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methane measurement units28 May methane measurement units

(2015) used a global model with a nested high-resolution grid for North America and found much higher U.S. emissions than EDGAR and EPA estimates (40-43 versus 25-27 Tg yr1), results consistent with other global time-dependent inversions (Bruhwiler et al., 2017; Saunois et al., 2016). In other applications for industrial point sources, measurement devices sampling at a known flow rate attempt to capture the entire emission streamthe methane emission rate is calculated by multiplying the sampling rate by the methane concentration minus the background air concentration. Sub-populations may not be sufficiently defined prior to data collection, and randomized. Compliance inspections have observed potential design constraints and operational issues that may result in chronic high emissions.5 Stochastic events arise from malfunctions that could result in high-emission events and are difficult to predict. employed. The measurement techniques used in EDF-coordinated and DOE studies and other recent emission studies have employed most of the methods described in Table 3.1. In the case of open path laser systems, the measured quantity is actually proportional to the distance the laser travels through the gas before being detected. Measures total methane emissions from individual point sources (e.g., stacks, animal). In ruminant production systems in which manure is handled as liquid (e.g., flush dairy barns, where manure is flushed from the barn with water), methane emissions from manure management can be as high as or even higher than emissions from enteric emissions. Therefore, the estimates carry larger uncertainties than those from underground mines. Airborne imaging spectroscopy (remote sensing of methane plumes). Earlier (Murray et al., 1976) and more recent (Muoz et al., 2012) data have unequivocally shown minimal contribution of methane (2-3 percent) emitted through flatulence, compared with methane emitted through expiration (exhaling) or eructation (belching). Concentration measurements, like ppm, measure How much of this gas is here? We assume you are converting between grams Methane and mole. Figure 2: Independent evaluation by Stanford University shows Kairos leak quantification is an effective way to measure leak volume. A recent analysis of emission estimates based on dispersion modeling downwind reports error bounds of +117/46 percent (Robertson et al., 2017). For example, facility aircraft measurements tend to be successful only under restricted conditions, when there are no confounding sources close to the facility and when aircraft can fly nearly to the bottom of the emission plume. Other investigators have used techniques that measure an integrated methane concentration in the entire atmospheric column above the vehicle rather than at specified heights (Mellqvist et al., 2016). Wecht et al. Some attempts to increase transport model resolution have been made using global models with increased horizontal resolution over regions of interest, a computationally cheaper alternative to global high resolution. Stanford recently published an independent verification of our leak rate quantification. Large reductions in emissions from high-emitting facilities, compared to measurements made in early 1990s (. The two major drivers for landfill methane emissions at specific sites are seasonal climate and site engineering/operational practices, including (1) the thickness and physical characteristics of cover materials and (2) the extent of engineered biogas extraction (Gebert et al., 2011; Goldsmith et al., 2012; Scheutz et al., 2009; Spokas et al., 2011, 2015). Because of the limitations of the standard gas content measuring method, different limits of gas content measurability can lead to significant differences in the estimation of methane emissions. In the atmosphere, it aggravates the climate change, but in industrial processes, it can be turned into useful products such as heat, electricity or biofuel. 3 Methane Emission Measurement and Monitoring Methods | Improving niques are also easily employed over longer time periods, which provide coverage of temporal variability, enabling more accurate prediction of longer-term emissions. Variability with the SF6 technique has been notoriously high (Clark. Another direct technique with limited application is the ventilated hood chamber or box (Kebreab, 2015), which is a polycarbonate chamber enclosing the head of the animal, allowing continuous collection and analysis of eructated and exhaled gases. One source of uncertainty in top-down emission estimates is uncertainties in atmospheric methane measurements. Generally limited to higher-emitting sources (lower detection limits are much higher than point-source techniques). Turner et al. For example, bottom-up estimates of emissions from