Assessment of the emissions and air quality impacts of biomass and biogas use in California

It is estimated that there is sufficient in-state “technically” recoverable biomass to support nearly 4000 MW of bioelectricity generation capacity. This study assesses the emissions of greenhouse gases and air pollutants and resulting air quality impacts of new and existing bioenergy capacity throughout the state of California, focusing on feedstocks and advanced technologies utilizing biomass resources predominant in each region. The options for bioresources include the production of bioelectricity and renewable natural gas (NG). Emissions of criteria pollutants and greenhouse gases are quantified for a set of scenarios that span the emission factors for power generation and the use of renewable natural gas for vehicle fueling. Emissions are input to the Community Multiscale Air Quality (CMAQ) model to predict regional and statewide temporal air quality impacts from the biopower scenarios. With current technology and at the emission levels of current installations, maximum bioelectricity production could increase nitrogen oxide (NO_x) emissions by 10% in 2020, which would cause increases in ozone and particulate matter concentrations in large areas of California. Technology upgrades would achieve the lowest criteria pollutant emissions. Conversion of biomass to compressed NG (CNG) for vehicles would achieve comparable emission reductions of criteria pollutants and minimize emissions of greenhouse gases (GHG). Air quality modeling of biomass scenarios suggest that applying technological changes and emission controls would minimize the air quality impacts of bioelectricity generation. And a shift from bioelectricity production to CNG production for vehicles would reduce air quality impacts further. From a co-benefits standpoint, CNG production for vehicles appears to provide the best benefits in terms of GHG emissions and air quality.

Implications:?This investigation provides a consistent analysis of air quality impacts and greenhouse gas emissions for scenarios examining increased biomass use. Further work involving economic assessment, seasonal or annual emissions and air quality modeling, and potential exposure analysis would help inform policy makers and industry with respect to further development and direction of biomass policy and bioenergy technology alternatives needed to meet energy and environmental goals in California.     

小型燃油锅炉NOx的排放特征与管理控制

以68台燃油锅炉（≤10～MW）NOx排放实测数据为基础,通过统计分析方法,研究了NOx的排放特征;通过对比分析,探讨了我国燃油锅炉NOx排放控制与管理现状,讨论了进一步加强我国燃油锅炉NOx排放管理控制的可能性与可行性,并提出了相应的管理控制建议。结果表明,NOx平均排放浓度为318．2mg／m^3,基于燃料消耗量的平均排放因子为4．4kg／t,基于燃料发热量的平均排放因子为102．8ng／J,基于燃料氮含量的平均排放因子为2．1mg／mg;建议采取分阶段控制的方式,逐步提高NOx排放限制,从而实现控源减排目标。     

The impact of NOx,CO and VOC emissions on the air quality of Zurich airport

To study the impact of emissions at an airport on local air quality, a measurement campaign at the Zurich airport was performed from 30 June 2004 to 15 July 2004. Measurements of NO, NO₂, CO and CO₂ were conducted with open path devices to determine real in-use emission indices of aircraft during idling. Additionally, air samples were taken to analyse the mixing ratios of volatile organic compounds (VOC). Temporal variations of VOC mixing ratios on the airport were investigated, while other air samples were taken in the plume of an aircraft during engine ignition. CO concentrations in the vicinity of the terminals were found to be highly dependent on aircraft movement, whereas NO concentrations were dominated by emissions from ground support vehicles. The measured emission indices for aircraft showed a strong dependence upon engine type. Our work also revealed differences from emission indices published in the emission data base of the International Civil Aviation Organisation. Among the VOC, reactive C₂–C₃ alkenes were found in significant amounts in the exhaust of an engine compared to ambient levels. Also, isoprene, a VOC commonly associated with biogenic emissions, was found in the exhaust, however it was not detected in refuelling emissions. The benzene to toluene ratio was used to discriminate exhaust from refuelling emission. In refuelling emissions, a ratio well below 1 was found, while for exhaust this ratio was usually about 1.7.     

