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Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Introduction
Quantification Methods
A guide for completing Natural Gas STAR Annual Reports
Reporting projects that voluntarily reduce methane emissions to the atmosphere is an important aspect of the Natural Gas STAR Program. Annual Reports help partner
companies maintain a permanent record of voluntary actions to reduce emissions, spread project ideas throughout the Partnership, and demonstrate that voluntary programs
can simultaneously increase profits and promote environmental stewardship. Data accuracy and transparency are therefore essential in a Natural Gas STAR Annual Report.
An accurate record of voluntary actions helps the Program understand what services and information to provide partner companies.
The goal of this document is to facilitate partner companies' ability to quantify activities reported in Natural Gas STAR Annual Reports. The following pages summarize
methods to quantify methane emission reductions achieved by the implementation of Program-recommended technologies and practices. Methane emission reduction
projects are based on existing Natural Gas STAR technical documents and are organized by equipment type. Up to five methods are given to help quantify methane savings.
In general, project-specific data such as direct measurement of emissions will result in a more accurate report than other methods such as calculations.
Please use this document as a reference guide to help you complete an accurate Natural Gas STAR Annual Report. Annual Reports are neither limited to specific
quantification methods nor to specific types of projects. Quantification guidance listed here is a compilation of quantification methods from the Program's technical documents,
but partners have the flexibility to use other methods and also to report additional projects to reduce methane emissions that are not listed in this document. Partners are
encouraged to report to Natural Gas STAR quantification methodologies that are not covered in this document.
For questions or comments on this document, or further guidance on completing the Annual Report, please contact an EPA representative:
Scott Bartos, Natural Gas STAR Program Manager, bartos.scott@epa.gov, 202-343-9167
Jerome Blackman, Natural Gas STAR Program Manager, blackman.jerome@epa.gov, 202-343-9630
Carey Bylin, Natural Gas STAR Program Manager, bylin.carey@epa.gov, 202-343-9669
Roger Fernandez, Natural Gas STAR Team Leader, fernandez.roger@epa.gov, 202-343-9386
Suzie Waltzer, Natural Gas STAR Program Manager, waltzer.suzanne@epa.gov, 202-343-9544
Last updated: February 2011
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Table of Contents
Equipment Type Technology/Practice Page Number
Compressors/Engines 1
Automate compressor systems operation to reduce venting 1
Install automated air-fuel ratio control systems 2
Install electric compressors 2
Redesign blowdown/alter ESD practices 3
Reduce frequency of engine starts 4
Reduce emissions when taking compressors off-line 5
Lower compressor purge pressure for shutdown 5
Replace compressor rod packing systems 6
Replace compressor cylinder unloaders 6
Replace gas starters with air 7
Install electric starters 7
Convert engine starting to nitrogen and/or CO2 rich gas 7
Replace ignition reduce/false starts 8
Replace wet compressor seals with dry seals 9
Dehydrators 10
Convert gas-driven chemical pumps to instrument air 10
Install flash tank separators on dehydrators 11
Replace glycol dehydration units with methanol injection 12
Pipe glycol dehydrator to vapor recovery unit (VRU) 13
Install portable desiccant dehydrators 13
Replace glycol dehydrator with separators and in-line heaters 14
Replacing gas-assisted glycol pumps with electric pumps 15
Replacing glycol dehydrators with desiccant dehydrators 16
Reroute glycol skimmer gas 18
Zero emissions dehydrators 19
Other 20
DI&M at remote sites 20
Leak imaging survey 20
Eliminate unnecessary equipment and/or systems 21
Directed inspection and maintenance (DI&M) at compressor stations 21
Directed inspection and maintenance (DI&M) at gas plants and booster stations 22
Directed inspection and maintenance (DI&M) at gate stations and surface facilities 24
Increase walking survey basis 24
Install flares 25
Nitrogen rejection unit (NRU) optimization 26
Require improvements in quality of gas received from producers 26
Pipelines 27
Composite wrap repair 27
Identify and rehabilitate leaky distribution pipes 28
Inject blowdown gas into low pressure system 29
Insert gas main flexible liners 29
Inspect flowlines annually 30
Install ejector 30
Install rupture pin shutoff device to reduce venting 31
Perform leak repair during pipeline replacement 31
Recover gas from pipeline pigging operations 32
Use inert gas/pigs for pipeline purges 33
Use of improved protective coating at pipeline canal crossings 34
Use hot taps for in-service pipeline connections 35
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Table of Contents
Equipment Type Technology/Practice Page Number
Use fixed/portable compressors for pipeline pumpdown 36
Pneumatics/Control Devices 37
Install electronic flare ignition devices 37
Options for reducing methane emissions from pneumatic devices 38
Reduce frequency of replacing turbine meter modules 39
Replace bi-directional orifice metering with ultrasonic meters 40
Convert gas pneumatic controls to instrument air 41
Tanks 42
Capture methane from pipeline liquid storage tanks (hydrocarbon condensate tanks) 42
Consolidate crude oil production and water storage tanks 43
Convert water tank blanket from natural gas to CO2 43
Install pressurized storage of condensate 44
Install vapor recovery units (VRUs) on crude oil storage tanks 45
Purge and retire low pressure gasholders 46
Recycle line recovers gas during condensate loading 47
Valves 48
Close valves during repair to minimize blowdown 48
Design isolation valves to minimize blowdown volumes 49
Inspect and repair compressor station blowdown valves 50
Reduce venting from unlit pilot: install BASO valves 51
Install excess flow valves 52
Move in fire gates at compressors 53
Replace burst plates with secondary relief valves 54
Test and repair pressure safety valves 55
Test gate station pressure relief valves with nitrogen 56
Use of YALE closures for ESD testing 57
Use ultrasound to identify leaks 58
Wells 59
Connect casing to vapor recovery unit 59
Install smart lift automated systems on gas wells 60
Optimize gas well unloading times 61
Green completions/perform reduced emissions completions 61
Install compressors to capture casinghead gas 62
Install downhole separator pumps 63
Install pumpjacks or rod pumps on gas wells 64
Install velocity tubing strings 64
Install plunger lift systems 65
Lower heater-treater temperature 66
Use foaming agents to reduce blowdown frequency 66
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Compressors/Engines
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Automate compressor Partner Quantified Methane Emissions Reductions Engineering Calculation
systems operation to
reduce venting Methane emission reductions from automating compressor start-up systems are highly variable. Calculate gas used to start compressor using the following equation:
Factors such as compressor size, operating conditions, and controller logic will affect methane B = 0.0005 Mcf/horsepower · P · S · XCH4
Production emission reductions for each specific application. Natural Gas STAR encourages partners to identify
Processing other methods to quantify methane emissions reductions. Please identify the basis for any alternate Calculate gas vented in compressor blowdown using the following equation:
Transmission emissions reduction estimate in the annual report. V = 15 Mcf/blowdown · N
Distribution
Calculate emissions reductions using the following equation:
ER = B + V
Where,
ER = Emissions Reductions (Mcf/year)
B = Gas at 250 psig used to start compressor (Mcf/year)
P = Compressor power (horsepower)
S = Number of start-ups/year
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.934 (Transmission)
V = Vented methane from compressor blowdowns (Mcf/year)
N = Number of compressor blowdown events (blowdowns/year)
References:
Automate Systems Operation to Reduce Venting PRO
http://www.epa.gov/gasstar/documents/automatesystemsoperationtoreduceventing.pdf
Install automated air-fuel Emission Factor Emission Factor Partner Quantified Methane Emissions Reductions
ratio control systems
Installing automated air-fuel ratio controllers can increase the efficiency of engines while reducing Installing automated air-fuel ratio controllers can increase the efficiency of engines while reducing Natural Gas STAR encourages partners to identify other
Production the fuel consumption and methane emissions. Partners report saving 128 Mcf/compressor/year of the fuel consumption and methane emissions. Partners report saving 758 Mcf/compressor/year of methods to quantify methane emissions reductions. Please
Processing methane. methane assuming a rich air/fuel ratio before installing automated controllers. identify the basis for any alternate emissions reduction
Transmission estimate in the annual report.
Distribution Calculate emissions reductions using the following equation: Calculate emissions reductions using the following equation:
ER = 128 Mcf methane/compressor/year · AF ER = 758 Mcf methane/compressor/year · AF
Where, Where,
ER = Emission Reductions (Mcf/year) from AP-42 ER = Emission Reductions (Mcf/year) from vendor factors assuming a rich air/fuel ratio before
AF = Activity Factor (Number of compressors) installing automated controllers
AF = Activity Factor (Number of compressors)
References:
Automated Air/Fuel Ratio Controls PRO References:
http://www.epa.gov/gasstar/documents/auto-air-fuel-ratio.pdf Automated Air/Fuel Ratio Controls PRO
http://www.epa.gov/gasstar/documents/auto-air-fuel-ratio.pdf
Compressors-Engines 1
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Compressors/Engines
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Install electric compressors Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
Production Electric compressors do not require burning gas in engines, thus saving uncombusted methane in If horsepower is unknown, Partners report savings of 6,440 Mcf/year for each electric compressor Natural Gas STAR encourages partners to identify other
Processing the exhaust from being emitted to the atmosphere. Partners report saving 2.11 Mcf/horsepower/year used to replace gas powered compressors (based on replacing 3,000 horsepower compressors). methods to quantify methane emissions reductions. Please
Transmission of methane. identify the basis for any alternate emissions reduction
Distribution Calculate emissions reductions using the following equation: estimate in the annual report.
Calculate emissions reductions using the following equation: ER = AF · 6,440 Mcf methane/year/compressor
ER = 2.11 Mcf methane/horsepower/year · P
Where,
Where, ER = Emissions Reductions (Mcf/year)
ER = Methane emission reductions (Mcf/year) AF = Activity Factor (Compressors replaced with electric compressors)
P = Compressor power (horsepower)
References:
References: Install Electric Compressor PRO
Install Electric Compressors PRO http://www.epa.gov/gasstar/documents/installelectriccompressors.pdf
http://www.epa.gov/gasstar/documents/installelectriccompressors.pdf
Redesign blowdown/alter Partner Quantified Methane Emissions Reductions Engineering Calculation
ESD practices
Methane emission reductions from redesigning blowdown systems and altering emergency shut Redesigning blowdown systems can reduce methane emissions by decreasing the volume of piping
Production down practices are highly variable. Factors such as reduction of piping volumes, re-routing of vented to the atmosphere.
Processing blowdown gas to sales, fuel lines, or low pressure pipelines will affect methane emission reductions
Transmission for each specific application. Natural Gas STAR encourages partners to identify other methods to Calculate blowdown volume BEFORE alterations by summing over all pipeline diameters and
Distribution quantify methane emissions reductions. Please identify the basis for any alternate emissions pressures:
reduction estimate in the annual report. VB = Σ{ 0.000372 · XCH4 · D^2 · P · L/1,000feet }
Calculate blowdown volume AFTER alterations by summing over all pipeline diameters and
pressures:
VA = Σ{ 0.000372 · XCH4 · D^2 · P · L/1,000feet }
Calculate emissions reductions using the following equation:
ER = (VB - VA) · AF
Where,
ER = Emissions Reductions (Mcf/year)
VB = Piping volume before altering blowdown system (Mcf)
VA = Piping volume after altering blowdown system (Mcf)
D = Inside diameter of pipeline (inches)
L = Length of pipeline between shutoff valves (feet)
P = Pipeline pressure (psia for less than 50psi, psig for more than 50psi)
AF = Number of blowdowns/year
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production), 0.87
(Processing), 0.934 (Transmission/Distribution)
Compressors-Engines 2
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Compressors/Engines
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
References:
Pipe Line Rules of Thumb Handbook 4th Edition, page 271
Redesign blowdown systems and alter ESD practices PRO
http://www.epa.gov/gasstar/documents/redesignblowdownsystems.pdf
Reduce frequency of Engineering Calculation Emission Factor Partner Quantified Methane Emissions Reductions
engine starts
Internal combustion engine driven turbine compressors are often started by directing unignited Internal combustion engine driven turbine compressors are often started by directing unignited Natural Gas STAR encourages partners to identify other
Production pipeline gas through the turbine compressor, rolling the turbine engine prior to ignition. The unignited pipeline gas through the turbine compressor, rolling the turbine engine prior to ignition. The methods to quantify methane emissions reductions. Please
Processing gas, or startup natural gas, is vented to the atmosphere. unignited gas, or startup natural gas, is vented to the atmosphere. Emissions can be estimated identify the basis for any alternate emissions reduction
Transmission based on partner experience of startup for a large LNG refrigeration compressor: estimate in the annual report.
Distribution Calculate gas used to start compressor using the following equation:
B = 0.5 scf/horsepower · P · 1 Mcf/1,000 scf · S · XCH4 Calculate emissions reductions using the following equation:
ER = 132 Mcf/start-up/year · AF
Calculate fugitive emissions from gas starter open-ended lines using the following equation:
F = 1,341 Mcf/OEL/year · N Where,
ER = Emission Reductions (Mcf/year) based on saving 132 Mcf on each avoided start-up for an
Calculate emissions reductions using the following equation: LNG refrigeration compressor
ER = B + F AF = Activity Factor (Number of avoided compressor start-ups)
Where, References:
ER = Emissions Reductions (Mcf/year) Reduce the Frequency of Engine Starts with Gas PRO
B = Gas at 250 psig used to start compressor (Mcf/year) http://www.epa.gov/gasstar/documents/reducethefrequencyofenginestarts.pdf
P = Compressor power (horsepower)
S = Number of start-ups/year
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production), 0.87
(Processing), 0.934 (Transmission)
F = Fugitive methane emissions from OELs (Mcf/year)
N = Number of OELs
References
Robert Perry, Don Green. Perry's Chemical Engineers' Handbook, Sixth Edition. p 24-15
Replace Gas Starters with Air PRO
http://www.epa.gov/gasstar/documents/replacegas.pdf
Install Electric Starters PRO
http://www.epa.gov/gasstar/documents/installelectricstarters.pdf
Convert Engine Starting to Nitrogen PRO
http://www.epa.gov/gasstar/documents/convertenginestartingtonitrogen.pdf
Compressors-Engines 3
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Compressors/Engines
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Reduce emissions when Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
taking compressors off-line
Calculate emissions. The total methane emissions from compressors taken offline and blown down Emissions reductions can be estimated depending on the method used when taking compressors Natural Gas STAR encourages partners to identify other
Lower compressor purge to the atmosphere is the sum of the losses from venting the compressor and the losses from valves offline: methods to quantify methane emissions reductions. Please
pressure for shutdown which leaks methane from the compressor to the atmosphere: identify the basis for any alternate emissions reduction
Ex = [(BD · V) + (OT · LR)] · XCH4 Method EF estimate in the annual report.