inventories often lack associated uncertainty. Inversions that sequentially estimate emissions over time (time-dependent inversions) are shown as lines, while inversions representing time averages are shown as points. The use of their water-vapor-constrained bias correction led Houweling et al. [2016] using an ensemble of global inversions and bottom-up data). They found agreement between their estimates and mass balance estimates based on aircraft observations, as well as leakage rates. One of the primary advantages of remote sensing is that, in principle, it enables global, frequent coverage with a single instrument. A detailed discussion on the design and operation of respiration chambers was provided in the Technical Manual on Respiration Chamber Designs, published by the Global Research Alliance (Pinares-Patio and Waghorn, 2012). Measures continuously over time to capture temporal trends in emissions. Aircraft-based measurements upwind and downwind of production regions. Consequently, the emissions are estimated using production data and coal and gas data. Materials from the Hammond et al. With the collective threat of climate disasters like flooding, drought, and more spreading around the globe, scientists are searching for ways to help reduce human-based impacts on the climate. Both forward and inverse modeling approaches are powerful analysis tools that can increase understanding of the global and regional budget of methane. This area of influence is called the footprint and is dependent on factors such as measurement height, roughness height, stratification, the standard deviation of the lateral wind component, and wind velocity. Schwietzke et al. Measuring Methane Emissions, Part 1: Units - Kairos Aerospace From. Greenhouse Gas Equivalencies Calculator | US EPA Therefore, to accurately assess source emissions, the footprint must cover a large enough area of the source to capture the spatial variability of emissions. In 2021, the United States used about 97.33 quadrillion Btu of energy. Challenging to account for transient plumes through the box.. These and other assumptions, such as limited sinks in the region, typically lead to uncertainty estimates for individual aircraft flights in the 20-40 percent range (see, e.g., Karion et al., 2015). The break down happens when the gas reacts with hydroxyl radicals (a naturally occurring atmospheric compound) to become CO2 and water vapor. When converted to parts per million mole fraction (the measurement units reported for atmospheric CO2), the equivalence reduces from about 32X (over 100 yrs) to less than 12X. In the petroleum industry, amounts are given by volume, commonly as trillions (10 12) of cubic feet (ft 3) or TCF and billions (10 9) of ft 3 (BCF) in the United States. In addition, in the petroleum and gas category, activity and emission factor data collection activities are linked. They found that the inverse estimates were substantially higher than those from bottom-up inventories and suggested that natural emissions from wetlands could be higher than bottom-up estimates. Analysis systems deployed at tall-tower monitoring sites are based on commercial nondispersive infrared absorption sensors. Aircraft-based measurements can be used to estimate emissions from individual facilities (e.g., an animal feeding operation, a landfill, or a natural gas processing facility). Accuracy is vital. Atmospheric methane by infrared spectrometry at precise infrared wavelengths for pristine sites remote from population centers. Reliant on modeled meteorological conditions, which may differ from reality and/or limited field measurements. For example, NOAA air samples are measured for 13CH4 by the Institute of Arctic and Alpine Research (INSTAAR) at the University of Colorado. In between those extremes are. Commonly used units to measure Natural Gas or Methane - LNG - volume and weight: Multiply with. The ratio of the emissions of these higher hydrocarbons relative to methane varies considerably and is not well characterized at present (Allen et al., 2017; Peischl et al., 2015, 2016). However, for CO2, there is still a warming effect because the gas is building up over time. Here the model provides a temporal framework for expected emissions using 30-year average weather data with and without oxidation for comparison to the field values. parallel to quantify the variability of emissions for individual cover materials at various temporal scales. The answer is 0.062334579609362. Recommended GF calibration and background gas collection procedures have to be strictly. For example, a too-stable planetary boundary layer could systematically lead to underestimated emissions. Imagine you have two bathtubs. The authors have reported a good correlation between the sniffer and chamber measurements for the same animals (Bell et al., 2014; Garnsworthy et al., 2012). SOURCE: Adapted and expanded from Allen, 