Determination of the emissions from an aircraft auxiliary power unit (APU) during the Alternative Aviation Fuel Experiment (AAFEX)

The emissions from a Garrett-AiResearch (now Honeywell) Model GTCP85-98CK auxiliary power unit (APU) were determined as part of the National Aeronautics and Space Administration's (NASA's) Alternative Aviation Fuel Experiment (AAFEX) using both JP-8 and a coal-derived Fischer Tropsch fuel (FT-2). Measurements were conducted by multiple research organizations for sulfur dioxide (SO2, total hydrocarbons (THC), carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), speciated gas-phase emissions, particulate matter (PM) mass and number, black carbon, and speciated PM. In addition, particle size distribution (PSD), number-based geometric mean particle diameter (GMD), and smoke number were also determined from the data collected. The results of the research showed PM mass emission indices (EIs) in the range of 20 to 700 mg/kg fuel and PM number EIs ranging from 0.5 x 10(15) to 5 x 10(15) particles/kg fuel depending on engine load and fuel type. In addition, significant reductions in both the SO2 and PM EIs were observed for the use of the FT fuel. These reductions were on the order of approximately 90% for SO2 and particle mass EIs and approximately 60% for the particle number EI, with similar decreases observed for black carbon. Also, the size of the particles generated by JP-8 combustion are noticeably larger than those emitted by the APU burning the FT fuel with the geometric mean diameters ranging from 20 to 50 nm depending on engine load and fuel type. Finally, both particle-bound sulfate and organics were reduced during FT-2 combustion. The PM sulfate was reduced by nearly 100% due to lack of sulfur in the fuel, with the PM organics reduced by a factor of approximately 5 as compared with JP-8.     

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.     

Physical characterization of the fine particle emissions from commercial aircraft engines during the Aircraft Particle Emissions eXperiment (APEX) 1–3

The fine particulate matter (PM) emissions from nine commercial aircraft engine models were determined by plume sampling during the three field campaigns of the Aircraft Particle Emissions Experiment (APEX). Ground-based measurements were made primarily at 30 m behind the engine for PM mass and number concentration, particle size distribution, and total volatile matter using both time-integrated and continuous sampling techniques. The experimental results showed a PM mass emission index (EI) ranging from 10 to 550 mg kg^?1 fuel depending on engine type and test parameters as well as a characteristic U-shaped curve of the mass EI with increasing fuel flow for the turbofan engines tested. Also, the Teflon filter sampling indicated that ～40–80% of the total PM mass on a test-average basis was comprised of volatile matter (sulfur and organics) for most engines sampled. The number EIs, on the other hand, varied from ～10¹⁵ to 10¹⁷ particles kg^?1 fuel with the turbofan engines exhibiting a logarithmic decay with increasing fuel flow. Finally, the particle size distributions of the emissions exhibited a single primary mode that were lognormally distributed with a minor accumulation mode also observed at higher powers for all engines tested. The geometric (number) mean particle diameter ranged from 9.4 to 37 nm and the geometric standard deviation ranged from 1.3 to 2.3 depending on engine type, fuel flow, and test conditions.     

A study of extractive and remote-sensing sampling and measurement of emissions from military aircraft engines

Aircraft emissions contribute to the increased atmospheric burden of particulate matter (PM) that plays an important role in air quality, human health, visibility, contrail formation and climate change. Sampling and measurement of modern aircraft emissions at the engine exhaust plane (EEP) for engine and fuel certification remains challenging, as no agency-certified method is available. In this paper we summarize the results of three recent field studies devoted to investigate the consistency and applicability of “extractive” and “optical remote-sensing” (ORS) technologies in the sampling and measurement of gaseous and PM emitted by a number of military aircraft engines. Three classes of military engines were investigated; these include T56, TF33, and T700 & T701C types of engines, which consume 70–80% of the military aviation fuel each year. JP-8 and Fischer–Tropsch (FT)-derived paraffinic fuels were used to study the effect of fuels. It was found that non-volatile particles in the engine emissions were in the 20 nm range for the low power condition of new helicopter engines to 80 nm for the high power condition of legacy engines. Elemental analysis indicated little metals were present on particles, while most of the materials on the exhaust particles were carbon and sulfate based. Alkanes, carbon monoxide, carbon dioxide, nitrogen oxides, sulfur dioxide, formaldehyde, ethylene, acetylene and propylene were detected. The last five species were most noticeable only under low engine power. The emission indices calculated based on the ORS data deviate significantly from those based on the extractive data. Nevertheless, the ORS techniques were useful in the sense that it provided non-intrusive real-time detection of species in the exhaust plume, which warrants further development. The results obtained in this program help validate sampling methodology and measurement techniques used for non-volatile PM aircraft emissions as described in the SAE AIR6037 (2009).     

