Emissions of PCDD and PCDF from combustion of forest fuels and sugarcane: a comparison between field measurements and simulations in a laboratory burn facility

Release of PCDD and PCDF from biomass combustion such as forest and agricultural crop fires has been nominated as an important source for these chemicals despite minimal characterisation. Available emission factors that have been experimentally determined in laboratory and field experiments vary by several orders of magnitude from <0.5 μg TEQ (t fuel consumed)⁻¹ to >100 μg TEQ (t fuel consumed)⁻¹. The aim of this study was to evaluate the effect of experimental methods on the emission factor.A portable field sampler was used to measure PCDD/PCDF emissions from forest fires and the same fuel when burnt over a brick hearth to eliminate potential soil effects. A laboratory burn facility was used to sample emissions from the same fuels. There was very good agreement in emission factors to air (EF_Air) for forest fuel (Duke Forest, NC) of 0.52 (range: 0.40-0.79), 0.59 (range: 0.18-1.2) and 0.75 (range: 0.27-1.2) μg TEQ_WHO2005 (t fuel consumed)⁻¹ for the in-field, over a brick hearth, and burn facility experiments, respectively. Similarly, experiments with sugarcane showed very good agreement with EF_Air of 1.1 (range: 0.40-2.2), 1.5 (range: 0.84-2.2) and 1.7 (range: 0.34-4.4) μg TEQ (t fuel consumed)⁻¹ for in-field, over a brick hearth, open field and burn facility experiments respectively. Field sampling and laboratory simulations were in good agreement, and no significant changes in emissions of PCDD/PCDF could be attributed to fuel storage and transport to laboratory test facilities.     

Monitoring of fuel consumption and aromatics formation in a kerosene spray flame as characterized by fluorescence spectroscopy

The large presence of aromatic compounds in distillate fossil fuels should allow, in line of principle, to follow the fuel consumption and/or the presence of unburned fuel in a high temperature environment like a burner or the exhaust of combustion systems by exploiting the high fluorescence emission of aromatic fuel components. To this aim an UV-excited fluorescence source has to be used since the aromatic fuel components are strongly fluorescing in the UV region of the emission spectrum.

In this work UV-excited laser induced fluorescence (LIF) diagnostics was applied to spray flames of kerosene in order to follow the fuel consumption and the formation of aromatic species. A strong UV signal was detected in the spray region of the flame that presented a shape similar to that found in the LIF spectra preliminary measured on the cold spray and in the room-temperature fluorescence of fuel solutions.

The decrease of UV signal along the spray flame region was associated to the consumption of the fuel, but more difficult seems to be the attribution of a broad visible emission, that is present downstream of the flame.

The visible emission feature could be assigned to flame-formed PAH species contained in the high molecular weight species, hypothesizing that their fluorescence spectra are shifted toward the visible for effect of the high temperature flame environment.     

Regulated and unregulated emissions from a diesel engine fueled with biodiesel and biodiesel blended with methanol

Experiments were carried out on a diesel engine operating on Euro V diesel fuel, pure biodiesel and biodiesel blended with methanol. The blended fuels contain 5%, 10% and 15% by volume of methanol. Experiments were conducted under five engine loads at a steady speed of 1800 rev min⁻¹ to assess the performance and the emissions of the engine associated with the application of the different fuels. The results indicate an increase of brake specific fuel consumption and brake thermal efficiency when the diesel engine was operated with biodiesel and the blended fuels, compared with the diesel fuel. The blended fuels could lead to higher CO and HC emissions than biodiesel, higher CO emission but lower HC emission than the diesel fuel. There are simultaneous reductions of NO_x and PM to a level below those of the diesel fuel. Regarding the unregulated emissions, compared with the diesel fuel, the blended fuels generate higher formaldehyde, acetaldehyde and unburned methanol emissions, lower 1,3-butadiene and benzene emissions, while the toluene and xylene emissions not significantly different.     

Formation and destruction of PCDD/F inside a grate furnace

Formation and destruction of polychlorinated dibenzo-p-dioxins and dibenzofurans PCDD/F during the combustion process was investigated experimentally in a pilot plant. All important process steps like the burnout of the fuel bed on the grate, the burnout of the flue gas inside the combustion chamber, the heat recovery in a boiler as well as influences of the fuel composition are described in detail.

