Academic literature on the topic 'CO2 and CH4 Leak detection'

We report on a direct detection differential absorption lidar (DIAL), designed for remote detection of CH4 and CO2. The system is based on a single-frequency optical parametric oscillator/amplifier system, tunable in the 1.57-1.65 µm range. The DIAL system, called NAOMI GAZL, was tested on a controlled gas release facility in October 2018.

Emissions of atmospheric methane (CH4), which greatly contributes to radiative forcing, have larger uncertainties than those for carbon dioxide (CO2). The Thermal And Near-infrared Sensor for carbon Observation Fourier-Transform Spectrometer (TANSO-FTS) onboard the Greenhouse gases Observing SATellite (GOSAT) launched in 2009 has demonstrated global grid observations of the total column density of CO2 and CH4 from space, and thus reduced uncertainty in the global flux estimation. In this paper, we present a case study on local CH4 emission detection from a single-point source using an available series of GOSAT data. By modifying the grid observation pattern, the pointing mechanism of TANSO-FTS targets a natural gas leak point at Aliso Canyon in Southern California, where the clear-sky frequency is high. To enhance local emission estimates, we retrieved CO2 and CH4 partial column-averaged dry-air mole fractions of the lower troposphere (XCO2 (LT) and XCH4 (LT)) by simultaneous use of both sunlight reflected from Earth’s surface and thermal emissions from the atmosphere. The time-series data of Aliso Canyon showed a large enhancement that decreased with time after its initial blowout, compared with reference point data and filtered with wind direction simulated by the Weather Research and Forecasting (WRF) model.

Hydrogen is one of the most important energy gases as it is carbon free and therefore can result in the emission reduction of the greenhouse gas CO2. However, hydrogen itself is a secondary greenhouse gas. As a secondary greenhouse gas, hydrogen does not directly add to global warming by entrapping heat. Instead, it reacts with molecules in the atmosphere that are needed to remove the greenhouse gas CH4. CH4 is comparably short-lived in the atmosphere with approximately 10 years compared to CO2 which can last in the atmosphere for centuries. However, CH4 traps at least 100 times as much heat as CO2. Considering the difference in heat capacities of CH4 and CO2, combined with the difference in lifetime, if the same amount of CH4 and CO2 were to be released into the atmosphere at the same time, the global warming effect of CH4 would be approximately 28 times higher than the warming effect of CO2. This means, by releasing hydrogen in the atmosphere, the global warming effect is indirectly enhanced by increasing the lifetime of CH4. Therefore, it is essential to be able to detect, locate and quantify hydrogen leaks right away. Due to the ever-growing hydrogen infrastructure including production facilities, transportation systems like pipelines, as well as storage facilities and user end stations, it is essential to create low-cost, low-power sensors that can be deployed in high numbers. Electrochemical sensors have the potential to fulfill all the needed criteria and are already used for the detection of hydrogen. However, in order to use these sensors to not only detect the leak, but also to locate and quantify the amount of hydrogen that leaked into the atmosphere, additional models and algorithms are needed. To our knowledge, no system currently exists on the market that can be used to fulfill all three tasks. We built a test chamber that enabled us to evaluate H2 leaks and to collect data with electrochemical sensors in a controlled room and environment. The chamber has the size of 800 x 400 x 450 mm3 with a total volume of 144 L. We placed seven of our commercial electrochemical sensors that can detect 0 – 250 ppm hydrogen at different positions inside the box. The box was equipped with one gas inlet and one gas outlet to ensure pressure stability inside the box during our leak test. The inlet was connected to a gas tube which was connected to two mass flow controllers as well as to an outlet tube via a three-way valve. This way, it could be ensured that the gas stream had a stable volume and a constant speed. We released controlled amounts of hydrogen into the box and collected the data with our seven sensors. We were able to see a location-dependent sensor response over time for a 1 second leak of H2 which indicates the capability of such a sensor system to be used for the location of a leak. Quantifying hydrogen is a very complex issue. It requires extremely accurate readings and an intelligent algorithm that is capable to use the reading from multiple sensors and turn that into a mass of hydrogen leaked or leaking. The extremely accurate reading is difficult because the zero and span readouts from the electrochemical sensor is dependent on temperature as well as humidity. This means that the readout zero and span will have to be compensated for both temperature and humidity. While we currently use algorithms to compensate for temperature, we found that these algorithms are not good enough when the sensors are used to measure concentrations in the low-ppm or ppb range. We are researching AI and other computational means to include both temperature and humidity in the compensation algorithms and how including both variables in the compensation process can improve the sensors performance at low concentrations. Both the H2 sensor and its deployment capabilities are technologically and economically significant to the rapidly expanding H2 market for protecting human health, the environment, stemming expensive product losses and promoting efficient use.

