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1.
Abstract Comprehensive surveys conducted at 5-yr intervals were used to estimate sulfur dioxide (SO 2) and nitrogen oxides (NO x) emissions from U.S. pulp and paper mills for 1980, 1985, 1990, 1995, 2000, and 2005. Over the 25-yr period, paper production increased by 50%, whereas total SO 2 emissions declined by 60% to 340,000 short tons (t) and total NO x emissions decreased approximately 15% to 230,000 t. The downward emission trends resulted from a combination of factors, including reductions in oil and coal use, steadily declining fuel sulfur content, lower pulp and paper production in recent years, increased use of flue gas desulfurization systems on boilers, growing use of combustion modifications and add-on control systems to reduce boiler and gas turbine NO x emissions, and improvements in kraft recovery furnace operations. 相似文献
2.
Abstract Recent regulations have required reductions in emissions of nitrogen oxides (NO x) from electric utility boilers. To comply with these regulatory requirements, it is increasingly important to implement state-of-the-art NO x control technologies on coal-fired utility boilers. This paper reviews NO x control options for these boilers. It discusses the established commercial primary and secondary control technologies and examines what is being done to use them more effectively. Furthermore, the paper discusses recent developments in NO x controls. The popular primary control technologies in use in the United States are low-NO x burners and overfire air. Data reflect that average NO x reductions for specific primary controls have ranged from 35% to 63% from 1995 emissions levels. The secondary NO x control technologies applied on U.S. coal-fired utility boilers include reburning, selective noncatalytic reduction (SNCR), and selective catalytic reduction (SCR). Thirty-six U.S. coal-fired utility boilers have installed SNCR, and reported NO x reductions achieved at these applications ranged from 15% to 66%. Recently, SCR has been installed at >150 U.S. coal-fired utility boilers. Data on the performance of 20 SCR systems operating in the United States with low-NO x emissions reflect that in 2003, these units achieved NO x emission rates between 0.04 and 0.07 lb/10 6 Btu. 相似文献
3.
The most effective control technology available for the reduction of oxides of nitrogen (NO x) from coal-fired boilers is selective catalytic reduction (SCR). Installation of SCR on coal-fired electric generating units (EGUs) has grown substantially since the onset of the U.S. Environmental Protection Agency’s (EPA) first cap and trade program for oxides of nitrogen in 1999, the Ozone Transport Commission (OTC) NO x Budget Program. Installations have increased from 6 units present in 1998 in the states that encompass the current Cross-State Air Pollution Rule (CSAPR) ozone season program to 250 in 2014. In recent years, however, the degree of usage of installed SCR technology has been dropping significantly at individual plants. Average seasonal NO x emission rates increased substantially during the Clean Air Interstate Rule (CAIR) program. These increases coincided with a collapse in the cost of CAIR allowances, which declined to less than the cost of the reagent required to operate installed SCR equipment, and was accompanied by a 77% decline in delivered natural gas prices from their peak in June of 2008 to April 2012, which in turn coincided with a 390% increase in shale gas production between 2008 and 2012. These years also witnessed a decline in national electric generation which, after peaking in 2007, declined through 2013 at an annualized rate of ?0.3%. Scaling back the use of installed SCR on coal-fired plants has resulted in the release of over 290,000 tons of avoidable NO x during the past five ozone seasons in the states that participated in the CAIR program. Implications: To function as designed, a cap and trade program must maintain allowance costs that function as a disincentive for the release of the air pollutants that the program seeks to control. If the principle incentive for reducing NO x emissions is the avoidance of allowance costs, emissions may be expected to increase if costs fall below a critical value, in the absence of additional state or federal limitations. As such, external factors as the cost of competing fuels and a low or negative growth of electric sales may also disincentivize the use of control technologies, the continuation of desirable emission rates will be best maintained by the implementation of performance standards that supplement and complement the emissions trading program. 相似文献
4.
