Methane Emission Rates Research Articles

Retrieving CH4-emission rates from coal mine ventilation shafts using UAV-based AirCore observations and the genetic algorithm–interior point penalty function (GA-IPPF) model

Abstract. There are plenty of monitoring methods to quantify gas emission rates based on gas concentration measurements around the strong sources. However, there is a lack of quantitative models to evaluate methane emission rates from coal mines with less prior information. In this study, we develop a genetic algorithm–interior point penalty function (GA-IPPF) model to calculate the emission rates of large point sources of CH4 based on concentration samples. This model can provide optimized dispersion parameters and self-calibration, thus lowering the requirements for auxiliary data accuracy. During the Carbon Dioxide and Methane Mission (CoMet) pre-campaign, we retrieve CH4-emission rates from a ventilation shaft in Pniówek coal mine (Silesia coal mining region, Poland) based on the data collected by an unmanned aerial vehicle (UAV)-based AirCore system and a GA-IPPF model. The concerned CH4-emission rates are variable even on a single day, ranging from 621.3 ± 19.8 to 1452.4 ± 60.5 kg h−1 on 18 August 2017 and from 348.4 ± 12.1 to 1478.4 ± 50.3 kg h−1 on 21 August 2017. Results show that CH4 concentration data reconstructed by the retrieved parameters are highly consistent with the measured ones. Meanwhile, we demonstrate the application of GA-IPPF in three gas control release experiments, and the accuracies of retrieved gas emission rates are better than 95.0 %. This study indicates that the GA-IPPF model can quantify the CH4-emission rates from strong point sources with high accuracy.

Composition, Emissions, and Air Quality Impacts of Hazardous Air Pollutants in Unburned Natural Gas from Residential Stoves in California.

The presence of hazardous air pollutants (HAPs) entrained in end-use natural gas (NG) is an understudied source of human health risks. We performed trace gas analyses on 185 unburned NG samples collected from 159 unique residential NG stoves across seven geographic regions in California. Our analyses commonly detected 12 HAPs with significant variability across region and gas utility. Mean regional benzene, toluene, ethylbenzene, and total xylenes (BTEX) concentrations in end-use NG ranged from 1.6-25 ppmv─benzene alone was detected in 99% of samples, and mean concentrations ranged from 0.7-12 ppmv (max: 66 ppmv). By applying previously reported NG and methane emission rates throughout California's transmission, storage, and distribution systems, we estimated statewide benzene emissions of 4,200 (95% CI: 1,800-9,700) kg yr-1 that are currently not included in any statewide inventories─equal to the annual benzene emissions from nearly 60,000 light-duty gasoline vehicles. Additionally, we found that NG leakage from stoves and ovens while not in use can result in indoor benzene concentrations that can exceed the California Office of Environmental Health Hazard Assessment 8-h Reference Exposure Level of 0.94 ppbv─benzene concentrations comparable to environmental tobacco smoke. This study supports the need to further improve our understanding of leaked downstream NG as a source of health risk.

Evaluating the detectability of methane point sources from satellite observing systems using microscale modeling

This study evaluates the efficacy of current satellite observing systems to detect methane point sources from typical oil and gas production (O&G) facilities using a novel very high-resolution methane concentration dataset generated using a microscale model. Transport and dispersion of typical methane emissions from seven well pads were simulated and the column enhancements for pseudo satellite pixel sizes of 3, 1, and 0.05 km were examined every second of the 2-h simulations (7200 realizations). The detectability of plumes increased with a pixel resolution, but two orders of magnitude change in emission rates at the surface results only in about 0.4%, 1.6%, and 47.8% enhancement in the pseudo-satellite retrieved methane column at 3, 1, and 0.05 km, respectively. Average methane emission rates estimated by employing the integrated mass enhancement (IME) method to column enhancements at 0.05 km showed an underestimation of the mean emissions by 0.2–6.4%. We show that IME derived satellite-based inversions of methane emissions work well for large persistent emission sources (e.g., super emitters), however, the method is ill-suited to resolve short-term emission fluctuations (< 20 min) in typical well site emissions due to the limitations in satellite detection limits, precision, overpass timing, and pixel resolution.