Quantification of variability and uncertainty in air pollutant emission inventories: method and case study for utility NOx emissions

The quality of stationary source emission factors is typically described using data quality ratings, which provide no quantification of the precision of the emission factor for an average source, nor of the variability from one source to another within a category. Variability refers to actual differences caused by differences in feedstock composition, design, maintenance, and operation. Uncertainty refers to lack of knowledge regarding the true emissions. A general methodology for the quantification of variability and uncertainty in emission factors, activity factors, and emission inventories (EIs) is described, featuring the use of bootstrap simulation and related techniques. The methodology is demonstrated via a case study for a selected example of NOx emissions from coal-fired power plants. A prototype software tool was developed to implement the methodology. The range of interunit variability in selected activity and emission factors was shown to be as much as a factor of 4, and the range of uncertainty in mean emissions is shown to depend on the interunit variability and sample size. The uncertainty in the total inventory of -16 to +19% was attributed primarily to one technology group, suggesting priorities for collecting data and improving the inventory. The implications for decision-making are discussed.     

中国山东电网燃煤锅炉NOx排放状况和治理技术试验研究

通过对山东电网所属发电厂锅炉NOx排放状况进行调查、测试，得出锅炉NOx排放量与煤种、炉型、燃烧器型式、运行中空气过剩系数、负荷等的关系。结果表明，山东省火力发电厂50MW及以上容量机组2003年的NOx排放总量超过40万t（按NO2计算）。控制和治理NOx排放已成为刻不容缓的重要工作。     

Anthropogenic emissions of SO2 and NOx in Asia: Emission inventories

The anthropogenic emissions of SO₂ and NO_x for 25 Asian countries east of Afghanistan and Pakistan have been calculated for 1975, 1980, 1985, 1986 and 1987 based on fuel consumption, sulfur content in fuels and emission factors for used fuels in each emission category. The provincial- and regional-based calculations have also been made for China and India. The total SO₂ emissions in these parts of Asia have been calculated to be 18.3 and 29.1 Tg in 1975 and 1987, respectively. The calculated total NO_x emissions were 9.4 and 15.5 Tg in 1975 and 1987, respectively. The SO₂ and NO_x emissions in East Asia (China, Japan, South Korea, North Korea and Taiwan) were 23.4 and 10.7 Tg in 1975 and 1987, respectively.Keyword: Emission inventories, sulfur dioxide emissions, nitrogen oxide emissions, Asian emissions, anthropogenic emissions.     

Modelling the spatial distribution of SO2 and NOx emissions in Ireland

The spatial distributions of sulphur dioxide (SO2) and nitrogen oxides (NOx) emissions are essential inputs to models of atmospheric transport and deposition. Information of this type is required for international negotiations on emission reduction through the critical load approach. High-resolution emission maps for the Republic of Ireland have been created using emission totals and a geographical information system, supported by surrogate statistics and landcover information. Data have been subsequently allocated to the EMEP 50 x 50-km grid, used in long-range transport models for the investigation of transboundary air pollution. Approximately two-thirds of SO2 emissions in Ireland emanate from two grid-squares. Over 50% of total SO2 emissions originate from one grid-square in the west of Ireland, where the largest point sources of SO2 are located. Approximately 15% of the total SO2 emissions originate from the grid-square containing Dublin. SO2 emission densities for the remaining areas are very low, < 1 t km-2 year-1 for most grid-squares. NOx emissions show a very similar distribution pattern. However, NOx emissions are more evenly spread over the country, as about 40% of total NOx emissions originate from road transport.     

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.     