High concentrations especially of PCDF are formed during the burnout of the fuel bed. The formation reaction is mainly influenced by the fuel composition and the burnout characteristic of the fuel bed. Fuels with low chlorine and low metal content (Cu) result only in negligible concentrations of PCDD/F.

Under stable combustion conditions characterized by an excellent flue gas burnout PCDD/F will almost be completely destroyed already inside the combustion chamber. “Cold strands” of unburned flue gas (high CO concentrations) caused by disturbed combustion conditions will result in high concentrations of PCDD and especially of PCDF in the raw gas.

A second place of PCDD/F formation is the well-known boiler section. Here fly ash deposits containing residual carbon (mainly soot particles) are the source for the formation reaction. Under stationary effective combustion conditions, they are dominant for PCDD/F concentrations in the raw gas over a very long period of time.

Stationary efficient flue gas burnout (especially soot) together with effective boiler cleaning will guaranty low concentrations of PCDD/F in the flue gas in front of the flue gas cleaning system.     

Developing a high-resolution vehicular emission inventory by integrating an emission model and a traffic model: Part 1--Modeling fuel consumption and emissions based on speed and vehicle-specific power

To improve the accuracy and applicability of vehicular emission models, this study proposes a speed and vehicle-specific power (VSP) modeling method to estimate vehicular emissions and fuel consumption using data gathered by a portable emissions monitoring system (PEMS). The PEMS data were categorized into discrete speed-VSP bins on the basis of the characteristics of vehicle driving conditions and emissions in Chinese cities. Speed-VSP modal average rates of emissions (or fuel consumption) and the time spent in the corresponding speed-VSP bins were then used to calculate the total trip emissions (or fuel consumption) and emission factors (or fuel economy) under specific average link speeds. The model approach was validated by comparing it against measured data with prediction errors within 20% for trip emissions and link-speed-based emission factors. This analysis is based on the data of light-duty gasoline vehicles in China; however, this research approach could be generalized to other vehicle fleets in other countries. This modeling method could also be coupled with traffic demand models to establish high-resolution emissions inventories and evaluate the impacts of traffic-related emission control measures.     

Effect of Methanol on Exhaust Composition of a Fuel Containing Toluene,n-Heptane,and Isooctane

This study describes the variations in the chemical composition of the exhaust from a single cylinder engine when up to 25% methanol is added to a fuel blend of toluene, isooctane, and n-heptane. Under fuel-rich conditions, and with increasing methanol concentration, it is observed that unburned fuel and benzene emissions increase, exhaust acetylene remains constant, and propylene, isobutylene, methane, ethylbenzene, and styrene concentrations decrease. As oxygen becomes more available, the effects of methanol are reduced, and at an equivalence ratio of 1.25—excess oxygen now is present—methanol no longer affects the concentration of exhaust hydrocarbons. These observations are explained by the reactions of formaldehyde—an incomplete combustion product of methanol— with alkyl radicals derived from the fuel. The photochemical reactivity of the exhaust is unchanged when up to 15% of methanol is present in the fuel at an equivalence ratio of 0.85, but increases at higher methanol contents because of the increase in unburned toluene in the exhaust.     

Indoor air pollution from solid fuel on children pneumonia in low- and middle-income countries: a systematic review and meta-analysis

An updated systematic review was conducted to assessing on the association between indoor air pollution caused by household energy consumption and childhood pneumonia in low- and middle-income countries. We performed a meta-analysis from the electronic databases of PubMed, Cochrane library, Web of Science, EMBASE. Studies were selected when they reported childhood pneumonia or ALRI in relation to indoor air pollution resulted from solid fuel. Studies must provide results on exposure prevalence of children aged below 5 years from Asia or Africa. We devoted ourselves to identifying randomized controlled experiments and observational epidemiological researches, which revealed the relation between household usage of solid fuel and childhood pneumonia. Among 1954 articles, 276 were reviewed thoroughly and 16 conduced to such a meta-analysis. It was found that there is a significant relationship between the solid fuel combustion and increasing risk of childhood pneumonia (OR?=?1.66, 95%CI 1.36–2.02). The summary odds ratios from biomass use and mixed fuel use were, respectively, 1.86 (95%CI 1.15–3.02) and 1.58 (95%CI 1.38–1.81), with substantial between study heterogeneity (I²?=?87.2% and 29.2%, respectively). According to the subgroup analysis along with the meta-regression analysis, the risk of using solid fuel in Asian regions is higher than that in African regions. Studies based on non-hospital participates (I²?=?49.5%) may also a source of heterogeneity. We found that indoor air pollution generated by the usage of solid fuel might be a significant risk factor for pneumonia in children and suggested improving the indoor air quality by promoting cleaner fuel will be important in undeveloped countries.

