1.
Mellqvist, Johan, 1965, et al.
(författare)
Mobile optical measurements of emissions and fenceline concentrations from oil and gas production
2019
Ingår i: AQM 2019 - Air Quality Measurement Methods and Technology Conference 2019.
Konferensbidrag (refereegranskat) abstract
The mobile measurement platform and optical methods used in the SQAMD project1 allowed for mapping concentrations and measuring fluxes from a large number of sources and source types, and provided very useful information on the relative contribution of small stationary sources to alkane and BTEX emissions in the SCAB. Sources ranged from single oil wells to large tank farms, refineries, and off shore installations. Note that these sources are not subjected to the same regulatory requirements as larger industrial facilities. Future studies aimed at improving the emission estimates in SCAB should include a larger subset of units from all major source categories, and a better characterization of their spatial and temporal variability.
2.
Vechi, Nathalia T., et al.
(författare)
Ammonia and methane emissions from dairy concentrated animal feeding operations in California, using mobile optical remote sensing
2023
Ingår i: Atmospheric Environment. - : Elsevier BV. - 1873-2844 .- 1352-2310. ; 293
Tidskriftsartikel (refereegranskat) abstract
Dairy concentrated animal feeding operations (CAFOs) are significant sources of methane (CH4) and ammonia (NH3) emissions in the San Joaquin Valley, California. Optical techniques, namely, remote sensing by Solar Occultation Flux (SOF) and Mobile extractive FTIR (MeFTIR), were used to measure NH3 air column and ground air concentrations of NH3 and CH4, respectively. Campaigns were performed in May and October 2019 and covered 14 dairies located near Bakersfield and Tulare, California. NH3 and CH4 emission rates from single CAFOs averaged 101.9 ± 40.6 kgNH3/h and 437.7 ± 202.0 kgCH4/h, respectively, corresponding to emission factors (EFs) per livestock unit of 9.1 ± 2.7 gNH3/LU/h and 40.1 ± 17.8 gCH4/LU/h. The NH3 emissions had a median standard uncertainty of 17% and an expanded uncertainty (95% Confidence Interval (CI)) of 37%; meanwhile, CH4 emissions estimates had greater uncertainty, median of 25% and 53% (in the 95% CI). Decreasing NH3 to CH4 ratios and NH3 EFs from early afternoon (13:00) to early night (19:00) indicated a diurnal emission pattern with lower ammonia emissions during the night. On average, measured NH3 emissions were 28% higher when compared to daytime emission rates reported in the National Emissions Inventory (NEI) and modeled according to diurnal variation. Measured CH4 emissions were 60% higher than the rates reported in the California Air Resources Board (CARB) inventory. However, comparison with airborne measurements showed similar emission rates. This study demonstrates new air measurement methods, which can be used to quantify emissions over large areas with high spatial resolution and in a relatively short time period. These techniques bridge the gap between satellites and individual CAFOs measurements.
3.
Zhou, L. Y., et al.
(författare)
A transition of atmospheric emissions of particles and gases from on-road heavy-duty trucks
2020
Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 20:3, s. 1701-1722
Tidskriftsartikel (refereegranskat) abstract
The transition, in extent and characteristics, of atmospheric emissions caused by the modernization of the heavy-duty on-road fleet was studied utilizing roadside measurements. Emissions of particle number (PN), particle mass (PM), black carbon (BC), nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbon (HC), particle size distributions, and particle volatility were measured from 556 individual heavy-duty trucks (HDTs). Substantial reductions in PM, BC, NOx, CO, and to a lesser extent PN were observed from Euro III to Euro VI HDTs by 99 %, 98 %, 93 %, and 57% for the average emission factors of PM, BC, NOx, and CO, respectively. Despite significant total reductions in NOx emissions, the fraction of NO2 in the NOx emissions increased continuously from Euro IV to Euro VI HDTs. Larger data scattering was evident for PN emissions in comparison to solid particle number (SPN) for Euro VI HDTs, indicating a highly variable fraction of volatile particle components. Particle size distributions of Euro III to enhanced environmentally friendly vehicle (EEV) HDTs were bimodal, whereas those of Euro VI HDTs were nucleation mode dominated. High emitters disproportionately contributed to a large fraction of the total emissions with the highest-emitting 10% of HDTs in each pollutant category being responsible for 65% of total PM, 70% of total PN, and 44% of total NOx emissions. Euro VI HDTs, which accounted for 53% of total kilometres driven by Swedish HDTs, were estimated to only contribute to 2 %, 6 %, 12 %, and 47% of PM, BC, NOx, and PN emissions, respectively. A shift to a fleet dominated by Euro VI HDTs would promote a transition of atmospheric emissions towards low PM, BC, NOx, and CO levels. Nonetheless, reducing PN, SPN, and NO2 emissions from Euro VI HDTs is still important to improve air quality in urban environments.
