Idle Emissions from Heavy-Duty Diesel Vehicles: Review and Recent Data

Abstract

Heavy-duty diesel vehicle idling consumes fuel and reduces atmospheric quality, but its restriction cannot simply be proscribed, because cab heat or air-conditioning provides essential driver comfort. A comprehensive tailpipe emissions database to describe idling impacts is not yet available. This paper presents a substantial data set that incorporates results from the West Virginia University transient engine test cell, the E-55/59 Study and the Gasoline/Diesel PM Split Study. It covered 75 heavy-duty diesel engines and trucks, which were divided into two groups: vehicles with mechanical fuel injection (MFI) and vehicles with electronic fuel injection (EFI). Idle emissions of CO, hydrocarbon (HC), oxides of nitrogen (NO_x), particulate matter (PM), and carbon dioxide (CO₂) have been reported. Idle CO₂ emissions allowed the projection of fuel consumption during idling. Test-to-test variations were observed for repeat idle tests on the same vehicle because of measurement variation, accessory loads, and ambient conditions. Vehicles fitted with EFI, on average, emitted [~20 g/hr of CO, 6 g/hr of HC, 86 g/hr of NO_x, 1 g/hr of PM, and 4636 g/hr of CO₂ during idle. MFI equipped vehicles emitted ~35 g/hr of CO, 23 g/hr of HC, 48 g/hr of NO_x, 4 g/hr of PM, and 4484 g/hr of CO₂, on average, during idle. Vehicles with EFI emitted less idleCO, HC, and PM, which could be attributed to the efficient combustion and superior fuel atomization in EFI systems. Idle NO_x, however, increased with EFI, which corresponds with the advancing of timing to improve idle combustion. Fuel injection management did not have any effect on CO₂ and, hence, fuel consumption. Use of air conditioning without increasing engine speed increased idle CO₂, NO_x, PM, HC, and fuel consumption by 25% on average. When the engine speed was elevated from 600 to 1100 revolutions per minute, CO₂ and NO_x emissions and fuel consumption increased by >150%, whereas PM and HC emissions increased by ~100% and 70%, respectively. Six Detroit Diesel Corp. (DDC) Series 60 engines in engine test cell were found to emit less CO, NO_x, and PM emissions and consumed fuel at only 75%of the level found in the chassis dynamometer data. This is because fan and compressor loads were absent in the engine test cell.     

Toward verifying fossil fuel CO2 emissions with the CMAQ model: Motivation,model description and initial simulation

Motivated by the question of whether and how a state-of-the-art regional chemical transport model (CTM) can facilitate characterization of CO₂ spatiotemporal variability and verify CO₂ fossil-fuel emissions, we for the first time applied the Community Multiscale Air Quality (CMAQ) model to simulate CO₂. This paper presents methods, input data, and initial results for CO₂ simulation using CMAQ over the contiguous United States in October 2007. Modeling experiments have been performed to understand the roles of fossil-fuel emissions, biosphere–atmosphere exchange, and meteorology in regulating the spatial distribution of CO₂ near the surface over the contiguous United States. Three sets of net ecosystem exchange (NEE) fluxes were used as input to assess the impact of uncertainty of NEE on CO₂ concentrations simulated by CMAQ. Observational data from six tall tower sites across the country were used to evaluate model performance. In particular, at the Boulder Atmospheric Observatory (BAO), a tall tower site that receives urban emissions from Denver, CO, the CMAQ model using hourly varying, high-resolution CO₂ fossil-fuel emissions from the Vulcan inventory and CarbonTracker optimized NEE reproduced the observed diurnal profile of CO₂ reasonably well but with a low bias in the early morning. The spatial distribution of CO₂ was found to correlate with NOx, SO₂, and CO, because of their similar fossil-fuel emission sources and common transport processes. These initial results from CMAQ demonstrate the potential of using a regional CTM to help interpret CO₂ observations and understand CO₂ variability in space and time. The ability to simulate a full suite of air pollutants in CMAQ will also facilitate investigations of their use as tracers for CO₂ source attribution. This work serves as a proof of concept and the foundation for more comprehensive examinations of CO₂ spatiotemporal variability and various uncertainties in the future.