Production Keep pressurized 4,400 Mcf/year
Processing Where, Keep pressurized/ 1,345 Mcf/year
Transmission E = Emissions baseline from taking compressors offline (Mcf/year) reroute gas
Distribution BD = Blowdowns (blowdowns/year) Keep pressurized/ 1,200 Mcf/year
V = Volume of compressed gas (Mcf) - default is 15 Mcf/blowdown event install static seal
OT = Offline time (hours/year)
LR = Leak rate for blowdown/unit valves and seals (Mcf/hour) - default is 1.525 Calculate emissions reductions summing over all compressors taken offline:
x = baseline case or controlled case ER = Σ{ AF · EF · XCH4 }
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.87 (Processing), 0.934
(Transmission) Where,
ER = Emissions Reductions
AF = Activity Factor (number of compressors taken offline)
Compressor emissions can be controlled through a number of options:
EF = Emissions Factor (Mcf/year)
Keep pressurized sets BD to zero and sets LR to the leak rate of only the blowndown valve and
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.87 (Processing), 0.934
seals - default is 0.575
(Transmission)
Route to fuel gas sets BD to zero and LR to 0.125 since all gas flows into the fuel system except
leakage from seals
References:
Route to fuel gas and install static seal sets BD to zero and LR to zero.
Reducing Emissions When Taking Compressors Off-Line Lessons Learned
http://www.epa.gov/gasstar/documents/ll_compressorsoffline.pdf
Calculate emissions reductions for each compressor by subtracting controlled emissions from
baseline emissions and summing reductions for all compressors:
ER = Σ(Econtrolled - Ebaseline)
Where,
ER = Emissions Reductions (Mcf/year)
References:
Reducing Emissions When Taking Compressors Off-Line Lessons Learned
http://www.epa.gov/gasstar/documents/ll_compressorsoffline.pdf
Compressors-Engines 4
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Compressors/Engines
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Replace compressor rod Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
packing systems
To estimate emissions reductions from rod packing first measure the current leakage rate and Pipeline Research Committee International reports typical emissions reductions of 865 Natural Gas STAR encourages partners to identify other
Production subtract the measured leak rate after the last packing ring rod replacement has worn in (one month). Mcf/year/packing replacement. methods to quantify methane emissions reductions. Please
Processing identify the basis for any alternate emissions reduction
Transmission Calculate emissions reductions using the following equation: Calculate the emissions reductions using the following equation: estimate in the annual report.
Distribution ER = CL - IL · XCH4 ER = AF · 865 Mcf/year/packing replacement · XCH4
Where, Where,
ER = Emissions Reductions (Mcf/year) ER = Emissions Reductions (Mcf/year)
CL = Current leak rate (Mcf/year) AF = Activity Factory (number of rod packing replacements/year)
IL = Initial leak rate at the last packing ring rod replacement (Mcf/year) - default is 100.74 Mcf/year XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production), 0.87
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production), 0.87 (Processing), 0.934 (Transmission)
(Processing), 0.934 (Transmission)
References:
References: Reducing Methane Emissions from Compressors and Rod Packing Systems Lessons Learned
Reducing Methane Emissions from Compressors and Rod Packing Systems Lessons Learned http://www.epa.gov/gasstar/documents/ll_rodpack.pdf
http://www.epa.gov/gasstar/documents/ll_rodpack.pdf
Replace compressor Direct Measurement Partner Quantified Methane Emissions Reductions
cylinder unloaders
Faulty unloaders can be a source of fugitive methane emissions to the atmosphere from leaking o- Methane emission reductions from replacing compressor cylinder unloaders are highly variable.
Production rings, covers, pressure packing, and frequent maintenance. If leakage rates are not too high, a high Factors such as number and size of fugitive leaks, unscheduled shutdowns, and compressor
Processing volume sampler or bagging techniques may be used to directly measure these fugitive methane maintenance activities will affect methane emission reductions for each specific application. Natural
Transmission emissions. Gas STAR encourages partners to identify other methods to quantify methane emissions
Distribution reductions. Please identify the basis for any alternate emissions reduction estimate in the annual
References: report.
Replace compressor cylinder unloaders PRO
http://www.epa.gov/gasstar/documents/replacecylinder.pdf
Compressors-Engines 5
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Compressors/Engines
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Replace gas starters with Engineering Calculation Emission Factor Partner Quantified Methane Emissions Reductions
air
Internal combustion engine driven turbine compressors are often started by directing unignited Internal combustion engine driven turbine compressors are often started by directing unignited Natural Gas STAR encourages partners to identify other
Install electric starters pipeline gas through the turbine compressor, rolling the turbine engine prior to ignition. The unignited pipeline gas through the turbine compressor, rolling the turbine engine prior to ignition. The methods to quantify methane emissions reductions. Please
gas, or startup natural gas, is vented to the atmosphere. unignited gas, or startup natural gas, is vented to the atmosphere. identify the basis for any alternate emissions reduction
Convert engine starting to estimate in the annual report.
nitrogen and/or CO2 rich Calculate gas used to start compressor using the following equation: Calculate emissions reductions using the following equation:
gas B = 0.5 scf/horsepower · P / 1000scf/Mcf · S · XCH4 ER = 132 Mcf/start-up/year · AF · XCH4
Production Calculate fugitive emissions from gas starter open-ended line using the following equation: Where,
Processing F = 1,341 Mcf/OEL/year ER = Emission Reductions (Mcf/year)
Transmission AF = Activity Factor (Number of avoided compressor start-ups)
Distribution Calculate emissions reductions using the following equation: XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production), 0.87
ER = B + F (Processing), 0.934 (Transmission)
Where, References:
ER = Emissions Reductions (Mcf/year) Reduce the Frequency of Engine Starts with Gas PRO
B = Gas at 250 psig used to start compressor (Mcf/year) http://www.epa.gov/gasstar/documents/reducethefrequencyofenginestarts.pdf
P = Compressor power (horsepower)
S = Number of start-ups/year
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production), 0.87
(Processing), 0.934 (Transmission)
F = Fugitive methane emissions from gas starter OEL (Mcf/year)
References:
Robert Perry, Don Green. Perry's Chemical Engineers' Handbook, Sixth Edition. p 24-15
Replace Gas Starters with Air PRO
http://www.epa.gov/gasstar/documents/replacegas.pdf
Install Electric Starters PRO
http://www.epa.gov/gasstar/documents/installelectricstarters.pdf
Convert Engine Starting to Nitrogen PRO
http://www.epa.gov/gasstar/documents/convertenginestartingtonitrogen.pdf
Compressors-Engines 6
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Compressors/Engines
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Replace ignition/reduce Emissions Factor Partner Quantified Methane Emissions Reductions
false starts
Partners report saving an average of 0.5 scf/horsepower for each false start avoided. Natural Gas STAR encourages partners to identify other methods to quantify methane emissions
Production reductions. Please identify the basis for any alternate emissions reduction estimate in the annual
Processing Calculate emissions reductions using the following equation and sum for all compressors: report.
Transmission ER = Σ(AF · EF · HP · 1Mcf/1,000scf · XCH4)
Distribution
Where,
ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (false-starts reduced/year)
EF = Emissions Factor (scf/horsepower/false-start) - default is 0.5 scf/horsepower/false-start
HP = Compressor power (horsepower)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production), 0.87
(Processing), 0.934 (Transmission)
References:
Replace Ignition - Reduce False Starts PRO
http://www.epa.gov/gasstar/documents/replaceignitionreducefalsestarts.pdf
Replace wet compressor Direct Measurement Engineering Calculation Partner Quantified Methane Emissions Reductions
seals with dry seals
To estimate dry seal savings, measure methane losses from wet seal compressors at the vent from Wet seal compressor leakage ranges from 40 to 200 scf/minute for a beam type compressor with Natural Gas STAR encourages partners to identify other
Production the seal oil degassing unit by bagging, hot wire anemometer, or high volume sampler with a filter. two seals and a seal oil circulation system. Dry seal compressor leakage ranges from 1 to 6 methods to quantify methane emissions reductions. Please
Processing Some gas also escapes at the seal face which can be measured with a high flow sampler. scf/minute for a beam type compressor with two seals. identify the basis for any alternate emissions reduction
Transmission Emissions reductions will be the sum of these two emissions rates minus dry seal leakage. estimate in the annual report.
Distribution Calculate emissions reductions using the following equation:
Dry seal leakage can be measured with a high flow sampler. Alternatively, data on leak rates from ER = O · 60minutes/hour · (W - D) · XCH4 · 1Mcf/1000scf
dry seals may be obtained from the vendor. Below is an example of the range of dry seal leak rates.
Where,
ER = Emissions Reductions (Mcf/year)
O = Annual operating time of the compressor (hours/year)
W = Wet seal leakage rate - default is 100 scf/minute
D = Dry seal leakage rate - default is 6 scf/minute
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.87 (Processing), 0.934
(Transmission)
References:
Replacing Wet Seals with Dry Seals in Centrifugal Compressors Lessons Learned
http://www.epa.gov/gasstar/documents/ll_wetseals.pdf
Methane Savings from Compressors Presentation
http://www.epa.gov/gasstar/documents/workshops/houston-
2004/ReducingEmissionsfromCompressorSeals.ppt
Compressors-Engines 7
To estimate dry seal savings, measure methane losses from wet seal compressors at the vent from Wet seal compressor leakage ranges from 40 to 200 scf/minute for a beam type compressor with Natural Gas STAR encourages partners to identify other
the seal oil degassing unit by bagging, hot wire anemometer, or high volume sampler with a filter. two seals and a seal oil circulation system. Dry seal compressor leakage ranges from 1 to 6 methods to quantify methane emissions reductions. Please
Some gas also escapes at the seal face which can be measured with a high flow sampler. scf/minute for a beam type compressor with two seals. identify the basis for any alternate emissions reduction
Emissions reductions will be the sum of these two emissions rates minus dry seal leakage. estimate in the annual report.
Calculate emissions reductions using the following equation:
Dry seal leakage can be measured with a high flow sampler. Alternatively, data on leak rates from ER = O · 60minutes/hour · (W - D) · XCH4 · 1Mcf/1000scf
dry seals may be obtained from the vendor. Below is an example of the range of dry seal leak rates.
Where,
ER = Emissions Reductions (Mcf/year)
O = Annual operating time of
Natural Gas STAR Recommended Technologies and Practices - Quantification Methodsthe compressor (hours/year)
W = Wet seal leakage rate - default is 100 scf/minute
Compressors/Engines D = Dry seal leakage rate - default is 6 scf/minute
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.87 (Processing), 0.934
(Transmission)
Technology/
References:
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Replacing Wet Seals with Dry Seals in Centrifugal Compressors Lessons Learned
Applicable Sector(s)
http://www.epa.gov/gasstar/documents/ll_wetseals.pdf
Methane Savings from Compressors Presentation
http://www.epa.gov/gasstar/documents/workshops/houston-
2004/ReducingEmissionsfromCompressorSeals.ppt
References:
Replacing Wet Seals with Dry Seals in Centrifugal Compressors Lessons Learned
http://www.epa.gov/gasstar/documents/ll_wetseals.pdf
Compressors-Engines 8
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Other
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3 Quantification Method 4
Applicable Sector(s)
DI&M at remote sites Direct Measurement Emission Factor Partner Quantified Methane Emissions Reductions
Leak imaging survey Organic vapor analyzers, toxic vapor analyzers, bagging techniques, high volume samplers, and Methane emissions savings will vary on the type of remote facility, methane content in the leaks, Natural Gas STAR encourages partners to identify other methods to quantify
rotameters can be used where appropriate to measure the emissions rates identified leaks. These number of leaking components, and type of leaking components. Below is a list of component leak methane emissions reductions. Please identify the basis for any alternate emissions
Production can be used to determine the amount of emissions reduced. rates suited for use as emission factors in the equation. The leak rates were taken from a study at reduction estimate in the annual report.
Processing natural gas processing facilities and can be used as surrogates for components at other types of
Transmission References: facilities.
Distribution Directed Inspection and Maintenance at Compressor Stations Lessons Learned
http://www.epa.gov/gasstar/documents/ll_dimcompstat.pdf
Equipment Component Type Lessons Clearstone
Conduct DI&M at Remote Sites PRO Type Learned
http://epa.gov/gasstar/documents/conductdimatremotefacilities.pdf Natural Gas Natural Gas
Leak Rate Leak Rate
per per
Component Component
(Mcf/year/ (Mcf/year/
component) component)
Gas Plant / Non-compressor related
Valve 28.74 4.49
Connection 7.70 0.80
Pressure Relief Valve 4.48 1.18
Blowdown OEL 852.87
Open ended line 49.43 24.11
Flange 101.38
Meter 6.94
Other 82.80
Reciprocating Compressor
Blowdown OEL 1,628.74 1,043.06
Starter OEL 1,541.38
Open Ended Line 111.25
Pressure Relief Valve 354.02 23.87
Compressor Seal 1,655.17 2,582.05
Miscellaneous 145.98
Valve 115.49
Connector 8.83
Crank case vent 932.66
Other 227.39
Centrifugal Compressor
Blowdown OEL 3,318.39
Starter OEL 1,541.38
Open Ended Line 14.59
Compressor Seal 557.47 62.26
Miscellaneous 72.87
Flange 132.18
Valve 1.23
Connector 0.15
Pressure Relief Valve 0.00
Meter 0.00
ER = EF · AF · XCH4 · 70% reduction on average through DI&M
Where,
ER = Emissions Reductions (Mcf/year)
EF = Emissions Reductions Factors (Mcf/year)
AF = Activity Factor (number of components)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production), 0.87
(Processing), 0.934 (Transmission/Distribution)
References:
Conduct DI&M at Remote Sites PRO
http://www.epa.gov/gasstar/documents/conductdimatremotefacilities.pdf
Fernandez, Roger and Robinson, Donald. “Study Comparison reveals methane-emissions
reduction opportunities in gas processing.” Oil & Gas Journal. June 14, 2005
Other 1
Equipment Component Type On Off
Type Compressor Compressor
Connector 0.15
Pressure Relief Valve 0.00
Meter 0.00
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Other
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3 Quantification Method 4
Applicable Sector(s)
Eliminate unnecessary Partner Quantified Methane Emissions Reductions
equipment and/or systems
Methane emission reductions from eliminating unnecessary equipment are highly variable. Factors
Production such as the type of equipment eliminated, the equipment's efficiency/ leakage rate, and
Processing equipment/facility throughput will affect methane emission reductions for each specific application.
Transmission Natural Gas STAR encourages partners to identify other methods to quantify methane emissions
Distribution reductions. Please identify the basis for any alternate emissions reduction estimate in the annual
report.
References:
Equipment Component Type Lessons Clearstone
Eliminate Unnecessary Equipment and/or Systems PRO Type Learned
http://epa.gov/gasstar/documents/eliminateunnecessaryequipmentandorsystems.pdf Natural Gas Natural Gas
Leak Rate Leak Rate
Directed inspection and Direct Measurement Emissions Factor - Compressor Station Total per per
Emissions Factor – Compressor Components Partner Quantified Methane Emissions Reductions
maintenance (DI&M) at Component Component A study of emissions from compressor related components has published emissions
compressor stations Organic vapor analyzers, toxic vapor analyzers, bagging techniques, high volume samplers, and (Mcf/year/ station.