Comparison of particle emissions from small heavy fuel oil and wood-fired boilers

Flue gas emissions of wood and heavy fuel oil (HFO) fired district heating units of size range 4–15 MW were studied. The emission measurements included analyses of particle mass, number and size distributions, particle chemical compositions and gaseous emissions. Thermodynamic equilibrium calculations were carried out to interpret the experimental findings.In wood combustion, PM1 (fine particle emission) was mainly formed of K, S and Cl, released from the fuel. In addition PM1 contained small amounts of organic material, CO₃, Na and different metals of which Zn was the most abundant. The fine particles from HFO combustion contained varying transient metals and Na that originate from the fuel, sulphuric acid, elemental carbon (soot) and organic material. The majority of particles were formed at high temperature (>800 °C) from V, Ni, Fe and Na. At the flue gas dew point (125 °C in undiluted flue gas) sulphuric acid condensed forming a liquid layer on the particles. This increases the PM1 substantially and may lead to partial dissolution of the metallic cores.Wood-fired grate boilers had 6–21-fold PM1 and 2–23-fold total suspended particle (TSP) concentrations upstream of the particle filters when compared to those of HFO-fired boilers. However, the use of single field electrostatic precipitators (ESP) in wood-fired grate boilers decreased particle emissions to same level or even lower as in HFO combustion. On the other hand, particles released from the HFO boilers were clearly smaller and higher in number concentration than those of wood boilers with ESPs. In addition, in contrast to wood combustion, HFO boilers produce notable SO₂ emissions that contribute to secondary particle formation in the atmosphere. Due to vast differences in concentrations of gaseous and particle emissions and in the physical and chemical properties of the particles, HFO and wood fuel based energy production units are likely to have very different effects on health and climate.     

PM2.5 chemical source profiles for vehicle exhaust, vegetative burning, geological material, and coal burning in Northwestern Colorado during 1995

PM_2.5 (particles with aerodynamic diameters less than 2.5 μm) chemical source profiles applicable to speciated emissions inventories and receptor model source apportionment are reported for geological material, motor vehicle exhaust, residential coal (RCC) and wood combustion (RWC), forest fires, geothermal hot springs; and coal-fired power generation units from northwestern Colorado during 1995. Fuels and combustion conditions are similar to those of other communities of the inland western US. Coal-fired power station profiles differed substantially between different units using similar coals, with the major difference being lack of selenium in emissions from the only unit that was equipped with a dry limestone sulfur dioxide (SO₂) scrubber. SO₂ abundances relative to fine particle mass emissions in power plant emissions were seven to nine times higher than hydrogen sulfide (H₂S) abundances from geothermal springs, and one to two orders of magnitude higher than SO₂ abundances in RCC emissions, implying that the SO₂ abundance is an important marker for primary particle contributions of non-aged coal-fired power station contributions. The sum of organic and elemental carbon ranged from 1% to 10% of fine particle mass in coal-fired power plant emissions, from 5% to 10% in geological material, >50% in forest fire emissions, >60% in RWC emissions, and >95% in RCC and vehicle exhaust emissions. Water-soluble potassium (K⁺) was most abundant in vegetative burning profiles. K⁺/K ratios ranged from 0.1 in geological material profiles to 0.9 in vegetative burning emissions, confirming previous observations that soluble potassium is a good marker for vegetative burning.     