Implications: Atmospheric CO₂ has long been modeled and studied on continental to global scales to understand the global carbon cycle. This work demonstrates the potential of modeling and studying CO₂ variability at fine spatiotemporal scales with CMAQ, which has been applied extensively, to study traditionally regulated air pollutants. The abundant observational records of these air pollutants and successful experience in studying and reducing their emissions may be useful for verifying CO₂ emissions. Although there remains much more to further investigate, this work opens up a discussion on whether and how to study CO₂ as an air pollutant.     

Emissions profile from new and in-use handheld, 2-stroke engines

The objective of this study was to characterize exhaust emissions from a series of handheld, 2-stroke small engines. A total of 23 new and used engines from model years 1981–2003 were studied; these engines spanned three phases of emission control (pre-control, phase-1, phase-2). Measured emissions included carbon monoxide (CO), carbon dioxide (CO₂), nitrogen oxides (NO_x), hydrocarbons (HC), fine particulate matter (PM_2.5), and sulfur dioxide (SO₂). Emissions reductions in CO (78%) and HC (52%) were significant between pre-control and phase-2 engines. These reductions can be attributed to improvements in engine design, reduced scavenging losses, and implementation of catalytic exhaust control. Total hydrocarbon emissions were strongly correlated with fuel consumption rates, indicating varying degrees of scavenging losses during the intake/exhaust stroke. The use of a reformulated gasoline containing 10% ethanol resulted in a 15% decrease in HC and a 29% decrease in CO emissions, on average. Increasing oil content of 2-stroke engine fuels results in a substantial increase of PM_2.5 emissions as well as smaller increases in HC and CO emissions. Results from this study enhance existing emission inventories and appear to validate predicted improvements to ambient air quality through implementation of new phase-2 handheld emission standards.     

Real-World Energy Use and Emission Rates for Idling Long-Haul Trucks and Selected Idle Reduction Technologies

Abstract

Long-haul freight trucks typically idle for 2000 or more hours per year, motivating interest in reducing idle fuel use and emissions using auxiliary power units (APUs) and shore-power (SP). Fuel-use rates are estimated based on electronic control unit (ECU) data for truck engines and measurements for APU engines. Engine emission factors were measured using a portable emission measurement system. Indirect emissions from SP were based on average utility grid emission factors. Base engine fuel use and APU and SP electrical load were analyzed for 20 trucks monitored for more than 1 yr during 2.76 million mi of activity within 42 U.S. states. The average base engine fuel use varied from 0.46 to 0.65 gal/hr. The average APU fuel use varied from 0.24 to 0.41 gal/hr. Fuel-use rates are typically lowest in mild weather, highest in hot or cold weather, and depend on engine speed (revolutions per minute [RPM]). Compared with the base engine, APU fuel use and emissions of carbon dioxide (CO₂) and sulfur dioxide (SO₂) are lower by 36–47%. Oxides of nitrogen (NO_x) emissions are lower by 80–90%. Reductions in particulate matter (PM), carbon monoxide (CO), and hydrocarbon emissions vary from approximately 10 to over 50%. SP leads to more substantial reductions, except for SO₂. The actual achievable reductions will be lower because only a fraction of base engine usage will be replaced by APUs, SP, or both. Recommendations are made for reducing base engine fuel use and emissions, accounting for variability in fuel use and emissions reductions, and further work to quantify real-world avoided fuel use and emissions.     

