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Quantifying Upstream and Downstream Emissions from Oil and Natural Gas

Jun 06, 2021
Thank you all for joining us in today's Brown Bag. Our speaker today is dr. Brian McDonald, who recently received the 2019 PK Sword, which is the presidential early career award for scientists and engineers, dr. McDonald is a research scientist at the University of Colorado Cooperative Environmental Sciences and Research Institute and works at NOAA's Earth Systems Research Laboratory in Boulder, Colorado. Before coming to Colorado, he received his doctorate in environmental engineering and his master's degree in public policy. from the University of California Berkeley, his expertise is in building


inventories, assessments of long-term air quality trends, and regional climate chemistry models, so I'm pleased to introduce you to Brian McDonald.
quantifying upstream and downstream emissions from oil and natural gas
Thank you for the opportunity to deliver this informal seminar today. I'll talk about the efforts we've been making to quantify


from the use of oil and


gas and, um, let's see, I can't, here we go, so I'd like to start with this graph on trends in energy consumption in the US. .US this comes from the Department of Energy and there are a few things to point out here, one is that the US is a pretty energy rich nation, so about 95 percent of national energy production can, if I have taking into account US consumption and then over time overall there has been an increase in the use of


gas from petroleum and the projections for 2050 are that oil is supposed to increase and then decrease by 2050, but it is assumed that the natural gas component will grow by approximately 50% in 2050 and the interesting thing is that if you look at where oil and natural gas is used, most of it works well, the largest source of oil and natural gas is used as fuel, so natural gas is used to power the buildings industry, we mainly use gasoline and diesel. to power our transportation sector, but there is also a fraction of oil and natural gas that is used for non-fuel purposes and is used to make plastic and rubber and also what we have called volatile chemicals or things like everyday chemicals that we use . things like pesticides, coatings, inks, adhesives, personal care products and cleaning products, and in general, one of the benefits of using oil and natural gas is that you can switch power plants from coal to natural gas and this reduces mission intensity.
quantifying upstream and downstream emissions from oil and natural gas

More Interesting Facts About,

quantifying upstream and downstream emissions from oil and natural gas...

Therefore, the amount of CO2 emitted per kilowatt hour of electrode electricity produced also reduces some of the co-emitted air pollutants depending on the intensity of emissions, including four NOx and SO2. However, there are many questions about possible methane leaks from extraction alone. and the production process in these fields and methane is also a potent greenhouse gas and there was a recent study suggesting that the methane emissions from these oil and gas fields were comparable to the 20-year radiative forcing of carbon dioxide of natural gas. combustion, so it is important to determine what the emissions are in these fields.
quantifying upstream and downstream emissions from oil and natural gas
As I mentioned, transportation is a pretty big use of oil, natural gas, primarily to fuel the transportation sector or other mobile sources, and when we talk about mobile sources, we're talking about. About 230 million cars and three million trucks are in the United States. You're also talking about other engines that can move things like locomotives, ship building equipment and also small two-stroke and four-stroke gasoline engines that are also considered mobile sources, so if we look at the overall budget, the sources cell phones count. for perhaps thirty percent of carbon dioxide emissions, about 50 percent of carbon monoxide emissions, 60 percent of nitrogen oxides, and about half of that black carbon in the U.S. . and this is important because these emissions can potentially contribute to the air quality challenges that many of As U.S. cities see, this is just a picture of the classic summer photochemical smog that occurs in Los Angeles but that It also happens in other cities in the US and these problems are also present in the winter.
quantifying upstream and downstream emissions from oil and natural gas
This is an image of the Salt Lake City basin, where when you have this capping inversion, you can trap air pollution near the surface and you can have high particulate production. And the last thing that sets the stage here is that one of the ingredients that contributes to this is volatile organic compounds and these, you can think of volatile organic compounds, it's just volatile, which means it wants to get in there and organic compounds just means which has a hydrocarbon backbone and our traditional idea of ​​where these VOCs come from is that you get the VOCs that are emitted in these oil and gas fields from the extraction of oil, natural gas, you can also get BOC emissions from petrochemical facilities or VOCs from industrial facilities can reach the middle of the vehicle exhaust pipe.