Partners report methane emissions reductions of 29,413 Mcf/year/compressor
(Mcf/year/ factors for the following components: Natural Gas STAR encourages partners to identify other
rotameters can be used where appropriate to measure the emissions rates of leaking equipment. component) component) methods to quantify methane emissions reductions. Please
Gas Plant / Non-compressor related
Transmission These can be used to determine the amount of emissions reduced. Calculate emissions reductions using the following equation:
Valve 28.74 4.49
identify the basis for any alternate emissions reduction
ER = AF · 29,413 Mcf/year/compressor station Equipment Component Type On Off estimate in the annual report.
Connection 7.70 0.80
References: Pressure Relief Valve 4.48 1.18 Type Compressor Compressor
Directed Inspection and Maintenance at Compressor Stations Lessons Learned Where, Blowdown OEL 852.87
Open ended line 49.43 24.11 Natural Gas Natural Gas
http://www.epa.gov/gasstar/documents/ll_dimcompstat.pdf ER = Emissions Reductions (Mcf/year)
Flange 101.38 Leak Rate Leak Rate per
AF = Activity Factor (compressor stations monitored)
Meter 6.94
per Component
Other 82.80
References:
Reciprocating Compressor Component (Mcf/year/
Blowdown OEL 1,628.74 1,043.06
Directed Inspection and Maintenance at Compressor Stations Lessons Learned (Mcf/year/ component)
Starter OEL 1,541.38
http://www.epa.gov/gasstar/documents/ll_dimcompstat.pdf component)
Open Ended Line 111.25
Components Under Main Line Pressure
Pressure Relief Valve 354.02 23.87
Ball/Plug Valve 0.64 5.33
Compressor Seal 1,655.17 2,582.05
Miscellaneous 145.98 Blowdown Valve 207.50
Valve 115.49 Compressor Cylinder Joint 9.90
Connector 8.83 Packing Seal – Running 865.00
Crank case vent 932.66 Packing Seal – Idle 1,266.00
Other 227.39 Compressor Valve 4.10
Centrifugal Compressor
Control Valve 4.26
Blowdown OEL 3,318.39
Starter OEL 1,541.38 Flange 0.81 0.32
Open Ended Line 14.59 Gate Valve 0.61
Compressor Seal 557.47 62.26 Loader Valve 17.20
Miscellaneous 72.87 Open-Ended Line (OEL) 81.80
Flange 132.18 Pressure Relief Valve (PRV) 57.50
Valve 1.23
Regulator 0.20
Connector 0.15
Pressure Relief Valve 0.00
Starter Gas Vent 40.80
Meter 0.00 Connector – Threaded 0.74 0.60
Centrifugal Seal – Dry 62.70
Centrifugal Seal – Wet 278.00
Unit Valve3 3,566.00
Partners have reported methane emission reductions of 70% of their total methane
emissions after implementing directed inspection and maintenance programs at their
compressor stations.
Calculate emissions reductions using the following equation:
ER = Σ{ AF · EF · XCH4} · 70%
Where,
ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (components replaced)
EF = Emissions Factor (Mcf/year/component)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.934
(Transmission/Distribution)
References:
Directed Inspection and Maintenance at Compressor Stations Lessons Learned
http://www.epa.gov/gasstar/documents/ll_dimcompstat.pdf
Equipment Component Type Lessons Clearstone
Type Learned
Other
Natural Gas Natural Gas
2
Leak Rate Leak Rate
per per
Component Component
(Mcf/year/ (Mcf/year/
component) component) Equipment Component Type On Off
Gas Plant / Non-compressor related Type Compressor Compressor
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Other
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3 Quantification Method 4
Applicable Sector(s)
Directed inspection and Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
maintenance (DI&M) at
gas plants and booster Organic vapor analyzers, toxic vapor analyzers, bagging techniques, high volume samplers, and The following equipment found at gate stations are typically associated with the following emissions: Natural Gas STAR encourages partners to identify other methods to quantify
stations rotameters can be used where appropriate to measure the emissions rates of leaking equipment. Equipment Component Type Lessons Clearstone
methane emissions reductions. Please identify the basis for any alternate emissions
These can be used to determine the amount of emissions reduced. Type Learned reduction estimate in the annual report.
Processing Natural Gas Natural Gas
Leak Rate Leak Rate
References: per per
Directed Inspection and at Gas Plants and Booster Stations Lessons Learned Component Component
http://www.epa.gov/gasstar/documents/ll_dimgasproc.pdf (Mcf/year/ (Mcf/year/
component) component)
Gas Plant /
Equipment Non-compressor related
Component Type Lessons Clearstone
Type Valve 28.74
Learned 4.49
Connection Natural 7.70
Gas Natural 0.80
Gas
Pressure Relief Valve 4.48
Leak Rate 1.18
Leak Rate
Blowdown OEL 852.87
per per
Open ended line 49.43 24.11
Component Component
Flange 101.38
(Mcf/year/ (Mcf/year/
Meter 6.94
component) component)
Other 82.80
Gas Plant / Non-compressor related
Reciprocating Compressor
Valve 28.74 4.49
Blowdown OEL 1,628.74 1,043.06
Connection
Starter OEL
7.70
1,541.38
0.80
Pressure Relief Valve
Open Ended Line 4.48 1.18
111.25
Pressure OEL
BlowdownRelief Valve 852.87
354.02 23.87
Open ended line
Compressor Seal 49.43
1,655.17 24.11
2,582.05
Flange
Miscellaneous 101.38
145.98
Meter
Valve 6.94
115.49
Connector
Other 8.83
82.80
Crank case vent
Reciprocating Compressor 932.66
Other
Blowdown OEL 1,628.74 227.39
1,043.06
Centrifugal Compressor
Starter OEL 1,541.38
Blowdown OEL 3,318.39
Open Ended Line 111.25
Starter OEL 1,541.38
Pressure Relief Valve 354.02 23.87
Open Ended Line 14.59
Compressor Seal 1,655.17 2,582.05
Compressor Seal 557.47 62.26
Miscellaneous 145.98
Miscellaneous 72.87
Valve
Flange 132.18 115.49
Connector
Valve 8.83
1.23
Crank case vent
Connector 932.66
0.15
Other
Pressure Relief Valve 227.39
0.00
Centrifugal Compressor
Meter 0.00
Blowdown
Cryogenic equipment OEL 3,318.39
Starter OEL 1,541.38
Valve 13.1
Open Ended Line 14.59
Connector 2.9
Compressor Seal 557.47 62.26
PRV
Miscellaneous 72.87 0.0
CS
Flange 132.18 0.0
Valve
OEL 1.23
8.9
Connector 0.15
Pressure Relief Valve 0.00
Meter 0.00
Note - Emissions factors have been adjusted to natural gas leak rates. Partners are encouraged to
use their own methane content of natural gas to improve the accuracy of their emissions estimates.
Partners have reported methane emission reductions of 70% of their total methane emissions after
implementing directed inspection and maintenance programs at their compressor stations.
Calculate emissions reductions using the following equation:
ER = Σ{ AF · EF · XCH4} · 70%
Where,
ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (components replaced)
EF = Emissions Factor (Mcf/year/component)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.87 (Processing)
References:
Directed Inspection and at Gas Plants and Booster Stations Lessons Learned
http://www.epa.gov/gasstar/documents/ll_dimgasproc.pdf
Fernandez, Roger and Robinson, Donald. “Study Comparison reveals methane-emissions
reduction opportunities in gas processing.” Oil & Gas Journal. June 14, 2005
Other 3
Equipment Component Type On Off
Type Compressor Compressor
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Other
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3 Quantification Method 4
Applicable Sector(s)
Directed inspection and Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
maintenance (DI&M) at
gate stations and surface Organic vapor analyzers, toxic vapor analyzers, bagging techniques, high volume samplers, and The following equipment found at gate stations are typically associated with the following emissions: Natural Gas STAR encourages partners to identify other methods to quantify
facilities rotameters can be used where appropriate to measure the emissions rates of leaking equipment. methane emissions reductions. Please identify the basis for any alternate emissions
These can be used to determine the amount of emissions reduced. Component EF reduction estimate in the annual report.
Distribution Ball/Plug Valve 0.21 Mcf/year/valve
References: Control Valve 0.46 Mcf/year/valve
Directed Inspection and Maintenance at Gate Stations and Surface Facilities Lessons Learned Flange 0.13 Mcf/year/flange
http://www.epa.gov/gasstar/documents/ll_dimgatestat.pdf Gate Valve 0.79 Mcf/year/valve
Pneumatic Vent 134.3 Mcf/year/device
Equipment Component Type Lessons Clearstone
Pressure Relief Valve 4.84 Mcf/year/valve
Type Learned
Connectors 0.11 Mcf/year/connector Natural Gas Natural Gas
Leak Rate Leak Rate
per per
Partners have reported methane emission reductions of 70% of their total methane emissions after
Component Component
programs
implementing directed inspection and maintenance (Mcf/year/at their compressor stations.
(Mcf/year/
component) component)
emissions / Non-compressor related
CalculateGas Plant reductions using the following equation:
Valve 28.74 4.49
ER = Σ{ AF · EF } · 70%
Connection 7.70 0.80
Pressure Relief Valve 4.48 1.18
Where, Blowdown OEL 852.87
ER = Emissions Reductions (Mcf/year)
Open ended line 49.43 24.11
AF = Activity Factor (components replaced)
Flange 101.38
EF = Emissions FactorMeter
(Mcf/year/component) 6.94
Other 82.80
Reciprocating Compressor
References: Blowdown OEL 1,628.74 1,043.06
and Surface Facilities
Directed Inspection and Maintenance at Gate Stations1,541.38
Starter OEL
Open Ended Line
http://www.epa.gov/gasstar/documents/ll_dimgatestat.pdf 111.25
Pressure Relief Valve 354.02 23.87
Compressor Seal 1,655.17 2,582.05
Miscellaneous 145.98
Increase walking survey Direct Measurement Emissions Factor Valve 115.49 Partner Quantified Methane Emissions Reductions
basis Connector 8.83
Crank case vent 932.66
Organic vapor analyzers, toxic vapor analyzers, bagging techniques, high volume samplers, and Methane emissions result from leaks at flanges, valves, and connectors227.39
Other
throughout the gas delivery Natural Gas STAR encourages partners to identify other methods to quantify
Transmission rotameters can be used where appropriate to measure the emissions rates identified leaks. These network. With early detection, methane leaks can be mitigated more promptly, therefore avoiding
Centrifugal Compressor methane emissions reductions. Please identify the basis for any alternate emissions
Distribution can be used to determine the amount of emissions reduced. Blowdown emissions. A program that inspects all services in three years
gas losses and reducing methane OEL 3,318.39 reduction estimate in the annual report.
rather than five years will find about 15% of the leaks a year earlier. Methane emissions reductions
Starter OEL 1,541.38
References: of 1,500 Mcf/year wereOpen Ended Line 14.59
estimated for a distribution system with 250,000 service connections and
Compressor Seal 557.47 62.26
Directed Inspection and Maintenance at Compressor Stations Lessons Learned one leak repair/100 service connections inspected, saving 4.4 Mcf methane/year/repair.
Miscellaneous 72.87
http://www.epa.gov/gasstar/documents/ll_dimcompstat.pdf Flange 132.18
ER = 4.4 Mcf/year/repair · AF
Valve 1.23
Connector 0.15
Where, Pressure Relief Valve 0.00
Meter 0.00
ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (number of repairs)
References:
Increase Walking Survey from a 5-to 3-Year Basis PRO
http://www.epa.gov/gasstar/documents/increasewalkingsurvey.pdf
Install flares Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
Production Typically 98% of natural gas directed to a flare is combusted. Partners report methane emissions savings of 2,000 Mcf/year for flares installed on tank vents, Natural Gas STAR encourages partners to identify other methods to quantify
Processing relief valves, and compressor blowdown; 4,000 Mcf/year for flares installed on low-pressure methane emissions reductions. Please identify the basis for any alternate emissions
Transmission Calculate emissions reductions using the following equation: separators; and 36,000 Mcf/year for flares installed on condensate tanks reduction estimate in the annual report.
ER = 98% · XCH4 · Q
Calculate emissions reductions using the following equation:
Where, ER = Σ{ AF · EF }
ER = Emissions Reductions (Mcf/year)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production), 0.87 Where,
(Processing), 0.934 (Transmission/Distribution) ER = Emissions Reductions (Mcf/year)
Q = Flow rate of gas stream to flare (Mcf/year) AF = Activity Factor (flares installed)
EF = Emissions Factor (Mcf/year/installment type)
References:
Install Flares PRO References:
http://www.epa.gov/gasstar/documents/installflares.pdf Install Flares PRO
http://www.epa.gov/gasstar/documents/installflares.pdf
Other 4
Equipment Component Type On Off
Type Compressor Compressor
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Other
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3 Quantification Method 4
Applicable Sector(s)
Nitrogen rejection unit Process Simulation Partner Quantified Methane Emissions Reductions
(NRU) optimization
The separated nitrogen from a Nitrogen Rejection Unit (NRU) along with a small percentage of Natural Gas STAR encourages partners to identify other methods to quantify methane emissions
Production methane is often vented to the atmosphere through a reject stream. The methane component can reductions. Please identify the basis for any alternate emissions reduction estimate in the annual
Processing be minimized with a unit specific process model and addition of monitoring and tracking equipment report.
such as a gas chromatograph. Process adjustments, exchanger cleaning, and other maintenance
based on the recommendations developed from the advanced NRU model reduces the methane
content.
References:
Equipment Component Type Lessons Clearstone
Nitrogen Rejection Unit Optimization PRO Type Learned
http://www.epa.gov/gasstar/documents/nruoptimization.pdf Natural Gas Natural Gas
Leak Rate Leak Rate
per per
Component Component
(Mcf/year/ (Mcf/year/
component) component)
Gas Plant / Non-compressor related
Valve 28.74 4.49
Require improvements in Emission Factor Partner Quantified Methane Emissions Reductions
Connection 7.70 0.80
quality of gas received Pressure Relief Valve 4.48 1.18
from producers Low quality natural gas can lead to excessive filtration unit liquid recovery and transmission line methods
Natural Gas STAR encourages partners to identify other852.87 to quantify methane emissions
Blowdown OEL
cleanings at compressor stations. Emissions reductions will vary based on venting from line 49.43 24.11
Open ended for any alternate emissions reduction estimate in the annual
reductions. Please identify the basis
Flange 101.38
Transmission accumulated liquids in atmospheric storage tanks and line cleaning frequency. One Partner has report.
Meter 6.94
Distribution reported methane reductions of more than 500 Mcf for one year based on a 600 psig system. Other 82.80
Reciprocating Compressor
ER = 500 Mcf/year/station · AF Blowdown OEL 1,628.74 1,043.06
Starter OEL 1,541.38
Open Ended Line 111.25
Where,
Pressure Relief Valve 354.02 23.87
ER = Emissions Reductions (Mcf/year) Compressor Seal 1,655.17 2,582.05
AF = Activity Factor (number of stations) Miscellaneous 145.98
Valve 115.49
References: Connector 8.83
Crank case vent 932.66
Require Improvements in the Quality of Gas Received from Producers PRO
Other 227.39
http://www.epa.gov/gasstar/documents/requireimprovements.pdf Centrifugal Compressor
Blowdown OEL 3,318.39
Starter OEL 1,541.38
Open Ended Line 14.59
Compressor Seal 557.47 62.26
Miscellaneous 72.87
Flange 132.18
Valve 1.23
Connector 0.15
Pressure Relief Valve 0.00
Meter 0.00
Other 5
Equipment Component Type On Off
Type Compressor Compressor
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Dehydrators
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Convert gas-driven Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
chemical pumps to
instrument air Annual methane emissions can be calculated using the following three steps: Partners report 2,500 Mcf/year of methane emissions are reduced for every gas driven chemical Natural Gas STAR encourages partners to identify other
pump converted to use instrument air. methods to quantify methane emissions reductions. Please
Production 1) Calculate water removal rate, WR (pounds water removed/MMcf gas processed) using the identify the basis for any alternate emissions reduction
Processing following graph which is also in the Lessons Learned document: Calculate emissions reductions using the following equation: estimate in the annual report.
