Environmental Protection Agency Emission Research Articles

Methane emissions from abandoned oil and gas wells in Colorado

Recent studies indicate emission factors used to generate bottom-up methane inventories may have considerable regional variability. The US's Environmental Protection Agency's emission factors for plugged and unplugged abandoned oil and gas wells are largely based on measurement of historic wells and estimated at 0.4 g and 31 g CH4 well−1 h−1, respectively. To investigate if these are representative of wells more recently abandoned, methane emissions were measured from 128 plugged and 206 unplugged abandoned wells in Colorado, finding the first super-emitting abandoned well (76 kg CH4 well−1 h−1) and average emissions of 0 and 586 g CH4 well−1 h−1, respectively. Combining these with other states' measurements, we update the US emission factors to 1 and 198 g CH4 well−1 h−1, respectively. Correspondingly, annual methane emissions from the 3.4 million abandoned wells in the US are estimated at between 2.6 Tg, following current methodology, and 1.1 Tg, where emissions are disaggregated for well-type. In conclusion, this study identifies a new abandoned well-type, recently-producing orphaned, that contributes 74 % to the total abandoned wells methane emissions. Including this new well-type in the bottom-up inventory suggests abandoned well emissions equate to between 22 and 49 % of total emissions from US active oil and gas production operations.

A System for Standardizing and Combining U.S. Environmental Protection Agency Emissions and Waste Inventory Data.

The U.S. Environmental Protection Agency (USEPA) provides databases that agglomerate data provided by companies or states reporting emissions, releases, wastes generated, and other activities to meet statutory requirements. These databases, often referred to as inventories, can be used for a wide variety of environmental reporting and modeling purposes to characterize conditions in the United States. Yet, users are often challenged to find, retrieve, and interpret these data due to the unique schemes employed for data management, which could result in erroneous estimations or double-counting of emissions. To address these challenges, a system called Standardized Emission and Waste Inventories (StEWI) has been created. The system consists of four python modules that provide rapid access to USEPA inventory data in standard formats and permit filtering and combination of these inventory data. When accessed through StEWI, reported emissions of carbon dioxide to air and ammonia to water are reduced approximately two- and four-fold, respectively, to avoid duplicate reporting. StEWI will greatly facilitate the use of USEPA inventory data in chemical release and exposure modeling and life cycle assessment tools, among other things. To date, StEWI has been used to build the recent USEEIO model and the baseline electricity life cycle inventory database for the Federal LCA Commons.

Plugging the holes—new Canadian and US regulations to reduce upstream methane emissions

Abstract In the USA and Canada where most of global shale oil and gas development has occurred, due to concerns about climate change the national governments have adopted new regulations to further significantly reduce national methane emissions from the upstream oil and gas industry. The 2016 US Environmental Protection Agency emissions standards and 2018 Canadian methane regulations build on decades old oil and gas conservation schemes to further reduce the volume of methane that is released from facility equipment leaks and venting. In Canada, venting methane at new oil and gas well sites is now prohibited. Operators are required to capture and use a much larger volume of natural gas than in the past. A negotiated settlement of the first US emissions reduction enforcement action was reached in April 2018. The facility operator agreed to pay a civil penalty of US $610,000 and spend a minimum of $2 million to install new technology at its facilities to further reduce methane emissions. The creative settlement agreement contains a comprehensive set of conditions to provide for a reduction in upstream industry emissions.

An assessment of important SPECIATE profiles in the EPA emissions modeling platform and current data gaps

The United States (US) Environmental Protection Agency (EPA)'s SPECIATE database contains speciated particulate matter (PM) and volatile organic compound (VOC) emissions profiles. Emissions profiles from anthropogenic combustion, industry, wildfires, and agricultural sources among others are key inputs for creating chemically-resolved emissions inventories for air quality modeling. While the database and its use for air quality modeling are routinely updated and evaluated, this work sets out to systematically prioritize future improvements and communicate speciation data needs to the research community. We first identify the most prominent profiles (PM and VOC) used in the EPA's 2014 emissions modeling platform based on PM mass and VOC mass and reactivity. It is important to note that the on-road profiles were excluded from this analysis since speciation for these profiles is computed internally in the MOVES model. We then investigate these profiles further for quality and to determine whether they were being appropriately matched to source types while also considering regional variability of speciated pollutants. We then applied a quantitative needs assessment ranking system which rates the profile based on age, appropriateness (i.e. is the profile being used appropriately), prevalence in the EPA modeling platform and the quality of the reference. Our analysis shows that the highest ranked profiles (e.g. profile assignments with the highest priority for updates) include PM2.5 profiles for fires (prescribed, agricultural and wild) and VOC profiles for crude oil storage tanks and residential wood combustion of pine wood. Top ranked profiles may indicate either that there are problems with the currently available source testing or that current mappings of profiles to source categories within EPA's modeling platform need improvement. Through this process, we have identified 29 emissions source categories that would benefit from updated mapping. Many of these mapping mismatches are due to lack of emissions testing for appropriate source categories. In addition, we conclude that new source emissions testing would be especially beneficial for residential wood combustion, nonroad gasoline exhaust and nonroad diesel equipment.

