Emissions of toxic pollutants from compressed natural gas and low sulfur diesel-fueled heavy-duty transit buses tested over multiple driving cycles

The number of heavy-duty vehicles using alternative fuels such as compressed natural gas (CNG) and new low-sulfur diesel fuel formulations and equipped with after-treatment devices are projected to increase. However, few peer-reviewed studies have characterized the emissions of particulate matter (PM) and other toxic compounds from these vehicles. In this study, chemical and biological analyses were used to characterize the identifiable toxic air pollutants emitted from both CNG and low-sulfur-diesel-fueled heavy-duty transit buses tested on a chassis dynamometer over three transient driving cycles and a steady-state cruise condition. The CNG bus had no after-treatment, and the diesel bus was tested first equipped with an oxidation catalyst (OC) and then with a catalyzed diesel particulate filter (DPF). Emissions were analyzed for PM, volatile organic compounds (VOCs; determined on-site), polycyclic aromatic hydrocarbons (PAHs), and mutagenic activity. The 2000 model year CNG-fueled vehicle had the highest emissions of 1,3-butadiene, benzene, and carbonyls (e.g., formaldehyde) of the three vehicle configurations tested in this study. The 1998 model year diesel bus equipped with an OC and fueled with low-sulfur diesel had the highest emission rates of PM and PAHs. The highest specific mutagenic activities (revertants/microg PM, or potency) and the highest mutagen emission rates (revertants/mi) were from the CNG bus in strain TA98 tested over the New York Bus (NYB) driving cycle. The 1998 model year diesel bus with DPF had the lowest VOCs, PAH, and mutagenic activity emission. In general, the NYB driving cycle had the highest emission rates (g/mi), and the Urban Dynamometer Driving Schedule (UDDS) had the lowest emission rates for all toxics tested over the three transient test cycles investigated. Also, transient emissions were, in general, higher than steady-state emissions. The emissions of toxic compounds from an in-use CNG transit bus (without an oxidation catalyst) and from a vehicle fueled with low-sulfur diesel fuel (equipped with DPF) were lower than from the low-sulfur diesel fueled vehicle equipped with OC. All vehicle configurations had generally lower emissions of toxics than an uncontrolled diesel engine. Tunnel backgrounds (measurements without the vehicle running) were measured throughout this study and were helpful in determining the incremental increase in pollutant emissions. Also, the on-site determination of VOCs, especially 1,3-butadiene, helped minimize measurement losses due to sample degradation after collection.     

Emissions from cooking microwave popcorn

This study characterized chemicals released into a chamber in the process of cooking microwave popcorn. Seventeen types of microwave popcorn from eight different brands were studied. The work proceeded in two phases: phase one investigated chemicals emitted during popping and opening, phase two investigated chemicals emitted at discrete intervals from 0-40 minutes post-pop opening. The research was performed using a microwave oven enclosed in a chamber with ports for air sampling of particulate matter (PM) and volatile organic compounds (VOCs). VOCs in the air samples were identified and quantified using gas chromatography/mass spectrometry (GC/MS). PM was characterized using both an aerodynamic particle sizer (APS) and a scanning mobility particle sizer (SMPS) to cover a full range of emitted sizes. The compounds measured during popping and opening included butter flavoring components such as diacetyl, butyric acid, acetoin, propylene glycol, 2-nonanone, and triacetin and bag components such as p-xylene and perfluorinated alcohol 8:2 telomer. The greatest chemical quantity is emitted when the bag is opened post-popping; more than 80% of the total chemical emissions occur at this time.     

Solar energy demand (SED) of commodity life cycles

The solar energy demand (SED) of the extraction of 232 atmospheric, biotic, fossil, land, metal, mineral, nuclear, and water resources was quantified and compared with other energy- and exergy-based indicators. SED represents the direct and indirect solar energy required by a product or service during its life cycle. SED scores were calculated for 3865 processes, as implemented in the Ecoinvent database, version 2.1. The results showed that nonrenewable resources, and in particular minerals, formed the dominant contribution to SED. This large share is due to the indirect solar energy required to produce these resource inputs. Compared with other energy- and exergy-based indicators, SED assigns higher impact factors to minerals and metals and smaller impact factors to fossil energetic resources, land use, and nuclear energy. The highest differences were observed for biobased and renewable energy generation processes, whose relative contribution of renewable resources such as water, biomass, and land occupation was much lower in SED than in energy- and exergy-based indicators.     