A tunnel study to estimate emission factors from mobile sources in Monterrey,Mexico

A six-day tunnel field study was conducted in the city of Monterrey, Mexico, during June 2009 to derive on-road emission factors (EFs) for trace gases and fine particulate matter from the local vehicle fleet. The Loma Larga Tunnel (LLT) is a 532-m-long structure that is mainly used by light-duty gasoline-powered vehicles. It is composed of two independent bores that have a semicircular cross section, 17 m in diameter with a 3.5% slope. During the study, a fleet of 108,569 vehicles with average speeds that ranged from 43 to 76 km/hr was sampled. Ambient air samples were taken inside each bore using 6-L SUMMA-polished canisters and low-volume samplers for the quantification of total nonmethane hydrocarbons (TNMHC) and PM_2.5, respectively. The effect of road dust resuspension was considered in the computation of PM_2.5 EFs. Additional equipment was used to measure real-time levels of CO₂ and NOx; CO EFs were estimated using NOx as a surrogate. TNMHC samples and NOx levels were obtained for 2-hr time periods, while PM_2.5 samples and CO₂ levels were obtained using 2.5-hr time periods, which included the time periods of the TNMHC and NOx measurements. Estimated EFs for TNMHC, CO, NOx, and PM_2.5 were 1.16 ± 0.05, 4.83 ± 2.9, and 0.11 ± 0.07 g/km-veh (2-hr average) and 17.5 ± 5.7 mg/veh-km (2.5-hr average), respectively, while CO₂ EFs were 182.7 ± 44 g/km-veh for the 2-hr time periods and 170 ± 22 g/veh-km for the 2.5-hr time periods. The average fuel economy estimated from the field data was 12.3 ± 2.3 km/L. The CO₂ and TNMHC EFs (on a mass per distance basis) tended to be higher for traffic moving upslope, while the inverse occurred for the PM_2.5 EFs. In comparison to other tunnel studies, the CO₂ EFs obtained were similar, the NOx and PM_2.5 EFs were lower, and the CO and TNMHC EFs were higher.

Implications Mobile source emission factors (EFs) for Mexican cities other than Mexico City are scarce. In Monterrey, Mexico, one of the three major cities in the country, emissions inventories are constructed based on EFs from other locations. However, it is quite relevant to obtain local information to construct reliable inventories. We present what is, to our knowledge, the first tunnel study conducted in a Mexican city other than Mexico City to estimate fleet-average mobile source EFs. This is also the first study that reports PM_2.5 EFs derived from a tunnel study in the country.     

The Relationship of Carbon Dioxide Emissions with Coal Rank and Sulfur Content

Carbon dioxide emissions, on an equivalent energy basis, were calculated for 504 North American coals to explore the effects of coal rank and sulfur content on CO₂ emissions. The data set included coals ranging in rank from lignite through low-volatile bituminous from 15 U.S. states and Alberta, Canada. Carbon dioxide emissions were calculated from the carbon content and gross calorific value of each coal. The lowest CO₂ emissions are calculated for the high-volatile bituminous coals (198 to 211 lbs CO₂/MMBtu) and the highest for lignites and subbituminous coals (209 to 224 lbs CO₂/MMBtu). The lower CO₂ emissions from the high-volatile bituminous coals result in part from their generally higher sulfur content. However, even at equivalent sulfur contents the high-volatile bituminous coals give lower CO₂ emissions than the lower-rank coals. On average, the lowerrank coals produce 5 percent more CO₂ upon combustion than the highvolatile bituminous coals, on the basis of gross calorific value. This difference increases to 9 percent on the basis of estimated net calorific value. The net calorific value is better indicator of power plant energy production than the gross calorific value. The difference in CO₂ emissions resulting from the use of high-volatile bituminous coals and lower-rank coals is of the same order of magnitude as reductions expected from near-term combustion efficiency improvements. These results are useful to those interested in current and future CO₂ emissions resulting from coal combustion.     