Exposure to traffic emission is harmful to human health. Emission inventories are essential to public health policies aiming at protecting human health, especially in areas with incomplete or nonexistent air pollution monitoring networks. In Brazil, for example, only 1.7% of municipal districts have a monitoring network, and only a few studies have reported data on vehicle emission inventories. No studies have presented emission inventories by municipality. In this study, we predicted vehicular emissions for 5570 municipal districts in Brazil during the period 2001–2012. We used a top-down method to estimate emissions. Carbon dioxide (CO 2) is the pollutant with the highest emissions, with approximately 190 million tons per year during the period 2001–2012). For the other traffic-related pollutants, we predicted annual emissions of 1.5 million tons for carbon monoxide (CO), 1.2 million tons of nitrogen oxides (NO x), 209,000 tons of nonmethane hydrocarbons (NMHC), 58,000 tons of particulate matter (PM), and 42,000 tons for methane (CH 4). From 2001 to 2012, CO, NMHC, and PM emissions decreased by 41, 33, and 47%, respectively, whereas those CH 4, NO x, and CO 2 increased by 2, 4, and 84%, respectively. We estimated uncertainties in our study and found that NO x was the pollutant with the lowest percentage difference, 8%, and NMHC with the highest one, 30%. For CO, CH 4, CO 2, and PM, the values were 22, 14, 21, and 20%, respectively. Finally, we found that during 2001 and 2012 emissions increased in the Northwest and Northeast. In contrast, pollutant emissions, except for CO 2, decreased in the Southeast, South, and part of Midwest. Our predictions can be critical to efforts developing cost-effective public policies tailored to individual municipal districts in Brazil. Implications: Emission inventories may be an alternative approach to provide data for air quality forecasting in areas where air quality data are not available. This approach can be an effective tool in developing spatially resolved emission inventories. 相似文献
5.
The Van Nuys Tunnel experiment conducted in 1987 by Ingalls et al. (see A&WMA Paper 89-137.3), to verify automotive emission inventories as part of the Southern California Air Quality Study (SCAQS), gave higher CO and HC emission-rate values than expected on the basis of automotive-emission models—by factors of approximately 3 and 4, respectively. The CO/NO X and HC/NO X emission-rate ratios moreover were higher than expected—by similar factors (NO X emission rates were about as expected). The purpose of the present paper is to review the literature on dynamometer and on-road (in tunnels and along roadways) testing of in-use vehicles, and on urban-air CO/HC/NO X concentration ratios, to see whether the Van Nuys Tunnel results are reasonable in terms of previous experience. The conclusions are that (1) on-road CO and HC emissions higher than expected have been reported before, (2) on-road CO and HC emissions consistent with the Van Nuys Tunnel results have been reported before, and (3) on-road CO/NO X and HC/NO X emission-rate ratios higher than expected have been reported before. The Van Nuys Tunnel NO X results actually are lower than in other on-road experiments, and the CO/NO X and HC/NO X ratios consequently are higher. The higher-than-predicted CO/NO X and HC/NO X ratios at Van Nuys and other on-road sites suggest richer operation on-road than predicted or than observed in the inuse- vehicle dynamometer tests which serve as the model inputs. Support for these suggestions and conclusions is found in comparison of urban-air and emission-inventory HC/NO X ratios. 相似文献
6.