Sometimes if you smell gasoline in your car, those are actually VOCs and they can come not only from the transportation sector but also from these small two-stroke and four-stroke engines, for example, things like lawn equipment, but what What surprised us is that when we looked at this mass balance of the petrochemical industry we found that actually one of the largest sources of VOCs, especially in the urban atmosphere, came from these everyday chemicals that we use, again, pesticides. coatings, adhesives, cleaning products and personal care products, and that surprised us simply because a relatively small fraction of oil and natural gas is used to make these everyday chemicals that we use, but it can contribute about half of the VOCs to the atmosphere, so in this talk I really want to focus on a couple of particular aspects of this system, so there are emissions associated with production and processing, so I'll talk about some work that we've been doing to quantify NOx , methane and non-methane, BOC. emissions in these oil and gas fields and then I'll go on to talk about efforts to quantify nitrogen oxide and non-methane BOC emissions in cities because that's where a lot of the oil and natural gas is consumed and not just I'm going Let's talk about the efforts we are making to create emissions inventories to be able to evaluate these emissions into the atmosphere, but it is also important to verify these emissions inventories with atmospheric observations that are available and these days there are a wide variety of assets that are can be used to evaluate these emissions, for example, satellite data are now beginning to obtain higher spatial and temporal resolutions that can allow information on the sources of emissions.
There is also aircraft data we can use, such as the NOAA p3. data during field campaigns we can also drive by Noah's chemical sciences division mobile laboratory and obtain information on the sources of emissions and there are also other land-based assets and monitoring-based approaches to understand both the impacts on quality of the air as well as learn more about mission sources and then just to get your bearings if you're not familiar with atmospheric chemistry, the reason we worry about nitrogen oxides or NOx and VOCs is because these are the two main ingredients which can contribute to tropospheric ozone as well as secondary organic aerosols, so you can consider them as the basic components of photochemical smog in cities, especially during the summer, and these particular VOC sources have both natural sources, for what vegetation can emit VOCs, such as human activities such as transportation and, as I will talk about it, also from buildings, while nitrogen oxides tend to come mainly from human activities such as combustion, so the first topic that I would like to address are the associated emissions in these oil and gas fields, and if you look at the trends, no. 2 so nitrogen dioxide over the US This is from the Omie satellite for the period between 2007 and 2008, so the first point is that, overall, there has been a decrease in number 2 in large part of the U.S.
You typically see these steeper declines in cities, as well as the Ohio River Valley, and this is because efforts have been made to make power plants cleaner by the installation of chimney purification technologies to eliminate NOx and then efforts have also been made to reduce. NOx tailpipe emissions from motor vehicles and transportation over time, but there is one area that sticks out here where number 2 is increasing and one is over West Texas in the Permian, so below I just want to dig deeper into what it's driving. This increase in NOx emissions here and we are going to approach this from two approaches: one is to perform a regression analysis of that satellite trend and see if it tells us anything about the oil and gas activities that are happening in these areas and then also talk about an independent way to estimate emissions using a bottom-up fuel-based approach and then start evaluating emissions with NOAA p3 aircraft data and see if it's consistent with what you'll see from the satellite and also to try to estimate things that are It's harder to quantify things like Kohima and methane and methane boc emissions, so this is a graph of how oil and natural gas activity in the Permian has trended between 2007 and 18, so what What you're seeing here on the top left is the trend in oil production and what you notice is that oil production over the last three four years and the Permian has grown by approximately a factor of four to five, similarly , the use of natural gas in a short period of time has grown by a factor of about four.