The right place for the right job in the photovoltaic life cycle

The potential for photovoltaic power generation (PV) to reduce primary energy consumption (PEC) and CO(2) emissions depends on the physical locations of each stage of its life cycle. When stages are optimally located, CO(2) emissions are reduced nearly ten times as much as when each stage is located in the country having the largest current market share. The usage stage contributes the most to reducing CO(2) emissions and PEC, and total CO(2) emissions actually increase when PV is installed in countries having small CO(2) emissions from electricity generation. Global maps of CO(2) reduction potential indicate that Botswana and Gobi in Mongolia are the optimal locations to install PV due to favorable conditions for PV power generation and high CO(2) emissions from current electricity generation. However, the small electricity demand in those countries limits the contribution to global CO(2) reduction. The type of PVs has a small but significant effect on life cycle PEC and CO(2) emissions.     

Emissions of volatile aldehydes from heated cooking oils

Emissions of volatile organic compounds, including aldehydes, formed during heating of cooking oils: coconut, safflower, canola, and extra virgin olive oils were studied at different temperatures: 180, 210, 240, and 240 °C after 6 h. Fumes were collected in Tedlar^® bags and later analysed by GC–MS. The emissions of volatiles were constant with time and increased with the oil temperature. When the temperature of the oil was above its smoke point, the emission of volatiles drastically increased, implying that oils with low smoke point, such as coconut, are not useful for deep-frying operations. Canola was the oil generating the lowest amount of potentially toxic volatile chemicals. Acrolein formation was found even at low temperatures, indicating that home cooking has to be considered as an indoor pollution problem.     

Emissions from ships in the northwestern United States

Recent inventory efforts have focused on developing nonroad inventories for emissions modeling and policy insights. Characterizing these inventories geographically and explicitly treating the uncertaintiesthat result from limited emissions testing, incomplete activity and usage data, and other important input parameters currently pose the largest methodological challenges. This paper presents a commercial marine vessel (CMV) emissions inventory for Washington and Oregon using detailed statistics regarding fuel consumption, vessel movements, and cargo volumes for the Columbia and Snake River systems. The inventory estimates emissions for oxides of nitrogen (NOx), particulate matter (PM), and oxides of sulfur (SOx). This analysis estimates that annual NOx emissions from marine transportation in the Columbia and Snake River systems in Washington and Oregon equal 6900 t of NOx (as NO2) per year, 2.6 times greater than previous NO, inventories for this region. Statewide CMV NO, emissions are estimated to be 9,800 t of NOx per year. By relying on a "bottom-up" fuel consumption model that includes vessel characteristics and transit information, the river system inventory may be more accurate than previous estimates. This inventory provides modelers with bounded parametric inputs for sensitivity analysis in pollution modeling. The ability to parametrically model the uncertainty in commercial marine vessel inventories also will help policy-makers determine whether better policy decisions can be enabled through further vessel testing and improved inventory resolution.     

Emissions of sesquiterpenes from spruce sawdust during drying

Large amounts of sawdust are dried to produce particleboard and pellets. During drying and densification, volatile organic compounds are emitted. These may contribute to the formation of tropospheric ozone. In this study, sesquiterpene emissions from Norway spruce sawdust dried in a continuous spouted bed at 140–200?°C have been investigated, and patterns of co-variation between sesquiterpene emissions and drying parameters have been elucidated. For sawdust dried to moisture contents suitable for pellets production, about 10–20?mg sesquiterpenes were emitted per kg oven dry sawdust. The sesquiterpene emissions amounted to about 20% of the monoterpene emissions. Drying at 200 °C caused markedly larger sesquiterpene emissions than did drying at 140 or 170 °C. The sesquiterpene emissions increased considerably at low wood moisture contents. While it has long been known that monoterpenes are emitted during the processing of wood, this study shows that sesquiterpenes are of considerable importance too.     