中小型燃用烟煤层燃炉NOx排放特征分析

以86台中小型燃烟煤层燃炉（≤65 MW）的燃料特性分析数据和NOx排放实测数据为基础,通过统计分析方法,研究了锅炉出力、过量空气系数、燃煤挥发分、燃煤氮含量对NOx排放浓度的影响,分析了我国中小型燃烟煤层燃炉NOx的排放与管理控制现状。结果表明,中小型燃用烟煤层燃炉NOx平均排放浓度为324.6 mg/m^3;锅炉出力对NOx排放浓度不具有显著影响;燃煤挥发分增高,NOx排放浓度降低;过量空气系数和燃煤氮含量增大,NOx排放浓度增高;并建议在国家层面上尽快制订燃煤锅炉NOx排放标准限值。     

Role of biological activity and biomass distribution in air biofilter performance

The effects of temporal and spatial changes in biological activity and biomass amount on biofilter performance were investigated in a lab-scale trickle-bed air biofilter at a toluene loading of 46.9gm(-3)h(-1) under two different experimental strategies, namely, periodic backwashing at a rate of 1h once a week and 2d starvation. Analysis of the overall reaction for toluene metabolism revealed that cell synthesis was relatively favored over toluene oxidation in the inlet section of the biofilter, but over time its oxidation became favored throughout the biofilter bed. Periodic in situ backwashing with media fluidization effectively made even spatial distribution of biomass along the bed media, by which consistent high removal performance in the biofilter has been attained. After 2d starvation, the ratio of the biofilm EPS to the total biomass increased along the media bed depth, while the total biomass in the media bed subsequently decreased. The presence of sufficient biomass and microbial activity favorably influenced biofilter reacclimation after restart-up following starvation.     

Thermodynamic analysis and kinetic modelling of dioxin formation and emissions from power boilers firing salt-laden hog fuel

Both organic chlorine (e.g. PVC) and inorganic chlorides (e.g. NaCl) can be significant chlorine sources for dioxin and furan (PCDD/F) formation in combustion processes. This paper presents a thermodynamic analysis of high temperature salt chemistry. Its influence on PCDD/F formation in power boilers burning salt-laden wood waste is examined through the relationships between Cl2, HCl, NaCl(g) and NaCl(c). These analyses show that while HCl is a product of combustion of PVC-laden municipal solid waste, NaCl can be converted to HCl in hog fuel boilers by reactions with SO2 or alumino-silicate materials. Cl2 is a strong chlorinating agent for PCDD/F formation. HCl can be oxidized to Cl2 by O2, and Cl2 can be reduced back to HCl by SO2. The presence of sulphur at low concentrations thus enhances PCDD/F formation by increasing HCl concentrations. At high concentrations, sulphur inhibits de novo formation of PCDD/Fs through Cl2 reduction by excess SO2. The effect of NH3, CO and NOx on PCDD/F formation is also discussed. A semi-empirical kinetic model is proposed. This model considers both precursor and de novo formation mechanisms. A simplified version is used as a stack emission model. The kinetic model indicates that stack dioxin emissions will increase linearly with decreasing electrostatic precipitator (ESP) efficiency and exponentially with increasing ESP temperature.     

奥里油燃烧过程中的NOx形成机理及控制技术

介绍了奥里油的特性及其在电厂中的应用情况，对奥里油燃烧过程中NOx的形成机理和影响因素作了初步分析，同时比较了燃烧粉煤、重油或奥里油时的NOx排放量，为我国开展相关研究提供了参考。     

Impact of anthropogenic emissions and open biomass burning on regional carbonaceous aerosols in South China

Carbonaceous aerosols were studied at three background sites in south and southwest China. Hok Tsui in Hong Kong had the highest concentrations of carbonaceous aerosols (OC = 8.7 ± 4.5 μg/m³, EC = 2.5 ± 1.9 μg/m³) among the three sites, and Jianfeng Mountains in Hainan Island (OC = 5.8 ± 2.6 μg/m³, EC = 0.8 ± 0.4 μg/m³) and Tengchong mountain over the east edge of the Tibetan Plateau (OC = 4.8 ± 4.0 μg/m³, EC = 0.5 ± 0.4 μg/m³) showed similar concentration levels. Distinct seasonal patterns with higher concentrations during the winter, and lower concentrations during the summertime were observed, which may be caused by the changes of the regional emissions, and monsoon effects. The industrial and vehicular emissions in East, Southeast and South China, and the regional open biomass burning in the Indo-Myanmar region of Asia were probably the two major potential sources for carbonaceous matters in this region.     