There are also emissions that can be associated with drilling and this tends to be more variable and can be driven more by the price of oil and then also NOx emissions could be obtained from flaring, where there is oil and natural gas production, but the infrastructure is not there to channel the natural gas to consumers, so one thing that can be done is to burn that natural gas and conserve the oil . This is the work of my colleague Barbara Dix from the University of Colorado Boulder and what she has. Done, he looked at satellite trend number 2 using Oh, I, and that's shown on the blue line here and what he did was he used those trends on drilling and oil production and natural gas production, and he attributed what part of this trend. is due to the drilling component, which part is due to the production of oil, natural gas, so the production piece is shown in grey, the drilling piece is shown in purple and the other thing you need to know is that in these oil and gas fields the bottom no2 is a significant fraction of the total, so you don't see as strong an improvement in number 2 in these oil and gas fields as in a city or a power plant;
However, it is sufficient that the increase during this time cannot be explained by changes in background levels; instead, it appears to be due to the production of oil and natural gas, as well as drilling for that oil and natural gas, and What Barbara also did was separate component number 2 which was due to drilling and component number 2 which was due to production and what this simply means is that in these fields you have to consume energy to extract oil and natural gas from the soil and then once the well has been dug, there is also energy associated with it. with the production of that oil, natural gas and when engines are used in these fields, that engine consumes fuel, but in that process it also emits Noxon and what Barbara has shown is that over time it is possible that more NOx has been obtained from that drilling phase than the production phase, but in more recent years, because of this increase in oil and natural gas production, the production phase can be as important as the drilling phase, so next I want dig a little deeper into this from an emissions and inventory standpoint. approach and, more generally, how emissions are calculated, that with a methodology called bottom-up approaches some activity of the emission source is necessary, so in this case I am going to use fuel use statistics available to the fuel industry. oil and gas specifically.
So in the drilling or exploration phase, there are a lot of diesel engines that are used to extract that oil and there are off-road diesel fuel usage sales that are available for the production phase, there are a lot of combustion engines in those. fields things like dehydrators heaters compressors that largely use natural gas that is consumed on site andthen you also have natural gas processing plants and there are CO2 emissions available at the facility level from the EPA greenhouse gas inventory and then to estimate NOx emissions you also need an emission factor or how much NOx is emitted for each kilogram of carbon dioxide that is emitted and we have largely used emission factors that are available from the EPA and we have also done a literature review for these emission factors and then for larger facilities there are some Some of them may have continuous emissions monitors, so two students of two colors worked with me to map these NOx oil and gas emissions and today we have been able to map a wide variety of watersheds across the United States.
Therefore, the areas shown span from Texas to the Bakken as well as parts of the Marcellus in the northeastern US and in total these areas account for approximately 80% of US oil gas production and The boxes indicate areas where NOAA p3 has flown. as part of the field campaigns, one that occurred in 2013 was called the Southeast Nexus study and the other was a field campaign that occurred in 2015 called the Shale Oil and Natural Gas Nexus study, so the point here is that half of these basins have ways of driving emissions just by using the aircraft itself and the way you can drive emissions in these oil and gas fields using data from the aircraft is to fly the aircraft in a way that you get this upwind segment at the bottom here and you cross the field and then If you see what the methane rise is in that downwind segment at the top, you need to know what the height of the planetary boundary layer is or the upper limit of that and then from that you can deduce what the emissions are over these fields and therefore between Cenex and the next campaign, my colleague Jeff Paschal here in NOAA's Chemical Sciences Division has estimated the flow of methane from nine oil and gas basins as shown in the map above and from that methane you can also derive what the NOx emissions are from oil and natural gas and the way you can do that is to look at these fields and eliminate the influence of possible point sources that could be a large source of NOx, as well as cities, and what is found is that when the measurements of total reactive nitrogen or Noi are observed and compared and correlated with methane, You see these consistent relationships between Noy. and methane, so if you've measured methane flux, that actually tells you the Noy flux that's associated with oil in natural gas development, so what we've done here is compare this bottom-up emissions inventory to this fuel base oil. and the gas inventory that we have developed and mapped in the US that is shown in the dark blue bars here we use the plane to derive NOx emissions from the atmospheric perspective and that is shown in the light blue bars here and it well here is that between these two field campaigns we are capturing a There is a wide range of basins here, some basins predominantly produce oil, others predominantly produce dry natural gas, but overall this fuel-based oil and gas inventory that we have developed to NOx is fairly consistent with all of these basins, although they capture a fairly wide range. of the type of combustion engines that you might need in these fields, whether it's a dry gas or a white gas, what's also interesting is that when we look at the NOAA p3 aircraft data again, looking at this ratio of Noy to methane, We tend to see a pretty consistent relationship in these basins here and why this would be because NOx comes primarily from combustion engines, not necessarily from fugitive leaks of methane or non-methane VOCs, and what we think is happening here is that you have the drilling component where you have NOx emissions from those big diesel engines and you can get bursts of methane emissions and non-methane emissions during the drilling phase and the well completion phase and then when you move into the production phase, it takes energy to produce that. energy, so there are many compressor engines that need to deliver that gas and in that protection phase there could be leaks in several valves, that is why we believe that there is a more or less consistent relationship, because in the drilling phase and in the production, methane and non-methane VOCs have been emitted associated with it, so this relationship between methane and NOx is taken advantage of, so in many of these basins and in half of the basins methane flocks derived from aircraft can be obtained , but in some of the basins the conditions are not ideal for estimating aircraft emissions, but if we can estimate NOx in these areas and use that relationship between methane and NOx, we can get a more complete picture of what methane means .