Emissions of polycyclic aromatic hydrocarbons (PAH) from creosoted railroad ties and their relevance for life cycle assessment (LCA)

Based on the analysis of cross sections of railroad ties, which were in use for up to 46 years, inventory, emission factors and total yearly emissions of creosote, PAH and phenols from the Swiss railway network were determined. During the service time of a railroad tie of 20 to 30 years, roughly 5 kg creosote are emitted. PAH emissions are in the order of about 0.5 kg (sum of 16 EPA-PAH) and occur as emissions of the volatile 2- and 3-ring PAH (such as naphthalene, acenaphthylene, acenaphthene, anthracene, fluorene, and phenanthrene). Emissions of phenolic compounds are in the range of 10 g for each tie. According to our study, about 1710 t of creosote components, 139 t of EPA-PAH and 4 t of phenolic compounds are emitted by the creosoted ties of the Swiss railway network, every year. Based on these results and on a previous study on environmental life cycle assessment (LCA) of railway ties made of creosoted beech, prestressed concrete and sectional steel, the environmental effects caused by wooden ties were compared with the environmental effects of rail and road traffic. The PAH emissions from wooden ties have an enormous influence on the two effect oriented impact categories photochemical ozone creation and human toxicity. For all other impact categories, the PAH emissions are not relevant. If the road traffic (including its upstream processes) is included in the LCA, it is clearly dominating all impact categories. The use of new creosotes according to the WEI-C standard (lower benzo[a]pyrene content, less evaporation) improves the rating in the impact category photochemical ozone creation. Less than 14% of the total impact are caused by PAH emissions if creosote WEI-C is used, compared to more than 50% for creosote WEI-A. The LCA also demonstrates that the most effective measure to reduce the potential of photochemical ozone creation and human toxicity is a reduction of the road traffic. Zusammenfassung Gestützt auf die Analyse von Querschnittsprofilen durch ausgewählte Eisenbahnschwellen, die bis zu 46 Jahre lang im Einsatz waren, wurden Inventar, Emissionsfaktoren und totale jährliche Emissionen von Teeröl, PAK und Phenolen aus dem Schweizer Schienennetz bestimmt. Eine teerölbehandelte Eisenbahnschwelle (Buchen- oder Eichenholz) emittiert während einer Einsatzdauer von 20 bis 30 Jahren rund 5 kg Teeröl. PAK Emissionen liegen im Bereich von etwa 0,5 kg (Summe der 16 EPA-PAK) und liegen als Emissionen der flüchtigen 2- und 3-Ring PAK (Naphthalin, Acenaphthylen, Acenaphthen, Anthracen, Fluoren und Phenanthren) vor. Die Emissionen phenolischer Verbindungen liegen im Bereich von 10 g pro Schwelle. Gemäss unseren Untersuchungen werden aus den teerölbehandelten Eisenbahnschwellen des schweizerischen Schienennetzes pro Jahr rund 1710 t Teeröl, 139 t EPA-PAK und 4 t phenolische Verbindungen emittiert. Basierend auf diesen Resultaten und einer bereits veröffentlichten Studie zur ökologischen Bewertung von Streckenschwellen aus vorgespanntem Beton, Profilstahl und teerölimprägniertem Buchenholz in der Schweiz wurden die Umwelteinflüsse von teerölbehandelten Eisenbahnschwellen mit denen des Schienen- und Strassenverkehrs verglichen. Die PAK Emissionen aus teerölbehandelten Holzschwellen haben einen enormen Einfluss auf die beiden effektorientierten Bewertungsparameter photochemische Ozonbildung und Humantoxizität. Für alle anderen Bewertungsparameter sind die PAK Emissionen nicht relevant. Falls der Strassenverkehr (inklusive Vorketten) mit in den Vergleich einbezogen wird, dominiert dieser alle Bewertungskategorien klar. Der Einsatz des neuen Teeröl nach WEI-C (tieferer Benzo[a]pyren Gehalt, tiefere Verdunstungsneigung) stellt in Bezug auf die photochemische Ozonbildung eine klare Verbesserung dar. Weniger als 14% der Gesamtbelastung werden erreicht, wenn Teeröl nach WEI-C eingesetzt wird, verglichen mit 50% im Falle von Teeröl nach WEI-A. Die ökologische Bewertung zeigt, dass die Bedeutung der PAK-Emissionen aus Holzschwellen im Vergleich zu anderen Emissionsquellen des Verkehrs gering ist. Ein größeres Potential zur Reduktion der Bewertungsparameter photochemische Ozonbildung und Humantoxizität besteht in einer Reduktion des Strassenverkehrs, insbesondere des motorisierten Individualverkehrs.     