This paper discusses results from a vehicular emissions research study of over 350 vehicles conducted in three communities in Los Angeles, CA, in 2010 using vehicle chase measurements. The study explores the real-world emission behavior of light-duty gasoline vehicles, characterizes real-world super-emitters in the different regions, and investigates the relationship of on-road vehicle emissions with the socioeconomic status (SES) of the region. The study found that in comparison to a 2007 earlier study in a neighboring community, vehicle emissions for all measured pollutants had experienced a significant reduction over the years, with oxides of nitrogen (NO X) and black carbon (BC) emissions showing the largest reductions. Mean emission factors of the sampled vehicles in low-SES communities were roughly 2–3 times higher for NO X, BC, carbon monoxide, and ultrafine particles, and 4–11 times greater for fine particulate matter (PM 2.5) than for vehicles in the high-SES neighborhood. Further analysis indicated that the emission factors of vehicles within a technology group were also higher in low-SES communities compared to similar vehicles in the high-SES community, suggesting that vehicle age alone did not explain the higher vehicular emission in low-SES communities. Evaluation of the emission factor distribution found that emissions from 12% of the sampled vehicles were greater than five times the mean from all of the sampled fleet, and these vehicles were consequently categorized as “real-world super-emitters.” Low-SES communities had approximately twice as many super-emitters for most of the pollutants as compared to the high-SES community. Vehicle emissions calculated using model-year-specific average fuel consumption assumptions suggested that approximately 5% of the sampled vehicles accounted for nearly half of the total CO, PM2.5, and UFP emissions, and 15% of the vehicles were responsible for more than half of the total NOX and BC emissions from the vehicles sampled during the study. Implications: This study evaluated the real-world emission behavior and super-emitter distribution of light-duty gasoline vehicles in California, and investigated the relationship of on-road vehicle emissions with local socioeconomic conditions. The study observed a significant reduction in vehicle emissions for all measured pollutants when compared to an earlier study in Wilmington, CA, and found a higher prevalence of high-emitting vehicles in low-socioeconomic-status communities. As overall fleet emissions decrease from stringent vehicle emission regulations, a small fraction of the fleet may contribute to a disproportionate share of the overall on-road vehicle emissions. Therefore, this work will have important implications for improving air quality and public health, especially in low-SES communities. 相似文献
7.
The information presented is directed to those individuals concerned with reducing nitrogen oxides (NO x ) emissions from gas, oil, or coal fired utility steam generators. First, this paper presents NO x emission data obtained in the testing of tangentially fired utility boilers; second, it relates these data to the general body of information developed by other investigators in the areas of theoretical analysis and bench scale and full scale testing; and finally, it discusses current design practice in relation to NO x emission control and the continuing R&D effort required to assure acceptable control technology. 相似文献
8.
Remote sensing devices have been used for decades to measure gaseous emissions from individual vehicles at the roadside. Systems have also been developed that entrain diluted exhaust and can also measure particulate matter (PM) emissions. In 2015, the California Air Resources Board (CARB) reported that 8% of in-field diesel particulate filters (DPF) on heavy-duty (HD) vehicles were malfunctioning and emitted about 70% of total diesel PM emissions from the DPF-equipped fleet. A new high-emitter problem in the heavy-duty vehicle fleet had emerged. Roadside exhaust plume measurements reflect a snapshot of real-world operation, typically lasting several seconds. In order to relate roadside plume measurements to laboratory emission tests, we analyzed carbon dioxide (CO 2), oxides of nitrogen (NO X), and PM emissions collected from four HD vehicles during several driving cycles on a chassis dynamometer. We examined the fuel-based emission factors corresponding to possible exceedances of emission standards as a function of vehicle power. Our analysis suggests that a typical HD vehicle will exceed the model year (MY) 2010 emission standards (of 0.2 g NO X/bhp-hr and 0.01 g PM/bhp-hr) by three times when fuel-based emission factors are 9.3 g NO X/kg fuel and 0.11 g PM/kg using the roadside plume measurement approach. Reported limits correspond to 99% confidence levels, which were calculated using the detection uncertainty of emissions analyzers, accuracy of vehicle power calculations, and actual emissions variability of fixed operational parameters. The PM threshold was determined for acceleration events between 0.47 and 1.4 mph/sec only, and the NO X threshold was derived from measurements where after-treatment temperature was above 200°C. Anticipating a growing interest in real-world driving emissions, widespread implementation of roadside exhaust plume measurements as a compliment to in-use vehicle programs may benefit from expanding this analysis to a larger sample of in-use HD vehicles. Implications: Regulatory agencies, civil society, and the public at large have a growing interest in vehicle emission compliance in the real world. Leveraging roadside plume measurements to identify vehicles with malfunctioning emission control systems is emerging as a viable new and useful method to assess in-use performance. This work proposes fuel-based emission factor thresholds for PM and NOx that signify exceedances of emission standards on a work-specific basis by analyzing real-time emissions in the laboratory. These thresholds could be used to prescreen vehicles before roadside enforcement inspection or other inquiry, enhance and further develop emission inventories, and potentially develop new requirements for heavy-duty inspection and maintenance (I/M) programs, including but not limited to identifying vehicles for further testing. 相似文献
9.