Development of enhanced emission factor equations for paved and unpaved roads using artificial neural network

Road dust is a primary source of PM that is having a significant impact on human health and air quality. In order to efficiently develop PM control strategies, it is critical to improving the ability to estimate the emission levels of PM resuspended from paved and unpaved roads. The U.S. Environmental Protection Agency (EPA) has developed emission factor equations to quantify the magnitude of PM for paved and unpaved roads based on multiple linear regression (MLR) models. However, the MLR models are not suitable to capture the complex and non-linear mechanisms of PM emissions, thereby limiting the accuracy of the MLR-based PM prediction models. This paper is to present a method to improve the quality of the existing EPA emission factor equations for paved and unpaved roads by employing an artificial neural network (ANN). The presented method consists of the following steps: data processing, ANN model training, and validation of the presented method through data testing. The data utilized for the case study were retrieved from the database used by the EPA to generate PM10 emission factor equations for the paved and unpaved roads for a fair comparison. The presented method was evaluated by demonstrating its improved performance as shown in the coefficient of determination (R2) and the root mean square error (RMSE) values. The empirical findings of the case study verified that the presented method using the ANN model is capable of improving the quality of the EPA emission factor equations, resulting in higher R2 and lower RMSE values for both paved and unpaved roads. The expected significance of this paper is that the presented method improves the ability to develop more reliable emission factor equations for predictable PM levels that can help agencies establish enhanced PM control strategies.

Evaluation of the carbon dioxide (CO2) emission factor from lime applied in temperate upland soil

Agricultural liming materials are broadly utilized in the world to ameliorate soil acidity. Crushed limestone (CaCO3) and dolomite (MgCO3·CaCO3) are most common liming materials. The CO2 emission coefficient was proposed as 0.12 Mg C per Mg for CaCO3 by the Intergovernmental Panel on Climate Change (IPCC), which indicates that 100% of C in CaCO3 is eventually released to the atmosphere in the form of CO2. However, this assumption appears unlikely based on current knowledge of the very low solubility of CaCO3 and carbonate transport through soil. To develop the direct CO2 emission factor from the C-containing liming materials applied in moderately acidic soil, CaCO3 was applied in a typical temperate upland soil at different levels (0–2 Mg ha−1 yr−1), and the CO2 emission rates were determined using the closed chamber method for two years. The direct CO2 emission factor from CaCO3 was estimated using 13CO2 fluxes from 13C-CaCO3 applied soils. Approximately 0.026 Mg C per Mg of CaCO3 was emitted as CO2 from CaCO3 in cropping lands. This value was much lower than the IPCC default value (0.12 Mg C per Mg of CaCO3). The current CO2 emission coefficient was comparable with the United States Environmental Protection Agency (EPA) emission factor (0.046 Mg C per Mg of CaCO3) from the agricultural field. If the EPA emission factor from the ocean (0.013 Mg C per Mg of CaCO3) is added to the currently developed CO2 emission factor of the inner agricultural field, the total CO2 emission factor from lime may be close to 0.039 Mg C per Mg of CaCO3 in the selected upland soil. Therefore, we propose that the current IPCC guideline value of the CO2 emission factor from lime should be revised as 0.039 Mg C per Mg of CaCO3 for Korean upland soils.

