regional methane emissions estimates in northern

Regional methane emissions estimates in northern

Pennsylvania gas fields using atmospheric inversions

Thomas Lauvaux, Zach Barkley

Kenneth Davis, Natasha Miles, Scott Richardson, Douglas Martins

Department of Meteorology, Pennsylvania State University

Yanni Cao, Eun-Kyeong Kim, Guido Cervone, Alan Taylor

Department of Geography, Pennsylvania State University

Colm Sweeney, Anna Karion, Kathryn McKain

ESRL/NOAA GMD, CIRES, Boulder

Tom Murphy

Marcellus Center for Outreach and Research, Pennsylvania State University

Penn State Extension webinar series, July 20th, 2017

Regional methane emissions estimates in northern


Project sponsored by the Department of Energy

National Energy Technology Laboratory

TA [2] Continuous, regional methane emissions estimates in northern


Natural gas production in the United States from the major shale gas formations

since 2008 (EIA data)



0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2009 2010 2011 2012 2013Na

tura

l G

as

Le

ak

Ra

te

(%)

Year

Production Processing

Bottom up estimates for the US

suggests that emissions from

production and processing of natural

gas account for less than 0.8% of total

production.

0.8%

• The NOAA mass balance estimates

from 9 different basins suggest that

the EPA estimate is too low.

• The smaller producing fields are

driving the average leak rate up.0

5

10

Na

tura

l G

as

Le

ak

Ra

te (

%) NOAA Mass Balance estimates

Karion et al. (2013;2015)

Petron et al. (2012;2014)

Peischl et al. (2015; 2016)

Smith et al. (2016)



Project goals and objectives

Overall objective: quantify fugitive emissions of CH4 from the

Marcellus gas production region of north-central Pennsylvania over a

period of two years (2015-2017)

1. Generate maps of CH4 emissions over the northeastern region of

the Marcellus shale formation

2. Break down of the relative contribution of various regional sources

(animal agriculture, wetlands, landfills, gas production, other

regional sources identified)

3. Compare to emissions-factor, activity-data based “inventory”

regional CH4 emissions estimates, evaluating both the accuracy of

the inventory methods, and our ability to detect changes.



Two new elements in this approach:

1. First long-term deployment (i.e. 2 years) of several

instruments to measure continuously the CH4 emissions

from the natural gas production activities (only short

aircraft or automobile campaign so far)

2. Use of 13CH4 to identify the contributions from

biogenic sources and thermogenic sources (no

calibration protocol to measure 13CH4 at high accuracy)



Objectives:

- Regional attribution of spatial and temporal variability

- Separation of source contributions using continuous 13CH4/CH4 measurements

CH4 CH4CH4

Upwind

Downwind

Upwind



Inventory of CH4

emissions

(Natural Gas Prod.)

Other sources of CH4

(Farming, wetlands,

industrial)

Atmospheric model

(1km resolution)

Atmospheric concentrations

of CH4

(modeled)


of CH4

(observations)

Optimization

(inversion system)

- Collection of inventory data to construct the a priori CH4 emissions

1. US EPA gridded product from Maasakkers et al., (2016)

2. Updated production rates for conv. & unconv. wells for selected months

3. Compressor stations as point sources (based on air permits)

Collection of activity data for the preparation of a bottom-up CH4 emission

map, including biogenic and thermogenic sources

from Barkley et al., under review



Animal Agriculture Coal mines/beds Landfill / Industry

Unconventional Production Conventional Production Distribution

from Barkley et al., under review



Map of the CH4 emissions inventory for the extended Pennsylvania study domain in

mol.km-2.hour-1 and our domain of interest (red box)

Deployment of calibrated CRDS instruments at the four identified tower

locations

Network design of the four instrumented towers:

• Two towers instrumented to measure the background mixing ratios (independent of wind

direction)

Background: Towers N and S

• Two towers downwind of the production wells, nearby the area of interest (maximum amplitude)

Downwind: Towers C and E

Installation of instruments

- Negotiation of lease agreement for the selected towers

- Installation of sheds for the duration of the deployment (no space for instruments indoor)

- Tubing installed to the top of the towers,

- Deployment before the aircraft campaign


locations

Definitive tower locations of the 4 towers called North (N),

East (E), South (S), and Central (C). Unconventional wells

are plotted in the background.