The existing and emerging international and European policy framework for the reduction of ship exhaust emissions dictates the need to produce reliable national, regional and global inventories in order to monitor emission trends and consequently provide the necessary support for future policy making. Furthermore, the inventories of ship exhaust emissions constitute the basis upon which their external costs are estimated in an attempt to highlight the economic burden they impose upon the society and facilitate the cost–benefit analysis of the proposed emission abatement technologies, operational measures and market-based instruments prior to their implementation.The case of Greece is of particular interest mainly because the dense ship traffic within the Greek seas directly imposes the impact of its exhaust emission pollutants (NO x, SO 2 and PM) upon the highly populated, physically sensitive and culturally precious Greek coastline, as well as upon the land and seas of Greece in general, whereas the contribution of Greece in the global CO 2 inventory at a time of climatic change awareness cannot be ignored. In this context, this paper presents the contribution of Greece in ship exhaust emissions of CO 2, NO x, SO 2 and PM from domestic and international shipping over the last 25 years (1984–2008), utilizing the fuel-based (fuel sales) emission methodology. Furthermore, the ship exhaust emissions generated within the Greek seas and their externalities are estimated for the year 2008, through utilizing the fuel-based (fuel sales) approach for domestic shipping and the activity-based (ship traffic) approach for international shipping.On this basis, it was found that during the 1984 to 2008 period the fuel-based (fuel sales) ship emission inventory for Greece increased at an average annual rate of 2.85%. In 2008, the CO 2, NO x, SO 2 and PM emissions reached 12.9 million tons (of which 12.4 million tons of CO 2) and their externalities were found to be around 3.1 billion euro. With regard to shipping within the Greek seas, the utilization of the fuel-based (fuel sales) analysis for domestic shipping and the activity-based (ship traffic) analysis for international shipping shows that the ship-generated emissions reached 7.4 million tons (of which 7 million tons of CO 2) and their externalities were estimated at 2.95 billion euro. Finally, the internalization of external costs for domestic shipping was found to produce an increase of 12.96 and 2.71 euro per passenger and transported ton, respectively. 相似文献
10.
This study quantifies the trade-offs and synergies between climate and air quality policy objectives for the European power and heat (P&H) sector. An overview is presented of the expected performance data of CO 2 capture systems implemented at P&H plants, and the expected emission of key air pollutants, being: SO 2, NO X, NH 3, volatile organic compounds (VOCs) and particulate matter (PM). The CO 2 capture systems investigated include: post-combustion, oxyfuel combustion and pre-combustion capture.For all capture systems it was found that SO 2, NO x and PM emissions are expected to be reduced or remain equal per unit of primary energy input compared to power plants without CO 2 capture. Increase in primary energy input as a result of the energy penalty for CO 2 capture may for some technologies and substances result in a net increase of emissions per kWh output. The emission of ammonia may increase by a factor of up to 45 per unit of primary energy input for post-combustion technologies. No data are available about the emission of VOCs from CO 2 capture technologies.A simple model was developed and applied to analyse the impact of CO 2 capture in the European P&H sector on the emission level of key air pollutants in 2030. Four scenarios were developed: one without CO 2 capture and three with one dominantly implemented CO 2 capture system, varying between: post-combustion, oxyfuel combustion and pre-combustion.The results showed a reduction in GHG emissions for the scenarios with CO 2 capture compared to the baseline scenario between 12% and 20% in the EU 27 region in 2030. NO x emissions were 15% higher in the P&H sector in a scenario with predominantly post-combustion and lower when oxyfuel combustion (?16%) or pre-combustion (?20%) were implemented on a large scale. Large scale implementation of the post-combustion technology in 2030 may also result in significantly higher, i.e. increase by a factor of 28, NH 3 emissions compared to scenarios with other CO 2 capture options or without capture. SO 2 emissions were very low for all scenarios that include large scale implementation of CO 2 capture in 2030, i.e. a reduction varying between 27% and 41%. Particulate Matter emissions were found to be lower in the scenarios with CO 2 capture. The scenario with implementation of the oxyfuel technology showed the lowest PM emissions followed by the scenario with a significant share allocated to pre-combustion, respectively ?59% and ?31%. The scenario with post-combustion capture resulted in PM emissions varying between 35% reduction and 26% increase. 相似文献
12.