Transmission ER = AF · 2,500 Mcf/year/pump converted
Distribution
Where,
ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (number of gas driven chemical pumps converted to instrument air)
References:
Convert Gas Driven Chemical Pumps to Instrument Air PRO
http://www.epa.gov/gasstar/documents/convertgasdrivenchemicalpumpstoinstrumentair.pdf
Dehydrators 1
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Dehydrators
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
2) Calculate the gas-assisted pump emissions factor using the following equation:
EF = PGU · G · WR · OC
Where,
EF = Emissions Factor (scf methane emitted/MMcf gas processed)
PGU = Pump gas usage (scf methane emitted/gallon of glycol) - default is 2 scf/gallon
G = Glycol-to-water ratio (gallon glycol/pound water removed) - default is 3 gallon/pound
WR = Water removal rate (pound water removed/MMcf gas processed)
OC = Over circulation ratio - default is 1 for no overcirculation, 2.1 for overcirculation
3) Calculate emissions reductions using the following equation:
ER = AF · EF / 1,000scf/Mcf
Where,
ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (MMcf gas processed annually)
References:
Replacing Gas-Assisted Glycol Pumps with Electric Pumps Lessons Learned
http://www.epa.gov/gasstar/documents/ll_glycol_pumps3.pdf
Install flash tank Process Simulation Emissions Factor Partner Quantified Methane Emissions Reductions
separators on dehydrators
To estimate flash tank separator savings, use process simulation software such as GRI-GLYCalc Installing flash tank separators on glycol dehydrators can save 90% of otherwise vented methane Natural Gas STAR encourages partners to identify other
Production TM. emissions. methods to quantify methane emissions reductions. Please
Processing identify the basis for any alternate emissions reduction
Transmission References: Calculate emissions reductions using the following equation: estimate in the annual report.
Optimize Glycol Circulation and Install Flash Tank Separators in Glycol Dehydrators Lessons ER = 90% · (L · G · O / 1,000scf/Mcf)
Learned
http://www.epa.gov/gasstar/documents/ll_flashtanks3.pdf Where,
ER = Emissions Reductions (Mcf/year)
O = Annual operating time of the dehydrator (hours) - default is 8,760 hours
L = Glycol circulation rate (gallon/hour)
G = Methane entrainment rate (scf/gallon) - default is 3 scf/gallon for a gas-powered energy-
exchange pump
References:
Optimize Glycol Circulation and Install Flash Tank Separators in Glycol Dehydrators Lessons
Learned
http://www.epa.gov/gasstar/documents/ll_flashtanks3.pdf
Dehydrators 2
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Dehydrators
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Replace glycol dehydration Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
units with methanol
injection Replacing glycol dehydration with methanol injection reduces all emissions associated with the Partners report replacing glycol dehydrators with methanol injection units saves 800 Mcf/installation Natural Gas STAR encourages partners to identify other
glycol dehydrator. Typically the methane makes up 90% of this gas. methods to quantify methane emissions reductions. Please
Production Calculate emissions reductions using the following equation: identify the basis for any alternate emissions reduction
Processing Total annual methane emissions savings can be calculated in 3 steps: ER = AF · 800 Mcf/year estimate in the annual report.
1) Calculate gas vented from the glycol dehydrator using the following equation: Where,
GV = VEF · VAF · VOF ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (number of installations)
Where,
GV = Gas vented (Mcf/year) References:
Replace Glycol Dehydrators with Methanol Injection PRO
Glycol dehydrator with gas pump without flash tank separator http://www.epa.gov/gasstar/documents/methanol_injection.pdf
VEF = 0.333 Mcf/MMcf throughput
Glycol dehydrator with gas pump with flash tank separator
VEF = 0.008 Mcf/MMcf throughput
Glycol dehydrator with electric pump without flash tank separator
VEF = 0.087 Mcf/MMcf throughput
Glycol dehydrator with electric pump with flash tank separator
VEF = 0.007 Mcf/MMcf throughput
VAF = Activity Factor (MMcf throughput/day)
VOF = Operating factor (days of operation/year)
2) Calculate the gas vented from pneumatic controllers using the following equation:
GB = EF · PD
Where,
GB = Gas bleed (Mcf/year)
EF = Emissions Factor (Mcf methane bleed/pneumatic device/year) - default is 126 Mcf/device/year
PD = Number of pneumatic devices (devices/dehydrator) - default is 4 devices/dehydrator
3) Calculate emissions reductions using the following equation:
ER = (GV + GB)
Where,
ER = Emissions Reductions (Mcf/year)
GV = Gas vented from glycol dehydrator (Mcf/year)
GB = Gas bled by pneumatic controllers (Mcf/year)
References:
Replace Glycol Dehydration Units with Methanol Injection PRO
http://www.epa.gov/gasstar/documents/methanol_injection.pdf
API. Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Gas Industry. Pg 5-
4. API, February 2004.
Dehydrators 3
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Dehydrators
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Pipe glycol dehydrator to Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
vapor recovery unit (VRU)
The methane savings of piping glycol dehydrators to VRUs can be estimated by calculating the Partners report for a 10 MMcf/day glycol dehydrator, piping to the vapor recovery unit will save Natural Gas STAR encourages partners to identify other
Production glycol dehydrator's vented emissions. Vapor recovery units will recover 95% of vapors. 3,300 Mcf/year methods to quantify methane emissions reductions. Please
Processing identify the basis for any alternate emissions reduction
Transmission Calculate gas vented from the glycol dehydrator using the following equation: Use the following equation to determine the annual methane emissions: estimate in the annual report.
ER = VEF · VAF · VOF · 95% E = Q · 330 Mcf/year/(MMcf/day)
Where, Where,
ER = Emissions Reductions (Mcf/year) E = Annual Emissions (Mcf/year)
Q = Throughput to dehydrator piped to VRU (MMcf/day)
Glycol dehydrator with gas pump without flash tank separator
VEF = 0.333 Mcf/MMcf throughput References:
Glycol dehydrator with gas pump with flash tank separator Pipe Glycol Dehydrator to Vapor Recovery Unit
VEF = 0.008 Mcf/MMcf throughput http://www.epa.gov/gasstar/documents/pipeglycoldehydratortovru.pdf
Glycol dehydrator with electric pump without flash tank separator
VEF = 0.087 Mcf/MMcf throughput
Glycol dehydrator with electric pump with flash tank separator
VEF = 0.007 Mcf/MMcf throughput
VAF = Activity Factor (MMcf throughput/day)
VOF = Operating factor (days of operation/year)
References:
Pipe Glycol Dehydrators to Vapor Recover Unit PRO
http://www.epa.gov/gasstar/documents/pipeglycoldehydratortovru.pdf
Replace Glycol Dehydrators with Desiccant Dehydrators Lessons Learned
http://www.epa.gov/gasstar/documents/ll_desde.pdf
API. Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Gas Industry. Pg 5-
4. API, February 2004.
Dehydrators 4
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Dehydrators
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Install portable desiccant Partner Quantified Methane Emissions Reductions Engineering Calculation
dehydrators
Methane emission reductions from using portable desiccant dehydrators during glycol dehydrator Methane savings are based on a nominal gas well that vents 30 Mcf/day. Portable desiccant
Production maintenance are highly variable. Factors such as well production rate and glycol dehydrator dehydrators are economical when used on gas wells larger than the average (15.6 Mcf/day) gas
maintenance period will affect methane emission reductions for each specific application. Natural stripper well. Set-up and removal of the portable desiccant dehydrator is assumed to take three
Gas STAR encourages partners to identify other methods to quantify methane emissions days each, meaning it is only in operation for a two day glycol dehydrator maintenance period.
reductions. Please identify the basis for any alternate emissions reduction estimate in the annual
report. ER = P · (1day/24 hours) · T · AF · XCH4
Where,
ER = Emission Reductions (Mcf/year)
P = Normal well production rate from the lease meter (Mcf/day)
T = Number of hours that gas is not vented during glycol dehydrator maintenance (hours/year) -
default is 48 hours/year
AF = Activity Factor (Number of applications/year)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production)
References:
Portable Desiccant Dehydrators PRO
http://www.epa.gov/gasstar/documents/portabledehy.pdf
Replace glycol dehydrator Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
with separators and in-line
heaters Replacing glycol dehydration with separators reduces all emissions associated with the glycol Partners report reductions of 800 Mcf/year/replacement of glycol dehydrator with separators and in- Natural Gas STAR encourages partners to identify other
dehydrator. Typically the methane makes up 90% of this gas. Total annual methane emissions line heaters to drop out the water. methods to quantify methane emissions reductions. Please
Transmission savings can be calculated in 4 steps: identify the basis for any alternate emissions reduction
Distribution Calculate emissions reductions using the following equation: estimate in the annual report.
1) Calculate gas vented from the glycol dehydrator using the following equation: ER = AF · 800 Mcf/year/replacement
GV = VEF · VAF · VOF
Where,
GV = Gas vented (Mcf/year) ER = Emissions Reductions (Mcf/year)
Glycol dehydrator with gas pump without flash tank separator AF = Activity Factor (replacements/year)
VEF = 0.333 Mcf/MMcf throughput
Glycol dehydrator with gas pump with flash tank separator References:
VEF = 0.008 Mcf/MMcf throughput Replace Glycol Dehydrator with Separators and In-line Heaters PRO
Glycol dehydrator with electric pump without flash tank separator http://www.epa.gov/gasstar/documents/replaceglycoldehydratorwithseparators.pdf
VEF = 0.087 Mcf/MMcf throughput
Glycol dehydrator with electric pump with flash tank separator
VEF = 0.007 Mcf/MMcf throughput
VAF = Activity Factor (MMcf throughput/day)
VOF = Operating factor (days of operation/year)
2) Calculate the gas vented from pneumatic controllers using the following equation:
GB = EF · PD
Dehydrators 5
ER = AF · 800 Mcf/year/replacement
Where,
ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (replacements/year)
References:
Replace Glycol Dehydrator with Separators and In-line Heaters PRO
http://www.epa.gov/gasstar/documents/replaceglycoldehydratorwithseparators.pdf
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Dehydrators
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Where,
GB = Gas bleed (Mcf/year)
EF = Emissions Factor (Mcf methane bleed/pneumatic device/year) - default is 126 Mcf/device/year
PD = Number of pneumatic devices (devices/dehydrator) - default is 4 devices/dehydrator
3) Calculate emissions from separators using the following equation:
SE = WR · 0.00000441 Mcf/gallon water
Where,
SE = Separator emissions (Mcf/year)
WR = Water removal rate (gallon water/year)
4) Calculate emissions reductions using the following equation:
ER = GV + GB - SE
Where,
ER = Emissions Reductions (Mcf/year)
GV = Gas vented from glycol dehydrator (Mcf/year)
GB = Gas bled by pneumatic controllers (Mcf/year)
SE = Separator emissions (Mcf/year)
References:
Replace Glycol Dehydrator with Separators and In-line Heaters PRO
http://www.epa.gov/gasstar/documents/replaceglycoldehydratorwithseparators.pdf
Replacing Glycol Dehydrators with Desiccant Dehydrators Lessons Learned
http://www.epa.gov/gasstar/documents/ll_desde.pdf
API. Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Gas Industry. Pg 5-
4. API, February 2004.
Dehydrators 6
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Dehydrators
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Replacing gas-assisted Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
glycol pumps with electric
pumps Emissions reductions can be calculated using the following three steps: On a national average, gas-assisted glycol pumps require an additional 177.75 scf of Natural Gas STAR encourages partners to identify other
methane/MMcf gas processed for mechanical advantage. Installing electric pumps eliminates these methods to quantify methane emissions reductions. Please
Production 1) Calculate water removal rate, WR (pound water removed/MMcf gas processed) using the additional methane emissions. identify the basis for any alternate emissions reduction
Processing following graph: estimate in the annual report.
Transmission Calculate emissions reductions using the following equation:
ER = AF · 177.75 scf methane/MMcf gas processed
Where,
ER = Emissions Reductions (scf/year)
AF = Activity Factor (MMcf gas processed annually)
References:
EPA Inventory of US Greenhouse Gas Emissions and Sinks: 1990 - 2004
http://www.epa.gov/climatechange/emissions/downloads06/06_Complete_Report.pdf
2) Calculate the gas-assisted pump emissions factor using the following equation:
EF = PGU · G · WR · OC
Where,
EF = Emissions Factor (scf methane emitted/MMcf gas processed)
PGU = Pump gas usage (scf methane emitted/gallon of glycol) - default is 2 scf/gallon
G = Glycol-to-water ratio (gallon glycol/pound water removed) - default is 3 gallon/pound
WR = Water removal rate (pound water removed/MMcf gas processed)
OC = Over circulation ratio - default is 1 for no overcirculation, 2.1 for overcirculation
3) Calculate emissions reductions using the following equation:
ER = AF · EF / 1,000scf/Mcf
Where,
ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (MMcf gas processed annually)
References:
Replacing Gas-Assisted Glycol Pumps with Electric Pumps Lessons Learned
http://www.epa.gov/gasstar/documents/ll_glycol_pumps3.pdf
Dehydrators 7
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Dehydrators
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Replacing glycol Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
dehydrators with desiccant
dehydrators The methane savings of replacing glycol dehydrators with desiccant dehydrators can be calculated Partners report that replacing glycol dehydrators with desiccant dehydrators saves and average of Natural Gas STAR encourages partners to identify other
by subtracting the desiccant dehydrator's vented methane emissions from the combination of the 69 Mcf/year/(MMcf/day) methods to quantify methane emissions reductions. Please
Production gas emitted by the glycol dehydrator and its pneumatic controllers. identify the basis for any alternate emissions reduction
Processing Calculate emissions reductions using the following equation: estimate in the annual report.