Coordinates, elevations, and sampling heights of the 4

towersPhoto of temporary shed (upper) and tube

inlet at tower N, 46m AGL (lower)

Field sampling flow schematic with automatic calibration system using

four gas-phase standards of unique isotopic 13CH4 values () and CH4

(X) mixing ratios at ambient (amb) and heavy and high (HI) and low

(Lo1, Lo2) mixing ratios, respectively.

Calibration of the four CRDS CH4/13CH4 instruments:

- Four standards for 13Ch4 measurements with various levels of enrichment/depletion and concentrations

- Dry air (use of Nafion) with automated valve (flow path selector) between calibration standards and

outdoor inlet tube

from Miles et al., in prep.


locations

Comparison between continuous CRDS mixing ratio measurements and flask samples for CO2 (in ppm),

CH4 (in ppb), and 13CH4 (in permil)


locations

from Miles et al., in prep.

CH4 mixing ratio measurements over 2015-2017 from the four CRDS CH4/13CH4 instruments (in ppb)


locations

CH4 mixing ratio enhancements over 2015-2017 from the four CRDS CH4/13CH4 instruments (in ppb)


locations

Aircraft campaign to quantify CH4 emissions over the entire northern

Marcellus region

NOAA Twin Otter on the tarmac of the Williamsport airport

List of flights, conditions, and durations for the 12 flights of the

aircraft campaign

Show flight pathsFlight patterns for the 12 flights of the aircraft campaign

with the mean wind direction during the flight (red

arrows). The flight on 14 May shows highly variable

winds across the domain.Colm Sweeney, NOAA

Anna Karion, NIST


Marcellus region

Example of flight measurements for May 24th, 2015 with vertical profiles of meteorological and greenhouse gas

measurements (upper left), wind direction and spedd (upper right), methane (lower left), and ethane (lower right)


Marcellus region

Inventory of CH4

emissions

(Natural Gas Prod.)

Other sources of CH4

(Farming, wetlands,

industrial)

Atmospheric model

(1km resolution)


of CH4

(modeled)


of CH4

(observations)

Optimization

(inversion system)

Quantification of emissions: Data Assimilation System

WRF-CH4 atmospheric modeling system:

- WRF-Chem, modified for CH4, v3.5.1,

- Physics configuration based on previous studies (Lauvaux et al., 2012; Deng et al., in prep.)

- 3 grids in nested mode (one-way): 9km/3km/1km resolution,

- Emission fields from inventory data coupled to the 3km and 1km grids,

- 3 modes developed for the project:

- Forecast: 9km/3km resolutions,12-hour assimilation, 24-hour forecast.

- Historical: initial and boundary conditions from North American Regional Reanalysis (NARR)

- Data assimilation: Four Dimensional Data Assimilation (FDDA) mode with nudging

of WMO surface stations and radiosondes

Evaluation –Aircraft campaign of May 2015

- Simulations of flight days at 1km resolution in the three different modes

Atmospheric modeling system: WRF-CH4

Atmospheric CH4 enhancement from the various

sectors of emissions over PA (in ppm)

Atmospheric modeling system: WRF-CH4

Modeling domain to simulate the

atmospheric conditions during the

deployment period (2015-2017) using the

Weather Research and Forecasting model

NG Transmission/Distribution

Unconventional Production/Gathering

May 24th 2015 Total

Enhancement

Modeled Methane Enhancement

(in ppm)

Conventional Wells

Coal Mines

Enteric Fermentation

Landfills and Other

May 29th 2015: A good day.

Wind

Speed

4.8 m/s

Atmospheric CH4 enhancement (in ppm)

Enhancem

ent

(ppm

)

A B C D

A

B C

D

Observed CH4 Enhancement

(ppm)

Aircraft emissions estimate on May 29th 2015

Observed CH4 Enhancement measured during the flight (in ppm)

Enhancem

ent

(ppm

)

A

B C

D

Non-NG CH4 Enhancement (ppm)

A B C D


Observed and modeled Non-Natural Gas CH4 enhancement for the May 29th flight (in ppm)

Enh

an

cem

en

t (p

pm

)

A

B C

D

Natural Gas CH4 Enhancement

(ppm)

A B C D


Observed CH4 enhancement for the May 29th flight (in ppm)

Enhancem

ent

(pp

m)