4.
Sha, Mahesh Kumar, et al.
(författare)
Validation of methane and carbon monoxide from Sentinel-5 Precursor using TCCON and NDACC-IRWG stations
2021
Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 14:9, s. 6249-6304
Tidskriftsartikel (refereegranskat) abstract
The Sentinel-5 Precursor (S5P) mission with the TROPOspheric Monitoring Instrument (TROPOMI) on board has been measuring solar radiation backscattered by the Earth's atmosphere and surface since its launch on 13 October 2017. In this paper, we present for the first time the S5P operational methane (CH4) and carbon monoxide (CO) products' validation results covering a period of about 3 years using global Total Carbon Column Observing Network (TCCON) and Infrared Working Group of the Network for the Detection of Atmospheric Composition Change (NDACC-IRWG) network data, accounting for a priori alignment and smoothing uncertainties in the validation, and testing the sensitivity of validation results towards the application of advanced co-location criteria. We found that the S5P standard and bias-corrected CH4 data over land surface for the recommended quality filtering fulfil the mission requirements. The systematic difference of the bias-corrected total column-averaged dry air mole fraction of methane (XCH4) data with respect to TCCON data is -0.26 +/- 0.56 % in comparison to -0.68 +/- 0.74 % for the standard XCH4 data, with a correlation of 0.6 for most stations. The bias shows a seasonal dependence. We found that the S5P CO data over all surfaces for the recommended quality filtering generally fulfil the missions requirements, with a few exceptions, which are mostly due to co-location mismatches and limited availability of data. The systematic difference between the S5P total column-averaged dry air mole fraction of carbon monoxide (XCO) and the TCCON data is on average 9.22 +/- 3.45 % (standard TCCON XCO) and 2.45 +/- 3.38 % (unscaled TCCON XCO). We found that the systematic difference between the S5P CO column and NDACC CO column (excluding two outlier stations) is on average 6.5 +/- 3.54 %. We found a correlation of above 0.9 for most TCCON and NDACC stations. The study shows the high quality of S5P CH4 and CO data by validating the products against reference global TCCON and NDACC stations covering a wide range of latitudinal bands, atmospheric conditions and surface conditions.
5.
Mellqvist, Johan, 1965
(författare)
Flare testing using the SOF method at Borealis Polyethylene in the summer of 2000
2001
Rapport (övrigt vetenskapligt/konstnärligt) abstract
A study of flaring efficiency at the Borealis low-pressure plant in Stenungsund was conducted using a new patented method called Solar Occultation Flux (SOF), in combination with a new type of direct measurement of flow rate and ethylene concentration in the flare stack. The SOF method is based on the measurement of hydrocarbon concentrations over a cross-section of the emission plume. Multiplied by wind speed, this gives the flux of gas through the cross-section, i.e., the source emission in kg·s-1. In the measurements, the sun was used as the light source. An infrared FTIR spectrometer linked to a sun tracker was placed on top of a van that was driven in such a way that the sunlight shone through a cross-section of the plume being measured. From the size of the molecular fingerprints in the infrared solar spectra, the concentration of ethylene and other constituents can be calculated.The results show that the flare we studied has a good combustion efficiency of about 98% at high loads (>1100 kg·h -1), but that at low loads, which are the normal operating conditions most of the time, it has a significantly lower efficiency (50-90%). Emissions thus appear to vary between 20 and 50 kg/h irrespective of load – a result that is consistent with other long-term FTIR measurements taken outside the plant. Similar emission results were also obtained during the course of the project from a newly installed flare, so that the problem does not appear to be specific to the flare that we studied.From the measurements in this study it can be concluded that a major contributing factor in the poor efficiency is an overdose of steam at low operating loads, as a result of trying to avoid soot formation by optimizing flare combustion at high loads. The problem can presumably be solved by introducing some form of dynamic steam metering linked to combustion load, or by eliminating the presence of ethylene at low operating loads. The direct flare stack measurements show that the heating value is generally low, and that theoretically we could therefore expect poorer efficiency levels. It was not possible to demonstrate this unambiguously in the present study, however, since the steam and ethylene levels were generally covariant. Only in a few cases did we find a low efficiency at low ethylene concentration, independent of steam quantity.
6.
Mellqvist, Johan, 1965, et al.