The observed ranges in nonmethane organic compound (NMOC) concentrations, NMOC composition and nitrogen oxides (NO X) concentrations have been evaluated for urban and nonurban areas at ground level and aloft of the contiguous United States. The ranges in NMOC to NO X ratios also are considered. The NMOC composition consistently shifts towards less reactive compounds, especially the alkanes, in air parcels over nonurban areas compared to the NMOC composition near ground level within urban areas. The values for the NMOC to NO X ratios, 1.2 to 4.2, in air aloft over nonurban areas are lower than in air at ground level urban sites, ≥8, and much lower than in air at ground level nonurban sites, ≥20. The layers of air aloft over a number of nonurban areas of the United States tend to accumulate NO X emissions from the tall stacks of large fossil fuel power plants located at nonurban sites. During the night into the morning hours, the air aloft is isolated from any fresh NMOC emissions predominately coming from near surface sources. Conversely, during this extended period of restricted vertical mixing, air near the surface accumulates NMOC emissions while this air is isolated from the major NO X sources emitting aloft. These differences in the distribution of NMOC and NO X sources appear to account for the much larger NMOC to NO X ratios reported near ground level compared to aloft over nonurban areas. Two types of experimental results are consistent with these conclusions: (1) observed increases in surface rural NO X concentrations during the morning hours during which the mixing depth increases to reach the altitude at which NO X from the stacks of fossil fuel power plants is being transported downwind; (2) high correlations of total nitrate at rural locations with Se, which is a tracer for coal-fired power plant NO X emissions. The implications of these conclusions from the standpoint of air quality strategies are suggested by use of appropriate scenarios applied to both urban and regional scale photochemical air quality models. The predictions from urban model scenarios with NMOC to NO X ratios up to 20 are that NO X control will result in the need for the control of more NMOC emissions than necessary in the absence of NO X control, in order to meet the O 3 standard. On a regional scale, control of NO X emissions from fossil fuel power plants has little overall effect regionally but does result on a more local scale in both small decreases and increases in O 3 concentrations compared to the baseline scenario without NO X control. The regional modeling results obtained to date suggest that NO X control may be effective in reducing O 3 concentrations only for a very limited set of conditions in rural areas. 相似文献
13.
An assessment of recent trends in primary NO 2 emissions has been carried out for ten case study locations across the European Union. Estimates of the percentage of NO x from road traffic emitted as primary NO 2 (f-NO 2) have been derived for 1995, 2000 and 2005 by combining the results of a literature survey of primary NO 2 emission factors for different vehicle types and technologies with an emission inventory. Estimates of f-NO 2 have also been derived from ambient monitoring data at roadside sites in each case study location using a model.The results of the analysis of trends show that f-NO 2 has increased in recent years and that the rate of increase has been greatest since 2000. f-NO 2 has increased from 8.6% in 2000 to 12.4% in 2004 as an average across the monitoring sites and from an average of 6.3% in 2000 to 10.6% in 2005 as an average of the emission inventory based calculations for the case study countries. f-NO 2 is predicted to increase further to an average of 19.6% in 2010 and 32.0% in 2020 as a result of the further penetration of exhaust after treatment technologies for diesel vehicles in the fleets. This increase is expected to be offset by the large reduction in NO x emissions over this period, resulting in an increase in NO 2 emissions from road traffic to 2015, followed by a decline to close to 2004 levels by 2020. Estimates of future ambient NO 2 concentrations have also been calculated for the roadside monitoring sites included in the study. At 29 out of 45 of these sites the annual mean NO 2 limit value is predicted to be exceeded in 2010. At 22 of these sites, the annual mean concentration is expected to remain above the limit value until 2020 and beyond. 相似文献
14.