Agricultural policies against invasive species generate contrasting outcomes for climate change mitigation and biodiversity conservation.

Direct consequences of biological invasions on biodiversity and the environment have been largely documented. Yet collateral indirect effects mediated by changes in agri-environmental policies aimed at combating invasions remain little explored. Here we assessed the effects of recent changes in water management in rice farming, which are aimed at buffering the impact of the invasive apple snail (Pomacea maculata, Lamarck) on greenhouse gas emissions and diversity of waterbird communities. We used observational data from a 2-year field monitoring (2015-2016) performed at the Ebro Delta regional scale. We found that drying rice fields reduced methane emission rates by 82% (2015) and 51% (2016), thereby reflecting the contribution of rice farming to climate change. However, there was a marked reduction (75% in 2015 and 57% in 2016) in waterbird diversity in dry fields compared with flooded fields, thus suggesting that post-invasion policies might hinder biodiversity conservation. Our results highlight the need for accounting for potential collateral effects during the policy decision-making process to design efficient agricultural management plans that lessen undesirable agri-environmental outcomes.

Estimation of greenhouse gas emission flux from agricultural lands of Khuzestan province in Iran.

Greenhouse gas emissions and their effects on global warming are one of the serious challenges of developed and developing countries. Investigating the amount of greenhouse gas emissions of different countries makes it possible to determine the share of countries in the production of greenhouse gases. The purpose of this study is to use DAYCENT and DNDC models to estimate the emission rate of methane, nitrous oxide, and carbon dioxide greenhouse gases as well as to estimate the global warming potential in Khuzestan agricultural lands in Iran. For this purpose, the gas sampling was done in rice, wheat, and sugarcane fields using a static chamber, and then the concentration of methane, nitrous oxide, and carbon dioxide was determined by using gas chromatography. In the following, DAYCENT and DNDC models were used to estimate gas emissions and the global warming potential of these gases was estimated. Finally, TOPSIS method was used to prioritize gas emissions. In order to evaluate the modeling accuracy, the statistical indicators of maximum error, root mean square error, determination coefficient, model efficiency, and residual mass coefficient were used. According to the results, the highest measured gas flux was obtained for rice fields at Baghmalek and the lowest for sugarcane in Abadan. The results of DAYCENT model estimation showed that the highest emissions were obtained for methane gas and rice cultivation, and lowest gas emissions were obtained for sugarcane cultivation. The results of DNDC model estimation also showed that the highest flux was determined for nitrous oxide gas in rice cultivation. The results of the estimation of global warming potential also showed that it was the highest in sugarcane cultivation (Shushtar station) and the DAYCENT model, and the lowest was also in wheat cultivation and the DNDC model. The statistical results of the estimation of DAYCENT and DNDC models showed that the DAYCENT model in sugarcane cultivation (Shushtar station) was the most accurate in estimating carbon dioxide gas, and the lowest accuracy was related to the DNDC model and sugarcane cultivation (Shushtar station) in estimating nitrous oxide gas. According to the results of agricultural activities in Khuzestan province, they have made a major contribution to the production of greenhouse gases, which, or the lack of attention to this issue, will have an effect on the future climate of this region.

Ratoon rice with direct seeding improves soil carbon sequestration in rice fields and increases grain quality.

