Air pollutant emissions from the development, production, and processing of Marcellus Shale natural gas

Figures & data

Figure 1. Flowchart showing inventory development.

Table 1. Activity data for the Marcellus region

Activity	State	2009	2020
		Actual Data	Low	High	Reference
Number of new Marcellus wells drilled (per year)	Pennsylvania	710 (PADEP, 2011)	1500	3600	Considine (2010), Considine et al. (2011), The Nature Conservancy (2010)
	West Virginia	411 (WVGES, 2011)	273	883	Considine (2010), NETL (2010)
	New York	n/a	0	500	Considine (2010), Weinstein and Clower (2009), Lillpopp and Lindell (2011)
Cumulative number of Marcellus wells	Overall	2050 (PADEP, 2011; WVGES, 2011)	29000	49000	Considine (2010), NETL (2010), The Nature Conservancy (2011)
Marcellus gas production, billion cubic feet per day	Pennsylvania	8.6 (PADEP, 2011)	93.5	382	Considine (2010), Considine et al. (2009, 2010, 2011)
	West Virginia	5.2	17.3	382	Considine (2010), NETL (2010)
	New York	0	0	51	Considine et al. (2010)
	Overall	13.8	101	815

Table 2. List of sources and their corresponding scaling activity parameters

	Source	Pollutant			Activity Scaling Parameter
Category		NOx	PM2.5	VOCs
Well development	Drill rigs	Y	Y	Y	Number of wells
	Frac pumps	Y	Y	Y	Number of wells
	Truck Traffic	Y	Y	Y	Number of wells
	Well completion	N	N	Y	Number of Wells
Gas production	Production fugitives	N	N	Y	Cumulative number of wells
	Pneumatics	N	N	Y	Cumulative number of wells
	Wellhead compressors	Y	Y	Y	Cumulative number of wells
	Blowdown venting	N	N	Y	Cumulative number of wells
	Heaters	Y	Y	Y	Cumulative number of wells
	Condensate tanks	N	N	Y	Condensate production
Midstream	Dehydrators	Y	Y	Y	Volume of gas production
	Compressor stations	Y	Y	Y	Volume of gas production
	Fugitives: Transmission Processing	NN	NN	YY	Volume of gas production Volume of gas production

Table 3. Emission factors for key sources (similar data for minor sources is in Table S10 in Supplementary Materials)

Source	Pollutant	Mean	Range(Min–Max)	Comments
Drill rigs (g bhp^−1 hr^−1)	NOx	5.8	2.5–10	Heavy-duty diesel engines of similar rating (500–1500 hp) (locomotives and generators)^a
	PM2.5	0.35	0.07–1
	VOCs	0.6	0.25–1.6
Frac pumps (g bhp^−1 hr^−1)	NOx	5.7	2.5–10	Heavy-duty diesel engines of similar rating (1000–1500 hp) (locomotives and generators)^b
	PM2.5	0.4	0.09–0.9
	VOCs	0.67	0.3–1.6
Trucks (g mile^−1)	NOx	50	9–90	Heavy-duty truck emission factors from literature^c
	PM2.5	0.32	7 × 10^−4 to 1.3
	VOCs	1.7	0.2–10
Compressor stations (g bhp^−1 hr^−1)	NOx	1.5	0.5–2.0	Data from PADEP^d
	PM2.5	0.014	2.5 × 10^−4 to 4 × 10^−2
	VOCs	0.46	0.1–1.8
Condensate tanks (lb bbl^−1)	NOx	n/a	n/a	Data from Barnett Shale and CENRAP basins used as surrogate (Armendariz, 2009; Bar-Ilan et al., 2008; Hendler et al., 2009)
	PM2.5	n/a	n/a
	VOCs	29	0.7–215
Notes: ^aEPA's AP-42, Shah et al. (2006), Chen et al. (2003). ^b Shah et al, (2006), Chen et al. (2003), Sawant et al. (2007), Comer et al. (2010). ^cFHWA (2011), Ban-Weiss et al. (2008), Prucz et al. (2001), Zhu et al. (2011), Shah et al. (2006), Johnson et al. (2009), Mazzoleni et al. (2007), Clagget and Houk (2008), Choi and Frey (2010). ^dPersonal communication with Naishadh Bhatt, [e-mail].