Total annual methane emissions savings can be calculated in four steps: ER = Q · 69 Mcf/year
1) Calculate gas vented from the glycol dehydrator using the following equation: Where,
GV = VEF · VAF · VOF ER = Emissions Reductions (Mcf/year)
Q = Throughput to desiccant dehydrators replacing glycol dehydrators (MMcf/day)
Where,
GV = Gas vented (Mcf/year) References:
Replace Glycol Dehydrators with Desiccant Dehydrators Lessons Learned
Glycol dehydrator with gas pump without flash tank separator http://www.epa.gov/gasstar/documents/ll_desde.pdf
VEF = 0.333 Mcf/MMcf throughput
Glycol dehydrator with gas pump with flash tank separator
VEF = 0.008 Mcf/MMcf throughput
Glycol dehydrator with electric pump without flash tank separator
VEF = 0.087 Mcf/MMcf throughput
Glycol dehydrator with electric pump with flash tank separator
VEF = 0.007 Mcf/MMcf throughput
VAF = Activity Factor (MMcf throughput/day)
VOF = Operating factor (days of operation/year)
2) Calculate the gas vented from pneumatic controllers using the following equation:
GB = EF · PD
Where,
GB = Gas bleed (Mcf/year)
EF = Emissions Factor (Mcf methane bleed/pneumatic device/year) - default is 126 Mcf/device/year
PD = Number of pneumatic devices (devices/dehydrator) - default is 4 devices/dehydrator
3) Calculate the gas lost from desiccant dehydrators using the following equation:
GLD = (H · D^2 · π · P2 · %G · 365days/year) / (4 · P1 · T · 1,000scf/Mcf)
Where,
GLD = Gas loss from desiccant dehydrator (Mcf/year)
H = Height of dehydrator vessel (ft) - default is 6.4 ft
D = Diameter of the vessel (ft) - default is 1.6 ft
P1 = Atmospheric pressure (psia) - default is 14.7psia
P2 = Pressure of gas (psig)
%G = Percent of packed vessel volume that is gas - default is 0.45
T = Time between refilling (days) - default is 7 days
Dehydrators 8
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Dehydrators
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
4) Calculate emissions reductions using the following equation:
ER = (GV + GB) - (GLD · XCH4)
Where,
ER = Emissions Reductions (Mcf/year)
GV = Gas vented from glycol dehydrator (Mcf/year)
GB = Gas bled by pneumatic controllers (Mcf/year)
GLD = Gas loss from desiccant dehydrator (Mcf/year)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788
References:
Replacing Glycol Dehydrators with Desiccant Dehydrators Lessons Learned
http://www.epa.gov/gasstar/documents/ll_desde.pdf
API Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Gas Industry. Page
5-4. API, February 2004.
Reroute glycol skimmer Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
gas
Rerouting the non-condensable skimmer gas from the reboiler vent gas condenser can prevent Partners report rerouting the glycol skimmer gas to the reboiler firebox or other low pressure fuel Natural Gas STAR encourages partners to identify other
Production vented methane emissions to the atmosphere. gas systems can save 7,600 Mcf/dehydrator/year methods to quantify methane emissions reductions. Please
Processing identify the basis for any alternate emissions reduction
Transmission Calculate emissions reductions using the following equation: Calculate emissions reductions using the following equation: estimate in the annual report.
Distribution ER = (L · G · O / 1,000 scf/Mcf) ER = AF · 7,600 Mcf/dehydrator/year
Where, Where,
ER = Emissions Reductions (Mcf/year) ER = Emissions Reductions (Mcf/year)
O = Annual operating time of the dehydrator (hours) - default is 8,760 hours AF = Activity Factor (number of dehydrators)
L = Glycol circulation rate (gallon/hour)
G = Methane entrainment rate (scf/gallon) - default is 3 scf/gallon (energy-exchange pump) or 1 References:
scf/gallon (electric pump) Reroute Glycol Skimmer Gas PRO
http://www.epa.gov/gasstar/documents/rerouteglycolskimmer.pdf
References:
Optimize Glycol Circulation and Install Flash Tank Separators in Glycol Dehydrators Lessons
Learned
http://www.epa.gov/gasstar/documents/ll_flashtanks3.pdf
Dehydrators 9
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Dehydrators
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Zero emissions Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
dehydrators
Replacing a conventional glycol dehydrator with a zero emissions reduces all methane emissions The methane emission savings are based on a conventional dehydrator processing 28 MMcf/day Natural Gas STAR encourages partners to identify other
Production associated with the glycol dehydrator vent stack and gas pneumatic controllers. with a glycol circulation rate of 4 gallons/minute. The zero emissions dehydrator eliminates methods to quantify methane emissions reductions. Please
Processing emissions from glycol circulation pumps, gas strippers, pneumatic devices, and the majority of the identify the basis for any alternate emissions reduction
Transmission Total annual methane emissions savings can be calculated in 3 steps: still column effluent. estimate in the annual report.
Distribution
1) Calculate gas vented from the glycol dehydrator using the following equation: ER = 31,400 Mcf/dehydrator/year · AF · XCH4
GV = VEF · VAF · VOF
Where,
Where, ER = Emission Reductions (Mcf/year)
GV = Gas vented (Mcf/year) AF = Activity Factor (Number of zero emissions dehydrators installed)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.87 (Processing), 0.934
Glycol dehydrator with gas pump without flash tank separator (Transmission)
VEF = 0.333 Mcf/MMcf throughput
Glycol dehydrator with gas pump with flash tank separator References:
VEF = 0.008 Mcf/MMcf throughput Zero Emissions Dehydrators PRO
Glycol dehydrator with electric pump without flash tank separator http://www.epa.gov/gasstar/documents/zeroemissionsdehy.pdf
VEF = 0.087 Mcf/MMcf throughput
Glycol dehydrator with electric pump with flash tank separator
VEF = 0.007 Mcf/MMcf throughput
VAF = Activity Factor (MMcf throughput/day)
VOF = Operating factor (days of operation/year)
2) Calculate the gas vented from pneumatic controllers using the following equation:
GB = EF · PD
Dehydrators 10
AF = Activity Factor (Number of zero emissions dehydrators installed)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.87 (Processing), 0.934
(Transmission)
References:
Zero Emissions Dehydrators PRO
http://www.epa.gov/gasstar/documents/zeroemissionsdehy.pdf
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Dehydrators
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Where,
GB = Gas Bleed (Mcf/year)
EF = Emissions Factor (Mcf methane bleed/pneumatic device/year) - default is 126 Mcf/device/year
PD = Number of pneumatic devices (devices/dehydrator) - default is 4 devices/dehydrator
3) Calculate emissions reductions using the following equation:
ER = (GV + GB)
Where,
ER = Emissions Reductions (Mcf/year)
GV = Gas vented from glycol dehydrator (Mcf/year)
GB = Gas bled by pneumatic controllers (Mcf/year)
References:
Zero Emissions Dehydrators PRO
http://www.epa.gov/gasstar/documents/zeroemissionsdehy.pdf
ETV Joint Verification Statement - Quantum Leap Dehydrator
http://www.epa.gov/etv/pdfs/vrvs/03_vs_quantum.pdf
API Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Gas Industry. Page
5-4. API, February 2004.
Dehydrators 11
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Pipelines
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Composite wrap repair Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
Production Installing composite wrap opposed to replacing pipelines with defects saves the methane that The volume of methane emissions saved by composite wrap is very sensitive to the specific details Natural Gas STAR encourages partners to identify other methods to quantify
Processing would otherwise be vented to the atmosphere during replacement. of the operation - pipeline length, pipeline diameter, and system pressure. If these quantities are methane emissions reductions. Please identify the basis for any alternate
Transmission known it is suggested to use the engineering calculation for better accuracy, otherwise Partners emissions reduction estimate in the annual report.
Distribution Calculate emissions reductions by summing over all pipeline diameters and pressures: report composite wrap can save 3,960 Mcf/installment.
ER = Σ{ (D^2 · P · [L/1,000] · 0.372) / 1,000 } · XCH4
Calculate emissions reductions using the following equation:
Where, ER = AF · 3,960 Mcf/installment
ER = Emissions Reductions (Mcf/year)
D = Inside diameter of pipeline (inches) Where,
L = Length of pipeline between shutoff valves (feet) ER = Emissions Reductions (Mcf/year)
P = Pipeline pressure (psia for less than 50psi, psig for more than 50psi) AF = Activity Factor (number of installments/year)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.87 (Processing), 0.934 (EF assumed repair of a 6" defect on a 24" diameter pipeline at 350psig with 10 miles between
(Transmission/Distribution) shutoff valves.)
References: References:
Composite Wrap for Non-Leaking Pipeline Defects Lessons Learned Composite Wrap for Non-Leaking Pipeline Defects Lessons Learned
http://www.epa.gov/gasstar/documents/ll_compwrap.pdf http://www.epa.gov/gasstar/documents/ll_compwrap.pdf
Identify and rehabilitate Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
leaky distribution pipes
To determine the leakage in MMcf/year at a reference pressure of 14.4 psia and temperature of Emissions reductions from repairing leaking distribution pipelines depends on the pipeline material. Natural Gas STAR encourages partners to identify other methods to quantify
Distribution 60°F, take as a basis a one mile section of line under one hour test. methane emissions reductions. Please identify the basis for any alternate
Material EF emissions reduction estimate in the annual report.
Calculate emissions reductions using the following equation: Mains - cast iron 238.7 Mcf/mile/year
ER = 9 · D^2 · [ (P1/(460+T1)) - (P2/(460+T2)) ] · L · XCH4 Mains - unprotected steel 110.53 Mcf/mile/year
Mains - protected steel 3.13 Mcf/mile/year
Where, Mains - plastic 12 Mcf/mile/year
ER = Emissions Reductions (MMcf/year) Services - unprotected steel 1.71 Mcf/service/year
D = Diameter of pipe (inches) Services - protected steel 0.18 Mcf/service/year
P1 = Pressure at the beginning of the test (psia) Services - plastic 0.01 Mcf/service/year
T1 = Temperature at the beginning of the test (°F) Services - copper 0.25 Mcf/service/year
P2 = Pressure at the end of the test (psia)
T2 = Temperature at the end of the test (°F) Calculate the emissions reductions using the following equation:
L = Length of pipeline (miles) ER = AF · EF
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.934 (Distribution)
Where,
References: ER = Emissions Reductions (Mcf/year)
Pipe Line Rules of Thumb Handbook 4th Edition, page 271 AF = Activity Factor (miles of main replaced or number of services replaced)
EF = Emissions Factor (Mcf/mile/year or Mcf/service/year)
References:
EPA/GRI Methane Emissions from the Natural Gas Industry Volume 9: Underground Pipelines
(1996)
http://www.epa.gov/gasstar/documents/emissions_report/9_underground.pdf
Pipelines 1
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Pipelines
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Inject blowdown gas into Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
low pressure system
Methane emissions savings can be derived from the measurement of gas flow routed to the low Methane emissions reduction levels are site specific and depend on the operating pressure of the Natural Gas STAR encourages partners to identify other methods to quantify
Production pressure main. compressors and low-pressure mains used for the blowdown, as well as the selected injection methane emissions reductions. Please identify the basis for any alternate
Processing technology (e.g. simple piping connection versus portable compressor). Partners have reported emissions reduction estimate in the annual report.
Transmission Calculate emissions reductions summing over all practices within the year: methane savings of 15 Mcf/compressor blowdown.
Distribution ER = Σ{ FR · XCH4 · OF }
Calculate emissions reductions using the following equation:
Where, ER = AF · 15 Mcf/blowdown
ER = Emissions Reductions (volume/year)
FR = Flow Rate (directly measured) Where,
OF = Operating factor (time operated) ER = Emissions Reductions (Mcf/year)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.934 AF = Activity Factor (compressor blowdowns captured/year)
(Transmission/Distribution)
References:
References: Inject Blowdown Gas into Low Pressure Mains PRO
Inject Blowdown Gas into Low Pressure Mains PRO http://www.epa.gov/gasstar/documents/injectblowdowngas.pdf
http://www.epa.gov/gasstar/documents/injectblowdowngas.pdf
Insert gas main flexible Direct Measurement Distribution Emissions Factor Partner Quantified Methane Emissions Reductions
liners
Use a high volume sampler to estimate the leakage rate of a pipe without plastic liners and then Methane emissions reductions come from the reduced leakages in plastic piping relative to cast Natural Gas STAR encourages partners to identify other methods to quantify
Production that of a pipe with plastic liners. The difference will be the emissions reductions. iron piping. Plastic pipelines in distribution mains have been measured to emit 101,897 methane emissions reductions. Please identify the basis for any alternate
Processing scf/mile/year, while for cast iron pipes emit 389,867 scf/mile/year. emissions reduction estimate in the annual report.
Transmission References:
Distribution Insert Gas Main Flexible Liners PRO Calculate emissions reductions using the following equation:
http://www.epa.gov/gasstar/documents/insertgasmainflexibleliners.pdf ER = AF · (389,867 - 101,897)scf/mile/year / 1,000scf/Mcf
Where,
ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (miles of cast iron pipeline with inserted plastic liners)
References:
Insert Gas Main Flexible Liners PRO
http://www.epa.gov/gasstar/documents/insertgasmainflexibleliners.pdf
EPA/GRI Methane Emissions from the Natural Gas Industry Volume 9: Underground Pipelines
(1996)
http://www.epa.gov/gasstar/documents/emissions_report/9_underground.pdf
Pipelines 2
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Pipelines
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Inspect flowlines annually Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
Production Use bagging techniques or a high volume sampler to determine the methane leakage from Partners report 53.2 scf/mile/day of methane is saved from detecting leaks in production Natural Gas STAR encourages partners to identify other methods to quantify
inspected and repaired pipelines. underground pipelines. methane emissions reductions. Please identify the basis for any alternate
emissions reduction estimate in the annual report.
References: Calculate emissions reduction using the following equation:
Replacing Wet Seals with Dry Seals in Centrifugal Compressors Lessons Learned ER = AF · 53.2 scf/mile/day · 365 days/year
http://www.epa.gov/gasstar/documents/ll_wetseals.pdf
Where,
ER = Emissions Reductions (scf/year)
AF = Activity Factor (miles of pipeline)
References:
Inspect Flowlines Annually PRO
http://www.epa.gov/gasstar/documents/inspectflowlines.pdf
Install ejector Partner Quantified Methane Emissions Reductions Direct Measurement Engineering Calculation
Production Methane emission reductions from installing ejectors are highly variable. Factors such as pipeline When pipelines are taken out of service, an ejector can suck gas from the pipeline and insert it into When pipelines are taken out of service, an ejector can suck gas from the
Transmission size, pipeline pressure, conduit size, and the pressure of pipeline to which the gas is deposited will another pipeline at moderate pressure, thus avoiding a blowdown. Use a high volume sampler or pipeline and insert it into another pipeline at moderate pressure, avoiding a
Distribution affect methane emission reductions for each specific application. Natural Gas STAR encourages rotameter to determine the volume of gas evacuated from a system about to be taken out of service blowdown.
partners to identify other methods to quantify methane emissions reductions. Please identify the and multiply by the methane content of the gas to determine the volume of emissions reductions.
basis for any alternate emissions reduction estimate in the annual report. Calculate emissions reductions using the following equation:
References: ER = ΔP · V · XCH4 · 0.035366 / (T + 460)
Install Ejector PRO
http://www.epa.gov/gasstar/documents/installejector.pdf Where,
ER = Emissions Reductions (Mcf/year)
ΔP = Pressure change (psi)
V = Volume of equipment between block valves (cubic feet)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788
(Production), 0.934 (Transmission/Distribution)
T = Temperature (°F)
References:
Install Ejector PRO
http://www.epa.gov/gasstar/documents/installejector.pdf
Pipelines 3
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Pipelines
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Install rupture pin shutoff Partner Quantified Methane Emissions Reductions Engineering Calculation
device to reduce venting
Methane emission reductions from installing "rupture pin" shutoff devices are highly variable. Rupture pin devices respond to over-pressurized systems by closing them off opposed to venting
Transmission Factors such as shut-in time, operating conditions, and frequency of pressure upsets will affect excess flow through a valve.
methane emission reductions for each specific application. Natural Gas STAR encourages
partners to identify other methods to quantify methane emissions reductions. Please identify the Calculate emissions reductions summing across all instances of rupture pin devices relieving
basis for any alternate emissions reduction estimate in the annual report. pressure upsets throughout the year:
ER = Σ{ R · T }
Where,
ER = Emissions Reductions (Mcf/year)
R = Design flowrate of relief device (scf/hour)
T = Time between shut-in (hours)
References:
Partner Update Winter 2004 - Technology Spotlight
http://epa.gov/gasstar/documents/rupture_pin_shutoff.pdf
Perform leak repair during Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
pipeline replacement
Gate valves in the vicinity of ongoing pipeline repair work can be directly measured and repaired The volume of avoided emissions is based on the typical leak rates through gate valves (130 Natural Gas STAR encourages partners to identify other methods to quantify
Transmission cost-effectively. Methane emissions savings can be measured by testing the leaking gate valves Mcf/year) and gate valve stem packing (120 Mcf/year). methane emissions reductions. Please identify the basis for any alternate
Distribution and their stem packing. Leakage through gate valve stem packing can be measured with a high emissions reduction estimate in the annual report.
volume sampler. Leakage through the valve may require use of stopples and a rotameter to isolate Calculate emissions reductions using the following equation:
and measure leakage. Maintaining these is assumed to curb 100% of the measured methane ER = (VR · 130Mcf/year/valve) + (SR · 120Mcf/year/stem)
emissions.
