In terms of monitoring, successive instruments will be needed to monitor over multiple decades, and care will have to be taken to ensure that instruments are comparable. Go to the equivalencies calculator page for more information. DOE estimates that the adopted standards will result in cumulative emission reductions (over the same period as for energy savings) of 91.69 million metric tons (``Mt'') \7\ of carbon dioxide (``CO 2 ''), 35.12 thousand tons of sulfur dioxide (``SO 2 ''), 148.74 thousand tons of nitrogen oxides (``NO X ''), 690.10 thousand tons of methane (``CH . In general, the bottom-up techniques described below have application in all source categories discussed in this report. In addition, the U.S. Department of Energy (DOE). Although these techniques can provide emission estimates for a given source area, there are several potential drawbacks to consider. The inversions by Wecht et al. Because they measure the emissions from the entire source area (or large portions of it), spatial variability of emissions is also accounted for. The uncertainty of network observations plays an important role in determining the sensitivity of the network to spatial and temporal variability of methane, and this translates into information about source distributions and their variability. (2017) employed a Bayesian inversion model to attribute methane and volatile organic compound emissions measured in the San Francisco Bay area. While inverse dispersion techniques can capture the temporal variability in emissions, individual sources within the facility may not be discernable. As previously discussed in Chapter 2, there are fundamental problems with the current inventory methodology, including a lack of systematic field validation for emissions as well as a lack of systematic correspondence with independent field measurements. Not a MyNAP member yet? Multiple field campaigns during the last two decades have greatly improved understanding of landfill methane emission processes at U.S. sites. Do you want to take a quick tour of the OpenBook's features? Within each of these categories, a variety of subcategories of sources may exist with variability in emissions among the subcategories. The answer is 0.062334579609362. Hellwing et al. However, underground mining has a much higher contribution to total methane emissions and therefore is a priority for efforts to improve methane emission estimates from coal mining. As science advances and manufacturing precision improves, so does our capacity to adhere to more rigorous standards of measurement. Understanding and quantifying the sources (and sinks) of atmospheric methane is integral for climate change mitigation and emission reduction strategies, such as those outlined in the 2015 UN Paris Agreement on Climate Change. In general, concentration is a measurement of the amount of some molecule (the solute) in some other medium (the solvent). Units are the scale we use to express the measurement. 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. The answer is 16.04246. Perimeter facility line measurements are conducted by equipping a site with open-path spectrometers (infrared, tunable diode laser), which measure average methane concentrations per meter distance on the upwind and downwind sides of a site. Units and calculators explained - U.S. Energy Information Its also common for leak rates to be expressed as Standard Cubic Feet per Day (SCFD) and Thousand Standard Cubic Feet per Day (MSCFD). In some cases, the changes in emissions are the result of changes in regulations and operating practices. Jump up to the previous page or down to the next one. Since 2013, however, a number of studies have reported new emission factor data for petroleum and natural gas. 3 See https://energy.gov/sites/prod/files/2016/08/f33/Methane%20Emissions.pdf and https://www.energy.gov/under-secretary-science-and-energy/articles/doe-announces-13-million-quantify-andmitigate-methane. A later study using the same WRF-STILT model configuration concluded that for 2007 and 2008, anthropogenic emissions were significantly underestimated for North America (Miller et al., 2013). The break down happens when the gas reacts with, While GWP100 does consider short-lived gases like methane, it does not account for removal from the atmosphere. The uncertainties of both the NOAA and AGAGE network observations are very small, amounting to only about 0.06 percent of global average methane mole fraction, meaning that the network observations are sensitive across. Therefore, care must be taken to ensure that temporal, spatial, and animal (enteric) variability in emissions is captured in order to accurately portray emissions from any given source category. Emissions from such sources are microbially driven or are subject to significant differences in equipment or operating practices, and as such, they are subjected to large temporal and spatial variability. 9 Ed Dlugokencky, NOAA/ESRL (www.esrl.noaa.gov/gmd/ccgg/trends_ch4/). The numerical techniques employed range from simple mass balance approaches to data assimilation methods similar to those used in numerical weather forecasting. Some flares with destruction efficiency <80%. Copyright The Regents of the University of California, Davis campus. Thus, rather than describe each of these techniques separately for each source, the general methodologies are described first, followed by those more specific to individual source categories. This indicator describes how the levels of major greenhouse gases in the atmosphere have changed over time. CH 4 emitted today lasts about a decade on average, which is much less time than CO 2. Methane from oil & gas - Methane Tracker 2020 - Analysis - IEA 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). (1997) used a full global atmospheric transport model to estimate global methane emissions and concluded that their estimated emissions reproduced large-scale features such as the interhemispheric methane gradient reasonably well, but not grid-scale emission variability. A typical approach is to fly concentric closed flight paths at multiple altitudes around a source while continuously measuring methane concentrations, wind speed, and wind. Emission factors both higher and lower than inventory factors observed; largest emission factor from open-ended lines (measurement factor of 5 greater than GHGRP emission factor). Appropriate meteorological conditions (sufficient vertical mixing of surface emissions at flyover elevations, typically midday conditions) are necessary. Similar to the SF6 technique, GF cannot measure methane excreted through the rectum. 