Increasing both carbon (C) sequestration and food production is essential for a sustainable future. However, increasing soil C sequestration or graining yield/quality in rice (Oryza sativa L.) systems has been a tradeoff in that pursuing one goal may compromise the other goal. Field experiments were designed to evaluate methane emission and grain yield in two rice systems in southern China, including the traditional double rice with a seedling transplanting system and innovative ratoon rice with a direct seeding system. Grain yield, grain quality, methane (CH4) emission, and total organic carbon (TOC) loss rate were investigated, and yield-scaled CH4 gas emission was assessed. It is found that double rice has a higher grain yield than ratoon rice. However, the grain quality (processing, appearance of chalkiness degree and chalky grain percentage, and nutritional quality) of ratoon rice is superior to double rice, especially the ratoon crop. The yield-scaled CH4 emission of ratoon rice (0.06kgkg-1) decreased by 49.29% than double rice (0.12kgkg-1) throughout the growth period. Compared with the TOC loss rate of double rice (2.95gkg-1), the rate of ratoon rice was lower (1.97gkg-1). As a result, ratoon rice with direct seeding can not only improve grain quality but also mitigate yield-scaled CH4 gas emission and TOC loss rate of rice fields. Therefore, we suggest to use ratoon rice with a direct seeding technique to promote agricultural C sequestration.

A methodology for quantifying combustion efficiencies and species emission rates of flares subjected to crosswind

Despite strong indications that flares subjected to crosswinds can undergo fuel stripping mechanisms that reduce efficiency and lead to emission of unburned fuel, most published flare experiments have not considered the impact of a crosswind. Knowledge of flare performance in turbulent crosswinds representative of atmospheric wind is especially lacking. Accurate experiments to fill this gap can only be achieved in an environment where the wind conditions can be controlled. This work presents a methodology to determine the carbon conversion efficiency and species emission rates of a flare burning in a closed-loop wind tunnel. The developed methodology is based on solving an unsteady mass balance to relate measured accumulation rates in a closed-loop wind tunnel to emission rates, while extending the applicability and correcting errors of an earlier method. The developed methodology considers complicating factors such as infiltration and exfiltration of gases into and out of the wind tunnel, potential for reburning of products within the wind tunnel, and presence of inert species in the fuel stream. The methodology is assessed with a comprehensive Monte Carlo uncertainty and sensitivity analysis. Results suggest that carbon conversion efficiency can be measured with a systematic bias uncertainty of ≲ ±0.5%, ranging from 0.04% for a 99% efficient flare to 0.55% for a 70% efficient flare at 95% confidence, and methane emission rates can be measured within ±3.25% at 95% confidence. Demonstration experiments in a large closed-loop wind tunnel show that precision (repeatability) uncertainties will be larger but that overall (combined bias and precision) uncertainties of <10% are readily achievable.

Prediction of the Absolute Methane Emission Rate for Longwall Caving Extraction Based on Rock Mass Modelling—A Case Study

This article presents a methodology for predicting the absolute methane emission rate for longwall caving extraction based on the determination of destressing zones generated by longwall mining operations, by means of numerical modelling. This methodology was applied for the conditions of the K-2 longwall panel in the KWK Pniówek mine. The finite difference method code FLAC2D was employed as an element of the methodology to determine the destressing zones. All results including the numerical modelling results, empirical results and the measured (in situ) results were gathered in the comparative analysis. As the final results, the accuracy and reliability of the proposed methodology were evaluated.

Methane and ethane emission quantifications from onshore oil and gas sites in Romania, using a tracer gas dispersion method