Regulated emissions from biodiesel fuels from on/off-road applications

This research is one of the largest studies of biodiesel in both on-road and off-road uses. The testing was conducted for the military and encompassed a wide range of application types including two medium-duty trucks, two Humvees, a heavy heavy-duty diesel truck, a bus, two stationary backup generators (BUGs), a forklift, and an airport tow vehicle. The full range of fuels tested included a California ultra-low sulfur diesel (ULSD) fuel, different blend ratios of two different yellow-grease biodiesels and one soy-based biodiesel, JP-8, and yellow-grease biodiesel blends with two different NO_x reduction additives. The B20-YGA, B20-YGB, and B20-Soy did not show trends relative to ULSD that were consistent over all applications tested. Higher biodiesel blends were tested on only one vehicle, but showed a tendency for higher total hydrocarbons (THC) and carbon monoxide (CO) emissions and lower particulate matter (PM) emissions. The JP-8 showed increases in THC and CO relative to the ULSD.     

Influence of Oxygenated Fuels on the Emissions from Three Pre-1985 Light-Duty Passenger Vehicles

Tailpipe and evaporative emissions from three pre-1985 passenger motor vehicles operating on an oxygenated blend fuel and on a nonoxygenated base fuel were characterized. Emission data were collected for vehicles operating over the Federal Test Procedure at 40,75, and 90°F to simulate ambient driving conditions. The two fuels tested were a commercial summer grade regular gasoline (the nonoxygenated base fuel) and an oxygenated fuel containing 9.5 percent methyl tert-butyl ether (MTBE), more olefins, and fewer aromatics than the base fuel. The emissions measured were total hydrocarbons (THCs), speciated hydrocarbons, speciated aldehydes, carbon monoxide (CO), oxides of nitrogen (NO_x), benzene, and 1,3-butadiene.

This study showed no pattern of tailpipe regulated emission reduction when oxygenated fuel was used. Tailpipe emissions from the 1984 Buick Century without a catalyst and the 1977 Mustang with catalyst decreased with the MTBE fuel. However, emissions from the 1984 Buick Century and the 1980 Chevrolet Citation, both fitted with catalysts increased. The vehicles emitted more 1,3- butadiene and, in general, more NO_x when operated with the base fuel.

THC, CO, benzene, and 1,3-butadiene emissions from both fuels and all vehicles, in general, decreased with increasing test temperature, whereas NO_x emissions, in general, increased with increasing test temperature. Formaldehyde, acetaldehyde, and total aldehydes also showed a decrease in emissions as test temperature increased. More formaldehyde was emitted when the MTBE fuel was used.

Evaporative, diurnal, and hot soak emissions from the base fuel were greater than those from the MTBE fuel. The evaporated emissions from both fuels increased with increasing test temperatures. Diurnal data indicate that canister conditioning (bringing the evaporative charcoal canister to equilibrium) is required before testing.     

Study of Miller timing on exhaust emissions of a hydrotreated vegetable oil (HVO)-fueled diesel engine

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.     

Air impacts from three alternatives for producing JP-8 jet fuel

To increase U.S. petroleum energy independence, the University of Texas at Arlington (UT Arlington) has developed a direct coal liquefaction process which uses a hydrogenated solvent and a proprietary catalyst to convert lignite coal to crude oil. This sweet crude can be refined to form JP-8 military jet fuel, as well as other end products like gasoline and diesel. This paper presents an analysis of air pollutants resulting from using UT Arlington's liquefaction process to produce crude and then JP-8, compared with 2 alternative processes: conventional crude extraction and refining (CCER), and the Fischer-Tropsch process. For each of the 3 processes, air pollutant emissions through production of JP-8 fuel were considered, including emissions from upstream extraction/production, transportation, and conversion/refining. Air pollutants from the direct liquefaction process were measured using a LandTEC GEM2000 Plus, Draeger color detector tubes, OhioLumex RA-915 Light Hg Analyzer, and SRI 8610 gas chromatograph with thermal conductivity detector.