Where,
References: ER = Emissions Reductions (Mcf/year)
Perform Leak Repair During Pipeline Replacement PRO VR = Valves maintained (number of valves in maintenance)
http://www.epa.gov/gasstar/documents/performleakrepairduringpipelinereplacement.pdf SR = Gate valve stem packing replacements (number of stem packings replaced in maintenance)
References:
Perform Leak Repair During Pipeline Replacement PRO
http://www.epa.gov/gasstar/documents/performleakrepairduringpipelinereplacement.pdf
Directed Inspection and Maintenance at Gate Stations and Surface Facilities Lessons Learned
http://www.epa.gov/gasstar/documents/ll_dimgatestat.pdf
Pipelines 4
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Pipelines
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Recover gas from pipeline Partner Quantified Methane Emissions Reductions Engineering Calculation Engineering Calculation - Graph
pigging operations
Methane emission reductions from recovering gas from pigging are highly variable. Factors such Condensate recovered in pigging operations is commonly sent to a tank at atmospheric pressure. Condensate recovered in pigging operations is commonly sent to a tank at
Production as condensate composition, storage conditions, and operation conditions will affect methane The gas that flashes off is vented to the atmosphere unless recovered. Hydrocarbon condensate atmospheric pressure. The gas that flashes off is vented to the atmosphere
Processing emission reductions for each specific application. Natural Gas STAR encourages partners to tank flashing can be estimated with the Vasquez-Beggs equation. For light condensate (with unless recovered. The graph below can be used to estimate the gas-oil ratio
Transmission identify other methods to quantify methane emissions reductions. Please identify the basis for any gravity much higher than 58), this equation becomes less reliable. VRU recovery rate is based on (GOR) from hydrocarbon condensate tank venting.
Distribution alternate emissions reduction estimate in the annual report. a 95% operating factor.
Calculate emissions reductions using the following equations:
ER = 95% · (GOR · Q) · 1Mcf/1,000scf · XCH4 · OF
Where,
ER = Emission Reductions (Mcf/year)
GOR = Ratio of flash gas production to standard stock tank barrels of oil produced, in scf/barrel oil
(barrels of oil corrected to 60°F)
Q = Oil throughput (barrels/year) Calculate emissions reductions using the following equation:
Gflash gas = Specific gravity of the tank flash gas, where air = 1 (default is 1.22) ER = (GOR · Q) · 1Mcf/1,000scf · XCH4 · OF
Goil = API gravity of stock tank oil at 60°F (ºAPI)
Psep = Pressure in separator (psig) Where,
Tsep = Temperature in separator (°F) ER = Emission Reductions (Mcf/year)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.335 (hydrocarbon condensate) GOR = Ratio of flash gas production to standard stock tank barrels of oil
OF = Operating factor - default is 95% produced, in scf/barrel oil (barrels of oil corrected to 60°F)
Q = Oil throughput (barrels/year)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.335
For Goil > 30º API: (hydrocarbon condensate)
A = 0.0178, B = 1.187, C = 23.931 OF = Operating factor - default is 95%
References: References:
API. Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Gas Industry. Pg 5- Installing Vapor Recovery Units on Crude Oil Storage Tanks Lessons Learned
34. API, February 2004. http://www.epa.gov/gasstar/documents/ll_final_vap.pdf
Pipelines 5
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Pipelines
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Use inert gas/pigs for Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
pipeline purges
The volume of methane saved by using inert gases to push pigs through pipelines being purged is The volume of methane saved by using inert gases to push pigs through pipelines being purged is Natural Gas STAR encourages partners to identify other methods to quantify
Processing equal to the volume of methane within that section of pipeline that would have been purged to the equal to the volume of methane within that section of pipeline that would have been purged to the methane emissions reductions. Please identify the basis for any alternate
Transmission atmosphere. atmosphere. On average, 31.65 Mcf of methane/year/mile of pipeline is purged to the atmosphere emissions reduction estimate in the annual report.
Distribution by venting.
Calculate emissions reductions for each instance of using inert gases and pigs to purge pipelines
and then sum for all instances: Calculate emissions reductions using the following equation:
ER = Σ{ 0.000372 · XCH4 · D^2 · P · L/1,000feet } ER = 31.65 Mcf/year/mile · AF
Where, Where,
ER = Emissions Reductions (Mcf/year) ER = Emissions Reductions (Mcf/year)
XCH4 = Mole fraction of methane in the gas (decimal) -default is 0.934 (Transmission) AF = Activity Factor (total miles of pipeline subject to maintenance)
D = Inside diameter of pipe (inches)
P = Pressure of pipe (psig) References:
L = Length of pipeline segment (feet) Use Inert Gases and Pigs to Perform Pipeline Purges PRO
http://www.epa.gov/gasstar/documents/useinertgases.pdf
References:
Use Inert Gases and Pigs to Perform Pipeline Purges PRO EPA Inventory of US Greenhouse Gas Emissions and Sinks: 1990 - 2004
http://www.epa.gov/gasstar/documents/useinertgases.pdf http://www.epa.gov/climatechange/emissions/downloads06/06_Complete_Report.pdf
Pipe Line Rules of Thumb Handbook Fourth Edition, page 270
Use of improved protective Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
coating at pipeline canal
crossings Deterioration of protective paint on pipelines crossing bridges can expose bare pipe to external Deterioration of protective paint on pipelines crossing bridges can expose bare pipe to external Natural Gas STAR encourages partners to identify other methods to quantify
corrosion resulting in leaks. Using protective coating is an alternative that is resistant to corrosion resulting in leaks. Using protective coating is an alternative that is resistant to methane emissions reductions. Please identify the basis for any alternate
Production deterioration. deterioration. Methane emissions reductions may be estimated using an emissions factor for emissions reduction estimate in the annual report.
Processing unprotected-steel pipelines; however, this method will only apply to the production, transmission,
Transmission Calculate emissions reductions by summing over all pipeline diameters and pressures: and distribution sectors.
Distribution ER = Σ{ 0.000372 · XCH4 · D^2 · P · L/1,000feet }
Calculate emissions reductions using the following equation:
Where, ER = EF · AF · XCH4
ER = Emissions Reductions (Mcf/year)
D = Inside diameter of pipeline (inches) Where,
L = Length of pipeline between shutoff valves (feet) ER = Emissions Reductions (Mcf/year)
P = Pipeline pressure (psia for less than 50psi, psig for more than 50psi) AF = Activity Factor (miles coated with PRITEC or leaks avoided using PRITEC)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production), 0.87 XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production), 0.87
(Processing), 0.934 (Transmission/Distribution) (Processing), 0.934 (Transmission/Distribution)
References: For production gathering lines
Use of Improved Protective Coating at Pipeline Canal Crossings PRO EF = 43.705 Mcf/year/leak
http://www.epa.gov/gasstar/documents/useofimproved.pdf For transmission mains
EF = 51.802 Mcf/mile/year
Pipe Line Rules of Thumb Handbook Fourth Edition, page 270 For distribution mains
EF = 110.53 Mcf/mile/year
References:
Use of Improved Protective Coating at Pipeline Canal Crossings PRO
http://www.epa.gov/gasstar/documents/useofimproved.pdf
EPA/GRI study “Methane Emissions from the Natural Gas Industry,” Volume 3, Appendix A,
Section P-3
EPA/GRI study “Methane Emissions from the Natural Gas Industry,” Volume 9, Page 37
Pipelines 6
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Pipelines
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Use hot taps for in-service Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
pipeline connections
Using hot taps saves the methane that would otherwise be lost during shutdown and venting to The volume of methane emissions saved by hot taps is sensitive to the specific details of the Natural Gas STAR encourages partners to identify other methods to quantify
Production create interconnects. operation - pipeline length, pipeline diameter, and system pressure, and the number of hot taps methane emissions reductions. Please identify the basis for any alternate
Processing performed that year. If these quantities are known it is suggested to use the engineering emissions reduction estimate in the annual report.
Transmission Calculate emissions reductions summing over all pipeline diameters, pressures, and lengths for calculation for accuracy, otherwise Partners report hot taps can save 24,400 Mcf/year based on
Distribution each hot tap: 320 hot taps of various sizes.
ER = Σ{ (D^2 · P · [L/1,000] · 0.372) / 1,000 } · XCH4
Calculate emissions reductions using the following equation:
Where, ER = AF · 24,400 Mcf/installment/year / 320
ER = Emissions Reductions (Mcf/year)
D = Inside diameter of pipeline (inches) Where,
L = Length of pipeline between shutoff valves (feet) ER = Emissions Reductions (Mcf/year)
P = Pipeline pressure (psia for less than 50psi, psig for more than 50psi) AF = Activity Factor (number of hot taps/year)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.934 (Transmission) (Derived for a sample of 320 hot taps of random various sizes/year)
References: References:
Using Hot Taps for In Service Pipeline Connections Lessons Learned Using Hot Taps for In Service Pipeline Connections Lessons Learned
http://www.epa.gov/gasstar/documents/ll_hottaps.pdf http://www.epa.gov/gasstar/documents/ll_hottaps.pdf
Use fixed/portable Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
compressors for pipeline
pumpdown First, calculate volume of gas contained in an isolated piping section: First, calculate volume of gas vented if all maintenance and repair work resulted in blowdowns Natural Gas STAR encourages partners to identify other methods to quantify
M = L · 5,280feet/mile · (π · [I^2]/4) · (P/14.65 psig) · 1Mcf/1,000scf rather than pumpdowns methane emissions reductions. Please identify the basis for any alternate
Production E = EF · AF emissions reduction estimate in the annual report.
Processing Next, calculate emissions reductions from pumpdown using the following equation:
Transmission ER = ( M - (M/Ri) ) · XCH4 Next, calculate emissions reductions from pumpdowns using the following equation:
Distribution ER = E · PD · Ra · XCH4
Where,
ER = Emissions Reductions (Mcf/year) Where,
M = Volume of gas in pipeline (Mcf) ER = Emissions Reductions (Mcf/year)
L = Pipeline length between block valves (miles) E = Natural gas lost from pipeline blowdowns (Mcf)
I = Pipeline interior diameter (feet) EF = Emissions Factor (Mcf/mile) - default is 0.392 Mcf/mile (Processing), 33.83 Mcf/mile
P = Pipeline operating pressure (psig) (Transmission), 0.109 Mcf/mile (Distribution)
Ri = Compression ratio AF = Activity Factor (Company-wide miles of pipeline)
(In-line compressors typically have ratios of up to 2:1, portable PD = Percentage of total blowdowns where pipeline pump-down techniques were employed
compressors have ratios up to 5:1) Ra = Average compression ratio of pipeline pump-downs performed
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.87 (Processing), 0.934 XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.87 (Processing), 0.934
(Transmission/Distribution) (Transmission/Distribution)
References:
Methane Emissions from the Natural Gas Industry. Volume 6: Vented and Combustion Source
Summary
http://www.epa.gov/gasstar/documents/emissions_report/6_vented.pdf
References: Methane Emissions from the Natural Gas Industry. Volume 7: Blow and Purge Activities
Partner Update, Summer 2004 - Minmizing Emissions from Pipeline Blowdowns http://www.epa.gov/gasstar/documents/emissions_report/7_blowandpurge.pdf
http://epa.gov/gasstar/documents/6-04newsletter.pdf
Using Pipeline Pump-Down Techniques to Lower Gas Line Pressure Before Maintenance
http://www.epa.gov/gasstar/documents/ll_pipeline.pdf
Pipelines 7
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Pneumatics/Control Devices
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Install electronic flare Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
ignition devices
When flare pilot flames are blown out, natural gas is vented directly to the atmosphere until the When flare pilot flames are blown out, natural gas is vented directly to the atmosphere until the Natural Gas STAR encourages partners to identify other
Production flame is relit. Electronic ignition devices can be used together with a sensor to automatically relight flame is relit. Electronic ignition devices can be used together with a sensor to automatically relight methods to quantify methane emissions reductions. Please
Processing when this occurs. Measure the rate of natural gas to the flare, multiply this by the methane content when this occurs. One partner reports methane savings of 70 scf/hour by using these devices to identify the basis for any alternate emissions reduction
Transmission of that gas, and then multiply by the fraction of time that blowouts occur. keep the pilot flame lit. estimate in the annual report.
References: Calculate emissions reductions using the following equation:
Install Electronic Flare Ignition Devices PRO ER = 70 scf/hour · AF · 1 Mcf/1,000 scf
http://www.epa.gov/gasstar/documents/installelectronicflareignitiondevices.pdf
Where,
ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (hours/year that pilot flame being blown out avoided)
References:
Install Electronic Flare Ignition Devices PRO
http://www.epa.gov/gasstar/documents/installelectronicflareignitiondevices.pdf
Options for reducing Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
methane emissions from
pneumatic devices Determine the volume of gas that can be saved with a low-bleed controller using field measurement On average, pneumatic devices in the production sector emit at 125.925 Mcf methane/year/device. Natural Gas STAR encourages partners to identify other
of the high-bleed controller and a similar low-bleed device in service using a high volume sampler. Pneumatic devices in the transmissions sector emit 162.197 Mcf methane/year/device. Pneumatic methods to quantify methane emissions reductions. Please
Production devices in the processing sector typically emit 165 Mcf methane/year/plant. identify the basis for any alternate emissions reduction
Processing Calculate emissions reductions using the following equation: estimate in the annual report.