A generalised additive modelling (GAM) approach is used to model daily concentrations of nitrogen oxides (NO X), nitrogen dioxide (NO 2), carbon monoxide (CO), benzene and 1,3-butadiene at a busy street canyon location in central London. The models were developed for the period July 1998–June 2005 using appropriate meteorological and road traffic covariates. For all models, the complex and localised wind-flow patterns resulting from the street canyon location of the monitoring site, which can be difficult to model deterministically, have a large influence on the model predictions. It is shown that GAMs built using simple covariates explain a large amount of the daily variation for these pollutants (mean r2=0.86). It is found that concentrations of benzene and 1,3-butadiene have declined in line with detailed calculations of emissions trends, with some evidence to suggest that reductions in benzene have been greater than estimated reductions in emissions. Although measured concentrations of NO X have declined from 1998 to 2005, much of the decline appears to be associated with reductions in overall traffic and meteorological factors rather than reduced emissions of NO X. Unadjusted NO X trends show a 28.6% reduction (95% confidence interval from 21.2% to 35.8%) from 1998 to 2005, whereas meteorologically adjusted trends show a 19.3% decline (95% confidence interval from 14.8% to 23.5%) over this period. Analysis shows that there were a higher number of occasions in the early part of the time series that led to strong recirculation of exhaust emissions and higher NO X concentrations at this location, thus affecting observed trends in concentration. 相似文献
15.
An investigation of the concentrations of nitrogen oxides (NO X) from an air quality model and observations at monitoring sites was performed to assess the changes in NO X levels attributable to changes in mobile emissions. This evaluation effort focused on weekday morning rush hours since urban NO X concentrations are strongly influenced by the significant loading of emissions associated with heavy commuter traffic. On-road vehicle NO X emissions generated by the MOBILE6 model revealed a steady decline with an overall decrease of 25% for 2002–2006. In this study, a dynamic model evaluation was undertaken that entails an assessment of the predicted concentration response of the Community Multiscale Air Quality (CMAQ) model due to changes in NO X emissions as well as to meteorological variability spanning 3-month summer periods over five consecutive years (2002–2006) against observed concentration changes at NO X monitoring sites located primarily in urban areas of the eastern United States. Both modeled and observed hourly NO X concentrations exhibited maximum values that coincided with the morning peak NO X emissions. The notable results, based on 3-h average (6–9 AM local time) NO X concentrations, derived between the 50th and 95th percentiles of cumulative concentration distributions, revealed that modeled changes at these elevated NO X levels generally tracked the year-to-year variations in the observed concentration changes. When summer 2002 values were used as a reference, both modeled and observed results also showed definitive decreases in weekday morning urban NO X concentrations over this multi-year period, which can be primarily attributed to the reductions in mobile source emissions. Whereas observed NO X concentrations have declined by about 25% over this period consistent with the decline in the modeled mobile emission sector, modeled NO X concentration changes were close to the decreases exhibited in all (mobile + other sectors) surface NO X emissions whose overall decline was about 15% over this multi-year period. 相似文献
16.