(författare)
Measurements of industrial emissions of alkenes in Texas using the solar occultation flux method
2010
Ingår i: Journal of Geophysical Research: Atmospheres. - : American Geophysical Union (AGU). - 2169-8996 .- 2169-897X .- 0148-0227. ; 115:D7
Tidskriftsartikel (refereegranskat) abstract
[1] Solar occultation flux (SOF) measurements of alkenes have been conducted to identify and quantify the largest emission sources in the vicinity of Houston and in SE Texas during September 2006 as part of the TexAQS 2006 campaign. The measurements have been compared to emission inventories and have been conducted in parallel with airborne plume studies. The SOF measurements show that the hourly gas emissions from the large petrochemical and refining complexes in the Houston Ship Channel area and Mount Belvieu during September 2006 corresponded to 1250 ± 180 kg/h of ethene and 2140 ± 520 kg/h of propene, with an estimated uncertainty of about 35%. This can be compared to the 2006 emission inventory value for ethene and propene of 145 ± 4 and 181 ± 42 kg/h, respectively. On average, for all measurements during the campaign, the discrepancy factor is 10.2(+8,-5) for ethene and 11.7(+7,-4) for propene. The largest emission source was Mount Belvieu, NE of the Houston Ship Channel, with ethene and propene emissions corresponding to 440 ± 130 kg/h and 490 ± 190 kg/h, respectively. Large variability of propene was observed from several petrochemical industries, for which the largest reported emission sources are flares. The SOF alkene emissions agree within 50% with emissions derived from airborne measurements at three different sites. The airborne measurements also provide support to the SOF error budget.
7.
Mellqvist, Johan, 1965, et al.
(författare)
Methane emissions from industrial activities using drones
2023
Rapport (övrigt vetenskapligt/konstnärligt) abstract
Innovative drone-based methods have been developed to map and quantify methane leakages from various industrial activities, such as refineries, Liquified Natural Gas (LNG) terminals, landfills, and water treatment facilities. These methods use a high-speed, high-sensitivity laser sensor and were validated through controlled gas releases. They were also compared to a ground-based infrared absorption-based technique. This initiative is supported by the Swedish Governmental Agency for Innovation Systems (Vinnova) and aligns with UN Sustainable Development Goals 9, 11, and 13. The goal is to reduce methane emissions significantly, aiding Sweden in achieving net-zero greenhouse gas emissions by 2045. Accurate measurements enable effective, targeted, and trackable measures to minimize emissions, resulting in a rapid positive climate impact. The project has led to the development of two distinct drone-based methods: the wall approach and the tracer approach. The wall approach measures gas concentrations across the entire cross-section of the plume, whereas the tracer approach measures the ratio of leaking gas to source gas. Depending on the source's size, one approach may be preferred over the other, with the tracer method being more suitable for point sources and the wall approach for larger sources. The custom-designed drone in this project, provided and operated by Gerdes Solution. is equipped with a high-sensitivity laser sensor and has a flight duration of about 12 minutes while carrying a 3 kg payload. This limitation presents a challenge when conducting wall measurements, which require approximately 25 minutes of flight time for the studied sources. Due to the drone's limited flight time, it necessitates landing and battery replacement, which complicates the process and limits the number of repeat measurements. In future endeavors, employing a drone with a longer flight duration would be advantageous. In total, the study detected about 220 kg/h of methane emissions and 3 kg/h of nitrous oxide emissions, equivalent to an emission rate of about 7 tons/h of carbon dioxide. The emissions were dominated by the water treatment plant and landfills, with relatively little coming from the refinery and LNG plant. However, the wall measurements in thus study serve as demonstrations of how the technique can be used and do not provide a comprehensive picture of the actual emissions from the individual sites; this would require more statistical data in terms of repeat measurements and measurement days. It is shown that drone measurements using the new high sensitivity laser is a valuable tool for mapping methane concentrations from various types of industrial sources, which are challenging to investigate today due to diffuse emissions, large dimensions, and complex geometries. The validation studies show that both the wall approach and controlled tracer releases can be used to quantify emissions, achieving an accuracy of up to 10 % for a simple, single, source. However, in the real measurement situation, the wall approach may be difficult to execute due to practical challenges like flying restrictions and the need for spatially dense data that can be interpolated to a homogenous grid and repeated measurements. In several cases, when the drone had to fly relatively close to the plumes, downwind of large buildings in complex and turbulent wind fields, the wall approach yielded large variability in the resulting flux. It is hence evident that the wall approach requires a thorough understanding of the measurement situation, and that repeated measurements are needed, at different distances from the source and in varying wind directions. The tracer approach was therefore preferred choice for obtaining emission rates in this study, although it is challenging to carry out representative tracer releases for larger sources and for cases when the measurements are performed near to the source, and in this case the wall approach is preferred. It was also shown that the drone-based tracer approach is advantageous to the ground based since it is then easier to capture the full plume.
8.
Van Roy, Ward, et al.