Abstract. In recent years several commercialised closed-path cavity-based spectroscopic instruments designed for eddy covariance flux measurements of carbon dioxide (CO2), methane (CH4), and water vapour (H2O) have become available. Here we compare the performance of two leading models – the Picarro G2311-f and the Los Gatos Research (LGR) Fast Greenhouse Gas Analyzer (FGGA) at a coastal site. Both instruments can compute dry mixing ratios of CO2 and CH4 based on concurrently measured H2O, temperature, and pressure. Additionally, we used a high throughput Nafion dryer to physically remove H2O from the Picarro airstream. Observed air–sea CO2 and CH4 fluxes from these two analysers, averaging about 12 and 0.12 mmol m−2 day−1 respectively, agree within the measurement uncertainties. For the purpose of quantifying dry CO2 and CH4 fluxes downstream of a long inlet, the numerical H2O corrections appear to be reasonably effective and lead to results that are comparable to physical removal of H2O with a Nafion dryer in the mean. We estimate the high-frequency attenuation of fluxes in our closed-path set-up, which was relatively small ( ≤ 10 %) for CO2 and CH4 but very large for the more polar H2O. The Picarro showed significantly lower noise and flux detection limits than the LGR. The hourly flux detection limit for the Picarro was about 2 mmol m−2 day−1 for CO2 and 0.02 mmol m−2 day−1 for CH4. For the LGR these detection limits were about 8 and 0.05 mmol m−2 day−1. Using global maps of monthly mean air–sea CO2 flux as reference, we estimate that the Picarro and LGR can resolve hourly CO2 fluxes from roughly 40 and 4 % of the world's oceans respectively. Averaging over longer timescales would be required in regions with smaller fluxes. Hourly flux detection limits of CH4 from both instruments are generally higher than the expected emissions from the open ocean, though the signal to noise of this measurement may improve closer to the coast.

According to the EPA, methane (CH4) emissions from oil and gas infrastructure accounted for 211 million metric tons of CO2 equivalent in 2020 [1]. Actual emissions may exceed this by a factor of three [2]. Current natural gas leak detection technologies largely consist of optical sensors such as IR spectrometers [3]. Optical sensors have high sensitivity, but the high cost and fragility of these sensors limit practical applications and continuous monitoring in the field. Mixed potential electrochemical sensors (MPES) are low cost, robust, selective and sensitive, making them a viable option for continuous natural gas leak detection [4]. While we have previously reported on the development of these sensors for natural gas detection in the laboratory, it is necessary to evaluate how these sensors perform in relevant environments. The MPES device consists of La0.87Sr0.13CrO3 (LSC), indium tin oxide (ITO, In2O3 90 wt%, SnO2 10 wt%), and Au sensing electrodes with a Pt pseudo-reference electrode, bridged by 3 mol% YSZ solid electrolyte. A low ionic conductivity magnesia stabilized zirconia (MSZ) substrate is used to enhance sensitivity with a demonstrated limit of detection (LOD) of < 40 ppm. The sensor is integrated with an internet of things (IoT) data collection and transmission package developed by SensorComm Technologies. Field testing was performed at Colorado State University’s Methane Emission Technology Evaluation Center (METEC). The sensors’ capability of detecting buried pipeline leaks was investigated by varying the leak rate from 7.2 SLPM to 37 SLPM, lateral sensor distance from 0 meters to 3 meters, and vertical distance from 0 meters to 0.28 meters (Figure 1). Machine learning methods were applied to a training dataset collected in the laboratory to quantify the CH4 concentration. These results serve as a first demonstration that a low-cost mixed potential electrochemical sensor system can successfully detect underground pipeline emissions and quantify CH4 concentrations that are in agreement with previously published results [6] collected using more complex and costly methods. References: [1] O. US EPA, “Estimates of Methane Emissions by Segment in the United States,” Aug. 27, 2018. https://www.epa.gov/natural-gas-star-program/estimates-methane-emissions-segment-united-states (accessed Dec. 08, 2022). [2] A. J. Marchese et al., “Methane Emissions from United States Natural Gas Gathering and Processing,” Environ. Sci. Technol., vol. 49, no. 17, pp. 10718–10727, Sep. 2015, doi: 10.1021/acs.est.5b02275. [3] T. Aldhafeeri, M.-K. Tran, R. Vrolyk, M. Pope, and M. Fowler, “A Review of Methane Gas Detection Sensors: Recent Developments and Future Perspectives,” Inventions, vol. 5, no. 3, Art. no. 3, Sep. 2020, doi: 10.3390/inventions5030028. [4] F. H. Garzon, R. Mukundan, and E. L. Brosha, “Solid-state mixed potential gas sensors: theory, experiments and challenges,” Solid State Ion., vol. 136–137, pp. 633–638, Nov. 2000, doi: 10.1016/S0167-2738(00)00348-9. [5] S. Halley, L. Tsui, and F. Garzon, “Combined Mixed Potential Electrochemical Sensors and Artificial Neural Networks for the Quantificationand Identification of Methane in Natural Gas Emissions Monitoring,” J. Electrochem. Soc., vol. 168, no. 9, p. 097506, Sep. 2021, doi: 10.1149/1945-7111/ac2465. [6] B. A. Ulrich, M. Mitton, E. Lachenmeyer, A. Hecobian, D. Zimmerle, and K. M. Smits, “Natural Gas Emissions from Underground Pipelines and Implications for Leak Detection,” Environ. Sci. Technol. Lett., vol. 6, no. 7, pp. 401–406, Jul. 2019, doi: 10.1021/acs.estlett.9b00291. Figure 1: Sensor response to various heights above a simulated buried pipeline leak on two successive days of testing (a and b), and estimated CH4 concentrations from sensor data (c). Figure 1