Emissions occur in these oil and gas fields, so when we do this in this


component we get approximately 14 teragrams of methane emitted. This is actually in line with a previous study that was published in Science last year that estimates about 11 or so. two teragrams of methane from oil and natural gas in these areas, so what's the point here? Overall, these methane emissions in these oil and gas fields are significant, driving a large portion of the fraction of methane emissions in this infrastructure from the projection and processing phase to the distribution phase and what this study by Álvarez noted was that if methane emissions are truly at this level, then that is comparable to the radiative forcing of carbon dioxide over 20 years from simply burning the natural environment. gas and finally, to complete, not only methane is emitted in these fields, but non-methane VOCs can also be emitted and one thing is that, although the ratio between methane and Noy, can be more or less in these areas The type of VOCs that are Emissions are not as high in more humid areas with wet gas use tend to see higher proportions of non-methane emissions in the sea relative to methane.
This is the work of my colleague Jessica Gilman and NOAA's Chemical Sciences Division, and as you get into these drier basins, things like places like Marcellus tend to get a lower fraction of non-methane VOCs in compared to methane and also the composition can vary quite a bit where you tend to get more aromatics and in humid areas where you tend to get more light alkanes in the dry areas, so the point is that VOCs are not methane in these basins. They vary quite a bit and this is where the NOAA p3 measurements in these areas have been quite valuable in


this, so to summarize, overall there has been an increase in the troposphere. .2 columns a view from satellites over some oil and gas regions, especially the Permian in West Texas, there has been rapid oil and natural gas production that has skyrocketed in recent years, which is why we see these increases in column number 2 about these oil and gas fields and we believe that this improvement is due to the combustion engines that are required for drilling and natural drilling in natural gas production and we have tried to devise bottom-up approaches to estimate the NOx emissions that we believe are fairly consistent with NOAA p3 aircraft measurements that occurred between 2013-15 and we hope that the use of NOx may provide additional constraint and potential leakage of methane emissions in these fields, so below I want to talk about the questions that have arisen. in the transportation sector, so in cities mobile sources are a major source of NOx and there have been several Sommerfeld campaigns, including NOAA's senex campaign in 2013, that suggested that by looking at aircraft data and comparing them with NOx emissions from mobile sources that were being reported According to the US Environmental Protection Agency, it seemed that the emissions inventories, the official inventories, were overestimating the NOx, but then there were several studies that came out during the campaigns winter field studies that suggested that when aircraft data were looked at and compared again to NOx inventories from mobile sources. from the EPA that there was no overestimation and this is that you know that these two realities can coexist because, in general, for nitrogen oxide emissions, engine emissions from mobile sources are generally not thought to vary much between seasons, unlike things like carbon monoxide in the BO seas where you tend to have more VOCs, let's say in winter your car takes longer to warm up and therefore the three way catalytic converter takes longer to work, for what CO and B OCS are expected.
Emissions from transportation are expected to be higher in winter than summer, but that is not expected to be the case for NOx, so the only thing that can really reconcile this is that there is a seasonal dependence on these NOx emissions from sources. mobiles that we didn't know about. from and so, to try to answer this question, we'll look at this from a couple of approaches again using bottom-up methods to estimate mobile sources and NOx emissions in the same way we've done for oil and gas and then also for take advantage of as data that can be measured between these two stations and see if there is observational evidence of these emissions from mobile sources that can explain this and therefore the approach that we have used to estimate the emissions again is for the activity component that We observe in fuel sales that are available.