     

Energy use and emissions from marine vessels: a total fuel life cycle approach

Regional and global air pollution from marine transportation is a growing concern. In discerning the sources of such pollution, researchers have become interested in tracking where along the total fuel life cycle these emissions occur. In addition, new efforts to introduce alternative fuels in marine vessels have raised questions about the energy use and environmental impacts of such fuels. To address these issues, this paper presents the Total Energy and Emissions Analysis for Marine Systems (TEAMS) model. TEAMS can be used to analyze total fuel life cycle emissions and energy use from marine vessels. TEAMS captures "well-to-hull" emissions, that is, emissions along the entire fuel pathway, including extraction, processing, distribution, and use in vessels. TEAMS conducts analyses for six fuel pathways: (1) petroleum to residual oil, (2) petroleum to conventional diesel, (3) petroleum to low-sulfur diesel, (4) natural gas to compressed natural gas, (5) natural gas to Fischer-Tropsch diesel, and (6) soybeans to biodiesel. TEAMS calculates total fuel-cycle emissions of three greenhouse gases (carbon dioxide, nitrous oxide, and methane) and five criteria pollutants (volatile organic compounds, carbon monoxide, nitrogen oxides, particulate matter with aerodynamic diameters of 10 microm or less, and sulfur oxides). TEAMS also calculates total energy consumption, fossil fuel consumption, and petroleum consumption associated with each of its six fuel cycles. TEAMS can be used to study emissions from a variety of user-defined vessels. This paper presents TEAMS and provides example modeling results for three case studies using alternative fuels: a passenger ferry, a tanker vessel, and a container ship.     

Modeling the emissions of a dual fuel engine coupled with a biomass gasifier—supplementing the Wiebe function

There is a growing market demand for small-scale biomass gasifiers that is driven by the economic incentives and the legislative framework. Small-scale gasifiers produce a gaseous fuel, commonly referred to as producer gas, with relatively low heating value. Thus, the most common energy conversion systems that are coupled with small-scale gasifiers are internal combustion engines. In order to increase the electrical efficiency, the operators choose dual fuel engines and mix the producer gas with diesel. The Wiebe function has been a valuable tool for assessing the efficiency of dual fuel internal combustion engines. This study introduces a thermodynamic model that works in parallel with the Wiebe function and calculates the emissions of the engines. This “vis-à-vis” approach takes into consideration the actual conditions inside the cylinders—as they are returned by the Wiebe function—and calculates the final thermodynamic equilibrium of the flue gases mixture. This approach aims to enhance the operation of the dual fuel internal combustion engines by identifying the optimal operating conditions and—at the same time—advance pollution control and minimize the environmental impact.     

Effect of start of main injection timing on performance,emission, and combustion characteristics of a VGT CI engine fueled with neem biodiesel

The performance of engine parameters is more influenced with fuel injection strategies namely start of main injection timing (SoMI). An experimental analysis was performed to find the optimum SoMI timing based on performance, emission, and combustion characteristics. Base fuel of diesel and neem biodiesel was used as test fuels. The neem biodiesel was prepared by esterification and transesterification process. It is found from literature that neem biodiesel blend NB20 with diesel gives optimum performance and emission characteristics; therefore, NB20 blend was used for experiments. A variable geometry turbocharger (VGT) compression ignition (CI) engine was used to conduct the experiments. Engine performance parameters were estimated and compared with a base fuel of diesel and with NB20 blends. In this experimentation, fuel injection pressure (FIP) of 800 bar and engine speed of 1700 rpm were considered. SoMI timing was varied from 2° to 10° bTDC with an increment of 2° bTDC timing. Cylinder pressure (CP) and heat release rate (HRR) were estimated and found that are higher for diesel fuel compared to NB20 blend at different SoMI timings. The addition of neem biodiesel NB20 blend to diesel fuel decreases the exhaust emissions except NOx emissions. The BSFC was considerably reduced and BTE was improved almost equivalent to the diesel fuel for NB20. From the results, it is concluded that 10° bTDC SoMI timing provides 13% improvement in BTE, 21% decrement in BSFC, and 7.5% reduction in CO₂ emissions.

     

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.     