Table 4. Values for input parameters for major sources

Source	Parameter	Range(Min–Max)	Mean	Comments
Drill rig	Horsepower (hp)	2000–7000	4260	Personal communication with PADEP (Chris Tersine, NYDEC (Leon Sedefian), and EQT Corporation (Andrew Place)^a
	Load factor	0.25–0.9	0.57	Texas drill rigs used as surrogate (Baker and Pring, 2009)
	Engine on-time	0.2–1	0.5	CENRAP values as surrogate (Bar-Ilan et al., 2008)
	Drilling time (days)	14–35	26	PADEP (Chris Tersine), NYDEC (Leon Sedefian), and WVGES (Megan Murphy)^b
	Control factorsNOx PM2.5 VOCs	0.1–0.96 0.6–0.97 0.6–0.97	0.44 0.81 0.81	Ignition timing retard and selective catalytic reduction for NOx, diesel particulate filters for PM, diesel oxidation catalysts for VOCs (USEPA Tier 4 standards, 2004)
	Cumulative % fleet turnover	50–100	76	USEPA Tier 4 (2004), Chesapeake Energy Corporation^c
Fracing	Number of stages2009 2020	4–35 10–35	19 25	Chesapeake Energy Corporation,^d EQT Corporation (Andrew Place)
	Horsepower/stage	35000–45000	40000	Chesapeake Energy Corporation
	Emission control factorsNOx PM2.5 VOCs	0.1–0.96 0.6–0.97 0.6–0.97	0.44 0.81 0.81	Same controls as drill rigs
	Cumulative % fleet turnover	50–100	76	NONROAD scrappage curve
Trucks	Truck trips/wellDevelopmentWastewater	295–1215 200–1125	661 460	Jiang et al. (2011).
	Distance per trip (miles) Distribution center to well (development) Well to wastewater disposal facility	0–20 3–280	9.9 119	Jiang et al. (2011), US National Park Service (2009)
	Emission control factors NOx PM2.5 VOCs	0.7–0.95 0.6–0.99 0.3–0.99	0.85 0.8 0.8	NOx adsorber and SCRs for NOx, DPF for PM, and DOC for VOCs (EPA Clean Diesel Rule)
Completion	Emission factors (MCF/well)	(18–24) × 10^3	3700	Bar-Ilan et al. (2008), Armendariz (2009); CENRAP and Barnett Shale data as surrogate
	Mole Fraction of VOCs in gasDry gasWet gas	5.9 × 10^−3 to 0.064 0.17–0.33	0.034 0.25	Chesapeake Energy Corporation
	Control factors (VOCs)	0.7–0.95	0.84	Green completion (Bar-Ilan et al., 2007)
Compressor stations	hp/BCF/day	125–145	135	PADEP, Considine (2010)
	Load factor	0.4–0.8	0.6	Data from DNREC (Robert Clausen), Burklin and Heaney (2005)
	Emission control factorsNOx VOCs	0.15–0.95 0.3–0.95	0.5 0.6	Selective and nonselective catalytic reduction
Condensate	Control factors (VOCs)	0.6–0.97	0.73	Flaring, vapor recovery units (Bar-Ilan et al., 2007)
Notes: ^a,b [e-mail]; [e-mail]; [e-mail]. ^c http://www.chk.com/Affiliates/Chesapeake-Oilfield-Services/Documents/COO_Annual_Report.pdf. ^dE-mail from Grover R. Campbell, Manager Regulatory Affairs, Air Regulations, Chesapeake Energy Corporation, to Michael E. Hopkins, Assistant Chief, Permitting Ohio EPA (May 16, 2011, 11:31 a.m. EST).

Figure 2. (a) Map of the Marcellus region (USGS, 2009) and (b) subregion covered by the new inventory.

Table 5. Process-level emission estimates, means (95% confidence intervals), for major sources

Source	Pollutant
	NOx		PM2.5		VOCs
	2009	2020	2009	2020	2009	2020
Drill rigs (tons/well drilled)	4.4 (0.8–11.5)	2.9 (0.5–8.1)	0.3 (0.03–1)	0.1 (0.01–0.4)	0.5 (0.1–1.8)	0.1 (0.02–0.5)
Frac pumps (tons/well drilled)	2.2 (0.7–4.3)	1.8 (0.6–3.4)	0.16 (0.03–0.4)	0.1 (0.01–0.3)	0.25 (0.07–0.7)	0.14 (0.03–0.5)
Trucks (tons/well drilled)	6.9 (1.4–20)	1.5 (0.2–4.5)	0.07 (4 × 10^−4 to 0.3)	0.02 (2 × 10^−4 to 0.09)	0.4 (0.02–2.2)	0.2 (0.01–1.2)
Completion (tons/well drilled)
Dry wellWet well	n/an/a	n/an/a	n/an/a	n/an/a	3.8 (2 × 10^−3 to 29) 21 (0.09–145)	1.01 (5 × 10^−4 to 8.3) 5.5 (0.02–37.5)
Pneumatics (tons/producing well)
Dry gasWet gas	n/an/a	n/an/a	n/an/a	n/an/a	0.5 (0.08–0.8) 3.3 (2.4–4.4)	0.1 (0.02–0.2) 0.8 (0.5–1)
Compressor stations (tons/BCF)	3.3 (1.0–5.2)	1.5 (0.3–3.0)	0.3 (4 × 10^−4 to 0.1)	0.3 (4 × 10^−4 to 0.1)	1.0 (0.3–3.0)	0.4 (0.06–1.0)
Note: Numbers presented for 2020 are for the baseline controls scenario.