According to the screening analysis presented here, producing jet fuel from UT Arlington crude results in lower levels of pollutants compared to international conventional crude extraction/refining. Compared to US domestic CCER, the UTA process emits lower levels of CO₂-e, NOx, and Hg, and higher levels of CO and SO₂. Emissions from the UT Arlington process for producing JP-8 are estimated to be lower than for the Fischer-Tropsch process for all pollutants, with the exception of CO₂-e, which were high for the UT Arlington process due to nitrous oxide emissions from crude refining. When comparing emissions from conventional lignite combustion to produce electricity, versus UT Arlington coal liquefaction to make JP-8 and subsequent JP-8 transport, emissions from the UT Arlington process are estimated to be lower for all air pollutants, per MJ of power delivered to the end user.

Implications: The United States currently imports two-thirds of its crude oil, leaving its transportation system especially vulnerable to disruptions in international crude supplies. At current use rates, U.S. coal reserves (262 billion short tons, including 23 billion short tons lignite) would last 236 years. Accordingly, the University of Texas at Arlington (UT Arlington) has developed a process that converts lignite to crude oil, at about half the cost of regular crude. According to the screening analysis presented here, producing jet fuel from UT Arlington crude generates lower levels of pollutants compared to international conventional crude extraction/refining (CCER).     

A Comparison of Tailpipe,Dilution Tunnel,and Wind Tunnel Data in Measuring Motor Vehicle PM

ABSTRACT

Comparison between particle size distributions recorded directly at the tailpipes of both diesel and gasoline vehicles and measurements made using a conventional dilution tunnel reveals two problems incurred when using the latter method for studying particle number emissions. One is the potential for particulate matter (PM) artifacts originating from hydrocarbon material stored in the transfer hose connecting the tailpipe to the dilution tunnel, and the other is the particle coagulation (as well as condensation and chemical changes) that occurs during the transport. Both are potentially generic to current PM emissions measurement practices. The artifacts typically occur as a nanoparticle mode (10–30 nm) that is 2–4 orders of magnitude larger than what is present in the vehicle exhaust and can easily be mistaken for a similar mode that can arise from the nucleation of hydrocarbon or SO₄ ^2-components in the exhaust under appropriate dilution rates. Wind tunnel measurements are in good agreement with those made directly from the tailpipe and substantiate the potential for artifacts. They reveal PM levels for the recent model port fuel injection (PFI) gasoline vehicles tested that are small compared with the ambient background particle level during steady-state driving. The PM emissions recorded for drive cycles such as the Federal Test Procedure (FTP) and US06 occur primarily during acceleration, as has been previously noted. Light-duty diesel vehicle emissions normally exhibit a single lognormal mode centered between 55 and 80 nm, although a nonartifact nanoparticle mode in some cases appears at a 70-mph cruise up a grade.     

The Effect of Ethanol Fuel on the Emissions of Vehicles over a Wide Range of Temperatures

ABSTRACT

The emissions from a fleet of 11 vehicles, including three from the State of Alaska, were tested at 75, 0, and -20 °F with base gasolines and E10 gasolines, that is, gasolines with 10% by volume ethanol added. The data for the changes in emissions for the test run at 75 °F are included, since most other studies on the effects of E10 gasoline on emissions were run at that temperature. The three Alaskan vehicles were also tested at 20 °F. The testing followed the Federal Test Procedure, and regulated emissions—CO, total hydrocarbons (THC), and nitrogen oxides (NO_x)—CO₂, speciated organics, and fuel economy were measured. A total of 490 FTP tests were run. The data obtained indicated that with most vehicles, at the temperatures tested, improvements in both CO and THC emissions were obtained with the use of E10 fuel. At the lowest temperature used, -20 °F, most vehicles had an increase in NO emissions with the use of E10 fuel. At the other temperatures, however, more vehicles showed a decrease in NO_x emissions with the use of E10. With all vehicles at all temperatures tested, the emissions of acetaldehyde increased significantly when E10 fuel was used. The highest increase was about 8 to 1. Benzene, formaldehyde, and 1,3 butadiene showed both increases and decreases in the emissions when using E10 fuel. Unexpected results were obtained with the fuel economy, with about half of the tests showing an increase in fuel economy with the use of E10 fuel.     

