming CaSO4, promoting the release of Se in S–rich coal.

Currunt status of NOx emission treatment in Marine Diesel Engine

Nitrogen oxide (NOx) of marine diesel engine is a great denger to environment, which is one of the world’s recognized atmospheric pollutants. In this paper, on the basis of describing the international emission regalations and the NOx generatingroute, we have introduced the emission control technology and the development tendency of the pretreatment, in—machine purification and after— treatment. It can provide some guidance for China’s reseach and development.

State-of-the-art outlook for light-duty vehicle emission control standards and technologies in China

A surge in the size of the automobile population has caused vehicular emissions to become a major source of urban atmospheric pollution. Elevating standards is an effective method of controlling vehicular emissions and improving air quality. Light-duty vehicles are the major contributors to HC and CO emissions as they constitute a large proportion of all vehicles. Consequently, controlling light-duty vehicular emissions has been the primary means of air pollution prevention in China. This paper first reviews the progress of emission control standards in mainland China. Second, it analyzes features of the China 6 emissions standards, namely the continuation of European standards, the harmony of global technology regulations, and fusion with the standards of the USA. This is followed by a description and discussion of the status of research on mainstream after-treatment technologies such as the gasoline particulate filter, lean-NOx trap, and selective catalytic reduction. Finally, this study argues that the technical routes for implementing three-way catalysts, gasoline particulate filters, and onboard refueling vapor recovery in gasoline vehicles and diesel oxidation catalysts, diesel particulate filters, and selective catalyst reduction in diesel vehicles meet China 6 standards. Moreover, onboard diagnostics-based control of light vehicle emissions is introduced, and the development directions of vehicle gasoline (the reduction in sulfur, olefin, and aromatic content and vapor pressure control in summer) and vehicle diesel (an increase in the Cetane number and reduction in the forecasted polycyclic aromatic content) are discussed. State-of-the-art outlook for light-duty vehicle emission control standards in China

Carbon dioxide capture by ammonium hydroxide solution and its possible application in cement industry

Abstract Carbon dioxide capture by ammonia is considered one of the promising technologies for emission control in cement plants. This paper focuses on the experimental investigation of the factors affecting the chemical absorption process of carbon dioxide by ammonium hydroxide solution. The factors include ammonia concentration below 14%, reaction temperature below 20 °C and reaction time 30 min as the optimum parameters. The paper also highlights the economic and practical aspects to be taken into consideration when applying this technology to cement plants.

Comprehensive Evaluation Method and Case Study on the Promotion and Application Effectiveness of Shore Power Supply Systems

The use of shore power supply system for ships at ports is one of the key promotion technologies for ship emission control according China’s 13th Five-Year Plan.However, there currently lacks established evaluation methods both in Chinaand abroad for the assessment ofshore power effectiveness. This study focuses on the most prevalent issues faced by various local regions in their promotion and application of shore power, proposes a set of evaluation methods tailoredfor local governments in the evaluation of promotion and application from five perspectives: construction and utilization of shore power facilities, institutional mechanisms, incentive policies and regulatory framework as well as a comprehensive evaluation of shore power effectivenessin Shenzhen as a case study. Results demonstrate that theevaluation method can fully reflect the effectiveness of local governments in their promotion of shore power, identify existing issues and opportunities for improvement, and may provide a baseline for the next-phase promotion of regional shore power facilities.

Estimating historical SO2 level across the whole China during 1973–2014 using random forest model

Ambient SO2 pollution poses a great threat on air quality, human health, and ecosystem safety. The ground-level SO2 monitoring sites over China have been established during the past years, while the long-term SO2 data was still missing before 2014, which cannot reveal the evolution trend of SO2 pollution and assess its response to the anthropogenic activity. In this work, we developed a high-quality random forest (RF) model to simulate the long-term SO2 concentration across the entire China from 1973 to 2014, based on substantial explanatory variables (e.g., meteorological factors, SO2 emission intensity, land use types). The 10-fold cross-validation R2 value and root mean square error (RMSE) over China reached 0.64 and 17.06 μg/m3, respectively, both of which were significantly higher than those of other models such as back propagation neural network (BPNN) and generalized regression neutral network (GRNN). Among all of the predictors, T displayed the highest relative importance value, followed by WS, Prec, SO2 emission intensity, RH, DOY, elevation, and the lower one for land use types and P. The estimated mean SO2 concentration during 1973–2014 displayed the remarkably spatial variation with the higher value in North China Plain (NCP) and Middle part of Inner Mongolia. This historical SO2 level estimation suggested that air pollution was not a new environmental issue that could be dated back to 1973. Overall, the annually mean SO2 level for each grid increased from 29.46 ± 9.79 to 31.44 ± 8.77 μg/m3 from 1973 to 2014. The annually mean SO2 concentration in NCP showed rapid increase from 34.32 ± 3.05 to 36.97 ± 3.18 μg/m3 during 1973–2002, whereas they decreased significantly after 2003 (from 37.46 ± 3.20 to 36.13 ± 3.48 μg/m3 during 2003–2014). The gradual decrease since 2003 was benefitted from the adjustment of the energy consumption structure and the adoption of emission control technologies. However, the SO2 levels in some western regions showed the violent increases since 2003 due to the proposal of “development of the western region”. The estimated daily SO2 concentration across the entire China could provide the essential data for epidemiological research and air pollution prevention.