2016. In this method, two or three core drillings per mine are typically required to characterize a gas-emitting zone and to provide the main input of the model. These include (1) high release rate of SF6 from the permeation tube, (2) at least five consecutive measurement days, and (3) low concentrations of SF6 and methane in background air (i.e., using the technique in enclosed barns is not recommended, unless there is adequate ventilation throughout the measurement period; Hristov et al., 2016). These differences account for the range in emission estimates. Since 2013, however, a number of studies have reported new emission factor data for petroleum and natural gas. For example, methane has a GWP of 34. While the forward approach uses models of atmospheric transport to convert emissions to atmospheric abundance, the inverse approach converts atmospheric abundance to emissions. You can view more details on each measurement unit: molecular weight of Methane or grams The molecular formula for Methane is CH4 . At regional scales, some analyses employ mass balance approaches. The disadvantage is that boundary conditions at the edge of the domain must be specified, and there is not good observational coverage to do this accurately. Challenging to apply to individual facilities and distinguish confounding sources. (2014) found that, because of a lack of detailed knowledge of underlying source distributions, they were unable to definitively show that a high-spatial-resolution transport model was able to simulate observations better than a coarser-resolution global model. Some measurements of single production sites. For petroleum and natural gas, factors that cause certain subpopulations to become high emitters are not well known. The emissions are typically reduced compared to their active phase, but can still be substantial if gas can find conduits to migrate to the surface. Emissions are measured, typically weekly, with handheld methane detectors and flowmeters at the base of the ventilation air shaft in the mine. During the last decade, a new process-based model (CALMIM) has been developed and field validated for use in quantifying whole-landfill methane emissions over an annual cycle. The main advantage of respiration chambers is that (1) they are accurate when properly calibrated and operated, (2) all methane emissions, including from the anus, are captured, and (3) measurements take place continuously over several days, accounting for diurnal variation in methane emissions. The high-emitting sites had total emissions greater than 6,000 g methane min1. Common Units for Reporting Methane Concentrations and Emissions Labor intensive to measure the spatial and temporal variability of emissions over many sources. The SI base unit for amount of substance is the mole. Goldsmith et al. The GHGI uses Tier 2 country-specific emission factors and the volumes of the produced coal (EPA, 2005). This principal is known as Beers Law, which is sometimes colloquially expressed as The bigger the glass, the darker the brew, the harder it is for light to get through.[3] As a result, open-path systems will often report concentration as parts per million meter (ppm-m), which takes into account the effect of path length on the measurement. Emissions will cause warming for about 12 years before dropping once again. Nonruminant farm animals, however, also emit methane through fermentative activities in their hindgut. Federal Register, Volume 88 Issue 105 (Thursday, June 1, 2023) - GovInfo This complexity further exacerbates use of atmospheric carbon isotopes to fingerprint landfill methane. At these intermediate scales, emissions from multiple sources or components within a facility may be aggregated like a top-down assessment. Mine-specific data are used to fit the decline curve equations (Karacan et al., 2011). . Instantaneous to annual or multiyear averages, Generally reported as annual averages for inventory purposes from limited time duration data collected at various temporal scales, Involves use of models and assumptions as well as molecular and isotopic tracers, Calculated from source-specific activity data, Measurements reflect all sources that contribute to observed atmospheric concentrations, May not account for all sources in a given region. If emissions increased, through greater use of fossil fuels or larger livestock herds, the higher concentrations of CO2 and methane in the atmosphere lead to greater warming from both gases. A widely used technique is the sulfur hexafluoride (SF6) tracer method (Figure 3.2). Methane is an important greenhouse gas, emissions of which have vital consequences for global climate change. This approach is at a relatively early stage compared to other methods (e.g., tracers), and there are several limitations that need to considered. with average values in the 30 percent range (Chanton and Liptay, 2000; Chanton et al., 2009, 