Abstract In this paper, we examine the changes in ambient ozone concentrations simulated by the Community Multiscale Air Quality (CMAQ) model for summer 2002 under three different nitrogen oxides (NO x) emission scenarios. Two emission scenarios represent best estimates of 2002 and 2004 emissions; they allow assessment of the impact of the NO x emissions reductions imposed on the utility sector by the NO x State Implementation Plan (SIP) Call. The third scenario represents a hypothetical rendering of what NO x emissions would have been in 2002 if no emission controls had been imposed on the utility sector. Examination of the modeled median and 95th percentile daily maximum 8-hr average ozone concentrations reveals that median ozone levels estimated for the 2004 emission scenario were less than those modeled for 2002 in the region most affected by the NO x SIP Call. Comparison of the “no-control” with the “2002” scenario revealed that ozone concentrations would have been much higher in much of the eastern United States if the utility sector had not implemented NO x emission controls; exceptions occurred in the immediate vicinity of major point sources where increased NO titration tends to lower ozone levels. 相似文献
17.
In this paper, the NOx emission scaling factors applied over the 2001 National Emissions Inventory (NEI) are estimated through a four-dimensional variational (4D-Var) approach using SCIAMACHY (Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY) tropospheric NO 2 columns measured during summer 2004. In the “top-down” approach, two-month average NO 2 columns are assimilated into a regional chemical transport model (CTM), STEM, using different assimilation setups. In a basic setup, NOx emissions are adjusted by assimilating the NO 2 columns. A more general setup of emission inversion allows the initial O 3 concentrations be adjusted along with the NOx emissions. A final case is set up to assimilate both the NO 2 columns and O 3 measurement from various platforms while allowing adjustments of both the NOx emissions and the initial O 3 concentrations. It is found that the addition of O 3 measurements did not improve the NOx emission inversion. With the NOx emission at surface and upper levels being adjusted separately, results from four cases show that the elevated NOx emission reduction ranges from 8.9% to 11.4%, and the surface NOx emission reduction is up to 6.6%. All the cases show NOx emission reduction in Ohio valley and Washington, District of Columbia areas. 相似文献
18.
This study proposes an easy-to-apply method, the Total Life Cycle Emission Model (TLCEM), to calculate the total emissions from shipping and help ship management groups assess the impact on emissions caused by their capital investment or operation decisions. Using TLCEM, we present the total emissions of air pollutants and greenhouse gases (GHGs) during the 25-yr life cycle of 10 post-Panamax containerships under slow steaming conditions. The life cycle consists of steel production, shipbuilding, crude oil extraction and transportation, fuel refining, bunkering, and ship operation. We calculate total emissions from containerships and compare the effect of emission reduction by using various fuels. The results can be used to differentiate the emissions from various processes and to assess the effectiveness of various reduction approaches. Critical pollutants and GHGs emitted from each process are calculated. If the containerships use heavy fuel oil (HFO), emissions of CO 2 total 2.79 million tonnes (Mt), accounting for 95.37% of total emissions, followed by NO x and SO x emissions,which account for 2.25% and 1.30%, respectively.The most significant emissions are from the operation of the ship and originate from the main engine (ME).When fuel is switched to 100% natural gas (NG), SO x, PM 10, and CO 2 emissions show remarkable reductions of 98.60%, 99.06%, and 21.70%, respectively. Determining the emission factor of each process is critical for estimating the total emissions. The estimated emission factors were compared with the values adopted by the International Maritime Organization (IMO).The proposed TLCEM may contribute to more accurate estimates of total life cycle emissions from global shipping. Implications: We propose a total life cycle emissions model for 10 post-Panamax container ships. Using heavy fuel oil, emissions of CO2 total 2.79 Mt, accounting for approximately 95% of emissions, followed by NOx and SOx emissions. Using 100% natural gas, SOx, PM10, and CO2 emissions reduce by 98.6%, 99.1%, and 21.7%, respectively. NOx emissions increase by 1.14% when running a dual fuel engine at low load in natural gas mode. 相似文献
19.