Comprehensive analysis of the carbon impacts of vehicle intelligent speed control

In recent years sophisticated technologies have been developed to control vehicle speed based on the type of road the vehicle is driven on using Global Positioning Systems and in-car technology that can alter the speed of the vehicle. While reducing the speed of road vehicles is primarily of interest from a safety perspective, vehicle speed is also an important determinant of vehicle emissions and thus these technologies can be expected to have impacts on a range of exhaust emissions. This work analyses the results from a very large, comprehensive field trial that used 20 instrumented vehicles with and without speed control driven almost 500,000 km measuring vehicle speed at 10 Hz. We develop individual vehicle modal emissions models for CO₂ for 30 Euro III and Euro IV cars at a 1-Hz time resolution. Generalized Additive Models were used to describe how emissions from individual vehicles vary depending on their driving conditions, taking account of variable interactions and time-lag effects. We quantify the impact that vehicle speed control has on-vehicle emissions of CO₂ by road type, fuel type and driver behaviour. Savings in CO₂ of ≈6% were found on average for motorway-type roads when mandatory speed control was used compared with base case conditions. For most other types of road, speed control has very little effect on emissions of CO₂ and in some cases can result in increased emissions for low-speed limit urban roads. We also find that there is on average a 20% difference in CO₂ emission between the lowest and highest emitting driver, which highlights the importance of driver behaviour in general as a means of reducing emissions of CO₂.     

Analysis of air quality in Dire Dawa,Ethiopia

Ambient air quality was monitored and analyzed to develop air quality index and its implications for livability and climate change in Dire Dawa, Ethiopia. Using survey research design, 16 georeferenced locations, representing different land uses, were randomly selected and assessed for sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon dioxide (CO₂), carbon monoxide (CO),volatile organic compounds (VOCs), and meteorological parameters (temperature and relative humidity). The study found mean concentrations across all land uses for SO₂ of 0.37 ± 0.08 ppm, NO₂ of 0.13 ± 0.17 ppm, CO₂ of 465.65 ± 28.63 ppm, CO of 3.35 ± 2.04 ppm, and VOCs of 1850.67 ± 402 ppm. An air quality index indicated that ambient air quality for SO₂ was very poor, NO₂ ranged from moderate to very poor, whereas CO rating was moderate. Significant positive correlations existed between temperature and NO₂, CO₂, and CO and between humidity and VOCs. Significant relationships were also recorded between CO₂ and NO₂ and between CO and CO₂. Poor urban planning, inadequate pollution control measure, and weak capacity to monitor air quality have implications for energy usage, air quality, and local meteorological parameters, with subsequent feedback into global climate change. Implementation of programs to monitor and control emissions in order to reduce air pollution will provide health, economic, and environmental benefits to the city.

Implications: The need to develop and implement emission control programs to reduce air pollution in Dire Dawa City is urgent. This will provide enormous economic, health, and environmental benefits. It is expected that economic effects of air quality improvement will offset the expenditures for pollution control. Also, strategies that focus on air quality and climate change present a unique opportunity to engage different stakeholders in providing inclusive and sustainable development agenda for Dire Dawa.     

Real-world fuel use and gaseous emission rates for flex fuel vehicles operated on E85 versus gasoline

Flex fuel vehicles (FFVs) typically operate on gasoline or E85, an 85%/15% volume blend of ethanol and gasoline. Differences in FFV fuel use and tailpipe emission rates are quantified for E85 versus gasoline based on real-world measurements of five FFVs with a portable emissions measurement system (PEMS), supplemented chassis dynamometer data, and estimates from the Motor Vehicle Emission Simulator (MOVES) model. Because of inter-vehicle variability, an individual FFV may have higher nitrogen oxide (NO_x) or carbon monoxide (CO) emission rates on E85 versus gasoline, even though average rates are lower. Based on PEMS data, the comparison of tailpipe emission rates for E85 versus gasoline is sensitive to vehicle-specific power (VSP). For example, although CO emission rates are lower for all VSP modes, they are proportionally lowest at higher VSP. Driving cycles with high power demand are more advantageous with respect to CO emissions, but less advantageous for NO_x. Chassis dynamometer data are available for 121 FFVs at 50,000 useful life miles. Based on the dynamometer data, the average difference in tailpipe emissions for E85 versus gasoline is ?23% for NO_x, ?30% for CO, and no significant difference for hydrocarbons (HC). To account for both the fuel cycle and tailpipe emissions from the vehicle, a life cycle inventory was conducted. Although tailpipe NO_x emissions are lower for E85 versus gasoline for FFVs and thus benefit areas where the vehicles operate, the life cycle NO_x emissions are higher because the NO_x emissions generated during fuel production are higher. The fuel production emissions take place typically in rural areas. Although there are not significant differences in the total HC emissions, there are differences in HC speciation. The net effect of lower tailpipe NO_x emissions and differences in HC speciation on ozone formation should be further evaluated.