Site-specific methane (CH4) and ethane (C2H6) emission rates from the onshore oil and gas (O&amp;G) sector in Romania were quantified, using the mobile tracer gas dispersion method. As part of the coordinated Romanian Methane Emission from Oil &amp; Gas measurement campaign, this study supported the investigation of CH4 emissions from the O&amp;G sector around Bucharest. CH4 emission rates measured at 200 O&amp;G sites were highly skewed with a heavy tail and described by a CH4 emission factor (EF) with a 95% confidence interval (CI) equal to 0.53 [0.32; 0.79] kg h–1 site–1. Of the investigated sites, 53% showed CH4 emission rates below 1 kg h–1, whereas only 6% had emission rates higher than 80 kg h–1, with the highest being equal to 297 kg h–1. CH4 emission rates from oil wells were not correlated to CH4 production rates but were negatively correlated to the amount of wastewater produced. C2H6 emissions were investigated from 95 O&amp;G sites, the emission rates of which were highly skewed with a heavy tail and described by a C2H6 EF with a 95% CI equal to 0.07 [0.04; 0.13] kg h–1 site–1. Almost 80% of the investigated sites showed C2H6 emission rates below 1 kg h–1, and 7% of them had emission rates higher than 9 kg h–1, with the highest being equal to 78 kg h–1. CH4 emission rates and EFs representing specific types of sites and geographical regions are provided in the manuscript. In terms of magnitude and distribution, these results are in line with published results from measurements at O&amp;G sites in North America, and a natural gas field in the Netherlands. The CH4 EF calculated in this study is close to the lower range of the majority of values in the literature, whereas C2H6 EF is the lowest among the literature values. The study also provided site-specific C2H6-to-CH4 molar ratios in different regions around Bucharest.

Enhanced monitoring of atmospheric methane from space over the Permian basin with hierarchical Bayesian inference

Methane is a strong greenhouse gas, with a higher radiative forcing per unit mass and shorter atmospheric lifetime than carbon dioxide. The remote sensing of methane in regions of industrial activity is a key step toward the accurate monitoring of emissions that drive climate change. Whilst the TROPOspheric Monitoring Instrument (TROPOMI) on board the Sentinal-5P satellite is capable of providing daily global measurement of methane columns, data are often compromised by cloud cover. Here, we develop a statistical model which uses nitrogen dioxide concentration data from TROPOMI to efficiently predict values of methane columns, expanding the average daily spatial coverage of observations of the Permian basin from 16% to 88% in the year 2019. The addition of predicted methane abundances at locations where direct observations are not available will support inversion methods for estimating methane emission rates at shorter timescales than is currently possible.

Methane emissions along biomethane and biogas supply chains are underestimated

Methane emissions along biomethane and biogas supply chains are underestimated

A Wavelength Modulation Spectroscopy-Based Methane Flux Sensor for Quantification of Venting Sources at Oil and Gas Sites.

An optical sensor employing tunable diode laser absorption spectroscopy with wavelength modulation and 2f harmonic detection was designed, prototyped, and tested for applications in quantifying methane emissions from vent sources in the oil and gas sector. The methane absorption line at 6026.23 cm–1 (1659.41 nm) was used to measure both flow velocity and methane volume fraction, enabling direct measurement of the methane emission rate. Two configurations of the sensor were designed, tested, and compared; the first used a fully fiber-coupled cell with multimode fibers to re-collimate the laser beams, while the second used directly irradiated photodetectors protected by Zener barriers. Importantly, both configurations were designed to enable measurements within regulated Class I / Zone 0 hazardous locations, in which explosive gases are expected during normal operations. Controlled flows with methane volume fractions of 0 to 100% and a velocity range of 0 to 4 m/s were used to characterize sensor performance at a 1 Hz sampling rate. The measurement error in the methane volume fraction was less than 10,000 ppm (1%) across the studied range for both configurations. The short-term velocity measurement error with pure methane was <0.3 m/s with a standard deviation of 0.14 m/s for the fiber-coupled configuration and <0.15 m/s with a standard deviation of 0.07 m/s for the directly irradiated detector configuration. However, modal noise in the multimode fibers of the first configuration contributed to an unstable performance that was highly sensitive to mechanical disturbances. The second configuration showed good potential for an industrial sensor, successfully quantifying methane flow rates up to 11 kg/h within ±2.1 kg/h at 95% confidence over a range of methane fractions from 25–100%, and as low as ±0.85 kg/h in scenarios where the source methane fraction is initially unknown within this range and otherwise invariant.

Reply to comment on “How Green is Blue Hydrogen?”