The effect of intake valve closure (IVC) timing by utilizing Miller cycle and start of injection (SOI) on particulate matter (PM), particle number, and nitrogen oxide (NO x) emissions was studied with a hydrotreated vegetable oil (HVO)-fueled nonroad diesel engine. HVO-fueled engine emissions, including aldehyde and polyaromatic hydrocarbon (PAH) emissions, were also compared with those emitted with fossil EN590 diesel fuel. At the engine standard settings, particle number and NO x emissions decreased at all the studied load points (50%, 75%, and 100%) when the fuel was changed from EN590 to HVO. Adjusting IVC timing enabled a substantial decrease in NO x emission and combined with SOI timing adjustment somewhat smaller decrease in both NO x and particle emissions at IVC??50 and??70 °CA points. The HVO fuel decreased PAH emissions mainly due to the absence of aromatics. Aldehyde emissions were lower with the HVO fuel with medium (50%) load. At higher loads (75% and 100%), aldehyde emissions were slightly higher with the HVO fuel. However, the aldehyde emission levels were quite low, so no clear conclusions on the effect of fuel can be made. Overall, the study indicates that paraffinic HVO fuels are suitable for emission reduction with valve and injection timing adjustment and thus provide possibilities for engine manufacturers to meet the strictening emission limits. Implications: NO x and particle emissions are dominant emissions of diesel engines and vehicles. New, biobased paraffinic fuels and modern engine technologies have been reported to lower both of these emissions. In this study, even further reductions were achieved with engine valve adjustment combined with novel hydrotreated vegetable oil (HVO) diesel fuel. This study shows that new paraffinic fuels offer further possibilities to reduce engine exhaust emissions to meet the future emission limits. Supplementary Materials: Supplementary materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association for a complete list of analysed PAH compounds. 相似文献
20.
The U.S. Environmental Protection Agency (EPA) established strict regulations for highway diesel engine exhaust emissions of particulate matter (PM) and nitrogen oxides (NO x) to aid in meeting the National Ambient Air Quality Standards. The emission standards were phased in with stringent standards for 2007 model year (MY) heavy-duty engines (HDEs), and even more stringent NO X standards for 2010 and later model years. The Health Effects Institute, in cooperation with the Coordinating Research Council, funded by government and the private sector, designed and conducted a research program, the Advanced Collaborative Emission Study (ACES), with multiple objectives, including detailed characterization of the emissions from both 2007- and 2010-compliant engines. The results from emission testing of 2007-compliant engines have already been reported in a previous publication. This paper reports the emissions testing results for three heavy-duty 2010-compliant engines intended for on-highway use. These engines were equipped with an exhaust diesel oxidation catalyst (DOC), high-efficiency catalyzed diesel particle filter (DPF), urea-based selective catalytic reduction catalyst (SCR), and ammonia slip catalyst (AMOX), and were fueled with ultra-low-sulfur diesel fuel (~6.5 ppm sulfur). Average regulated and unregulated emissions of more than 780 chemical species were characterized in engine exhaust under transient engine operation using the Federal Test Procedure cycle and a 16-hr duty cycle representing a wide dynamic range of real-world engine operation. The 2010 engines’ regulated emissions of PM, NO X, nonmethane hydrocarbons, and carbon monoxide were all well below the EPA 2010 emission standards. Moreover, the unregulated emissions of polycyclic aromatic hydrocarbons (PAHs), nitroPAHs, hopanes and steranes, alcohols and organic acids, alkanes, carbonyls, dioxins and furans, inorganic ions, metals and elements, elemental carbon, and particle number were substantially (90 to >99%) lower than pre-2007-technology engine emissions, and also substantially (46 to >99%) lower than the 2007-technology engine emissions characterized in the previous study.Implications:? Heavy-duty on-highway diesel engines equipped with DOC/DPF/SCR/AMOX and fueled with ultra-low-sulfur diesel fuel produced lower emissions than the stringent 2010 emission standards established by the U.S. Environmental Protection Agency. They also resulted in significant reductions in a wide range of unregulated toxic emission compounds relative to older technology engines. The increased use of newer technology (2010+) diesel engines in the on-highway sector and the adaptation of such technology by other sectors such as nonroad, displacing older, higher emissions engines, will have a positive impact on ambient levels of PM, NOx, and volatile organic compounds, in addition to many other toxic compounds. 相似文献
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