Implications: Reported comparisons of flex fuel vehicle (FFV) tailpipe emission rates for E85 versus gasoline have been inconsistent. To date, this is the most comprehensive evaluation of available and new data. The large range of inter-vehicle variability illustrates why prior studies based on small sample sizes led to apparently contradictory findings. E85 leads to significant reductions in tailpipe nitrogen oxide (NO_x) and carbon monoxide (CO) emission rates compared with gasoline, indicating a potential benefit for ozone air quality management in NO_x-limited areas. The comparison of FFV tailpipe emissions between E85 and gasoline is sensitive to power demand and driving cycles.     

Biomass consumption and CO2, CO and main hydrocarbon gas emissions in an Amazonian forest clearing fire

Biomass consumption and CO₂, CO and hydrocarbon gas emissions in an Amazonian forest clearing fire are presented and discussed. The experiment was conducted in the arc of deforestation, near the city of Alta Floresta, state of Mato Grosso, Brazil. The average carbon content of dry biomass was 48% and the estimated average moisture content of fresh biomass was 42% on wet weight basis. The fresh biomass and the amount of carbon on the ground before burning were estimated as 528 t ha^?1 and 147 t ha^?1, respectively. The overall biomass consumption for the experiment was estimated as 23.9%. A series of experiment in the same region resulted in average efficiency of 40% for areas of same size and 50% for larger areas. The lower efficiency obtained in the burn reported here occurred possibly due to rain before the experiment. Excess mixing ratios were measured for CO₂, CO, CH₄, C₂–C₃ aliphatic hydrocarbons, and PM_2.5. Excess mixing ratios of CH₄ and C₂–C₃ hydrocarbons were linearly correlated with those of CO. The average emission factors of CO₂, CO, CH₄, NMHC, and PM_2.5 were 1,599, 111.3, 9.2, 5.6, and 4.8 g kg^?1 of burned dry biomass, respectively. One hectare of burned forest released about 117,000 kg of CO₂, 8100 kg of CO, 675 kg of CH₄, 407 kg of NMHC and 354 kg of PM_2.5.     

Trends in vehicular emissions in China's mega cities from 1995 to 2005

Multiyear inventories of vehicular emissions in Beijing, Shanghai and Guangzhou from 1995 through 2005 have been developed in this paper to study the vehicle emissions trends in China's mega cities during the past decade. The results show that the vehicular emissions of CO, HC, NO_x and PM₁₀ have begun to slow their growth rates and perhaps even to decline in recent years due to the implementation of measures to control vehicular emissions in these cities. However, vehicular CO₂ emissions have substantially increased and still continue to grow due to little fuel economy improvement. Passenger cars and large vehicles (including heavy duty trucks and buses) are the major sources of vehicular CO₂ and CO emissions while large vehicles were responsible for nearly 70% and 80% of the vehicular NO_x and PM₁₀ emissions in these mega cities. Motorcycles are also important contributors to vehicular emissions in Guangzhou and Shanghai.     