The impact of biomass burning emissions on protected natural areas in central and southern Mexico

Environmental Science and Pollution Research - Biomass burning from grassland, forests, and agricultural waste results in large amounts of gases and particles emitted to the atmosphere, which...     

Effects of combustion and operating conditions on PCDD/PCDF emissions from power boilers burning salt-laden wood waste

This paper discusses the effects of combustion conditions on PCDD/PCDF emissions from pulp and paper power boilers burning salt-laden wood waste. We found no correlation between PCDD/PCDF emissions and carbon monoxide emissions. A good correlation was, however, observed between PCDD/PCDF emissions and the concentration of stack polynuclear aromatic hydrocarbons (PAHs) in the absence of TDF addition. Thus, poor combustion conditions responsible for the formation of products of incomplete combustion (PICs), such as PAHs and PCDD/PCDF precursors, increase PCDD/PCDF emissions. PAH concentrations increased with higher boiler load and/or low oxygen concentrations at the boiler exit, probably because of lower available residence times and insufficient excess air. Our findings are consistent with the current understanding that high ash carbon content generally favours heterogeneous reactions leading to either de novo synthesis of PCDD/PCDFs or their direct formation from precursors. We also found that, in grate-fired boilers, a linear increase in the grate/lower furnace temperature produces an exponential decrease in PCDD/PCDF emissions. Although the extent of this effect appears to be mill-specific, particularly at low temperatures, the results indicate that increasing the combustion temperature may decrease PCDD/PCDF emissions. It must be noted, however, that there are other variables, such as elevated ESP and stack temperatures, a high hog salt content, the presence of large amounts of PICs and a high Cl/S ratio, which contribute to higher PCDD/PCDFs emissions. Therefore, higher combustion temperatures, by themselves, will not necessarily result in low PCDD/PCDFs emissions.     

Scenarios of global anthropogenic emissions of air pollutants and methane until 2030

We have used a global version of the Regional Air Pollution Information and Simulation (RAINS) model to estimate anthropogenic emissions of the air pollution precursors sulphur dioxide (SO₂), nitrogen oxides (NO_x), carbon monoxide (CO), primary carbonaceous particles of black carbon (BC), organic carbon (OC) and methane (CH₄). We developed two scenarios to constrain the possible range of future emissions. As a baseline, we investigated the future emission levels that would result from the implementation of the already adopted emission control legislation in each country, based on the current national expectations of economic development. Alternatively, we explored the lowest emission levels that could be achieved with the most advanced emission control technologies that are on the market today. This paper describes data sources and our assumptions on activity data, emission factors and the penetration of pollution control measures. We estimate that, with current expectations on future economic development and with the present air quality legislation, global anthropogenic emissions of SO₂ and NO_x would slightly decrease between 2000 and 2030. For carbonaceous particles and CO, reductions between 20% and 35% are computed, while for CH₄ an increase of about 50% is calculated. Full application of currently available emission control technologies, however, could achieve substantially lower emissions levels, with decreases up to 30% for CH₄, 40% for CO and BC, and nearly 80% for SO₂.     

Biofiltration of cyclic air emissions of alpha-pinene at low and high frequencies

Biofiltration of periodically fluctuating concentrations of an alpha-pinene-laden waste gas was investigated to treat both high-frequency and low-frequency fluctuations. The effects of periodic concentration fluctuations on biofilter performance were measured. Controlled variables of periodic operation included cycle period and amplitude. The cycle period ranged from 10 min to 6 days, with the inlet alpha-pinene concentration fluctuating between 0 and 100 parts per million volume. At high-frequency concentration cycling (i.e., on the order of minutes), both cyclic and constant concentration biofilters maintained similar long-term performance with an average removal efficiency of 77% at an averaged loading rate of 29 g alpha-pinene/m3 bed/hr. A first approximation suggests kinetics that are time-independent, indicating that steady-state data can be used to predict transient behavior at this time scale. Cyclic biofilter operation with a cycle period of 24 hr (with equal on/off time) was achievable for biofilters without a significant loss in performance. At longer time scales, cyclic biofilter performance decreased at the restart of the ON cycle. The recovery time to previous levels of performance increased with increasing cycle period; the recovery time was less than 1 hr for a cycle period of 24 hr and between 6 and 8 hr for a cycle period of 6 days.     