Road-rail intermodal freight transport as a strategy for climate change mitigation

When attempting to reduce atmospheric emissions, a strategy commonly suggested by experts is the replacement of road transport with rail transport. However, in many countries and for many companies worldwide a complete transition to rail transport of freight is not feasible due to either a lack of available railway infrastructure or high investment costs. With that in mind, this paper aims to assess the potential of road-rail intermodal operations as a strategy to reduce atmospheric emissions, and thereby help mitigate climate change worldwide. This was achieved by quantifying and comparing emissions of CO2, CO, CH4, NOx, hydrocarbons and particulate matter in a case-study that considered road-only and intermodal road-rail routes from 17 production facilities to their nearest port, according to International Panel on Climate Change (IPCC) and the United Nations Framework Convention on Climate Change (UNFCCC) policies, as well as Euro V and EPA (United State Environmental Protection Agency) emission standards. The results showed that an intermodal road-rail operations would reduce emissions by up to 77.4%, be up to 43.48% more fuel-efficient and up to 80% cheaper than operating solely with road transport, posing as a viable strategy to enable more companies and countries to mitigate climate change.

Targeting existing power plants: EPA emission reduction with wind and demand response

Electricity generation accounts for 40% of CO2 emissions from fossil fuel combustion in the United States. Section 111 of the Clean Air Act (CAA) allows for greenhouse gas emission regulation by the US Environmental Protection Agency (EPA). In June 2014, EPA issued the Clean Power Plan that proposes regulation of existing power plants via a “best system of emission reduction” or BSER. Reducing carbon dioxide emissions caused by electricity generation is one of the main motivations for increasing wind power and other renewable energy use, and this option is included in the BSER. This paper applies Monte Carlo simulation with a two-stage power flow optimization framework to analyze the potential CO2 emission reduction with 10% and 20% wind penetration using the proposed BSER. The results show that EPA's BSER does achieve significant emission reduction, but an increase in cost of electricity and load curtailment can result if significant wind is installed without other measures. These concerns are eliminated by including recourse to real-time demand response along with EPA's BSER, suggesting that the proposed BSER, implemented alone, could be insufficient for reaching EPA's target CO2 reductions while also safeguarding power system reliability and cost.

A study of the effects of vehicle emissions on the atmosphere of Sultan Qaboos University in Oman

Traffic jams have become a serious matter at Sultan Qaboos University (SQU) in Muscat, Oman due to an increase in student numbers. Therefore, the main objective of this research study is to apply the information gained by running CALPUFF software to model and investigate the concentration dispersion of the three most dominant vehicle emissions carbon monoxide (CO), mononitrogen oxides (NOx), and carbon dioxide (CO2) at SQU. The study was divided into two main parts: a line source study focused on investigating the dispersion of CO, NOx, and CO2 for a street located within the university's boundaries, and a study of the university domain as an area source. The study was based on statistical data collected on April 2, 2014, between 00h00 and 23h00 Local Standard Time (LST). Information related to both surface and upper air quality was obtained and processed into data files which were used to activate CALMET. For selecting vehicle emission factors, a comparison between different studies was conducted. CALPUFF line source case study simulation results showed that CO levels were within the allowable concentrations assigned by the United States' Environmental Protection Agency (EPA) standards. On the other hand, the NOx and CO2 simulated results were higher than the allowable amounts according to the EPA emission standards. Moving to the area source study, results demonstrated that the three pollutants significantly exceeded the allowable standards. The top five maximum concentrations were located near the origin of the study domain for both line and area source measurements. At the times that maximum concentrations were recorded, the wind was blowing from the sea toward the land. As a result, the greatest accumulation of pollutants was located close to the domain of the area of study.

Air quality assessment of benzo(a)pyrene from asphalt plant operation

A study has been carried out to assess the contribution of Polycyclic Aromatic Hydrocarbons (PAHs) from asphalt plant operation, utilising Benzo(a)pyrene (BaP) as a marker for PAHs, to the background air concentration around asphalt plants in the UK. The purpose behind this assessment was to determine whether the use of published BaP emission factors based on the US Environmental Protection Agency (EPA) methodology is appropriate in the context of the UK, especially as the EPA methodology does not give BaP emission factors for all activities. The study also aimed to improve the overall understanding of BaP emissions from asphalt plants in the UK, and determine whether site location and operation is likely to influence the contribution of PAHs to ambient air quality. In order to establish whether the use of US EPA emissions factors is appropriate, the study has compared the BaP emissions measured and calculated emissions rates from two UK sites with those estimated using US EPA emission factors. A dispersion modelling exercise was carried out to show the BaP contribution to ambient air around each site. This study showed that, as the US EPA methodology does not provide factors for all emission sources on asphalt plants, their use may give rise to over- or under-estimations, particularly where sources of BaP are temperature dependent. However, the contribution of both the estimated and measured BaP concentrations to environmental concentration were low, averaging about 0.05 ng m(-3) at the boundary of the sites, which is well below the UK BaP assessment threshold of 0.25 ng m(-3). Therefore, BaP concentrations, and hence PAH concentrations, from similar asphalt plant operations are unlikely to contribute negatively to ambient air quality.