From the US Department of Transportation on these off-road engines there are surveys on gasoline and diesel off-road engines, so off-road engines mainly refer to construction equipment and also agricultural equipment, and in the US. Gasoline is consumed mainly by light passenger vehicles and diesel mainly heavy trucks, and the good thing about fuel sales is that it is reported annually and by state, so the second half of the equation looks at an emissions factor, so the NOx emissions in grams of NOx that is emitted per kilogram of fuel, so what is shown here are the NOx emission trends and factors of gasoline vehicles in green diesel vehicles in blue, so again the green is primarily light vehicles in the US and the blue is heavy vehicles and each of These points represent a near road study that has been done over the last thirty years and much of This work comes from the University of Denver.
Sometimes if you're at least in the Colorado area and I think Virginia as well. they can have this tailpipe infrared remote sensing beam that they're pointing at and they're able to measure the emission factors of individual vehicles passing by, and we did a study that looked at aircraft data in 2013 from the senex campaign. from NOAA and Our explanation for why these summer NOx emissions seemed to be over-requested for mobile sources is that, if you notice, the dashed line shows the emission factor from the EPA's vehicle emissions model, which It's called movements, and when you compare it to these road studies, it seemed like it was a factor two bigger when these field studies were done in this period from 2011 to 2016, however, this doesn't really explain what happens in the winter and one thing I will point out is that if you look at the Heavy Truck NOx Emission Factors, all the open markers show studies that have been done in California and if you look at almost all the studies from the year 2000, these experiments near highways have been done for trucks in California and one thing you notice in In California, since I did my PhD, AI has relatively mild winters there, while in other parts of the US it can be a little colder in winter and there has only been one recent study on winter and summer tunnels in Baltimore in recent years. and what they noticed is that if they looked at the NOx emission factors for the transportation sector between winter and summer, the emission factors in winter tended to be about 2 times higher, so what I would like to do here is now. look at some satellite data to be able to discern if there really is evidence of differences in emissions from mobile sources between winter and summer and then one of the reasons satellite data is quite useful is because it's difficult to do a field study. in both winter and summer in the same place, but the beauty of satellite data is that it is always there and is potentially a useful resource to be able to especially evaluate patterns between seasons, so this is my colleague's job on a monthly basis. she is showing column number 2 about the USA this is from a recently launched satellite called troppo me these are results with a resolution of 12 kilometers by 12 kilometers for the period of July 2018 and what you notice if you look at this satellite Recovery of number 2, that the number 2 hot spots are over these cities and may also be over somelarge power plant facilities, so what we have done here is compare our NOx emissions that we have developed for mobile. source sector using the fuel-based approach that we've talked about before, we update NOx emissions from power plants because there have actually been pretty significant decreases in NOx emissions at power plants in recent years and then we update other sources of NOx from the national emissions inventory reported in 2014, so the point here is that we have tried to get the best estimate of NOx emissions that we could for this period in 2018 and when we compare our inventory and modeling with what you see the satellite troppo me.
In general we are quite in agreement with that tropospheric column number 2 observed by tropa open and also if we focus on cities like the New York City region we are also within 20% of the satellite recovery which is approximately the uncertainty of the inventory of emissions and also satellite column number 2, so overall there is reasonable agreement between our best estimate of nitrogen oxide emissions with the satellite data during the summer and, as another check, there was a group of ground spectrometers that were located in the Long Island Sound area during this period of July 2018 and when we model these NOx emissions in weather research and forecasting with a chemical model or a value chamber, we also get relatively good agreement between our inventory and the model. with these ground-based spectrometers, so we're pretty sure we're doing a reasonable job of estimating these NOx emissions in the summer;
However, the hypothesis here is that if NOx are indeed underestimated in the winter, then if we do not have a seasonal dependence on the mobile source of NOx, then we should underestimate the number 2 in the model quite significantly relative to with Trapani and this is a picture of the number 2 columns of troppo me in the winter, this is for March 2019 one thing What you notice is that the number 2 columns are much stronger in winter than in summer, this actually has more to do with the lifespan of the number 2 columns and winter is longer than summer, but now, if we simulate our best guess of nitrogen oxide emissions and compare it with the troppome satellite in winter, we see quite an underestimation significant in our model relative to what satellites see, so what we tend to see is roughly underestimated by about 30% or so in the US and this coming under SMA is even stronger in areas like cities in the northeast as the New York region, where we are now underestimating by 60%, whereas before we were roughly in the uncertainty range of the satellite in the inventory, so it is possible that mobile source emissions could close This gap and also that Baltimore study suggested that if NOx emission factors from mobile sources are potentially underestimated by a factor of two in winter and if NOx emissions from mobile sources account for approximately one-third of US NOx emissions , then doubling emissions from these mobile sources could help close that gap.