AbstractIn their comment on our 2021 paper “How Green is Blue Hydrogen,” Romano et al. purport to provide “a more balanced perspective on blue hydrogen, which is in line with current best available practices.” We strongly disagree. First, we categorically dismiss their presentation on methane emissions. Methane dominates the greenhouse gas footprint of blue hydrogen in our analysis, and our estimates were based on very recent, peer‐reviewed science. Romano et al., in sharp contrast, use only three sources: (1) a 2015 non‐peer‐reviewed report (which gave reasonable values, although at the low end, since based on older science, but nonetheless compatible with our paper); (2) a 2018 report from the International Energy Agency (which also gave values consistent with ours, but has been updated by the Agency in a 2022 report to give much higher values that are very consistent with ours); and (3) a value from a cartoon on a web site from an oil and gas industry trade group (i.e., not supported by any data or references and is simply wrong based on peer‐reviewed science). We cannot stress enough that the Romano et al. criticism of our methane emission rates is based totally on this industry web‐site cartoon. Beyond the methane issue, our analysis used actual data for capture of carbon dioxide from real‐world operations. Romano et al. dismiss the use of real‐world data, and instead rely on presentations from theoretical studies. We find this fanciful. But even if one accepts their theoretical values for carbon capture, the greenhouse gas footprint of blue hydrogen remains unacceptably high because of methane. We unequivocally stand by our analyses and conclusions: There is no room for blue hydrogen in a decarbonized energy future. The Romano et al. result derives from a cartoon and hypothetical guesses, not scientific data.

Methane hazard in high-productive coal mine

Extensive underground mining of gas-bearing coal seams is carried out mainly in the Kuznetsk Coal Basin and the Vorkuta deposit of the Pechora Basin, where the coal sea m methane content is from 8 to 2 1.2 m3/t. At the average daily longwall productivity of 4100&ndash;13075 tons, methane emission in the longwalls varies from 18.8 to 113.1 m3/min. The influence of partings and longwall advance velocity in coal seams on the degree of natural degassing of contiguous seams is shown. The use of a package o f gas drainage methods and schemes in contiguous coal seams and in mined-out areas changes the structure of the gas balance in a mine. An increase in the rate of methane release into the mined-out void is associated with the main coal roof subsidence, which causes stress relaxation in contiguous coal seams and also contributes to fracture of strong floor rocks and to liberation of methane accumulated in the voids in the floor rocks. The current assessment procedure of methane hazard category of a mine based on the methane emission rate longwalls with high-performance coal mining equipment fails to meet mining safety by gas criterion. At high longwall outputs, methane content in longwalls decreases and, according to the accepted assessment procedure of methane hazard, puts them on a lower hazard level, which leads to the underestimation of the role of the gas factor in underground mining. It is recommended to classify methane hazard of high-productive coal mines by the absolute methane emission value.

Quantification of methane emissions from cattle farms, using the tracer gas dispersion method

In Denmark, agriculture is the largest source of anthropogenic methane emissions (81%), mainly from cattle (dairy and beef) farms. Whole-farm methane emissions were quantified at nine Danish cattle farms, using the tracer gas dispersion method. Five to six measurement campaigns were carried out at each farm, covering a full year. Of the nine cattle farms, seven were home to dairy cows and two to beef cattle. The farms represented typical breeds, housing and management systems used in Denmark. Whole-farm methane emission rates ranged from 0.7 to 28 kg h−1, with the highest measurements seen at locations with the highest number of animals. Emissions tended to be higher from August to October, due to elevated temperatures and high amounts of stored manure during this period of the year. The average emission factor (EF) for dairy cow farms was 26 ± 8.5 g Livestock Unit (LU)−1 h−1, whereas it was 16 ± 4.1 LU−1 h−1 for beef cattle farms, i.e. 38% lower for the latter. The use of deep litter house management explained some of the differences found in the EFs for dairy cows. Methane emission rates estimated using IPCC models and national guidelines tended, on average for all farms and measurements, to be underestimated by 35% in comparison with the measured methane emissions, for all models and farms. The results suggest that future improvements to inventory models should focus on enteric methane emissions from beef cattle and manure methane emissions for both dairy cows and beef cattle, especially from deep litter management.