Figure 3. Estimated cumulative distributions of emissions for drilling one well: (a) NO_x, (b) PM_2.5, and (c) VOCs. The 2020 distributions correspond to the base scenario. The estimates made by (NYDEC, 2011) are shown for reference.

Figure 4. Cumulative distribution functions for well development emissions of (a) NO_x and (b) VOCs. The vertical lines labeled “HS” refers to the Haynesville Shale inventory developed by Grant et al. (2009).

Table 6. Unit activity emissions: means (95% CIs)

Activity	Pollutant
	NOx		PM2.5		VOCs
	2009	2020	2009	2020	2009	2020
	Development (tons/well drilled)
Dry wellWet well	12.8 (5.1–28.3) 12.8 (5.1–28.3)	7.2 (2.6–16) 7.2 (2.6–16)	0.5 (0.1–1.5) 0.5 (0.1–1.5)	0.2 (0.06–0.5) 0.2 (0.06–0.5)	5.0 (0.3–30) 22 (0.4–145)	1.3 (0.2–5.4) 5.6 (10^−3 to 36)
	Production (tons/producing well)
Dry wel	1.2 (0.2–2.5)	0.6 (0.1–1.0)	0.01 (6 × 10^−5 to 5 × 10^−2)	0.01 (6 × 10^−5 to 5 × 10^−2)	0.9 (0.3–1.9)	0.2 (0.04–0.6)
Wet well	1.2 (0.2–2.5)	0.6 (0.1–1.0)	0.01 (6 × 10^−5 to 5 × 10^−2)	0.01 (6 × 10^−5 to 5 × 10^−2)	4.0 (2.6–6)	1.0 (0.6–1.5)
Midstream (tons/BCF)	3.3 (1.0–5.2)	1.5 (0.3–3)	0.3 (4 × 10^−4 to 0.1)	0.3 (4 × 10^−4 to 0.1)	8.1 (2.6–14)	2.2 (0.7–4.5)

Figure 5. Source-resolved Marcellus emissions for (a) NO_x, (b) PM_2.5, and (c) VOCs in 2009 and 2020 (base scenario). The results are mean estimates. Other sources of VOCs include drilling, fracing truck traffic, and blowdown venting.

Figure 6. Source-resolved emissions of (a) NO_x, (b) PM_2.5, and (c) VOCs for the Marcellus region (Figure 1b). The 2020 emissions correspond to the average of the baseline controls scenario. The open black squares denote the 95% confidence intervals on the estimated Marcellus emissions. The cumulative distributions of emissions are plotted in Figure S19. VOCs correspond to anthropogenic VOC emissions.

Figure 7. Comparison of different control scenarios for 2020 Marcellus emissions: (a) total NO_x emissions, (b) contribution of Marcellus to regional NO_x emissions, (c) total VOC emissions, and (d) contribution of Marcellus to regional VOC emissions.

Table 7. Estimates of 2020 Marcellus emissions for three control scenarios

	Pollutant
Control Scenario	NOx	VOCs
Pre-2009	251 (122–504) 21% (11–35%)	345 (146–999) 34% (19–62%)
Baseline	129 (56–210) 12% (6–18%)	100 (45–243) 14% (7–28%)
Tight	51 (16–120) 5% (1.6–11%)	41 (20–80) 6% (3–11%)
Notes: The first line of data denotes absolute Marcellus-related emissions in tons per day: mean (95% CI). The second line denotes contributions to percent contribution to regional anthropogenic emissions: mean (95% CI).

Table 8. Correlation coefficients (R ²) between total emissions, key sources, and input parameters for 2020 baseline case

Pollutant	Source	Correlation of Source Contribution with Total Emissions	Key Uncertain Parameter	Correlation of Parameter with Source Emissions
NOx	Drill rigs	0.61	Engine on-time	0.5
	Trucks	0.75	Trip VMT	0.5
VOC	Completion	0.73	Emission factor (volume vented/event)	0.9

Considine. 2010. The economic impacts of the Marcellus Shale: Implications for New York, Pennsylvania, and West Virginia; a report to the American Petroleum Institute. http://www.api.org~/media/Files/Policy/Exploration/API-Economic-Impacts Marcellus-Shale.pdf (http://www.api.org~/media/Files/Policy/Exploration/API-Economic-Impacts Marcellus-Shale.pdf) (Accessed: 4 February 2011 ).