Commercial Bus Emissions and Fuel Use

This paper summarizes the results of emissions testing conducted on six motor coaches with engines between model years 1997 and 2004. Each bus was tested while idling and also while being driven in simulated low-speed urban traffic. The intent of this program was to evaluate the potential effects of idle restriction policies on coach buses, particularly when coaches are forced to circulate in urban traffic to maintain appropriate cabin temperatures if restricted from idling. All tested buses used more fuel and emitted more nitrogen oxides (NOx) when being driven in simulated urban traffic than when idling. Fuel use at least doubled for all tested buses when driven compared with idling. For older coaches, NOx also doubled, whereas for newer coaches NOx emissions increased by 40%. If a coach bus is forced to circulate in traffic to maintain appropriate cabin temperatures, rather than idling while stationary, it will use up to 375 more gallons of fuel and emit up to 22 lb of excess NOx annually for only 1 h/day of circulating. Both fuel use and NOx emissions generally increased for all buses when the air conditioning was on, compared with when it was not, both while idling and while being driven. In this test program, the increase was less during urban driving than while idling, but given the relatively low ambient temperatures during the testing, the results may not be fully reflective of actual summer results in many parts of the country. For both idling and urban driving, the two newest buses (2004 engines) produced significantly less NOx than the four older buses. This finding is consistent with more stringent U.S. Environmental Protection Agency emissions standards for newer engines.

GETTING A GRIP ON WASTED ENERGY

In a single year, the U.S. chemical industry burns up about 6 quadrillion Btu of energy. That works out to 7% of all domestic energy used and 25% of the energy used in all manufacturing, says a new report by the Department of Energy. Making the chemical sector more energy efficient and cutting its $29 billion annual energy bill is the goal of a DOE program under which the report was prepared. Energy & Environmental Profile of the U.S. Chemical Industry was developed by the DOE Office of Industrial Technologies (OIT), which will use the report to guide decisionmakers in better determining which energy-reducing projects should be funded through DOE's large grant-making program. Lou Sousa, OITs director of communication, says the data and report will serve as a benchmark for energy use in the chemical industry. The report also provides pollution emissions data based on several Environmental Protection Agency emissions ...

Combustion toxics: Available data and additional needs

With the continuing expansion of air pollution regulations there is an increasing awareness of the potential need to assess the emissions and impact of trace compounds from combustion sources in refineries and chemical plants. It has been found that these trace compounds may be emitted as the result of incomplete fuel combustion, formation of new compounds during combustion, or the presence of inorganics (e.g. metals) in the fuel. Emission factors based on field data from these sources have recently been published by both the US Environmental Protection Agency (EPA) and the American Petroleum Institute (API). The emission factors indicate that a large number of trace compounds may be emitted from combustion sources including volatiles, semi-volatiles, PAHs, metals, and dioxins/furans. Some of these trace compounds have been classified as hazardous or toxic. A review of the EPA and API published data sets indicates that, while there is some overlap, many gaps exist in specific source and emission types. Where gaps exist, there is a lack of confirmation for the reported emission factor. Comparison of the EPA and API emission factors for gas and fuel oil fired boilers, however, indicates reasonable agreement for several metals and some PAHs where the data overlap. EPA, however, has sampled for many more metals than API and several EPA factors for PAHs are significantly higher than reported by API. Additional tests may be warranted where there is insufficient overlap. Much additional work needs to be done to provide reliable factors which can be used to estimate trace toxic emissions from combustion. Many gaps and inconsistencies exist in the emission factors database and changes to existing factors are expected as the database is expanded.

Characteristics of Administrative Decisions About Regulatory Form

Attempts to reform regulation by introducing economic incentives raise questions about how admimstrative agencies choose regulatory forms. The Environmental Protection Agency's emissions trading program provides one of the few opportunities to explore such questions. Analysis of data from interviews with individuals who participated in developing the program reveals that professional background, support for key environmentalist values, and political ideology played varying roles in shaping policymakers' decisions about air pollution regulatory form. One possible argument that links these factors is that professional paradigms and social movements provide the conceptual schema for ideologically based decisions about regulatory form. The potential role of ideology in administrative decisions about regulatory form points to further avenues for research on administrative policymaking.