Effect of micro-aerobic conditions based on semipermeable membrane-covered on greenhouse gas emissions and bacterial community during dairy manure storage at industrial scale

This study evaluated the greenhouse gas emissions of solid dairy manure storage with the micro-aerobic group (MA; oxygen concentration <5%) and control group (CK; oxygen concentration <1%), and explained the difference in greenhouse gas emissions by exploring bacterial community succession. The results showed that the MA remained the micro-aerobic conditions, which the maximum and average oxygen concentrations were 4.1% and 1.9%, respectively; while the average oxygen concentrations of the CK without intervention management was 0.5%. Compared with the CK, carbon dioxide and methane emissions in MA were reduced by 78.68% and 99.97%, respectively, and nitrous oxide emission was increased by almost three times with a small absolute loss, but total greenhouse gas emissions decreased by 91.23%. BugBase analysis showed that the relative abundance of aerobic bacteria in CK decreased to 0.73% on day 30, while that in MA increased to 6.56%. Genus MBA03 was significantly different between the two groups (p < 0.05) and was significantly positively correlated with carbon dioxide and methane emissions (p < 0.05). A structural equation model also revealed that the oxygen concentration and MBA03 of the MA had significant direct effects on methane emission rate (p < 0.001). The research results could provide theoretical basis and measures for directional regulation of greenhouse gas emission reduction during dairy manure storage.

Potential GHG emission benefits of Asparagopsis taxiformis feed supplement in Australian beef cattle feedlots

The red macroalgae Asparagopsis taxiformis has been identified as a promising feed supplement to inhibit enteric methane formation during ruminant livestock production and thereby contribute to GHG emissions reduction. Some studies also suggest improvements to animal weight gain through enhanced feed conversion efficiency. In this study, the potential GHG emissions reduction benefits were assessed from a life cycle perspective and in an actual industry context – the large Australian beef cattle sector, where feed supplementation occurred during feedlot finishing, when farmers have greatest control over animal diets. Seven adoption scenarios were compared to a baseline emissions inventory that was extrapolated to 2030. Feed supplementation with A. taxiformis had the potential to reduce the sector's carbon footprint by 1–4% in 2030, which due to the scale of the industry is a relevant emissions reduction (0.6–2.0 Mt CO2e), but modest in relation to the industry's goal of carbon neutrality by 2030. When emissions were assessed using alternative climate metrics that are more sensitive to changes in the rate of methane emission than the GWP100 climate metric (i.e. GWP*, radiative forcing climate footprint), larger potential benefits were found. Considering only the feedlot subsector, the radiative forcing climate footprint reached a plateau under most scenarios, indicating that climate neutrality is realistically achievable for the feedlot subsector within 5 years. That said, concurrent action on CO2 and N2O emissions will be needed, as even steep reductions in methane emissions at the expense of additional long-lived emissions will only achieve a short-term climate benefit and will make long-term climate stabilization more difficult.

Field measurements of fugitive methane emissions from three Australian waste management and biogas facilities.