Transmission ER = (HB - LB) · XCH4 · 8,670 hours/year Calculate emissions reductions using the following equation:
Distribution ER = (AF · EF) - 2.190 Mcf/year
Where,
ER = Emissions Reductions (Mcf/year) Where,
HB = High bleed rate (Mcf/hour) ER = Emissions Reductions (Mcf/year)
LB = Low bleed rate (Mcf/hour) AF = Activity Factor (number of devices, or number of plants in processing sector case)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production), 0.87 EF = Emissions Factor (Mcf/year/device) - default is 125.925 Mcf/year/device (Production), 162.197
(Processing), 0.934 (Transmission/Distribution) Mcf/year (Transmission), 165 Mcf/year/plant (Processing)
References: References:
Options for Reducing Methane Emissions from Pneumatic Devices in the Natural Gas Industry EPA/GRI Methane Emissions from the Natural Gas Industry Volume 12: Pneumatic Devices (1996)
Lessons Learned http://www.epa.gov/gasstar/documents/emissions_report/12_pneumatic.pdf
http://www.epa.gov/gasstar/documents/ll_pneumatics.pdf
Pneumatics-Controls 1
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Pneumatics/Control Devices
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Reduce frequency of Engineering Calculation Emission Factor Partner Quantified Methane Emissions Reductions
replacing turbine meter
modules First, use an ideal gas relationship to calculate the methane emissions from each meter change. This emissions factor is based on a transmission system with 500 turbine meters that have 8-inch Natural Gas STAR encourages partners to identify other
Sum emissions from all meter runs depressured over a one year period. diameters and are measuring gas at 900 psig. Turbine meter replacement frequency is reduced methods to quantify methane emissions reductions. Please
Transmission from every two years to every three years. The volume of gas in the turbine meter run assumes the identify the basis for any alternate emissions reduction
Calculate emissions summing over all meter runs depressured: block valves are spaced 11 pipe diameters up and downstream of the meters. estimate in the annual report.
E = Σ { ( π · D^2/4 · L · P · XCH4 ) / 14.7 psi }
Calculate emissions reductions using the following equation:
Where, ER = 0.054 Mcf methane/year/meter · AF
E = Emissions from all meter runs (Mcf)
D = Pipeline diameter (feet) Where,
L = Length of meter run between isolation valves (feet) ER = Emissions Reductions (Mcf/year)
P = Pressure (psia) AF = Activity Factor (Number of turbine meters)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.934 (Transmission)
References:
Next, calculate methane emissions reductions from changing replacement frequency. Assume Reduce Frequency of Replacing Modules in Turbine Meters PRO
meter replacement activities are ongoing at a constant rate but less meters are replaced in a given http://www.epa.gov/gasstar/documents/reducefrequency.pdf
year.
Calculate emissions reductions using the following equation:
ER = (1/x - 1/y) · E
Where,
ER = Emissions Reductions (Mcf/year)
x = Old replacement frequency (years)
y = New replacement frequency (years)
References:
Reduce Frequency of Replacing Modules in Turbine Meters PRO
http://www.epa.gov/gasstar/documents/reducefrequency.pdf
Leecraft, Jodie, ed. Field Handling of Natural Gas, Fourth Edition. page 9 (Ideal Gas Laws)
Pneumatics-Controls 2
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Pneumatics/Control Devices
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Replace bi-directional Engineering Calculation Emission Factor Partner Quantified Methane Emissions Reductions
orifice metering with
ultrasonic meters For accurate measurement of gas injected into and withdrawn from storage, the orifice plate is This emissions factor is based on partner reported savings from 14 units ranging from 6-inch to 10- Natural Gas STAR encourages partners to identify other
removed, inspected, and replaced which requires venting a pipeline segment to the atmosphere. inch. methods to quantify methane emissions reductions. Please
Transmission To estimate emissions savings, first use an ideal gas relationship to calculate the methane identify the basis for any alternate emissions reduction
emissions from each meter inspection/change. Calculate emissions reduction using the following equation: estimate in the annual report.
ER = 8.5 Mcf methane/year/meter · AF
Calculate emissions summing over all meter runs depressed in given year:
E = Σ { ( π · D^2/4 · L · P · XCH4 ) / 14.7 psi } Where,
ER = Emissions Reductions (Mcf/year)
Where, AF = Activity Factor (Number of meter replacements to ultrasonic)
E = Emissions from all meter runs (Mcf)
D = Pipeline diameter (feet) References:
L = Length of meter run between isolation valves (feet) Replace Bi-Direction Orifice Metering with Ultrasonic Meters PRO
P = Pressure (psia) http://www.epa.gov/gasstar/documents/replacebidirectional.pdf
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.934 (Transmission)
Next, calculate methane emissions reductions based on the inspection/change frequency.
Calculate emissions reductions using the following equation:
ER = n · E
Where,
ER = Emissions Reductions (Mcf/year)
n = number of inspections/changes per year
References:
Replace Bi-Direction Orifice Metering with Ultrasonic Meters PRO
http://www.epa.gov/gasstar/documents/replacebidirectional.pdf
Leecraft, Jodie, ed. Field Handling of Natural Gas, Fourth Edition. page 9 (Ideal Gas Laws)
Pneumatics-Controls 3
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Pneumatics/Control Devices
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Convert gas pneumatic Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
controls to instrument air
Use a high volume sampler and/or engineering calculations to measure pneumatic gas rates for all A conservative estimate of typical emissions from pneumatic devices in processing plants is 1 scf Natural Gas STAR encourages partners to identify other
Production devices converted to instrument air or mechanical controls. methane/control loop/minute, and 10 scf/minute of utility gas usage for pneumatic devices and methods to quantify methane emissions reductions. Please
Processing compressor engine starting. If these pneumatic gas rates are unavailable, use pneumatic gas rate identify the basis for any alternate emissions reduction
Transmission Calculate emissions reductions using the following equation: specifications provided by manufacturers. estimate in the annual report.
Distribution ER = BR · XCH4 · 8,670 hours/year
Calculate emissions reductions using the following equation:
Where, ER = (AF · EF + 10 scf/minute) · OF · 1 Mcf/1,000 scf
ER = Emissions Reductions (Mcf/year)
BR = Bleed rate (Mcf/hour) Where,
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.87 (Processing) ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (number of control loops) - default is 35 control loops
References: EF = Emissions Factor (scf/control loop/minute) - default is 1 scf/control loop/minute
Convert Gas Pneumatic Controls to Instrument Air Lessons Learned OF = Operating factor (minutes/year for operation)
http://www.epa.gov/gasstar/documents/ll_instrument_air.pdf
References:
Convert Gas Pneumatic Controls to Instrument Air Lessons Learned
http://www.epa.gov/gasstar/documents/ll_instrument_air.pdf
Pneumatics-Controls 4
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Tanks
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3 Quantification Method 4 Quantification Method 5
Applicable Sector(s)
Capture methane from Direct Measurement Engineering Calculation Engineering Calculation - Graph Emissions Factor Partner Quantified Methane Emissions Reductions
pipeline liquid storage
tanks (hydrocarbon Vapor recovery unit vendors offer tank testing services to measure the volume of vapor emitted Hydrocarbon condensate tank flashing: Vasquez-Beggs equation. For light condensate (with The graph below can be used to estimate the gas-oil ratio (GOR) to help calculate methane Methane emissions from tank venting can be characterized Natural Gas STAR encourages partners to identify other
condensate tanks) from fixed roof tank vents. These tank testing surveys take into account flashing, working, and gravity much higher than 58), this equation becomes less reliable. VRUs typically recover 95% of emissions from hydrocarbon condensate tank venting. by the following emissions factors: methods to quantify methane emissions reductions. Please
standing losses that can fluctuate from day to day and are more accurate than using engineering emitted vapors. identify the basis for any alternate emissions reduction
Production calculations. Condensate tanks without control devices: 21.87 scf/barrel estimate in the annual report. For example, several Gas
Processing Calculate emissions reductions using the following equations: Condensate tanks with control devices: 4.37 scf/barrel STAR partners have reported using computer programs
Transmission References: ER = 95% · (GOR · Q) · 1Mcf/1,000scf · XCH4 · OF such as TankCALC to estimate methane emissions from
Installing Vapor Recovery Units on Crude Oil Storage Tanks Lessons Learned Calculate emissions reductions from condensate tanks storage tanks.
http://www.epa.gov/gasstar/documents/ll_final_vap.pdf using the following equation:
ER = [(21.87 scf/barrel - 4.37 scf/barrel) · Q] /
1000scf/Mcf
Where,
Where, ER = Methane emissions reductions (Mcf/year)
ER = Emission Reductions (Mcf/year) Q = Throughput (barrel/year)
GOR = Ratio of flash gas production to standard stock tank barrels of oil produced, in scf/barrel oil
(barrels of oil corrected to 60°F) References:
Q = Oil Throughput (barrels/year) EPA Inventory of US Greenhouse Gas Emissions and
Gflash gas = Specific gravity of the tank flash gas, where air = 1 (default is 1.22) Sinks: 1990 - 2004
Goil = API gravity of stock tank oil at 60°F (ºAPI) http://www.epa.gov/climatechange/emissions/downloads06/
Psep = Pressure in separator (psig) 06_Complete_Report.pdf
Tsep = Temperature in separator (°F)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.335 (hydrocarbon Capture Methane from Pipeline Liquid Storage Tanks PRO
condensate) Calculate emissions reductions using the following equation: http://www.epa.gov/gasstar/documents/capturemethane.pdf
OF = Operating Factor - default is 95% ER = (GOR · Q) · 1Mcf/1,000scf · XCH4 · OF
For Goil > 30º API: Where,
A = 0.0178, B = 1.187, C = 23.931 ER = Emission Reductions (Mcf/year)
GOR = Ratio of flash gas production to standard stock tank barrels of oil produced, in scf/barrel oil
References: (barrels of oil corrected to 60°F)
API Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Gas Industry. Q = Oil Throughput (barrels/year)
Page 5-34. API, February 2004. XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.335 (hydrocarbon
condensate)
OF = Operating Factor - default is 95%
References:
Installing Vapor Recovery Units on Crude Oil Storage Tanks Lessons Learned
http://www.epa.gov/gasstar/documents/ll_final_vap.pdf
Consolidate crude oil Process Simulation Engineering Calculation Partner Quantified Methane Emissions Reductions
production and water
storage tanks Methane emissions reductions can be estimated using API's "E&P Tank" software program for Methane emissions can be estimated using EPA's AP-42 guidelines for specific tankage Natural Gas STAR encourages partners to identify other methods to quantify methane emissions
specific tankage alternatives. alternatives. Parameters required include tank diameter, vapor space, ambient temperature reductions. Please identify the basis for any alternate emissions reduction estimate in the annual
Production range, and pressure range. Emissions savings equal the difference between emissions estimates report.
References: from initial tanks and consolidated tanks.
Consolidate Crude Oil Production and Water Storage Tanks PRO
http://www.epa.gov/gasstar/documents/consolidatecrudeoilproduction.pdf References:
Consolidate Crude Oil Production and Water Storage Tanks PRO
http://www.epa.gov/gasstar/documents/consolidatecrudeoilproduction.pdf
EPA AP-42 Emissions Calculations for Liquid Storage Tanks
http://www.epa.gov/ttn/chief/ap42/ch07/final/c07s01.pdf
Convert water tank blanket Direct Measurement Partner Quantified Methane Emissions Reductions Direct Measurement
from natural gas to CO2
Tank measurement surveys can quantify tank vents with orifice recording methods or a high Methane emission reductions from CO2 tank blanketing are highly variable. Factors such as size Tank measurement surveys can quantify tank vents with orifice recording methods or a high
Production volume sampler. of the tank(s) relative to produced water rate and withdrawal rate will affect methane emission volume sampler.
Processing reductions for each specific application. Natural Gas STAR encourages partners to identify other
References: methods to quantify methane emissions reductions. Please identify the basis for any alternate References:
Convert Water Tank Blanket from Natural Gas to Produced CO2 PRO emissions reduction estimate in the annual report. Convert Water Tank Blanket from Natural Gas to Produced CO2 PRO
http://www.epa.gov/gasstar/documents/convertwatertank.pdf http://www.epa.gov/gasstar/documents/convertwatertank.pdf
Tanks 1
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Tanks
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3 Quantification Method 4 Quantification Method 5
Applicable Sector(s)
Install pressurized storage Engineering Calculation - Graph Partner Quantified Methane Emissions Reductions
of condesate
The graph below can be used to estimate the gas-oil ratio (GOR) to help calculate methane Methane emission reductions from pressurized condensate storage are highly variable. Factors
Production emissions from hydrocarbon condensate tank venting. such as the gas-oil ratio and throughput will affect methane emission reductions for each specific
Processing application. Natural Gas STAR encourages partners to identify other methods to quantify methane
Transmission emissions reductions. Please identify the basis for any alternate emissions reduction estimate in
the annual report.
Calculate emissions reductions using the following equation:
ER = (GOR · Q) · 1Mcf/1,000scf · XCH4 · OF
Where,
ER = Emissions Reductions (Mcf/year)
GOR = Ratio of flash gas production to standard stock tank barrels of oil produced, in scf/barrel oil
(barrels of oil corrected to 60°F)
Q = Oil throughput (barrels/year)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.335 (hydrocarbon
condensate)
References:
Installing Vapor Recovery Units on Crude Oil Storage Tanks Lessons Learned
http://www.epa.gov/gasstar/documents/ll_final_vap.pdf
Install Pressurized Storage of Condensate PRO
http://www.epa.gov/gasstar/documents/installpressurized.pdf
Install vapor recovery units Direct Measurement Engineering Calculation Engineering Calculation - Graph Emissions Factor Partner Quantified Methane Emissions Reductions
(VRUs) on crude oil
storage tanks Vapor recovery unit vendors offer tank testing services to measure the volume of vapor emitted Tank flashing: Vasquez-Beggs equation The graph below can be used to estimate the gas-oil ratio (GOR) to help calculate methane Methane emissions from tank venting can be characterized Natural Gas STAR encourages partners to identify other
from fixed roof tank vents. These tank testing surveys take into account flashing, working, and emissions from tank venting. by an average of 5.28 scf/barrel of crude throughput. methods to quantify methane emissions reductions. Please
Production standing losses that can fluctuate from day to day and are more accurate than using engineering Calculate emissions reductions using the following equations: identify the basis for any alternate emissions reduction
calculations. ER = (GOR · Q) · 1Mcf/1,000scf · XCH4 · OF Calculate emissions reductions using the following estimate in the annual report. For example, several Gas
equation: STAR partners have reported using computer programs
References: ER = 95% · [5.28 scf/barrel · Q] / 1,000scf/Mcf such as TankCALC to estimate methane emissions from
Installing Vapor Recovery Units on Crude Oil Storage Tanks Lessons Learned storage tanks.
http://www.epa.gov/gasstar/documents/ll_final_vap.pdf Where,
ER = Methane emissions reductions (Mcf/year)
Where, Q = Throughput (barrel/year)
ER = Emission Reductions (Mcf/year)
GOR = Ratio of flash gas production to standard stock tank barrels of oil produced, in scf/barrel oil References:
(barrels of oil corrected to 60°F) EPA Inventory of US Greenhouse Gas Emissions and
Q = Oil Throughput (barrels/year) Sinks: 1990 - 2004
Gflash gas = Specific gravity of the tank flash gas, where air = 1 (default is 1.22) http://www.epa.gov/climatechange/emissions/downloads06/
Goil = API gravity of stock tank oil at 60°F (ºAPI) 06_Complete_Report.pdf
Psep = Pressure in separator (psig)
Tsep = Temperature in separator (°F) Installing Vapor Recovery Units on Crude Oil Storage Tanks
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.274 (crude oil) Calculate emissions reductions using the following equation: Lessons Learned
OF = Operating Factor - default is 95% ER = (GOR · Q) · 1Mcf/1,000scf · XCH4 · OF http://www.epa.gov/gasstar/documents/ll_final_vap.pdf
For Goil ≤ 30º API: Where,
A = 0.0362, B = 1.0937, C = 25.724 ER = Emission Reductions (Mcf/year)
For Goil > 30º API: GOR = Ratio of flash gas production to standard stock tank barrels
A = 0.0178, B = 1.187, C = 23.931 of oil produced, in scf/barrel oil (barrels of oil corrected to
60°F)
References: Q = Oil Throughput (barrels/year)
API Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Gas Industry. XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.274 (crude oil)
Page 5-34. API, February 2004. OF = Operating Factor - default is 95%
References:
Installing Vapor Recovery Units on Crude Oil Storage Tanks Lessons Learned
http://www.epa.gov/gasstar/documents/ll_final_vap.pdf
Tanks 2
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Tanks
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3 Quantification Method 4 Quantification Method 5
Applicable Sector(s)
Purge and retire low Partner Quantified Methane Emissions Reductions Engineering Calculation
pressure gasholders
Methane emission reductions from retiring gas holders are highly variable. Factors such as tank Estimate methane emissions reductions from displacing residual methane in a gasholder by
Transmission dimensions will affect methane emission reductions for each specific application. Natural Gas venting it through a thermal oxidizer instead of directly to the atmosphere. Gasholder volume with
Distribution STAR encourages partners to identify other methods to quantify methane emissions reductions. all lifts landed approximates the volume of a cylinder. Use an ideal gas relationship to calculate
Please identify the basis for any alternate emissions reduction estimate in the annual report. the methane emissions from each gasholder.