 Google Scholar

Considine, T.J., R.W. Watson, and S. Blumsack. 2011. The Pennsylvania Marcellus natural gas industry: Status, economic impacts and future potential http://marcelluscoalition.org/wp-conent/uploads/2011/07/Final-2011-PA-Marcellus-Economic-Impacts.pdf (http://marcelluscoalition.org/wp-conent/uploads/2011/07/Final-2011-PA-Marcellus-Economic-Impacts.pdf) (Accessed: 4 February 2011 ).

 Google Scholar

Zhang , K.M. , Wexler , A.S. , Niemeier , D.A. , Zhu , Y.F. , Hinds , W.C. and Sioutas , C. 2005 . Evolution of particle number distributions near roadways. Part III: Traffic analysis and on-road size resolved particulate emission factors . Atmos. Environ , 39 : 4155 – 4166 . doi: 10.1016/j.atmosenv.2005.04.003

 Web of Science ®Google Scholar

Lillpopp, R.M., and S.A. Lindell. 2011. Drilling for jobs: What the Marcellus Shale could mean for New York http://www.ppinys.org/reports/2011/Drilling-for-jobs-what-marcellus-shale-could-mean-for-NY.pdf (http://www.ppinys.org/reports/2011/Drilling-for-jobs-what-marcellus-shale-could-mean-for-NY.pdf) (Accessed: 24 January 2012 ).

 Google Scholar

Considine, T.J., R. Watson, and S. Blumsack. May 24, 2010. The economic aspects of the Pennsylvania Marcellus natural gas play: An update http://marcelluscoalition.org/wp-content/uploads/2010/05/PA-Marcellus-Updated-Economic-Impacts-5.24.10.3.pdf (http://marcelluscoalition.org/wp-content/uploads/2010/05/PA-Marcellus-Updated-Economic-Impacts-5.24.10.3.pdf) (Accessed: 4 February 2011 ).

 Google Scholar

Armendariz, A. 2009. Emissions from natural gas production in the Barnett Shale area and opportunities for cost-effective improvements http://www.edf.org/documents/9235_Barnett_Shale_Report.pdf (http://www.edf.org/documents/9235_Barnett_Shale_Report.pdf) (Accessed: 20 January 2011 ).

 Google Scholar

Bar-Ilan, A., R. Parikh, J. Grant, T. Shah, A.K. Pollack. 2008. Final report: Recommendations for improvements to the CENRAP states’ oil and gas emissions inventories http://www.wrapair.org/forums/ogwg/documents/2008-11_CENRAP_O&G_Report_11-13.pdf (http://www.wrapair.org/forums/ogwg/documents/2008-11_CENRAP_O&G_Report_11-13.pdf) (Accessed: 27 January 2011 ).

 Google Scholar

Hendler, A., J. Nunn, J. Lundeen, and R. McKaskle. 2009. VOC emissions from oil and condensate storage tanks. Prepared for the Texas Environmental Consortium http://files.harc.edu/Projects/AirQuality/Projects/H051C/H051CFinalReport.pdf (http://files.harc.edu/Projects/AirQuality/Projects/H051C/H051CFinalReport.pdf) (Accessed: 9 June 2011 ).

 Google Scholar

Shah , S.D. , Cocker , D.R. , Johnson , K.C. , Lee , J.M. , Soriano , B.L. and Miller , J.W. 2006 . Emissions of regulated pollutants from in-use diesel back-up generators . Atmos. Environ , 40 : 4199 – 4209 . doi: 10.1016/j.atmosenv.2005.12.063

 Web of Science ®Google Scholar

Chen , G. , Flynn , P.L. , Gallagher , S.M. and Dillier , E.R. 2003 . Development of the low emission GE-7FDL high power medium speed locomotive diesel engine . J. Eng. Gas Turbines Power , 125 : 505 – 512 . doi: 10.1115/1.1563241

 Web of Science ®Google Scholar

Sawant , A.A. , Nigam , A. , Miller , J.W. , Johnson , K.C. and Cocker , D.R. 2007 . Regulated and non-regulated emissions from in-use diesel-electric switching locomotives . Environ. Sci. Technol , 41 : 6074 – 6083 . doi: 10.1021/es061672d