Current Status of Air Quality Models for Particulate Matter

ABSTRACT

The current status of the mathematical modeling of atmospheric particulate matter (PM) is reviewed in this paper. Simulating PM requires treating various processes, including the formation of condensable species, the gas/ particle partitioning of condensable compounds, and in some cases, the evolution of the particle size distribution. The algorithms available to simulate these processes are reviewed and discussed. Eleven 3-dimensional (3-D) Eulerian air quality models for PM are reviewed in terms of their formulation and past applications. Results of past performance evaluations of 3-D Eulerian PM models are presented. Currently, 24-hr average PM_2.5 concentrations appear to be predicted within 50% for urban-scale domains. However, there are compensating errors among individual particulate species. The lowest errors tend to be associated with SO₄ ^2-, while NO₃ ^-, black carbon (BC), and organic carbon (OC) typically show larger errors due to uncertainties in emissions inventories and the prediction of the secondary OC fraction. Further improvements and performance evaluations are recommended.     

Emissions Variability Processor (EMVAP): Design,evaluation, and application

Emissions of pollutants such as SO₂ and NOx from external combustion sources can vary widely depending on fuel sulfur content, load, and transient conditions such as startup, shutdown, and maintenance/malfunction. While monitoring will automatically reflect variability from both emissions and meteorological influences, dispersion modeling has been typically conducted with a single constant peak emission rate. To respond to the need to account for emissions variability in addressing probabilistic 1-hr ambient air quality standards for SO₂ and NO₂, we have developed a statistical technique, the Emissions Variability Processor (EMVAP), which can account for emissions variability in dispersion modeling through Monte Carlo sampling from a specified frequency distribution of emission rates. Based upon initial AERMOD modeling of from 1 to 5 years of actual meteorological conditions, EMVAP is used as a postprocessor to AERMOD to simulate hundreds or even thousands of years of concentration predictions. This procedure uses emissions varied hourly with a Monte Carlo sampling process that is based upon the user-specified emissions distribution, from which a probabilistic estimate can be obtained of the controlling concentration. EMVAP can also accommodate an advanced Tier 2 NO₂ modeling technique that uses a varying ambient ratio method approach to determine the fraction of total oxides of nitrogen that are in the form of nitrogen dioxide. For the case of the 1-hr National Ambient Air Quality Standards (NAAQS, established for SO₂ and NO₂), a “critical value” can be defined as the highest hourly emission rate that would be simulated to satisfy the standard using air dispersion models assuming constant emissions throughout the simulation. The critical value can be used as the starting point for a procedure like EMVAP that evaluates the impact of emissions variability and uses this information to determine an appropriate value to use for a longer term (e.g., 30-day) average emission rate that would still provide protection for the NAAQS under consideration. This paper reports on the design of EMVAP and its evaluation on several field databases that demonstrate that EMVAP produces a suitably modest overestimation of design concentrations. We also provide an example of an EMVAP application that involves a case in which a new emission limitation needs to be considered for a hypothetical emission unit that has infrequent higher-than-normal SO₂ emissions.

ImplicationsEmissions of pollutants from combustion sources can vary widely depending on fuel sulfur content, load, and transient conditions such as startup and shutdown. While monitoring will automatically reflect this variability on measured concentrations, dispersion modeling is typically conducted with a single peak emission rate assumed to occur continuously. To realistically account for emissions variability in addressing probabilistic 1-hr ambient air quality standards for SO₂ and NO₂, the authors have developed a statistical technique, the Emissions Variability Processor (EMVAP), which can account for emissions variability in dispersion modeling through Monte Carlo sampling from a specified frequency distribution of emission rates.     