The contribution from shipping emissions to air quality and acid deposition in Europe

A global three-dimensional Lagrangian chemistry-transport model STOCHEM is used to describe the European regional acid deposition and ozone air quality impacts along the Atlantic Ocean seaboard of Europe, from the SO2, NOx, VOCs and CO emissions from international shipping under conditions appropriate to the year 2000. Model-derived total sulfur deposition from international shipping reaches over 200 mg S m(-2) yr(-1) over the southwestern approaches to the British Isles and Brittany. The contribution from international shipping to surface ozone concentrations during the summertime, peaks at about 6 ppb over Ireland, Brittany and Portugal. Shipping emissions act as an external influence on acid deposition and ozone air quality within Europe and may require control actions in the future if strict deposition and air quality targets are to be met.     

Atmospheric polycyclic aromatic hydrocarbons and isomer ratios as tracers of biomass burning emissions in Northern India

Emission from large-scale post-harvest agricultural-waste burning (paddy-residue burning during October–November and wheat-residue burning in April–May) is a conspicuous feature in northern India. The poor and open burning of agricultural residue result in massive emission of carbonaceous aerosols and organic pollutants to the atmosphere. In this context, concentrations of atmospheric polycyclic aromatic hydrocarbons (PAHs) and their isomer ratios have been studied for a 2-year period from a source region (Patiala: 30.2°N; 76.3°E) of two distinct biomass burning emissions. The concentrations of 4—6 ring PAHs are considerably higher compared to 2–3 ring PAHs in the ambient particulate matter (PM_2.5). The crossplots of PAH isomer ratios, fluoranthene?/?(fluoranthene?+?pyrene) and indeno[1,2,3-cd]pyrene/(indeno[1,2,3-cd]pyrene?+?benzo[g,h,i]perylene) for two biomass burning emissions, exhibit distinctly different source characteristics compared to those for fossil-fuel combustion sources in south and south-east Asia. The PAH isomer ratios studied from different geographical locations in northern India also exhibit similar characteristics on the crossplot, suggesting their usefulness as diagnostic tracers of biomass burning emissions.     

Remote monitoring of air pollutant emissions from point sources by a mobile lidar/sodar system

This paper describes remote monitoring of air pollutant emissions by a mobile lidar (light detection and ranging)/ sodar (sound detection and ranging) system. First, measurements are carried out in the flue gas plume of a public power plant. The investigations focus mainly on quantifying SO2 emissions, but the uncertainties of such measurements are also emphasized. Furthermore, an example providing valuable data sets for the development and validation of plume dispersion models is outlined with measurements of the dilution of SO2 along the plume axis. Series of repeated determinations of SO2 emissions show a large variation in the obtained flux values, with moderate margins of error. Incomplete recording of the plume within the individual lidar scans, induced by strong looping movements of the flue gas plume, predominantly causes the variations of flux values. Therefore, the highest flux values determined are considered to be the most exact. This is verified by a comparison of measured fluxes with in situ measurements made by the plant operators. The results further indicate that lidar measurements illustrate the location and dimension of aerosol plumes better than the location and dimension of the plumes of gaseous compounds. The wind direction affecting the plume at any moment can be determined faster by lidar than by sodar because the latter requires much longer time intervals of signal averaging. Measurements show higher concentrations of SO2 compared with results from a Gaussian plume model for periods of less than 5 min after dispersion. The findings emphasize the suitability of remote sensing for detecting emissions and for investigating the propagation and dilution of air pollutant plumes.