Emissions of polycyclic aromatic hydrocarbons (PAH) from creosoted railroad ties and their relevance for life cycle assessment (LCA)

Based on the analysis of cross sections of railroad ties, which were in use for up to 46 years, inventory, emission factors and total yearly emissions of creosote, PAH and phenols from the Swiss railway network were determined. During the service time of a railroad tie of 20 to 30 years, roughly 5 kg creosote are emitted. PAH emissions are in the order of about 0.5 kg (sum of 16 EPA-PAH) and occur as emissions of the volatile 2- and 3-ring PAH (such as naphthalene, acenaphthylene, acenaphthene, anthracene, fluorene, and phenanthrene). Emissions of phenolic compounds are in the range of 10 g for each tie. According to our study, about 1710 t of creosote components, 139 t of EPA-PAH and 4 t of phenolic compounds are emitted by the creosoted ties of the Swiss railway network, every year. Based on these results and on a previous study on environmental life cycle assessment (LCA) of railway ties made of creosoted beech, prestressed concrete and sectional steel, the environmental effects caused by wooden ties were compared with the environmental effects of rail and road traffic. The PAH emissions from wooden ties have an enormous influence on the two effect oriented impact categories photochemical ozone creation and human toxicity. For all other impact categories, the PAH emissions are not relevant. If the road traffic (including its upstream processes) is included in the LCA, it is clearly dominating all impact categories. The use of new creosotes according to the WEI-C standard (lower benzo[a]pyrene content, less evaporation) improves the rating in the impact category photochemical ozone creation. Less than 14% of the total impact are caused by PAH emissions if creosote WEI-C is used, compared to more than 50% for creosote WEI-A. The LCA also demonstrates that the most effective measure to reduce the potential of photochemical ozone creation and human toxicity is a reduction of the road traffic.     

Water footprint of European cars: potential impacts of water consumption along automobile life cycles

Due to global increase of freshwater scarcity, knowledge about water consumption in product life cycles is important. This study analyzes water consumption and the resulting impacts of Volkswagen's car models Polo, Golf, and Passat and represents the first application of impact-oriented water footprint methods on complex industrial products. Freshwater consumption throughout the cars' life cycles is allocated to material groups and assigned to countries according to import mix shares or location of production sites. Based on these regionalized water inventories, consequences for human health, ecosystems, and resources are determined by using recently developed impact assessment methods. Water consumption along the life cycles of the three cars ranges from 52 to 83 m(3)/car, of which more than 95% is consumed in the production phase, mainly resulting from producing iron, steel, precious metals, and polymers. Results show that water consumption takes place in 43 countries worldwide and that only 10% is consumed directly at Volkswagen's production sites. Although impacts on health tend to be dominated by water consumption in South Africa and Mozambique, resulting from the production of precious metals and aluminum, consequences for ecosystems and resources are mainly caused by water consumption of material production in Europe.     

Emissions of acrolein and other aldehydes from biodiesel-fueled heavy-duty vehicles

Aldehyde emissions were measured from two heavy-duty trucks, namely 2000 and 2008 model year vehicles meeting different EPA emission standards. The tests were conducted on a chassis dynamometer and emissions were collected from a constant volume dilution tunnel. For the 2000 model year vehicle, four different fuels were tested, namely California ultralow sulfur diesel (CARB ULSD), soy biodiesel, animal biodiesel, and renewable diesel. All of the fuels were tested with simulated city and high speed cruise drive cycles. For the 2008 vehicle, only soy biodiesel and CARB ULSD fuels were tested. The research objective was to compare aldehyde emission rates between (1) the test fuels, (2) the drive cycles, and (3) the engine technologies. The results showed that soy biodiesel had the highest acrolein emission rates while the renewable diesel showed the lowest. The drive cycle also affected emission rates with the cruise drive cycle having lower emissions than the urban drive cycle. Lastly, the newer vehicle with the diesel particulate filter had greatly reduced carbonyl emissions compared to the other vehicles, thus demonstrating that the engine technology had a greater influence on emission rates than the fuels.     