Methodology for calculating diesel SCR systems

Selective catalytic reduction systems are widely applied as a NOX emission control technology in modern onand off highway diesel engines. Considering the stringent limits of emission standards, they should ensure high rates of conversion efficiency. To achieve that at the design stage numerical modelling is used to optimize physical and chemical processes. New mathematical models and methods that can provide the reduction of calculation time and related costs keeping the acceptable level of prediction accuracy are desired. In this study a methodology for calculating SCR systems based on the use both of CFD models and simplified catalyst models are presented. The capabilities of the suggested numerical approach were demonstrated during the simulations of a SCR system where the influence of UWS injection angle on NOX reduction efficiency was investigated.

Spatial and temporal variation in the value of solar power across United States electricity markets

The cost of utility-scale photovoltaics (PV) has declined rapidly over the past decade. Yet increased renewable electricity generation, decreased natural gas prices, and deployment of emissions-control technology across the United States have led to concurrent changes in electricity prices and power system emissions rates, each of which influence the value of PV electricity. An ongoing assessment of the economic competitiveness of PV is therefore necessary as PV cost and value continue to evolve. Here, we use historical nodal electricity prices, capacity market prices, marginal power system emissions rates of CO2 and air pollutants, and weather data to model the energy, capacity, health, and climate value of PV electricity at over 10 000 locations across six U.S. Independent System Operators (ISOs) from 2010 to 2017. On the energy and capacity markets, transmission congestion in some locations and years results in PV revenues that are more than double the median across the relevant ISO. While the marginal public health benefits from avoided SO2, NOx, and PM2.5 emissions have declined over time in most ISOs, monetizing the health benefits of PV generation in 2017 would increase median PV energy revenues by 70% in MISO and NYISO and 100% in PJM. Given 2017 PV costs, electricity prices, and grid conditions, PV breaks even at 30% of modeled locations on the basis of energy, capacity, and health benefits, at 75% of modeled locations with the addition of a 50 $/ton CO2 price, and at 100% of modeled locations with a 100 $/ton CO2 price. These results suggest that PV cost decline has outpaced value decline over the past decade, such that in 2017 the net benefits of utility-scale PV outweigh the cost at the majority of modeled locations.

An advanced, ammonia-based combined NOx/SOx/CO2 emission control process towards a low-cost, clean coal technology

Traditional method of removing gas pollutants from a coal-fired power station involves a series of separate processes, which include selective catalytic reduction for NOx treatment, flue gas desulfurisation for SOx removal, and post-combustion CO2 capture. Each of these individual processes involves significant capital investment. To reduce costs, we propose an alternative approach to simultaneously remove these three pollutants by incorporating NOx/SOx treatment into an aqueous NH3-based CO2 capture process. In our advanced process design, NOx/SOx pollutants are effectively scrubbed by sodium chlorite (NaClO2) oxidizing reagent, with the resultant acidic solution efficiently reducing NH3 emissions from CO2 absorber to <1 ppmv. An advanced, NH3-based flash stripper is used to achieve high capture energy performance, and flue gas heat integration is employed to further reduce the regeneration energy to 2.17 GJ/tonne CO2. Techno-economic evaluation revealed that our NH3-based combined NOx/SOx/CO2 removal process has great advantages in capital and energy saving, resulting in a CO2-avoided cost of $46.2/tonne, which is significantly lower than the cost of the conventional, monoethanolamine-based process ($79.1/tonne CO2) and the base NH3 process ($56.2/tonne CO2). This simultaneous NOx/SOx/CO2 capture technology provides an alternative approach to advancing multi-pollutant emission control and CO2-capture technology, leading to the development of a cost-effective clean coal technology.

Significant climate impacts of aerosol changes driven by growth in energy use and advances in emission control technology

Abstract. Anthropogenic aerosols have increased significantly since the industrial revolution, driven largely by growth in emissions from energy use in sectors including power generation, industry, and transport. Advances in emission control technologies since around 1970, however, have partially counteracted emissions increases from the above sectors. Using the fully coupled Community Earth System Model, we quantify the effective radiative forcing (ERF) and climate response to 1970–2010 aerosol changes associated with the above two policy-relevant emission drivers. Emissions from energy-use growth generate a global mean aerosol ERF (mean ± 1 standard deviation) of -0.31±0.22 W m−2 and result in a global mean cooling (-0.35±0.17 K) and a precipitation reduction (-0.03±0.02 mm d−1). By contrast, the avoided emissions from advances in emission control technology, which benefit air quality, generate a global mean ERF of +0.21±0.23 W m−2, a global warming of +0.10±0.13 K, and global mean precipitation increase of +0.01±0.02 mm d−1. Despite the relatively small changes in global mean precipitation, these two emission drivers have profound impacts at regional scales, in particular over Asia and Europe. The total net aerosol impacts on climate are dominated by energy-use growth, from Asia in particular. However, technology advances outweigh energy-use growth over Europe and North America. Various non-linear processes are involved along the pathway from aerosol and their precursor emissions to radiative forcing and ultimately to climate responses, suggesting that the diagnosed aerosol forcing and effects must be interpreted in the context of experiment designs. Further, the temperature response per unit aerosol ERF varies significantly across many factors, including location and magnitude of emission changes, implying that ERF, and the related metrics, needs to be used very carefully for aerosols. Future aerosol-related emission pathways have large temporal and spatial uncertainties; our findings provide useful information for both assessing and interpreting such uncertainties, and they may help inform future climate change impact reduction strategies.