A key environmental sustainability requirement for the treatment of organic waste via anaerobic digestion (AD) is the prevention of unwanted methane emissions in the production chain whenever possible. Identifying and quantifying these emissions has been frequently investigated, particularly in Europe. However, the challenges of climate change are also becoming vitally important in Australia. This novel study presents the results from emission measurement campaigns carried out at two biogas plants and one landfill site in Australia. An on-site approach consisting of leakage detection and emission quantification by a static chamber method was applied. Twenty-nine leakages were detected predominantly on the digesters (gastight covered anaerobic lagoons) of the biogas plants. Ten emission hot spots were found on the surface cover of a landfill site. Methane emission rates of 9.9±2.3kgh-1 (10.5±2.4% CH4) for biogas plant A, 3.0±1.9kgh-1 (8.1±5.2% CH4) for biogas plant B and 41-211gh-1 for the two largest emission hot spots from the landfill were measured. Since not every single leakage or hot spot could be quantified separately, the stated overall emission rates had to be extrapolated. Importantly, the emission rates from the landfill should be interpreted carefully due to the limited overall area which could be practicably investigated. Leakages occurred at common components of the covered anaerobic lagoons such as the membrane fixation or concrete walls. Repairing these parts would increase the plant safety and mitigate negative environmental effects.

Phytoplankton photosynthesis: an unexplored source of biogenic methane emission from oxic environments

Abstract Recent studies show that all evaluated Cyanobacteria, diatoms and haptophytes, major constituents of freshwater and marine phytoplankton, emit methane during photosynthesis. This is independent of external methylated precursors, whose demethylation by prokaryotic phytoplankton (and other microorganisms) has been already shown to be a potent methane source. Methane is the second most significant anthropogenically influenced greenhouse gas with a global warming potential 85 times higher than carbon-dioxide, over a period of 20 years. Atmospheric methane has been steadily increasing, yet its natural sources are not well constrained, with the largest uncertainties occurring in aquatic ecosystems. Already for several decades, increasing evidence has been pointing out that methane produced under oxic conditions through non-traditional pathways (i.e. not archaeal methanogenesis) significantly contributes to the methane flux from marine and freshwater environments. This paper highlights the potential significance of phytoplankton as methane producers, particularly through the ubiquitous process of photosynthesis. Currently, available data serve as a proof of principle for the process and its potential rates, yet further extensive research is required to successfully provide emission estimates at a global scale. Therefore, studies investigating the taxonomic breadth of the process and the correlation of the methane emission rate with environmental factors should be conducted.

Sweet and sour: A quantitative analysis of methane emissions in contrasting Alberta, Canada, heavy oil developments

Cold heavy oil production with or without sand (CHOPS, or CHOP) are prevalent methods of oil extraction in western Canada. CHOP(S) sites account for over 40% of all reported vented methane (CH4) from oil production in Alberta, and high rates of CH4 emissions have been confirmed in independent measurement studies. In this study, we used truck-based surveys coupled with qualitative optical gas imaging (OGI) to quantify and characterize methane emission rates and sources at nearly 1350 and 940 well sites in two major CHOP(S) developments respectively in 2016 and 2018. The studies were conducted in Lloydminster, Alberta, where produced gases are sweet (i.e., <0.5% sulfur) and non-olfactory, and Peace River, Alberta, where regulations were implemented in 2017 to manage sour (i.e., >0.5% sulfur) odorous emissions (hydrogen sulfide, BTEX, etc.). Based on results from all surveys, in Peace River, 43% of measured sites were emitting CH4, compared to 37% in Lloydminster. The measured CH4 emission rates in Peace River were, however, significantly lower than in Lloydminster for both years, and had fallen from 2016 to 2018. In 2018, emissions in Lloydminster were fairly unchanged relative to previous measurements taken in 2016. OGI showed that tanks in Peace River continue to emit CH4 despite regulatory interventions and a reported venting rate of zero. The continued emissions were thus classified as “unintended venting”, which can be a consequence of the non-routine malfunction (e.g., inappropriate operator action or poor equipment design/sizing) of vapor recovery equipment. Mitigation strategies implemented in Peace River targeting olfactory compounds were beneficial in reducing and keeping CH4 emissions lower, since these gases are co-emitted, and could even be co-regulated provincially. Reciprocal to that, we might expect future air quality improvements as a consequence of the new provincial requirements to reduce CH4 emissions under amended Directives 060 and 017.