 PubMed Web of Science ®Google Scholar

Ban-Weiss , G.A. , McLaughlin , J.P. , Harley , R.A. , Lunden , M.M. , Kirchstetter , T.W. , Kean , A.J. , Strawa , A.W. , Stevenson , E.D. and Kendall , G.A. 2008 . Long term changes in emissions of nitrogen oxide and particulate matter from on-road gasoline and diesel vehicles . Atmos. Environ , 42 : 220 – 232 . doi: 10.1016/j.atmosenv.2007.09.049

 Web of Science ®Google Scholar

Prucz , J.C. , Clark , N.N. , Gautam , M. and Lyons , D.W. 2001 . Exhaust emissions from engines of the Detroit diesel corporation in transit buses: A decade of trends . Environm. Sci. Technol , 35 : 1755 – 1764 . doi: 10.1021/es001416f

 PubMed Web of Science ®Google Scholar

Zielinska, B., E. Fujita, and D. Campbell. 2010. Monitoring of emissions from Barnett Shale natural gas production facilities for population exposure assessment http://sph.uth.edu/mleland/attachments/Barnett%20Shale%20Study%20Final%20Report.pdf (http://sph.uth.edu/mleland/attachments/Barnett%20Shale%20Study%20Final%20Report.pdf)

 Google Scholar

Johnson , J.P. , Kittelson , D.B. and Watts , W.F. 2009 . The effect of federal fuel sulfur regulations on in-use fleets: On-road heavy duty source apportionment . Environ. Sci. Technol , 43 : 5358 – 5364 . doi: 10.1021/es8037164

 PubMed Web of Science ®Google Scholar

Mazzoleni , C. , Kuhns , H.D. , Moosmuller , H. , Witt , J. , Nussbaum , N.N. , Chang , M.-C.O. , Parthasarathy , G. , Nathagoundenpalayam , S.K.K. , Nikolich , G. and Watson , J.G. 2007 . A case study of real world tailpipe emissions for school buses using a 20% biodiesel blend . Sci. Total Environ , 385 : 146 – 159 . doi: 10.1016/j.scitotenv.2007.06.018

 PubMed Web of Science ®Google Scholar

Choi , H.-W. and Frey , H.C. 2010 . Estimating diesel vehicle emission factors at constant and high speeds for short road segments . Transport. Res. Rec , 2158 : 19 – 27 . doi: 10.3141/2158-03

 Web of Science ®Google Scholar

Baker, R., and M. Pring. 2009. Drilling rig inventory for the state of Texas http://www.tceq.state.tx.us/assets/public/implementation/air/am/contracts/reports/ei/5820783985FY0901-20090715-ergi-Drilling_Rig_EI.pdf (http://www.tceq.state.tx.us/assets/public/implementation/air/am/contracts/reports/ei/5820783985FY0901-20090715-ergi-Drilling_Rig_EI.pdf) (Accessed: 16 June 2011 ).

 Google Scholar

M , Jiang , Griffin , W.M. , Hendrickson , C.T. , Jamarillo , P. , VanBriesen , J. and Venkatesh , A. 2011 . Life Cycle greenhouse gas emissions of Marcellus Shale gas. Environ Res. Lettdoi:10.1088/1748-9326/6/3/034014

 Google Scholar

Bar-Ilan, A., R. Friesen, A. Pollack, and A. Hoats. 2007. WRAP area source emissions inventory projections and control strategy evaluation phase II http://www.wrapair.org/forums/ogwg/documents/2007-10_Phase_II_O&G_ Final)Report(v10-07%20rev.s.pdf (http://www.wrapair.org/forums/ogwg/documents/2007-10_Phase_II_O&G_ Final)Report(v10-07%20rev.s.pdf) (Accessed: 9 November 2011 ).

 Google Scholar

Burklin, C.E., and M. Heaney. 2005. Natural gas compressor engine survey and engine NOx emissions at gas production facilities: Final report http://www.utexas.edu/research/ceer/GHG/files/ConfCallSupp/H40T121FinalReport.pdf (http://www.utexas.edu/research/ceer/GHG/files/ConfCallSupp/H40T121FinalReport.pdf)

 Google Scholar

Grant, J., L. Parker, A. Bar-Ilan, S. Kemball-Cook, and G. Yarwood. 2009. Draft report: Development of emissions inventories for natural gas exploration and production activity in the Haynesville Shale. Environ International Corporation, CA http://www.netac.org/UserFiles/File/NETAC/9_29_09/Enclosure_2b.pdf (http://www.netac.org/UserFiles/File/NETAC/9_29_09/Enclosure_2b.pdf) (Accessed: 27 January 2011 ).

 Google Scholar