And what are the possible explanations for that? As I mentioned, in the US, NOx emissions, at least from transportation, come primarily from cars and heavy trucks, so in the US most cars run on gasoline and there was a big study which, in the 2000s, did not find a big difference between winter and summer emission factors, so it is unlikely to be due to gasoline cars. There have been studies in Europe where we have looked at the emission factors of diesel cars and have shown that in colder cities, such as Sweden, you see higher NOx emission factors than in warmer cities in Europe, such as Athens, Greece, and then there has been some work done in the US showing that under certain driving conditions, such as stop-start traffic, higher NOx emission factors can be obtained from trucks and therefore to the extent driving in cities, this potentially has an associated temperature dependency because the engine is not as hot when it is in stop-start conditions and this is relevant because if you look at the fine particles that form in winter in places like Salt Lake City, when we look at the composition of PM 2.5, the blue shows nitrate, so this would be pm. which would be formed from NOx emissions and oxidized to form nitrate, so this nitrate formation is a significant fraction and, to the extent that NOx occurs in cities, it is important to obtain good estimates of these sources to summarize a current vehicle assembly plant.
The emission models lack strong seasonality for NOx emissions. We think satellite data can be useful to better monitor whether there is a seasonal dependence and hopefully motivate more studies of the near-road environment to get a better constraint of what is happening in the winter from tailpipe emissions. versus summer and just to point out why this is important is that NOx contributes to both ozone in the summer and ammonium nitrate problems in the winter, so it affects air quality in both seasons, so the latter The topic I want to talk about focuses on VOC sources and looks at non-traditional VOC sources, like these volatile chemicals, so we published our paper last year using data from Los Angeles, but there was actually a group in Innsbruck as well, Austria, which noticed that there was a large flow of VOCs. emissions of oxygenated BOCs that cannot be explained by fossil fuel sources and also suggested that these chemicals could be a source and the general question I want to address in this last segment of the presentation is whether anthropogenic VOCs contribute to the excesses of ozone because our The idea is that in the areas of the eastern US, where there is a lot of education, there are a lot of isoprene emissions and in order to answer this question, we are first going to quantify what the anthropogenic emissions of vo C using recent field data. measurements that NOAA's chemical sciences division made in New York City and then also used a chemical transport model to model impacts on ozone during a heat wave in New York, so last year the division of NOAA Chemical Sciences conducted a small field experiment both in the winter During the summer, we brought with us our advanced vo C instrumentation and, in use, we put this instrumentation on top as a ground site on top of the engineering building and the City College of New York, where there is a NOAA Crest Center and the City College of New York.
York is located in Upper Manhattan, we also put this instrumentation in our mobile laboratory and drove around the city and I want to especially thank my colleagues who do the experimental work here and again, the approach to estimating VOC emissions is to calculate first We found out how much fuel is consumed in New York, so there are statistics on gasoline and diesel sales. Also for the gasoline and diesel engine offering we also analyze the natural gas that is consumed in buildings, especially during the winter in Manhattan, and then also. We know approximately how many volatile chemicals people use and we believe these vary approximately with the population in the US so with fuel use then we need an emission factor to estimate vo emissions so in our In last year's article we quantified what these emission factors were, so these are the emission factors in grams of vo C emitted per kilogram of product. on a logarithmic scale and the thing to keep in mind here is that the yellow bars (these are the volatile chemical emission factors) are about one or two orders of magnitude larger than the third bar on the left, which is the vo C emission factor from the tailpipe of a modern passenger vehicle, so you don't need a lot of chemicals that used to have a huge influence on vo C emissions in the urban atmosphere, so if we combine those statistics of fuel use with those emission factors, we can derive this pie chart on the left of vo C emissions in New York City, on the right is what we published for Los Angeles last year and what to look out for Keep in mind here is that the orange part in blue is our orange and brown part of the cake. graph for these to be the emissions associated with volatile chemicals is a fairly visible fraction of the toll in both New York City and Los Angeles.
