5 research outputs found
Characterizing Fugitive Methane Emissions in the Barnett Shale Area Using a Mobile Laboratory
Atmospheric
methane (CH<sub>4</sub>) was measured using a mobile
laboratory to quantify fugitive CH<sub>4</sub> emissions from Oil
and Natural Gas (ONG) operations in the Barnett Shale area. During
this Barnett Coordinated Campaign we sampled more than 152 facilities,
including well pads, compressor stations, gas processing plants, and
landfills. Emission rates from several ONG facilities and landfills
were estimated using an Inverse Gaussian Dispersion Model and the
Environmental Protection Agency (EPA) Model AERMOD. Model results
show that well pads emissions rates had a fat-tailed distribution,
with the emissions linearly correlated with gas production. Using
this correlation, we estimated a total well pad emission rate of 1.5
Ć 10<sup>5</sup> kg/h in the Barnett Shale area. It was found
that CH<sub>4</sub> emissions from compressor stations and gas processing
plants were substantially higher, with some āsuper emittersā
having emission rates up to 3447 kg/h, more then 36,000-fold higher
than reported by the Environmental Protection Agency (EPA) Greenhouse
Gas Reporting Program (GHGRP). Landfills are also a significant source
of CH<sub>4</sub> in the Barnett Shale area, and they should be accounted
for in the regional budget of CH<sub>4</sub>
Toward a Functional Definition of Methane Super-Emitters: Application to Natural Gas Production Sites
Emissions from natural gas production sites are characterized by
skewed distributions, where a small percentage of sitesīøcommonly
labeled super-emittersīøaccount for a majority of emissions.
A better characterization of super-emitters is needed to operationalize
ways to identify them and reduce emissions. We designed a conceptual
framework that <i>functionally</i> defines superemitting
sites as those with the highest proportional loss rates (methane emitted
relative to methane produced). Using this concept, we estimated total
methane emissions from natural gas production sites in the Barnett
Shale; functionally superemitting sites accounted for roughly three-fourths
of total emissions. We discuss the potential to reduce emissions from
these sites, under the assumption that sites with high proportional
loss rates have excess emissions resulting from abnormal or otherwise
avoidable operating conditions, such as malfunctioning equipment.
Because the population of functionally superemitting sites is not
expected to be static over time, continuous monitoring will likely
be necessary to identify them and improve their operation. This work
suggests that achieving and maintaining uniformly low emissions across
the entire population of production sites will require mitigation
steps at a large fraction of sites
Do We Understand What the Mercury Speciation Instruments Are Actually Measuring? Results of RAMIX
From August 22 to September 16, 2012, atmospheric mercury
(Hg)
was measured from a common manifold in the field during the Reno Atmospheric
Mercury Intercomparison eXperiment. Data were collected using Tekran
systems, laser induced fluorescence, and evolving new methods. The
latter included the University of Washington-Detector for Oxidized
Mercury, the University of Houston Mercury instrument, and a filter-based
system under development by the University of Nevada-Reno. Good transmission
of total Hg was found for the manifold. However, despite application
of standard protocols and rigorous quality control, systematic differences
in operationally defined forms of Hg were measured by the sampling
systems. Concentrations of reactive Hg (RM) measured with new methods
were at times 2-to-3-fold higher than that measured by Tekran system.
The low RM recovery by the latter can be attributed to lack of collection
as the system is currently configured. Concentrations measured by
all instruments were influenced by their sampling location in-the-manifold
and the instrument analytical configuration. On the basis of collective
assessment of the data, we hypothesize that reactions forming RM were
occurring in the manifold. Results provide a new framework for improved
understanding of the atmospheric chemistry of Hg
Constructing a Spatially Resolved Methane Emission Inventory for the Barnett Shale Region
Methane emissions from the oil and gas industry (O&G) and other
sources in the Barnett Shale region were estimated by constructing
a spatially resolved emission inventory. Eighteen source categories
were estimated using multiple data sets, including new empirical measurements
at regional O&G sites and a national study of gathering and processing
facilities. Spatially referenced activity data were compiled from
federal and state databases and combined with O&G facility emission
factors calculated using Monte Carlo simulations that account for
high emission sites representing the very upper portion, or fat-tail,
in the observed emissions distributions. Total methane emissions in
the 25-county Barnett Shale region in October 2013 were estimated
to be 72,300 (63,400ā82,400) kg CH<sub>4</sub> h<sup>ā1</sup>. O&G emissions were estimated to be 46,200 (40,000ā54,100)
kg CH<sub>4</sub> h<sup>ā1</sup> with 19% of emissions from
fat-tail sites representing less than 2% of sites. Our estimate of
O&G emissions in the Barnett Shale region was higher than alternative
inventories based on the United States Environmental Protection Agency
(EPA) Greenhouse Gas Inventory, EPA Greenhouse Gas Reporting Program,
and Emissions Database for Global Atmospheric Research by factors
of 1.5, 2.7, and 4.3, respectively. Gathering compressor stations,
which accounted for 40% of O&G emissions in our inventory, had
the largest difference from emission estimates based on EPA data sources.
Our inventoryās higher O&G emission estimate was due primarily
to its more comprehensive activity factors and inclusion of emissions
from fat-tail sites
Constructing a Spatially Resolved Methane Emission Inventory for the Barnett Shale Region
Methane emissions from the oil and gas industry (O&G) and other
sources in the Barnett Shale region were estimated by constructing
a spatially resolved emission inventory. Eighteen source categories
were estimated using multiple data sets, including new empirical measurements
at regional O&G sites and a national study of gathering and processing
facilities. Spatially referenced activity data were compiled from
federal and state databases and combined with O&G facility emission
factors calculated using Monte Carlo simulations that account for
high emission sites representing the very upper portion, or fat-tail,
in the observed emissions distributions. Total methane emissions in
the 25-county Barnett Shale region in October 2013 were estimated
to be 72,300 (63,400ā82,400) kg CH<sub>4</sub> h<sup>ā1</sup>. O&G emissions were estimated to be 46,200 (40,000ā54,100)
kg CH<sub>4</sub> h<sup>ā1</sup> with 19% of emissions from
fat-tail sites representing less than 2% of sites. Our estimate of
O&G emissions in the Barnett Shale region was higher than alternative
inventories based on the United States Environmental Protection Agency
(EPA) Greenhouse Gas Inventory, EPA Greenhouse Gas Reporting Program,
and Emissions Database for Global Atmospheric Research by factors
of 1.5, 2.7, and 4.3, respectively. Gathering compressor stations,
which accounted for 40% of O&G emissions in our inventory, had
the largest difference from emission estimates based on EPA data sources.
Our inventoryās higher O&G emission estimate was due primarily
to its more comprehensive activity factors and inclusion of emissions
from fat-tail sites