2011; Liptay et al., 1998; see also Chapter 2). Common simple methods of measuring flow rates are bagging, in the case of leaks, or in the case of controlled flow, by using a flow metering device. Both have faucets that are on and water is flowing. Since most aircraft flights sample at a single elevation or do only limited vertical spirals, the method also assumes that air pollutants (including methane emissions) are uniformly distributed throughout the mixed layer. The measurements were . (1994), the method was recently modified and improved by Deighton et al. A significant portion of methane produced in the rumen, the largest organ of the digestive tract of the ruminant animal, is absorbed into the bloodstream (12 percent in a study by Reynolds et al., 2013). Measurement of methane within the barn, along with the estimated ventilation rates, is used to calculate the overall emission rate (Fiedler and Muller, 2011; Snell et al., 2003). Aircraft measurements are used to estimate regional emissions by multiplying (1) the methane concentration difference between upwind and downwind measurements by (2) the ventilation rate for the region. The carbon dioxide balance technique utilizes carbon dioxide formed by animal respiration as a natural tracer gas with the ventilation rate estimated by calculating the mass balance of carbon dioxide flow (Pedersen et al., 1998). Methane (CH 4) is a powerful greenhouse gas, and is the second-largest contributor to climate warming after carbon dioxide (CO 2).A molecule of methane traps more heat than a molecule of CO 2, but methane has a relatively short lifespan of 7 to 12 years in the atmosphere, while CO 2 can persistfor hundreds of years or more.. Methane comes from both natural sources and human . The seasonal cycle of methane is on the order of tens of parts per billion, while decadal trends have ranged from <1 to >10 ppb yr1.9 The ability to accurately quantify trends and spatial gradients that allow continental or regional emissions to be inferred places strong demands on the precision and accuracy of network observations. This method is based on the fact that most of the carbon dioxide is produced by intermediary metabolism of the animal and can be predicted. The flux gradient technique determines the vertical flux of a gas at a given height as a product of the gass turbulent diffusivity and the concentration gradient at that height (Laubach and Kelliher, 2004). We include emissions from the end use of oil products and natural gas for the first time in the 2022 Global Methane Tracker (4 Mt or 3% energy-related methane). In the United States, Btu, a measure of heat energy, is the most common unit for comparing energy sources or fuels. These results are described by Saunois et al. uncertainties in top-down and bottom-up methods are addressed in detail later in this chapter and in Chapter 4. A methane molecule is made from one carbon atom and four hydrogen atoms. Many surface network sites have been selected to represent the background atmosphere remote from strong local sources. Measurement of emissions from fixed points based on flow rate and methane composition. Methane analyzers use IR methodology to measure methane gas. However, policy still does not take the new metric into consideration. However, for some anthropogenic sources of methane (e.g., landfills, manure), such simple calculations are generally inappropriate. For example, a natural gas processing plant with a capacity of greater than 1 metric ton (or 0.000001 Tg) per hour might be expected to have greater emissions than a plant with a capacity of less than 1 metric ton per hour; however, even when emissions are normalized by gas throughput or gas produced, a small number of observations with high normalized emissions have been identified. An important prerequisite for using the GF system is that all animals visit the unit at all times of the day and night. Coal extracted by underground techniques is expected to have more methane because of its better preservation at greater depth. For example, the California Air Resources Board (CARB) has a network of eight sites that have been continuously collecting methane data since 2010. In particular, robustly linking cover-specific oxidation to site-specific climate is warranted. The commitment to regularly submit data to the WDCGG varies, with some institutions providing frequent updates and others lagging by years. Differences between atmospheric methane simulated using atmospheric transport models, first-guess emissions (i.e., priors), and observed atmospheric methane are used to solve for revised emissions. (2017) employed a Bayesian inversion model to attribute methane and volatile organic compound emissions measured in the San Francisco Bay area. This method does not account for methane exhaled through the lungs. Its also common for leak rates to be expressed as Standard Cubic Feet per Day (SCFD) and Thousand Standard Cubic Feet per Day (MSCFD). Aircraft-based measurements of methane, ethane, carbon dioxide, carbon monoxide, and other compounds downwind of production region (but not upwind). Do you want to take a quick tour of the OpenBook's features? Aircraft-based measurements of methane, carbon dioxide, and carbon monoxide, upwind and downwind of production region, complemented by facility-scale emission estimates; data used for aircraft mass balance inversions and atmospheric transport model optimization. Total methane emissions are shown because estimates of total emissions are more robust while source attribution is less certain due to sparse observations and inaccurate prior estimates. (2010) found emissions that were considerably higher than those of EDGARv4.0 (21 percent) and the UNFCCC (40 percent). At smaller spatial scales, measurements from single processes, individual sources, or components within a facility are extrapolated to larger scales (regional, national, global). Studies conducted in pasture conditions may need longer time to achieve the number of required visits than those conducted in confinement. 2023 KAIROS AEROSPACE All rights reserved by the content holders, independent verification of our leak rate quantification, this page put up by Highwood Emissions Management. If we weigh the bucket, and then an hour later weigh it again, we will know the flow rate in kg/hr. Examples include flux gradient, integrated horizontal flux, eddy covariance, etc. Coupling increased observations of atmospheric methane with improved measurements of important diagnostic quantities for atmospheric modeling (such as planetary boundary-layer depth) will likely help improve the accuracy of emission estimates, increasing observational constraints and providing critical datasets that may be used to improve atmospheric transport models. Often limited to measurements from normal operations or where there are no safety concerns. Another indirect method proposed by Garnsworthy et al. To search the entire text of this book, type in your search term here and press Enter. You can view more details on each measurement unit: molecular weight of Methane or mol The molecular formula for Methane is CH4. Schwietzke et al. Difficult to isolate various sources within the source area depending on source layout and meteorological conditions. For regional inverse modeling, McKain et al. Barkley et al. In our next post on this topic, well explore in greater depth how leak rate and concentration measures differ, why theyre so incompatible, and the problems associated with using concentration measures for quantifying leak rates. Facility-level emissions will include emissions originating from both enteric emissions and manure management, while manure management emissions aim to target those emissions originating from manure in housing as well as manure handling and storage areas. In 2013, the Environmental Defense Fund organized a coordinated top-down and bottom-up measurement campaign in the Barnett Shale petroleum and gas production region in north central Texas. There are several assumptions associated with this approach to estimating emissions. (2012) relies on estimating methane emissions during an eructation event and the frequency of eructation during a measurement period. The sampling frequency is about once per week, although at NOAA observatories, continuous observations are possible because air is sampled and analyzed in situ. Show this book's table of contents, where you can jump to any chapter by name. The Four Corners region in the United States is a primary example of how a regional hotspot was detected from space; the ensuing follow-up field investigations used both in situ samples and airborne remote sensing (e.g., Frankenberg et al., 2016; Kort et al., 2014; Smith et al., 2017). Captures temporal trends if deployed for extended time periods. Consistent measurements across multiple sites. [1] See https://gml.noaa.gov/aggi/aggi.html for details. Coordinated, contemporaneous top-down and bottom-up measurement campaigns, conducted in a variety of source regions for anthropogenic methane emissions, are crucial for identifying knowledge gaps and prioritizing emission inventory improvements. However, even small changes in head position can result in large differences in gas concentration (Huhtanen et al., 2015). Methods for measuring enteric methane from livestock include enclosure chambers, tracer techniques, sniffer techniques, and handheld laser methane detectors.1 The gold standard for measuring enteric methane emissions from farm animals (ruminants and nonruminants) is the respiration chamber. The Mine Safety and Health Administration (MSHA) requires that trained MSHA inspectors perform mine safety inspections at least quarterly by testing methane emission rates at each coal mine.

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