Biocatalyst physiology and interplay: a protagonist of MFC operation

Environmental Science and Pollution Research - Microbial fuel cells (MFC) have been foreseen as a sustainable renewable energy resource to meet future energy demand. In the past, several studies...     

Method for reporting in-use vehicle fuel consumption and carbon dioxide emissions from a fast-pass transient inspection

A method has been developed that allows reporting of the fuel consumption and carbon dioxide (CO2) emissions for in-use vehicles from a fast-pass transient (IM240) inspection. The major technical obstacle to reporting CO2 emission rate and fuel consumption is that inspection and maintenance tests do not all use a standardized test duration or test method. The method is able to project full-duration fuel consumption from IM240 tests that actually fast-passed as early as just 30 sec from starting the test. It is based on basic considerations of the work done in driving the inspection cycle, with additional empirical adjustments. The initial application examined the differences between passing and failing inspections, and this did confirm that there are significant differences.     

Impact of NOx Emissions Released from a Gas Turbine-Based Power Plant on the Ambient Air Quality

The number of gas turbine- (GT-) based power plants is rapidly increasing to meet the world’s power demands. Until a few years ago, fossil fuel, and specifically fuel oil, was considered the major energy source for gas turbine operation. Due to the high amount of pollution that fuel oil generates, natural gas has become a popular source of energy due to its lower emissions compared to fuel oil. As a result, many GTs have switched to natural gas as an alternative to fuel oil. However, pollutants expelled from GT-based power plants operating on natural gas impact surrounding air quality. The objective of this study was to examine the dispersion of nitrogen oxides (NO_x) emitted from a GT-based power plant located in the Sultanate of Oman. Supported by CALPUFF dispersion modeling software, six scenarios were investigated in this study. The first four scenarios considered a case where the GT-based power plant was operating on natural gas during winter and summer and for open and combined cycle modes. The remaining two scenarios considered, for both open and combined cycle modes, the case where the GT-based power plant was operating on fuel oil. Whether run by natural gas or fuel oil, CALPUFF simulation results for both seasons showed that NO_x concentrations were higher when GTs were used in the combined cycle mode. The concentrations were still lower than the allowable concentrations set by the United States Environmental Protection Agency (U.S. EPA) standards. In contrast, for the case where the power plant operated on fuel oil, the NO_x one-hour average simulated results exceeded the allowable limits only when the combined cycle mode was activated.     

In Situ Measurement of Hydrochloric Acid in Rocket Exhaust Clouds Using a Remotely Piloted Aircraft

Abstract

An instrumentation system employing an RPV (remotely piloted vehicle) platform was developed for temporally and spatially resolved air pollution measurements, and was used to measure the evolution of gas-phase HC1 in exhaust clouds from a solid rocket motor firing and fuel pit burns. A thermistor and a sensitive (ppmv-level), rapid-response (<0.1 sec) infrared absorption sensor for HC1 were mounted in a flow channel in the RPV, permitting concentration and temperature measurements to be made in the cloud on a several-meter scale. The RPV system was flown in a series of field tests at Thiokol Corporation’s Elkton, MD division to evaluate the HC1 content of the exhaust products of a new Mg-based fuel formulation. Measurements were made in the clouds from Al-based and Mg-based solid fuel pit burns and a Mg-fueled motor firing over periods of several minutes. Elevated temperatures and HC1 concentrations were found to be temporally correlated with video images of the particulate cloud. Cl originating from the ammonium perchlorate oxidizer appeared in the exhaust as HC1 in each of the tests. Both the macroscopic and local cloud parameters indicate that the Mg-based fuel may provide some reduction in HC1 concentration compared to the standard Al-based fuel.     

Feasibility of Landfill Gas as a Liquefied Natural Gas Fuel Source for Refuse Trucks

Abstract

The purpose of this paper is to develop a methodology to evaluate the feasibility of using landfill gas (LFG) as a liquefied natural gas (LNG) fuel source for heavy-duty refuse trucks operating on landfills. Using LFG as a vehicle fuel can make the landfills more self-sustaining, reduce their dependence on fossil fuels, and reduce emissions and greenhouse gases. Acrion Technologies Inc. in association with Mack Trucks Inc. developed a technology to generate LNG from LFG using the CO₂ WASH process. A successful application of this process was performed at the Eco Complex in Burlington County, PA. During this application two LNG refuse trucks were operated for 600 hr each using LNG produced from gases from the landfill. The methodology developed in this paper can evaluate the feasibility of three LFG options: doing nothing, electricity generation, and producing LNG to fuel refuse trucks. The methodology involved the modeling of several components: LFG generation, energy recovery processes, fleet operations, economic feasibility, and decision-making. The economic feasibility considers factors such as capital, maintenance, operational, and fuel costs, emissions and tax benefits, and the sale of products such as surplus LNG and food-grade carbon dioxide (CO₂).