Abstract. Until recently, atmospheric carbon dioxide (CO2) and methane (CH4) measurements were made almost exclusively using nondispersive infrared (NDIR) absorption and gas chromatography with flame ionisation detection (GC/FID) techniques, respectively. Recently, commercially available instruments based on spectroscopic techniques such as cavity ring-down spectroscopy (CRDS), off-axis integrated cavity output spectroscopy (OA-ICOS) and Fourier transform infrared (FTIR) spectroscopy have become more widely available and affordable. This resulted in a widespread use of these techniques at many measurement stations. This paper is focused on the comparison between a CRDS "travelling instrument" that has been used during performance audits within the Global Atmosphere Watch (GAW) programme of the World Meteorological Organization (WMO) with instruments incorporating other, more traditional techniques for measuring CO2 and CH4 (NDIR and GC/FID). We demonstrate that CRDS instruments and likely other spectroscopic techniques are suitable for WMO/GAW stations and allow a smooth continuation of historic CO2 and CH4 time series. Moreover, the analysis of the audit results indicates that the spectroscopic techniques have a number of advantages over the traditional methods which will lead to the improved accuracy of atmospheric CO2 and CH4 measurements.

Fires and gas leaks are events that still occur frequently. This incident is usually caused by various factors including leakage of LPG gas cylinders, cigarette butts that are disposed of carelessly, short circuits of electric current and so on. Generally, fires and gas leaks can only be detected if the fire has already grown or a lot of smoke comes out of the building. Therefore, a monitoring system for detecting dangerous gases and fires in buildings based on the Internet of Things was created that can monitor the condition of the building through a website as well as send notifications to the Telegram application on smartphones. The detection system implemented uses a flame sensor as a fire detector, an MQ-2 gas sensor as a detector of hazardous gases (CO, CO2, and CH4), and NodeMCU as a module to transmit data. The system will work continuously in real time, if gas is detected that exceeds the threshold or a fire is detected, the system will send a notification to Telegram and the website will display the value and status of the sensor and a map of the area where the fire or gas leak occurred. The results of the detection system created to be able to provide solutions so that cases of fire and gas leaks can be handled early by detecting signs of fire or gas leaks and sending the information to users via the website and notifications.