Emissions from charbroiling and grilling of chicken and beef

Emission rates for fine particle (<2.5 microm) mass (PM2.5), carbon (organic/elemental), inorganic ions (SO4(2-), NO3-, NH4+), elements (primarily metals), and speciated organic compounds are reported for charbroiling hamburger, steak, and chicken. The PM2.5 rates for charbroiling meats ranged from 4.4 to 11.6 g/kg of uncooked meat in this study. No mass-emission rates are available from grilling, but the speciated organic data are available for these samples. Emission rates varied by type of appliance, meat, meat-fat content, and cooking conditions. High-fat hamburger cooked on an underfired charbroiler emitted the highest amount of PM2.5. The emissions were almost exclusively composed of organic carbon, with small amounts of elements and inorganic ions. Water-soluble K+ and Cl-, which are used as indicators of wood smoke in source apportionment studies, were also present in meat-cooking emissions. The speciated organic compounds that were measured include polycyclic aromatic hydrocarbons (PAHs), cholesterol, and the long-chain gamma-lactones. Charbroiling emissions yielded an average of approximately 3-5 times more PAHs, approximately 20 times more cholesterol, and approximately 10 times more lactones than grilling. These data were utilized in the ambient source apportionment analysis for the 1997 Northern Front Range Air Quality Study source apportionment.     

Characterization of exhaust particles from military vehicles fueled with diesel,gasoline, and JP-8

Diluted exhaust from selected military aircraft ground-support equipment (AGE) was analyzed for particulate mass, elemental carbon (EC) and organic carbon (OC), SO4(2-), and size distributions. The experiments occurred at idle and load conditions and utilized a chassis dynamometer. The selected AGE vehicles operated on gasoline, diesel, and JP-8. These military vehicles exhibited concentrations, size distributions, and emission factors in the same range as those reported for nonmilitary vehicles. The diesel and JP-8 emission rates for PM ranged from 0.092 to 1.1 g/kg fuel. The EC contributed less and the OC contributed more to the particulate mass than reported in recent studies of vehicle emissions. Overall, the particle size distribution varied significantly with engine condition, with the number of accumulation mode particles and the count median diameter (CMD) increasing as engine load increased. The SO4(2-) analyses showed that the distribution of SO4(2-) mass mirrored the distribution of particle mass.     

Evaluation of a unified regional air-quality modeling system (AURAMS) using PrAIRie2005 field study data: The effects of emissions data accuracy on particle sulphate predictions

The effects of the accuracy of major-point source emissions input data on the predictions of a regional air-quality model (AURAMS) were investigated through a series of scenario simulations. The model domain and time period were chosen to correspond to that of PrAIRie2005, an air-quality field study with airborne and ground-based mobile measurement platforms that took place between August 12th and September 7th, 2005, over the city of Edmonton, Alberta, Canada. The emissions data from standard sources for three coal-fired power-plants located west (typically upwind) of the city were compared to the continuous emissions monitoring system (CEMS) taking place at the time of the study – the latter showed that the original emissions inventory data considerably overestimated NO_x, SO₂, and primary particulate emissions during the study period. Further field investigation (stack sampling) in the fall of 2006 showed that the measured primary particle size distribution and chemical speciation for the emissions were strikingly different from the distribution and speciation originally used in the model. The measured emissions were used to scale existing emissions data in accord with the CEMS and in-stack measurements.The effects of these improvements to the emissions data were examined sequentially in nested AURAMS simulations (finest horizontal resolution 3 km), and were compared to airborne aerosol mass spectrometer (Aerodyne AMS) measurements of particle sulphate, and particle distributions from an airborne passive cavity aerosol spectrometer probe (PCASP). The emissions of SO₂ had the greatest impact on predicted PM₁ sulphate, while the primary particle size distribution and chemical speciation had a smaller role. The revised emissions data greatly improved the comparisons between observations and model values, though over-predictions of fine-mode sulphate still occur near the power-plants, with the use of the revised emissions data. The modified emissions also had a significant impact on the larger particles of the particulate matter, with more primary PM in sizes greater than 1 μm diameter than had previously been estimated, and higher large particle concentrations close to the power-plants.     