(författare)
International maritime regulation decreases sulfur dioxide but increases nitrogen oxide emissions in the North and Baltic Sea
2023
Ingår i: Communications Earth and Environment. - 2662-4435. ; 4:1
Tidskriftsartikel (refereegranskat) abstract
Sulfur dioxide and nitrogen oxide emissions from shipping have been regulated internationally for more than fifteen years. Emissions reduction from shipping provides benefits for human health and the environment, but the effectiveness of regulations in reducing ship emissions is less well understood. Here, we examine how the establishment of European Emission Control Areas and other international maritime regulations in the North and Baltic Seas affect sulfur dioxide and nitrogen oxide emissions in the region. We combine and analyze more than 110,000 ship plume measurements, inspection results, and satellite data from 2018 to 2022. We find that compliance rates for sulfur emissions are higher near ports than in open waters. However, the regulations did not affect the concentration of nitrogen oxide emissions, which increased in the past three years. These findings highlight the need for enhanced emission regulations that improve air quality.
9.
Alföldy, B., et al.
(författare)
Measurements of air pollution emission factors for marine transportation in SECA
2013
Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 6:7, s. 1777-1791
Tidskriftsartikel (refereegranskat) abstract
The chemical composition of the plumes of seagoing ships was measured during a two week long measurement campaign in the port of Rotterdam, Hoek van Holland The Netherlands, in September 2009. Altogether, 497 ships were monitored and a statistical evaluation of emission factors (g kg(-1) fuel) was provided. The concerned main atmospheric components were SO2, NO2, NOx and the aerosol particle number. In addition, the elemental and water-soluble ionic composition of the emitted particulate matter was determined. Emission factors were expressed as a function of ship type, power and crankshaft rotational speed. The average SO2 emission factor was found to be roughly half of what is allowed in sulphur emission control areas (16 vs. 30 g kg(-1) fuel), and exceedances of this limit were rarely registered. A significant linear relationship was observed between the SO2 and particle number emission factors. The intercept of the regression line, 4.8 x 10(15) (kg fuel)(-1), gives the average number of particles formed during the burning of 1 kg zero sulphur content fuel, while the slope, 2 x 10(18), provides the average number of particles formed with 1 kg sulphur burnt with the fuel. Water-soluble ionic composition analysis of the aerosol samples from the plumes showed that similar to 144 g of particulate sulphate was emitted from 1 kg sulphur burnt with the fuel. The mass median diameter of sulphate particles estimated from the measurements was similar to 42 nm.
10.
Angelbratt, Jon, 1981, et al.
(författare)
A new method to detect long term trends of methane (CH4) and nitrous oxide (N2O) total columns measured within the NDACC ground-based high resolution solar FTIR network
2011
Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:13, s. 6167-6183
Tidskriftsartikel (refereegranskat) abstract
Total columns measured with the ground-based solar FTIR technique are highly variable in time due to atmospheric chemistry and dynamics in the atmosphere above the measurement station. In this paper, a multiple regression model with anomalies of air pressure, total columns of hydrogen fluoride (HF) and carbon monoxide (CO) and tropopause height are used to reduce the variability in the methane (CH(4)) and nitrous oxide (N(2)O) total columns to estimate reliable linear trends with as small uncertainties as possible. The method is developed at the Harestua station (60 degrees N, 11 degrees E, 600 ma.s.l.) and used on three other European FTIR stations, i.e. Jungfraujoch (47 degrees N, 8 degrees E, 3600 ma.s.l.), Zugspitze (47 degrees N, 11 degrees E, 3000 ma.s.l.), and Kiruna (68 degrees N, 20 degrees E, 400 ma.s.l.). Linear CH(4) trends between 0.13 +/- 0.01-0.25 +/- 0.02% yr(-1) were estimated for all stations in the 1996-2009 period. A piecewise model with three separate linear trends, connected at change points, was used to estimate the short term fluctuations in the CH(4) total columns. This model shows a growth in 1996-1999 followed by a period of steady state until 2007. From 2007 until 2009 the atmospheric CH(4) amount increases between 0.57 +/- 0.22-1.15 +/- 0.17% yr(-1). Linear N(2)O trends between 0.19 +/- 0.01-0.40 +/- 0.02% yr(-1) were estimated for all stations in the 1996-2007 period, here with the strongest trend at Harestua and Kiruna and the lowest at the Alp stations. From the N(2)O total columns crude tropospheric and stratospheric partial columns were derived, indicating that the observed difference in the N(2)O trends between the FTIR sites is of stratospheric origin. This agrees well with the N(2)O measurements by the SMR instrument onboard the Odin satellite showing the highest trends at Harestua, 0.98 +/- 0.28% yr(-1), and considerably smaller trends at lower latitudes, 0.27 +/- 0.25% yr(-1). The multiple regression model was compared with two other trend methods, the ordinary linear regression and a Bootstrap algorithm. The multiple regression model estimated CH(4) and N(2)O trends that differed up to 31% compared to the other two methods and had uncertainties that were up to 300% lower. Since the multiple regression method were carefully validated this stresses the importance to account for variability in the total columns when estimating trend from solar FTIR data.