Analysis and modelling of the pollutant emissions from European cars regarding the driving characteristics and test cycles

Within the European research project ARTEMIS, significant works have been conducted to analyse the hot emissions of pollutant from the passenger cars regarding the driving cycles and to propose modelling approaches taking into account large but heterogeneous datasets recorded in Europe. The review and analysis of a large range of test cycles enabled first the building-up of a set of contrasted cycles specifically designed for characterizing the influence of the driving conditions. These cycles were used for the measurement of the pollutants emission rates from nine passenger cars on a chassis dynamometer.Emissions measured on 30 vehicles tested on cycles adapted to their motorization (i.e., cycles for high- or low-powered cars, inducing thus a significant difference in the dynamic) were also considered for analysing the influence of the cycles and of the kinematic parameters on the hot emission rates of the regulated pollutants (CO, HC, NO_x, CO₂, PM). An analyses of variance demonstrated the preponderance of the driving type (urban, rural road, motorway), of the vehicle category (fuel, emission standard) and emitting status (high/normal emitter) and thus the pertinence of analysing and modelling separately the corresponding emissions. It also demonstrated that Urban driving led systematically to high diesel emission rates and to high CO₂, HC and NO_x emissions from petrol cars. Congested driving implied high CO₂ (diesel and petrol) and high diesel NO_x emission. On motorway, the very high speeds generated high CO₂, while unsteady speeds induced diesel NO_x and petrol CO over-emissions. A search for pertinent kinematic parameters showed that urban diesel emissions were mostly sensitive to stops and speed parameters, while petrol emissions were rather sensitive to acceleration parameters. On the motorway, diesel NO_x and CO₂ emissions rates increased with the speed variability and occurrence of high speeds, while CO₂ and CO over-emission from petrol cars were linked to the occurrence of strong acceleration at high speeds.A modelling approach based on partial least square regression was tested, which demonstrates its ability to discriminate satisfactorily the emissions according to dynamic related parameters and in particular when considering the two-dimensionnal distribution of instantaneous speed and acceleration.Finally, a strategy was proposed to analyse the large but heterogeneous set of hot emission data collected within the ARTEMIS project. The approach consisted in analysing the similarity of the numerous cycles as regards their kinematic, grouping them into reference test patterns through an automatic clustering, and then computing reference emissions for these patterns. These principles enabled the development of a method to compute the emissions at a low spatial scale, i.e. the so-called traffic situation approach, which was implemented in the European Artemis model for estimating the cars’ pollutant emissions.     

European Community Can Reduce CO2 Emissions by Sixty Percent: A Feasibility Study

Carbon dioxide (CO₂,) emissions in the European Community (EC) can be reduced by roughly 60 percent. A great many measures need to be taken to reach this reduction, with a total annual cost of ECU 55 milliard. Fossil fuel use is the main cause of CO2 emissions into the atmosphere; CO₂ emissions are to a large extent responsible for the greenhouse effect. Energy saving (conservation) and nuclear energy appear to be the least expensive methods of CO₂, abatement, directly followed by renewables. More expensive alternatives include the separation of CO₂, at the source (e.g., power plants), followed by storage in depleted gas fields, aquifers, or in the ocean. Biological options, such as reforestation and energy farming, are the most expensive abatement methods; however, they do have secondary advantages, such as avoided fallow premiums and avoided export premiums on cereals. Application of all measures together can lead to the 60 percent reduction goal.     

Emission inventory for greenhouse gases in the City of Barcelona, 1987–1996

Emissions of greenhouse gases for the City of Barcelona are estimated for the period 1987–1994. The sources considered are: public and private transportation; industrial, commercial and domestic activities; and municipal solid waste disposal. The results show that the main source of CO₂ emissions in Barcelona is private vehicle transportation, which accounts, as an average for the period studied, for 35% of total emissions. The second most important source is the municipal solid waste landfill facility of the city (24% of total emissions). The percentages for the remaining sources under consideration were: 14% electricity, 12% natural gas, 5% incineration, and 3% liquefied petroleum gases. However, the values for CO₂ emissions per inhabitant over the period studied are lower than those for any other industrialized city available for comparison. This is closely related to the high percentage of electricity generation from nuclear power stations and hydro power facilities, and also to the extensive use of natural gas for domestic uses.     