Impacts of Biodiesel on Pollutant Emissions of a JP-8–Fueled Turbine Engine

Abstract

The impacts of biodiesel on gaseous and particulate matter (PM) emissions of a JP-8–fueled T63 engine were investigated. Jet fuel was blended with the soybean oil-derived methyl ester biofuel at various concentrations and combusted in the turbine engine. The engine was operated at three power settings, namely ground idle, cruise, and takeoff power, to study the impact of the biodiesel at significantly different pressure and temperature conditions. Particulate emissions were characterized by measuring the particle number density (PND; particulate concentration), the particle size distribution, and the total particulate mass. PM samples were collected for off-line analysis to obtain information about the effect of the biodiesel on the polycyclic aromatic hydrocarbon (PAH) content. In addition, temperature-programmed oxidation was performed on the collected soot samples to obtain information about the carbonaceous content (elemental or organic). Major and minor gaseous emissions were quantified using a total hydrocarbon analyzer, an oxygen analyzer, and a Fourier Transform IR analyzer. Test results showed the potential of biodiesel to reduce soot emissions in the jet-fueled turbine engine without negatively impacting the engine performance. These reductions, however, were observed only at the higher power settings with relatively high concentrations of biodiesel. Specifically, reductions of ～15% in the PND were observed at cruise and takeoff conditions with 20% biodiesel in the jet fuel. At the idle condition, slight increases in PND were observed; however, evidence shows this increase to be the result of condensed uncombusted biodiesel. Most of the gaseous emissions were unaffected under all of the conditions. The biodiesel was observed to have minimal effect on the formation of polycyclic aromatic hydrocarbons during this study. In addition to the combustion results, discussion of the physical and chemical characteristics of the blended fuels obtained using standard American Society for Testing and Materials (ASTM) fuel specifications methods are presented.     

Ship emissions and their externalities for Greece

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, SO₂ 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 CO₂ 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 CO₂, NO_x, SO₂ 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 CO₂, NO_x, SO₂ and PM emissions reached 12.9 million tons (of which 12.4 million tons of CO₂) 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 CO₂) 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.     

Estimation of Organic Compound Emissions from Waste Lagoons

Abstract

With the recent focus on fine particle matter (PM_2.5),new, self-consistent data are needed to characterize emissions from combustion sources. Such data are necessary for health assessment and air quality modeling. To address this need, emissions data for gas-fired combustors are presented here, using dilution sampling as the reference.The dilution method allows for collection of emitted particles under conditions simulating cooling and dilution during entry from the stack into the air. The sampling and analysis of the collected particles in the presence of precursor gases, SO₂, nitrogen oxide, volatile organic compound, and NH₃ is discussed; the results include data from eight gas fired units, including a dual-fuel institutional boiler and a diesel engine powered electricity generator. These data are compared with results in the literature for heavy-duty diesel vehicles and stationary sources using coal or wood as fuels. The results show that the gas-fired combustors have very low PM_2.5 mass emission rates in the range of ～10_-4 lb/million Btu (MMBTU) compared with the diesel backup generator with particle filter, with ～5 × 10_-3 lb/MMBTU. Even higher mass emission rates are found in coal-fired systems, with rates of ～0.07 lb/MMBTU for a bag-filter-controlled pilot unit burning eastern bituminous coal. The characterization of PM_2.5 chemical composition from the gas-fired units indicates that much of the measured primary particle mass in PM_2.5 samples is organic or elemental carbon and, to a much less extent, sulfate. Metal emissions are quite low compared with the diesel engines and the coal- or woodfueled combustors. The metals found in the gas-fired combustor particles are low in concentration, similar in concentration to ambient particles. The interpretation of the particulate carbon emissions is complicated by the fact that an approximately equal amount of particulate carbon (mainly organic carbon) is found on the particle collector and a backup filter. It is likely that measurement artifacts, mostly adsorption of volatile organic compounds on quartz filters, are positively biasing “true” particulate carbon emission results.