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). Animals are usually placed in chambers for several days (recommendations are for at least 3 days), during which they are fed and milked (if lactating), and manure is removed from the chamber. Careful evaluation of such data for use in national methane inventories is necessary to ensure representativeness of annual average assessments. More recently, an automated head chamber system, GreenFeed (GF), was developed for spot sampling of exhaled and eructated gases (Zimmerman and Zimmerman, 2012). Understanding, quantifying, and tracking atmospheric methane and emissions is essential for addressing concerns and informing decisions that affect the climate, economy, and human health and safety. Recently, joint efforts between the waste industry and the EPA have focused on developing a standardized field methodology for whole-landfill emissions with the goal of certification by the EPA as an other test method. If the vehicle drives along a path that is perpendicular to the wind direction, the horizontal extent of the plume can be determined. 2-3% of wells account for more than half of national unloading emissions. However, cavity ring-down spectrometers (Crosson, 2008) or off-axis integrated cavity output spectrometers (OKeefe et al., 1999), which do measure methane, have been installed at two tower sites in California. Observations of some hydrocarbons such as ethane and propane may also help to quantify emissions from petroleum and natural gas production since they are co-emitted with methane from this source. (2011) evaluated and compared a suite of atmospheric transport models for 1990-2007 using observations of methane, radon, SF6, and methyl chloroform at background sites and satellite retrievals of methane in the upper troposphere and stratosphere. In general, emission estimates from abandoned underground mines are based on the emissions during the active phase of the mine, assuming that emissions experience a hyperbolic decline after abandonment. While the forward approach uses models of atmospheric transport to convert emissions to atmospheric abundance, the inverse approach converts atmospheric abundance to emissions. One of the most common ways to measure the flow rate of natural gas is kilograms per hour (kg/hr). The level of emissions varies depending upon many factors including gas content of the coal, mine flooding, the presence of conduits, the quality of mine seals, and the time since the mine closure. Federal Register, Volume 88 Issue 105 (Thursday, June 1, 2023) - GovInfo 12 See http://www.globalcarbonproject.org/methanebudget/index.htm. Profiles are made during ascents and descents mostly in polluted urban environments, potentially making them useful for estimating urban emissions. And as renewables continue to make up a larger fraction of the US energy landscape, natural gas peaker plants are becoming more important for load balancing. Its short-lived nature means that the gas is actively being removed from the atmosphere and thereby reduces its contribution to warming over long periods of time. The strengths and weaknesses of various top-down and bottom-up approaches are summarized in Tables 3.1 and 3.2. However, constant or decreasing emissions paint a different picture. In addition, it is especially challenging to quantify model transport error, especially for measurement sites where the distribution of local sources may not be adequately known; therefore, it is difficult to determine whether model-data differences are due to a lack of knowledge of sources or transport errors. British thermal units (Btu) - U.S. Energy Information Administration (EIA) The accuracy of this method depends on the situation in which it is used. 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). Even so, methane that has broken down into CO2 is still carbon in the atmosphere. Some micrometeorological techniques and high-tower monitoring may provide information from days to years. The attractiveness of this approach (also referred to as the sniffer method) is that emissions can be measured in on-farm conditions and on a large number of animals. Improving Characterization of Anthropogenic Methane Emissions in the United States summarizes the current state of understanding of methane emissions sources and the measurement approaches and evaluates opportunities for methodological and inventory development improvements. The sampling frequency is about once per week, although at NOAA observatories, continuous observations are possible because air is sampled and analyzed in situ. 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. NOAA aircraft and tower measurements are mainly at sites in the United States. For example, a too-stable planetary boundary layer could systematically lead to underestimated emissions. Flow meters can measure flow rates either by mass or by volume. 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. Measurement of emissions from fixed points based on flow rate and methane composition. The technology provides rapid measurements in percent (%) ranges, and in some applications, parts per million (ppm) ranges. There is a wide range of signals to be detected in atmospheric methane using spatially distributed observations that are sustained over time. In contrast, biogenic coal-bed methane is generated by the breakdown of coal organic matter by methanogenic consortia of microorganisms at lower temperature, usually below 56C. Ability to target specific emission source regions and obtain vertical profiles of methane concentrations. Often limited to measurements from normal operations or where there are no safety concerns. parallel to quantify the variability of emissions for individual cover materials at various temporal scales. The forward approach involves use of bottom-up estimates of emissions and sinks, along with an atmospheric transport model to simulate atmospheric methane that can be compared with observations. (2011) based on comparisons of SCIAMACHY retrievals with model simulations of column-average methane using multiple inversion emission estimates. Both gaseous transport and oxidation rates are dependent on dynamic changes in soil temperature and moisture resulting from local weather fluctuations, as well as longer-term climate trends (Spokas et al., 2011). Defining the prior uncertainty estimates is challenging and may not be well constrained by independent information. 