Texas was used as a case study. The 96 landfills in Texas were prioritized and 17 landfills were identified that showed potential for converting LFG to LNG for use as a refuse truck fuel. The methodology was applied to a pilot landfill in El Paso, TX. The analysis showed that converting LFG to LNG to fuel refuse trucks proved to be the most feasible option and that the methodology can be applied for any landfill that considers this option.     

Effect of fuel aromatic content on PAH emission from a heavy-duty diesel engine

Polycyclic aromatic hydrocarbons (PAHs) emission tests for a heavy-duty diesel engine fueled with blend base diesel fuel by adding batch fractions of poly-aromatic and mono-aromatic hydrocarbons, Fluorene and Toluene, respectively, were simulated to five steady-state modes by a DC-current dynamometer with fully automatic control system. The main objective of this study is to investigate the effect of total aromatic content and poly-aromatic content in diesel fuels on PAH emission from the HDD engine exhaust under these steady-state modes. The results of this study revealed that adding 3% and 5% (fuel vol%) Fluorene in the diesel fuel increases the amount of total-PAH emission by 2.6 and 5.7 times, respectively and increases the amount of Fluorene emission by 52.9 and 152 times, respectively, than no additives. However, there was no significant variation of PAH emission by adding 10% (vol%) of Toluene. To regulate the content of poly-aromatic content in diesel fuel, in contrast to the total aromatic content, will be more suitable for the management of PAH emission.     

Are fuel additives a viable contrail mitigation option?

Fuel additives have been proposed as a potential mitigation option for contrails. They could change the thermodynamic conditions necessary for contrail formation in a way that makes contrail formation more difficult than with standard kerosene fuel. Here I show how additives could affect contrail formation, and I conclude that fuel additives are not a useful way to avoid contrails.     

Feasibility of landfill gas as a liquefied natural gas fuel source for refuse trucks

The purpose of this paper is to develop a methodology to evaluate the feasibility of using landfill gas (LFG) as a liquefied natural gas (LNG) fuel source for heavy-duty refuse trucks operating on landfills. Using LFG as a vehicle fuel can make the landfills more self-sustaining, reduce their dependence on fossil fuels, and reduce emissions and greenhouse gases. Acrion Technologies Inc. in association with Mack Trucks Inc. developed a technology to generate LNG from LFG using the CO2 WASH process. A successful application of this process was performed at the Eco Complex in Burlington County, PA. During this application two LNG refuse trucks were operated for 600 hr each using LNG produced from gases from the landfill. The methodology developed in this paper can evaluate the feasibility of three LFG options: doing nothing, electricity generation, and producing LNG to fuel refuse trucks. The methodology involved the modeling of several components: LFG generation, energy recovery processes, fleet operations, economic feasibility, and decision-making. The economic feasibility considers factors such as capital, maintenance, operational, and fuel costs, emissions and tax benefits, and the sale of products such as surplus LNG and food-grade carbon dioxide (CO2). Texas was used as a case study. The 96 landfills in Texas were prioritized and 17 landfills were identified that showed potential for converting LFG to LNG for use as a refuse truck fuel. The methodology was applied to a pilot landfill in El Paso, TX. The analysis showed that converting LFG to LNG to fuel refuse trucks proved to be the most feasible option and that the methodology can be applied for any landfill that considers this option.     

A description of a test plant for combustion on a pilot scale

A plant for combustion on a pilot scale is described.The plant is comprised of two shaft furnaces connected to a common afterburning chamber. Sawmill chips and LP-gas are used as supporting fuel. The plant is provided with equipment for continuous feeding-in of both solid and liquid wastes.The products of decomposition and residual concentrations resulting from combustion of the wastes are analysed with respect to different organic compounds. These analyses are made on ingoing product, slag, dust and fuel gases. In addition, temperature, transit time, gas composition (CO, CO₂, O₂), fuelgas flow and - in some cases - parameters such as total hydrocarbon and nitrogen oxides are investigated.