Emissions of volatile organic compounds originating from UK livestock agriculture

In this paper we estimate the quantity of non‐methane volatile organic compounds (NMVOCs) emitted from UK livestock. The final estimate is derived from published values and from direct measurements of NMVOC emissions from dairy cattle slurry and laying hen manure. Emission rates of NMVOCs were determined for fresh dairy cattle slurry and laying hen manure using a 40 m³ emissions chamber. Dimethyl sulphides dominated emissions from laying hen manure at 753 ± 263 g m^?3 day^?1. Emissions from dairy cattle slurry were dominated by volatile fatty acids (C₂? C₅, 6.3 ± 3.1 g m^?3 day^?1) and phenols (2.4 ± 1.2 g m^?3 day^?1). Many of these NMVOCs are decomposition products from protein sources from which ammonia is also a by‐product. There is a close association between ammonia and NMVOC production from manure, and on this basis we estimated the annual NMVOC emissions from UK livestock as 165 ± 56 kt for 2002. These emissions compare to those from the larger industrial and transport sectors and exceed the 50–100 kt C year^?1 currently determined as originating from biogenic sources including agriculture. These findings have implications for air quality, and these NMVOCs may affect the cleansing capacity of the troposphere. Copyright © 2004 Society of Chemical Industry     

Emissions of polycyclic aromatic hydrocarbons from batch hot mix asphalt plants

This study was set out to assess the characteristics of polycyclic aromatic hydrocarbon (PAH) emissions from batch hot mix asphalt (HMA) plants and PAH removal efficiencies associated with their installed air pollution control devices. Field samplings were conducted on six randomly selected batch HMA plants. For each selected plant, stack flue gas samples were collected from both stacks of the batch mixer (n = 5) and the preheating boiler (n = 5), respectively. PAH samples were also collected from the field to assess PAHs that were directly emitted from the discharging chute (n = 3). To assess PAH removal efficiencies of the installed air pollution control devices, PAH contents in both cyclone fly ash (n=3) and bag filter fly ash (n = 3) were analyzed. Results show that the total PAH concentration (mean; RSD) in the stack flue gas of the batch mixer (354 microg/Nm3; 78.5%) was higher than that emitted from the discharging chute (107 microg/Nm3; 70.1%) and that in the stack flue gas of the preheating boiler (83.7 microg/Nm3; 77.6%). But the total BaPeq concentration of that emitted from the discharging chute (0.950 microg/Nm3; 84.4%) was higher than contained in the stack flue gas of the batch mixer (0.629 microg/Nm3; 86.8%) and the stack flue gas of the preheating boiler (= 0.112 microg/Nm3; 80.3%). The mean total PAH emission factor for all selected batch mix plants (= 139 mg/ton x product) was much higher than that reported by U.S. EPA for the drum mix asphalt plant (range = 11.8-79.0 mg/ton x product). We found the overall removal efficiency of the installed air pollution control devices (i.e., cyclone + bag filter) on total PAHs and total BaPeq were 22.1% and 93.7%, respectively. This implies that the installed air pollution control devices, although they have a very limited effect on the removal of total PAHs, do significantly reduce the carcinogenic potencies associated with PAH emissions from batch HMA plants.     

食物系统的温室气体排放及其减排策略研究进展

食物系统是一个由食物生产、加工、分配、制备和消费相关的所有要素和活动组成的复杂巨系统,其贡献了全球34%的温室气体排放,成为全球气候变化最大的驱动力之一。本文采用文献分析法,从评价方法、系统评价、减排策略和不确定性分析4 个层面综述食物系统温室气体排放研究进展,提出在未来研究中亟需从准确评价各国居民膳食消费量、完善碳足迹核算系统边界、使用区域本地化碳足迹参数3 个方面提高评价结果的准确性,以期为实现食物系统低碳可持续转型提供理论依据。     

Emissions of regulated pollutants from a spark ignition engine. Influence of fuel and air/fuel equivalence ratio

A spark ignition engine is used to determine the influence of fuel composition and air/fuel equivalence ratio on the exhaust emissions of regulated pollutants. Two specific fuel matrices are used: the first contains eight hydrocarbons and the second contains four oxygenated compounds. A specific experimental design is used for these tests. Fuel aromatics increase the exhaust CO, HC, and NOx at stoichiometry, lean and rich conditions. Lambda is more important than fuel composition in the case of CO and HC. At stoichiometry, the addition of oxygenated compounds can decrease exhaust CO, HC, and NOx up to 30%, 50%, and 60%, respectively. Under these conditions, the addition of 5% of 2-propanol is the most effective for the reduction of CO, the addition of 20% of ethanol forthe reduction of HC, and this of 5% of methyl tributyl ester (MTBE) for the NOx. The addition of oxygenated compounds can decrease CO by 30% at lean conditions, while no decrease is observed at rich ones; HC and NOx can decrease up to 30% and 80%, respectively, under lean conditions and 50% under rich ones. At all lambda tested, exhaust NOx increases with the addition of 20% of 2-propanol.     

Research Watch: Emissions

Monitoring.