1 A comprehensive review of enteric methane measurement techniques was recently published by an international team of scientists (Hammond et al., 2016) as part of the Global Network project (http://animalscience.psu.edu/fnn/current-research/global-network-for-enteric-methane-mitigation). TABLE 3.3 A Sample of Bottom-Up Measurement Studies in the Natural Gas Supply Chain. Aircraft-based measurements of methane, carbon dioxide, carbon monoxide, and C2C5 alkanes using high-precision, high-time-resolution instruments. For example, in the 2011 GHGI for natural gas, an activity count for pneumatic controllers averaging one controller per well was used. Inversions using space-based retrievals of column average do not appear to significantly differ from those using only in situ observations, at least for the continental United States. 6 Transformation of plant biomass into peat and coal (Diessel, 1992). Labor intensive to measure the spatial and temporal variability of emissions. Estimates temporal trends when measurements are made continuously. Activating CO2 to form methane is a potential strategy for energy decarbonization, but to activate CO2 typically requires high temperatures. Schwietzke et al. Studies conducted in pasture conditions may need longer time to achieve the number of required visits than those conducted in confinement. (e.g., IPCC, 2006). It could also provide important insights into performance of bottom-up emission models, some of which may be coupled with climate models that are capable of predicting feedbacks between trace gas emissions and climate, leading to improved confidence in climate predictions. This has included the development and application of a tracer correlation method using a C2H2 tracer with the Piccaro cavity ring-down spectrometer (Foster-Wittig et al., 2015). (2016) and represent an ensemble of global inverse model results contributed to the Global Carbon Project by the international global modeling community.12 The inversions use different combinations of observations (in situ and retrievals of column-average methane from SCIAMACHY and GOSAT), different atmospheric transport models, and different inversion setup choices (prior emissions and uncertainties, inverse technique). Measuring the concentration of methane gas is important for many industries, including oil and gas, for both safety and for effective methane emissions reduction programs. Labor intensive to measure the variability of emissions over large source areas (requires geostatistical techniques, a large number of chamber measurements, and ancillary information). The integrated horizontal flux technique depends on a mass budget equation, simplified for two-dimensional flow (Laubach and Kelliher, 2005). Field measurement techniques for landfills range from square meter to square kilometer scales, including chambers, tracer techniques, micrometeorological approaches, vertical radial plume mapping (VRPM), and aircraft mass balance approaches, as discussed below and previously summarized in Table 3.3. The GHGI uses Tier 2 country-specific emission factors and the volumes of the produced coal (EPA, 2005). Most of these tech-. or thermogenic sources (Schaefer et al., 2016; Schwietzke et al., 2016). You're looking at OpenBook, NAP.edu's online reading room since 1999. The latitudinal gradient of methane (the annual mean difference between the North and South Poles) is about 150 ppb, compared to the global average dry-air mole fraction (the ratio of moles of methane compared to number of moles of all components) concentration. If emissions from a source area cannot be enclosed or captured, there are several micrometeorological techniques that can estimate methane emissions using towers with fast-response methane sensors and wind speed/direction sensors, combined with atmospheric transport modeling. relative to total production for unconventional production and gathering facilities that were low compared to other basins (0.36 0.09 percent). Site-specific research projects have applied multiple field techniques to measure methane emissions. 3 Methane Emission Measurement and Monitoring Methods, 5 Presenting Methane Emission Data and Results, 6 Meeting the Challenges of Characterizing Methane Emissions, Appendix B: Definition of U.S. Greenhouse Gas Inventory Categories, Appendix C: Other Anthropogenic Sources of Methane, Appendix D: U.S. Greenhouse Gas Inventory Development, Appendix E: Acknowledgment of Those Who Provided Input to the Committee, Appendix F: Common Units for Reporting Methane Concentrations and Emissions, Appendix G: Biographical Sketches of Committee Members, Appendix H: Disclosure of Conflict of Interest, Facility-scale in situ aircraft measurements, U.S. national sample of natural gas sites, Well completions, unloadings, leaks, pneumatic pumps, and controllers. Much smaller longitudinal gradients occur between the Pacific and Atlantic: 10-20 ppb, based on estimates of U.S. emissions and transit times across the United States. Therefore, to accurately assess source emissions, the footprint must cover a large enough area of the source to capture the spatial variability of emissions. This method does not account for methane exhaled through the lungs. Results indicated that the tracer method had minimum error and lowest variability; however, the VRPM, DiAL, and tracer results were all within the same order of magnitude. Limited to sunlit, cloud-free, snow-free scenes. First of all, methane and the CO2 that it becomes, are part of the biogenic carbon cycle. 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. (2009) noted good agreement between inversions using only surface network observations and inversions using surface observations and the revised retrievals at large scales. Atmospheric methane is a potent greenhouse gas (GHG) that contributes to global warming. (2015), and Lamb et al. The advantage of using a regional atmospheric model is that transport can be simulated at higher resolution and is likely to be more accurate than with a coarser global model.

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