B C

DA


(ppm)

Emission Rate = 0.13%

A B C D


Observed and modeled Natural Gas CH4 Enhancement for the May 29th flight (in ppm)

Enhancem

ent

(ppm

)

A

B C

D


(ppm)

Emission Rate = 0.26%

A B C D


Observed and optimized Natural Gas CH4 enhancement for the May 29th flight (in ppm)

CASE STUDY: MAY 24th, 2015

The Importance of a Good Methane Inventory

31


Observed CH4 enhancement for the May 24th flight at 20z (in ppm)

Importance of the inventory with the projected atmospheric enhancement from

Coal mines/beds explaining the observed spatial gradients

Coal Plume Final Result: All Emissions

UNG Emission Rate=0.29%


Best-guess upstream emission estimates

Optimal mean leakage rate based on 10 flights in May 2015: 0.39% of production

Marcellus Mass Balance: valid over 4 days out of 10

May 22nd, 2015

May 23nd, 2015 May 29th, 2015

May 29th, 2015

Best-guess upstream emission estimates

Optimal mean leakage rate based on 10 flights in May 2015: 0.39% of production

TOWER INVERSION: June to December, 2015

Time-dependent flux estimate for NE PA

Tower-based inversion for June-December 2015

Inversion

window

Diagram of the different flux sub-regions used

in the inversion. Towers (green pins) and wells

(pink dots) are plotted overtop

Map of the percent change in the posterior flux

compared to the prior flux using tower

observations from Oct-Dec 2015



Conclusions

Successful calibration of 13CH4 continuous CRDS sensors (about 0.2 permil)

Leakage rate equivalent to 0.4% of production (wells and gathering compressors)

Site-level estimate (about 15 wells in PA), Omara et al. (2016): 0.64% of production (wells only)

EPA-derived estimate for NE PA (Maasakkers et al., 2016): 0.13% of production

Aircraft mass-balance (1 flight only) for NE PA (Peischl et al., 2013): 0.3% of production

Initial tower-based inversion results suggest lower leakage rates over June to December 2015

Future work

ACT-America study on unconventional and coal mines in SW PA and WV ongoing

Perform tower-based inversion over June 2015 to December 2016



Publications and references

Barkley, Z. R., Lauvaux, T., Davis, K. J., Deng, A., Cao, Y., Sweeney, C., Martins, D., Miles, N. L., Richardson, S. J.,

Murphy, T., Cervone, G., Karion, A., Schwietzke, S., Smith, M., Kort, E. A., and Maasakkers, J. D.: Quantifying methane

emissions from natural gas production in northeastern Pennsylvania, Atmos. Chem. Phys. Discuss.,

https://doi.org/10.5194/acp-2017-200, in review, 2017.

Cao, Y., Cervone, G., Barkely, Z., Lauvaux, T., Deng, A., and Taylor, A.: Influence of Geographic Coordinate System on

Weather Simulations of Atmospheric Emissions, Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2016-253, in

review, 2016.

Miles, N., D. K. Martins, S. J. Richardson, C. Rella, C. Arata, T. Lauvaux, K. J. Davis, Z. Barkley, K. McKain, C.

Sweeney: Calibration and Field Testing of Cavity Ring-Down Laser Spectrometers Measuring Methane Mole Fraction

and Isotopic Ratio Deployed on Towers in the Marcellus Shale Region, in prep.

Data from towers

2015-2017 data archive for CH4 and 13CH4 continuous tower measurements in northeastern PA:

http://www.datacommons.psu.edu/commonswizard/MetadataDisplay.aspx?Dataset=6134

Data from the 2015 aircraft campaign

Aircraft Campaign over the Northeastern Marcellus Shale (May 2015):

https://doi.org/10.15138/G35K54

http://www.datacommons.psu.edu/commonswizard/MetadataDisplay.aspx?Dataset=6134

https://doi.org/10.15138/G35K54



Publications in preparation

Barkley, Z. R., et al.: Regional inversion of methane emissions from natural gas production in northeastern Pennsylvania,

in prep.

Barkley, Z. R., et al.: Methane emissions from coal mines and natural gas production in southwestern PA, in prep.

Project Website

http://sites.psu.edu/marcellus/

http://sites.psu.edu/marcellus/

regional methane emissions estimates in northern

Documents