Measurement of black carbon aerosols near two Chinese megacities and the implications for improving emission inventories

Knowledge of the distribution and sources of black carbon (BC) is essential to understanding its impact on radiative forcing and the establishment of a control strategy. In this study, we analyze atmospheric BC and its relationships with fine particles (PM_2.5) and trace gases (CO, NO_y and SO₂) measured in the summer of 2005 in two areas frequently influenced by plumes from Beijing and Shanghai, the two largest cities in China. The results revealed different BC source characteristics for the two megacities. The average concentration of BC was 2.37 (±1.79) and 5.47 (±4.00) μg m^?3, accounting for 3.1% and 7.8% of the PM_2.5 mass, in Beijing and Shanghai, respectively. The good correlation between BC, CO and NO_y (R² = 0.54–0.77) and the poor correlation between BC and SO₂ suggest that diesel vehicles and marine vessels are the dominant sources of BC in the two urban areas during summer. The BC/CO mass ratio in the air mass from Shanghai was found to be much higher than that in the air mass from Beijing (0.0101 versus 0.0037 ΔgBC/ΔgCO), which is attributable to a larger contribution from diesel burning (diesel-powered vehicles and marine vessels) in Shanghai. Based on the measured ratios of BC/CO and annual emissions of CO, we estimate that the annual emissions of BC in Beijing and Shanghai are 9.51 Gg and 18.72 Gg, respectively. The improved emission rates of BC will help reduce the uncertainty in the assessment of the impact of megacities on regional climate.     

Emissions from India's transport sector: Statewise synthesis

A decentralized emission inventories are prepared for road transport sector of India in order to design and implement suitable technologies and policies for appropriate mitigation measures. Globalization and liberalization policies of the government in 90's have increased the number of road vehicles nearly 92.6% from 1980–1981 to 2003–2004. These vehicles mainly consume non-renewable fossil fuels, and are a major contributor of green house gases, particularly CO₂ emission. This paper focuses on the statewise road transport emissions (CO₂, CH₄, CO, NO_x, N₂O, SO₂, PM and HC), using region specific mass emission factors for each type of vehicles. The country level emissions (CO₂, CH₄, CO, NO_x, N₂O, SO₂ and NMVOC) are calculated for railways, shipping and airway, based on fuel types. In India, transport sector emits an estimated 258.10 Tg of CO₂, of which 94.5% was contributed by road transport (2003–2004). Among all the states and Union Territories, Maharashtra's contribution is the largest, 28.85 Tg (11.8%) of CO₂, followed by Tamil Nadu 26.41 Tg (10.8%), Gujarat 23.31 Tg (9.6%), Uttar Pradesh 17.42 Tg (7.1%), Rajasthan 15.17 Tg (6.22%) and, Karnataka 15.09 Tg (6.19%). These six states account for 51.8% of the CO₂ emissions from road transport.     

An air quality survey and emissions inventory at Aberdeen Harbour

A network of 10 stations, with passive sampling for VOCs (including benzene), NO₂, and SO₂, over 2-week periods, grab sampling for CO, and 48-h pumped sampling for PM₁₀, was set up to make an air quality survey for 12 months around Aberdeen Harbour. Benzene, CO, SO₂ and PM₁₀ were always well below the AQS target values. However, NO₂ frequently showed a pronounced gradient across the harbour reaching its highest concentrations at the city end, indicating that the road traffic was the principal source of the pollution. This was backed up by the predominance of aromatics in the VOCs in the city centre, derived from petrol engined vehicles, compared to the predominance of alkanes and alkenes around the docks, derived from diesel engined heavy trucks and possibly ships. Black carbon on the PM₁₀ filters also showed a gradient with highest levels in the city centre. It is proposed that for such surveys in future, NO₂ and black carbon would be the two most informative parameters.This emissions inventory has shown first, that trucks contribute very little to the total, and second, that the ro-ro ferries are the major contributors as they burn light fuel oil while the oil platform supply vessels burn low-sulphur marine gas oil with around 0.1% S. When the whole picture of the emissions from the city is considered, the emissions from the harbour constitute only a small part.     