Abstract. Atmospheric methane (CH4) is the second-most-important anthropogenic greenhouse gas and has a 20-year global warming potential 82 times greater than carbon dioxide (CO2). Anthropogenic sources account for ∼ 60 % of global CH4 emissions, of which 20 % come from oil and gas exploration, production and distribution. High-resolution satellite-based imaging spectrometers are becoming important tools for detecting and monitoring CH4 point source emissions, aiding mitigation. However, validation of these satellite measurements, such as those from the commercial GHGSat satellite constellation, has so far not been documented for active leaks. Here we present the monitoring and quantification, by GHGSat's satellites, of the CH4 emissions from an active gas leak from a downstream natural gas distribution pipeline near Cheltenham, UK, in the spring and summer of 2023 and provide the first validation of the satellite-derived emission estimates using surface-based mobile greenhouse gas surveys. We also use a Lagrangian transport model, the UK Met Office's Numerical Atmospheric-dispersion Modelling Environment (NAME), to estimate the flux from both satellite- and ground-based observation methods and assess the leak's contribution to observed concentrations at a local tall tower site (30 km away). We find GHGSat's emission estimates to be in broad agreement with those made from the in situ measurements. During the study period (March–June 2023) GHGSat's emission estimates are 236–1357 kg CH4 h−1, whereas the mobile surface measurements are 634–846 kg CH4 h−1. The large variability is likely down to variations in flow through the pipe and engineering works across the 11-week period. Modelled flux estimates in NAME are 181–1243 kg CH4 h−1, which are lower than the satellite- and mobile-survey-derived fluxes but are within the uncertainty. After detecting the leak in March 2023, the local utility company was contacted, and the leak was fixed by mid-June 2023. Our results demonstrate that GHGSat's observations can produce flux estimates that broadly agree with surface-based mobile measurements. Validating the accuracy of the information provided by targeted, high-resolution satellite monitoring shows how it can play an important role in identifying emission sources, including unplanned fugitive releases that are inherently challenging to identify, track, and estimate their impact and duration. Rapid, widespread access to such data to inform local action to address fugitive emission sources across the oil and gas supply chain could play a significant role in reducing anthropogenic contributions to climate change.

Abstract. We developed and tested a complete measurement system to quantify CO2 and CH4 emissions at the scale of an industrial site based on the innovative sensor Airborne Ultra-light Spectrometer for Environmental Application (AUSEA), operated on board uncrewed aircraft vehicles (UAVs). The AUSEA sensor is a new light-weight (1.4 kg) open-path laser absorption spectrometer simultaneously recording in situ CO2 and CH4 concentrations at high frequency (24 Hz in this study) with precisions of 10 ppb for CH4 and 1 ppm for CO2 (when averaged at 1 Hz). It is suitable for industrial operation at a short distance from the sources (sensitivity up to 1000 ppm for CO2 and 200 ppm for CH4). Greenhouse gas concentrations monitored by this sensor throughout a plume cross section downwind of a source drive a simple mass balance model to quantify emissions from this source. This study presents applications of this method to different pragmatic cases representative of real-world conditions for oil and gas facilities. Two offshore oil and gas platforms were monitored for which our emissions estimates were coherent with mass balance and combustion calculations from the platforms. Our method has also been compared to various measurement systems (gas lidar, multispectral camera, infrared camera including concentrations and emissions quantification system, acoustic sensors, ground mobile and fixed cavity ring-down spectrometers) during controlled-release experiments conducted on the TotalEnergies Anomaly Detection Initiatives (TADI) test platform at Lacq, France. It proved suitable to detect leaks with emission fluxes down to 0.01 g s−1, with 24 % of estimated CH4 fluxes within the −20 % to +20 % error range, 80 % of quantifications within the −50 % to +100 % error range and all of our results within the −69 % to +150 % error range. Such precision levels are better ranked than current top-down alternative techniques to quantify CH4 at comparable spatial scales. This method has the potential to be operationally deployed on numerous sites and on a regular basis to evaluate the space- and time-dependent greenhouse gas emissions of oil and gas facilities.

ἀe purpose of this study was to analyze the trend of climate change through changes in the elements of Green House Gases (GHGs), includes the trend of CO2, N2O, and CH4. ἀe change of the extreme rainfall and temperature indices due to land cover change into developed area in Padang. IdentiḀcation and analysis trends of climate change and extreme climatic events were analyzed by using RclimDex the Expert Team for Climate Change Detection and Indices (ETCCDMI) technique. Where as the analysis and interpretation of land cover changes into developed area used Landsat TM 5 and Landsat 1985 7 ETM + of 2011 by ERDAS 9.2 GIS with the supervised classiḀcation method and GIS Matrix. ἀe results of the study provide informations of land cover changes into developed area at forest land (11,758.9 ha), shrub (3,337.3 ha), rice Ḁelds (5,977.1 ha), and garden (5,872.4 ha). It has an implication on increasing of the ele-ments of GHGs concentration such as CO2 (14,1 ppm), N2O (5,4 ppb) and CH4 (24,8 ppb). ἀis condition lead to an extreme temperature and presipitation indexs trends in Padang.