In order to compare these emissions with our environmental measurements that we do in New York City, we can It's not enough to just look at the vo, look at the total, but we have to look at what the individual VOCs C are being emitted and all we need to know is which here is the composition of VOCs from fossil fuel sources on the left and then the volatile chemicals on the left. right and notice that volatile chemicals have a lot of red fraction here and this red fraction denotes vo C emissions that are oxygenated in nature, things like alcohols, ketones, esters, the reason volatile chemicals are auctioned is that a lot of these products or while you're water soluble, so you want these kinds of compounds in there, whereas you don't see a lot of oxygenated compounds in fossil fuel sources except gasoline, which is 10% ethanol these days, and so on the x axis I show the proportions. of vo C 2 Co that we measure at our land site in New York City, on the left axis I show the vo C 2 co emissions that we estimate using our inventory and this only takes into account emissions from fossil fuel sources, but The point here is that we cannot explain the ambient level of VOCs in Manhattan using fossil fuels alone, so we underestimate what we measure in the ambient atmosphere by 64% and it is only when we include the emissions of these volatile chemicals that we begin to achieve a better agreement with our environment. observations in New York City and also get better correlation between all of these 30+ species that we measured with our vo C instrumentation, so the last thing I want to talk about is how we now start to put the pieces of this puzzle together to look at how an area is affected, so in the second part of the talk I talked about the ways that we estimate NOx emissions and here now we are adding up BOC emissions and we are doing this modeling across the United States. a resolution of 12 kilometers and also over the eastern US at a resolution of 4 kilometers in the Wharf regional camera model and this is work that I have done with my colleagues at McKean and NOAA and generally when we model this heat wave episode that occurred in July. 2 of 2018, so our model results are shown with that color on the back and the mapping here and the dots represent the air quality monitors that are routine monitors that the EPA has and generally the model agrees quite well with the spatial distribution of ozone here and The main point is that during these heat waves there is quite a bit of area where there are levels of ozone that can be harmful to health, so in this area the areas that are shown in orange, red and purple are shown below using the air quality index where Ozone can be harmful to the health of sensitive populations, so approximately 25 million people in this area and then we have also tested where we simply activate and we deactivate anthropogenic emissions of vo to the sea and you notice this hot spot that is located just north and downwind of Manhattan on this day, so you can get a 30 parts per billion impact on the ozone maximum of eight hours.
Consider that the standard is 70 parts per billion of our maximum ozone, so 30 ppb is not a trivial fraction and my colleague Matt Coggan has done some source distribution using box modeling techniques and what he finds is that of This anthropogenic contribution is about half due to mobile sources of marine emissions and the other half to these BCPs, so to summarize, we believe these volatile chemical emissions are important in New York. very similar to Los Angeles or about half of that vo C total anthropogenic and they are contributing to ozone excesses during things like heat waves, about half from VOCs from mobile sources and the other half from BCP, so I would like to recognize to many of my colleagues here who actually did much of this work between NOAA and the series at the University of Colorado Boulder, as well as some of the international collaborators in the Netherlands and also the funding sources, including an Act Map award from NASA for oil and gas work and the Co-opting Institute AgreementNOAA and a number of innovative research proposals that funded much of the urban work, so I'd like to thank them for their attention.
Very good, thank you very much for that great presentation. We have a question online. So if anyone else has a question, go ahead and submit it now, but this first person would like to know, considering the uncertainty and the methane emissions and the dispersion and the NRI versus methane graph, what is your estimate of the uncertainty and NOx emissions for oil? and operation with natural gas using the NOx - methane ratio, yes, so we think it is somewhere in between for the NOx emissions part, we are talking about an uncertainty of around 30% and then for the dispersion, I think I would add another 10 or 20% to that, so the other thing we can do to try to reduce this uncertainty in our emissions is to take advantage of that troppo me satellite, so one of the things about the troppo me satellite is that it measures both the methane number 2 like formaldehyde, so formaldehyde is a potential diagnostic for VOCs, so the next step will be to look at this relationship on the p3 plane between Noi and methane.
Do we see a similar type of relationship in the commercial satellite troppo mi data for number 2 and methane? Please help reduce this dispersion in the sense that the relationship is great and I don't see any more questions online at this time, but if anyone has any additional comments or questions we will be sure to put them in touch with dr. McDonald, so I just want to thank everyone for coming and thank you to dr. McDonald thanks for having me, goodbye.

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