A Life-Cycle Inventory Model of Municipal Solid Waste Combustion

ABSTRACT

Evaluation of alternate strategies for municipal solid waste (MSW) management requires models to calculate environmental emissions as a function of both waste quantity and composition. A methodology to calculate waste component-specific emissions associated with MSW combustion is presented here. The methodology considers emissions at a combustion facility as well as those avoided at an electrical energy facility because of energy recovered from waste combustion. Emission factors, in units of kg pollutant per metric ton MSW entering the combustion facility, are calculated for CO₂-biomass, CO₂-fossil, SO_x , HCl, NO_x , dioxins/furans, PM, CO, and 11 metals. Water emissions associated with electrical energy offsets are also considered. Reductions in environmental emissions for a 500-metric-ton-per-day combustion facility that recovers energy are calculated.     

Effects of biodiesel made from swine and chicken fat residues on carbon monoxide,carbon dioxide,and nitrogen oxide emissions

The effects of two alternative sources of animal fat-derived biodiesel feedstock on CO₂, CO, NO_x tailpipe emissions as well as fuel consumption were investigated. Biodiesel blends were produced from chicken and swine fat waste (FW-1) or floating fat (FW-2) collected from slaughterhouse wastewater treatment processes. Tests were conducted in an unmodified stationary diesel engine operating under idling conditions in attempt to simulate slow traffic in urban areas. Significant reductions in CO (up to 47% for B100; FW-2) and NO_x (up to 20% for B5; FW-2 or B100; FW-1) were attained when using biodiesel fuels at the expense of 5% increase in fuel consumption. Principal component analysis (PCA) was performed to elucidate possible associations among gas (CO₂, CO, and NO_x) emissions, cetane number and iodine index with different sources of feedstock typically employed in the biodiesel industry. NO_x, cetane number and iodine index were inversely proportional to CO₂ and biodiesel concentration. High NO_x emissions were reported from high iodine index biodiesel derived especially from forestry, fishery and some agriculture feedstocks, while the biodiesel derived from animal sources consistently presented lower iodine index mitigating NO_x emissions. The obtained results point out the applicability of biodiesel fuels derived from fat-rich residues originated from animal production on mitigation of greenhouse gas emissions. The information may encourage practitioners from biodiesel industry whilst contributing towards development of sustainable animal production.

Implications: Emissions from motor vehicles can contribute considerably to the levels of greenhouse gases in the atmosphere. The use of biodiesel to replace or augment diesel can not only decrease our dependency on fossil fuels but also help decrease air pollution. Thus, different sources of feedstocks are constantly being explored for affordable biodiesel production. However, the amount of carbon monoxide (CO), carbon dioxide (CO₂), and/or nitrogen oxide (NO_x) emissions can vary largely depending on type of feedstock used to produce biodiesel. In this work, the authors demonstrated animal fat feasibility in replacing petrodiesel with less impact regarding greenhouse gas emissions than other sources.     

Responses of CH(4), CO(2) and N(2)O fluxes to increasing nitrogen deposition in alpine grassland of the Tianshan Mountains

To assess the effects of nitrogen (N) deposition on greenhouse gas (GHG) fluxes in alpine grassland of the Tianshan Mountains in central Asia, CH₄, CO₂ and N₂O fluxes were measured from June 2010 to May 2011. Nitrogen deposition tended to significantly increase CH₄ uptake, CO₂ and N₂O emissions at sites receiving N addition compared with those at site without N addition during the growing season, but no significant differences were found for all sites outside the growing season. Air temperature, soil temperature and water content were the important factors that influence CO₂ and N₂O emissions at year-round scale, indicating that increased temperature and precipitation in the future will exert greater impacts on CO₂ and N₂O emissions in the alpine grassland. In addition, plant coverage in July was also positively correlated with CO₂ and N₂O emissions under elevated N deposition rates. The present study will deepen our understanding of N deposition impacts on GHG balance in the alpine grassland ecosystem, and help us assess the global N effects, parameterize Earth System models and inform decision makers.