Calculate emissions reductions summing over all gasholders:
ER = Σ { ( π · D^2/4 · L · P · XCH4 ) / 14.7psi }
Where,
ER = Emissions Reductions (Mcf/year)
D = Tank diameter (feet)
L = Tank length (feet)
P = Pressure (psia)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.934
(Transmission/Distribution)
References:
Purge and Retire Low Pressure Gasholders PRO
http://www.epa.gov/gasstar/documents/purgeandretirelowpressuregasholders.pdf
Leecraft, Jodie, ed. Field Handling of Natural Gas, Fourth Edition. page 9 (Ideal Gas Laws)
Recycle line recovers gas Engineering Calculation Partner Quantified Methane Emissions Reductions
during condensate loading
Considering that a loading cycle may occur every three to five days, approximately 100 loading Methane emission reductions from condensate loading are highly variable. Factors such as
Production transfers can occur each year. The rate of methane emissions from evaporation can be estimated condensate volatility and loading frequency will affect methane emission reductions for each
Processing as 50 percent of the total volume filled. Partners have reported reducing methane emissions by specific application. Natural Gas STAR encourages partners to identify other methods to quantify
Transmission 6,500 Mcf to 39,000 Mcf/year, which includes flashing losses. methane emissions reductions. Please identify the basis for any alternate emissions reduction
estimate in the annual report.
References:
Pipe Line Rules of Thumb Handbook, Fourth Edition, page 492.
Recycle Line Recovers Gas During Condensate Loading PRO
http://www.epa.gov/gasstar/documents/recyclelinerecovers.pdf
Tanks 3
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Valves
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Close valves during repair Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
to minimize blowdown
During routine operation and maintenance shutdowns, main valves are closed off, and the gas is During routine operation and maintenance shutdowns, main valves are closed off, and the gas is Natural Gas STAR encourages partners to identify other
Transmission vented to the atmosphere. By closing the main valves AND the unit valves emissions reductions vented to the atmosphere. By closing the main valves AND the unit valves emissions reductions methods to quantify methane emissions reductions. Please
Distribution are due to the volume of methane contained within the pipelines that are no longer blown down. are due to the volume of methane contained within the pipelines that are no longer blown down. identify the basis for any alternate emissions reduction
One partner reports methane savings of 4,500 Mcf/year by closing off an additional 1 mile of 24- estimate in the annual report.
Calculate emissions reductions summing across all instances of closing mains and unit valves inch pipeline at 900 psia from four blowdowns/year.
before blowdown:
ER = Σ{ 0.000372 · XCH4 · D^2 · P · L/1,000feet · n } Calculate emissions reductions using the following equation:
ER = 1,125 Mcf/mile-blowdown · L · n
Where,
ER = Emissions Reductions (Mcf/year) Where,
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.934 (Transmission/Distribution) ER = Emissions Reductions (Mcf/year)
D = Inside diameter of pipe (inches) L = Length of blown down pipeline segment reduced (miles)
P = Pressure of pipe (psig) n = Number of events (blowdowns/year)
L = Length of blown down pipeline segment reduced (feet) Assumes 24-inch pipeline at 900 psia
n = Number of events (blowdowns/year)
References:
References: Close Main and Unit Valves Prior to Blowdown PRO
Close Main and Unit Valves Prior to Blowdown PRO http://www.epa.gov/gasstar/documents/closemainandunitvalvespriortoblowdown.pdf
http://www.epa.gov/gasstar/documents/closemainandunitvalvespriortoblowdown.pdf
Pipe Line Rules of Thumb Handbook 4th Edition, page 270
Valves 1
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Valves
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Design isolation valves to Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
minimize blowdown
volumes When compressors or other equipment are taken out of service, isolation valves are shut, and the When compressors or other equipment are taken out of service, isolation valves are shut and the Natural Gas STAR encourages partners to identify other
gas contained between them is vented. By designing these segments to be closer together, the gas contained between them is vented. By excluding 200 feet of 24-inch pipeline at 600 psig from methods to quantify methane emissions reductions. Please
Processing volume of methane contained in the reduced length of pipeline between isolation valves is saved. being blown down five times a year between these isolation valves, one Partner reports methane identify the basis for any alternate emissions reduction
Transmission savings of 130 Mcf/year. estimate in the annual report.
Distribution Calculate emissions reductions summing across all instances of reducing distance between
isolation valves: Calculate emissions reductions using the following equation:
ER = Σ{ 0.000372 · XCH4 · D^2 · P · L/1,000feet · n } ER = 0.13 Mcf/blowdown/foot decreased · L · n
Where, Where,
ER = Emissions Reductions (Mcf/year) ER = Emissions Reductions (Mcf/year)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.934 (Transmission/Distribution) L = Length of pipeline segment reduced (feet)
D = Inside diameter of pipe (inches) n = Number of events (blowdowns/year)
P = Pressure of pipe (psig) Assumes 24-inch pipeline at 600 psig
L = Length of pipeline segment reduced (feet)
n = Number of events (blowdowns/year) References:
Design Isolation Valves to Minimize Gas Blowdown Volumes PRO
References: http://www.epa.gov/gasstar/documents/designisolationvalvestominimizegasblowdownvolumes.pdf
Design Isolation Valves to Minimize Gas Blowdown Volumes PRO
http://www.epa.gov/gasstar/documents/designisolationvalvestominimizegasblowdownvolumes.pdf
Pipe Line Rules of Thumb Handbook 4th Edition, page 270
Inspect and repair Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
compressor station
blowdown valves Measurement of leak rates from compressor station blowdown valves may require the use of Partners report that fugitive emissions from compressor station blowdown valves can be Natural Gas STAR encourages partners to identify other
ladders or a bucket-truck to access the vent stack. Bagging techniques, rotameters, or a high characterized by an emissions factor of approximately 200 Mcf/year/valve. methods to quantify methane emissions reductions. Please
Production volume sampler may be used to quantify the leak rate and calculate the annual emissions from a identify the basis for any alternate emissions reduction
Processing leaking valve. Emissions reductions are the difference between the leak rates before and after the Calculate emissions reductions using the following equation: estimate in the annual report.
Transmission repairs. ER = 200 Mcf/year/valve · AF
References: Where,
Inspect and Repair Compressor Station Blowdown Valves PRO ER = Total annual emission reductions from repairing leaking blowdown valves (Mcf/year)
http://www.epa.gov/gasstar/documents/inspectandrepaircompressorstationblowdownvalves.pdf AF = Activity Factor (number of leaking valves repaired)
References:
Inspect and Repair Compressor Station Blowdown Valves PRO
http://www.epa.gov/gasstar/documents/inspectandrepaircompressorstationblowdownvalves.pdf
Valves 2
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Valves
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Reduce venting from unlit Engineering Calculation Emissions Factor Partner Quantified Methane Emissions reductions
pilot: install BASO valves
Installing BASO valves closes off the gas supply to air-aspirated burners when the pilot flame goes Installing BASO valves closes off the gas supply to air-aspirated burners when the pilot flame goes Natural Gas STAR encourages partners to identify other
Production out, preventing a flow of uncombusted gas containing methane to the atmosphere. out, preventing a flow of uncombusted gas containing methane to the atmosphere. One partner methods to quantify methane emissions reductions. Please
Processing reports saving 203 Mcf/year/BASO valve installed on a 1,000 barrel/day heater-treater that identify the basis for any alternate emissions reduction
Calculate emissions reductions using the following equation: experiences a flameout period of 10 days annually. estimate in the annual report.
ER = (ΔH / HV) · XCH4 · OF
Calculate emissions reductions using the following equation:
Where, ER = 20.3 Mcf/year/BASO valve · AF · OF
ER = Emissions Reductions (Mcf/year)
ΔH = Heat rate supplied by flame (Btu/hour) Where,
HV = Heat content of gas (Btu/Mcf) ER = Emissions Reductions (Mcf/year)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production) AF = Activity Factor (number of BASO valves installed)
OF = Operating factor (hours of flameout period annually) OF = Operating factor (number of days/year of flameout)
References: References:
Install BASO Valves PRO Install BASO Valves PRO
http://www.epa.gov/gasstar/documents/installbaso.pdf http://www.epa.gov/gasstar/documents/installbaso.pdf
Valves 3
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Valves
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Install excess flow valves Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
Transmission Two types of excess flow valves are available: “By-Pass” (Bleed By) or “Non-By-Pass” (Positive Partners report excess flow valves typically save 16 Mcf/hour/valve of otherwise vented methane in Natural Gas STAR encourages partners to identify other
Distribution Shut Off). A By-Pass EFV allows no more than 5% of the manufacturer’s specified closure flow rate, the event of a rupture. methods to quantify methane emissions reductions. Please
up to a maximum value. A Non-By-Pass valve will close the flow of gas completely. identify the basis for any alternate emissions reduction
Calculate emissions reductions using the following equation: estimate in the annual report.
Calculate emissions reductions using the following equation: ER = 16 Mcf/hour/valve · AF
Non-By-Pass Valves Where,
ER = XCH4 · Q · T ER = Total annual emission reductions from installing excess flow valves (Mcf/year)
AF = Total duration of rupture events before repair (hours/year)
By-Pass Valves
ER = XCH4 · (Q - BP) · T References:
Install Excess Flow Valves PRO
Where, http://www.epa.gov/gasstar/documents/installexcessflowvalves.pdf
ER = Emissions reductions (Mcf/year)
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.934 (Transmission/Distribution)
Q = Flowrate of natural gas in the pipeline (Mcf/hour)
T = Time that gas is allowed to vent before repairs are completed (hours/year)
BP = By-Pass flow rate (scf/hour) - default is 20 scf/hour
References:
Install Excess Flow Valves PRO
http://www.epa.gov/gasstar/documents/installexcessflowvalves.pdf
Partner Update Winter 2005
http://www.epa.gov/gasstar/documents/partner-updates/ngspartnerup_winter05.pdf
Partner Update Spring 2006
http://www.epa.gov/gasstar/documents/partner-updates/ngspartnerup_spring06.pdf
Valves 4
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Valves
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Move in fire gates at Engineering Calculation Emissions Factor Partner Quantified Methane Emissions Reductions
compressors
During an emergency at a compressor station, fire gate valves close off, and the gas contained During an emergency at a compressor station, fire gate valves close off, and the gas contained Natural Gas STAR encourages partners to identify other
Transmission between the valves and the compressor station is vented to the atmosphere. Emissions reductions between the valves and the compressor station is vented to the atmosphere. By moving these methods to quantify methane emissions reductions. Please
Distribution are due to the volume of methane contained within distance of pipeline between the fire gate valves valves closer, one partner reports methane savings of 1,700 Mcf/year/facility by avoiding identify the basis for any alternate emissions reduction
and the compressor station that is reduced. blowdowns of 2,000 feet of 24-inch pipeline operating at 900 psia four times/year. Emissions estimate in the annual report.
reductions will depend greatly on the distance decreased between fire gate valves and compressor
Calculate emissions reductions summing across all instances of moving in fire gates using a stations, the diameter of pipeline, and the pressure of the pipeline.
relationship from the Pipe Line Rules of Thumb Handbook:
ER = Σ{ 0.000372 · XCH4 · D^2 · P · L/1,000feet · BD } Calculate emissions reductions at a station using the following equation:
ER = 0.21 Mcf/blowdown/foot decreased · L · n
Where,
ER = Emissions Reductions (Mcf/year) Where,
XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.934 (Transmission/Distribution) ER = Emissions Reductions (Mcf/year)
D = Inside diameter of pipe (inches) L = Length between fire gate valves and compressor station reduced (feet)
P = Pressure of pipe (psig) n = Number of events (blowdowns/year)
L = Length of pipeline segment reduced (feet) Assumes 24-inch pipeline at 900 psia
BD = Number of events (blowdowns/year)
References:
References: Move Fire Gates In to Reduce Venting at Compressor Stations PRO
Move Fire Gates In to Reduce Venting at Compressor Stations PRO http://www.epa.gov/gasstar/documents/movefiregatesin.pdf
http://www.epa.gov/gasstar/documents/movefiregatesin.pdf
Pipe Line Rules of Thumb Handbook 4th Edition, page 270
Valves 5
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Valves
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Replace burst plates with Vendor Data Emissions Factor Partner Quantified Methane Emissions Reductions
secondary relief valves
When pressure surges cause burst plates to rupture, a large volume of natural gas is vented to the When pressure surges cause burst plates to rupture, a large volume of natural gas is vented to the Natural Gas STAR encourages partners to identify other
Production atmosphere until the plate is blocked in. By installing a secondary relief valve on top of the burst atmosphere until the plate is blocked in. By installing a secondary relief valve on top of the burst methods to quantify methane emissions reductions. Please
Processing plate these vents automatically are shut off once the system returns to an operable pressure. The plate that automatically turns off once the system returns to an operable pressure, one partner identify the basis for any alternate emissions reduction
Transmission methane emissions reductions can be estimated using vendor data, which is readily available for reports saving 500 Mcf/plate/hour for a 2-inch burst plate on a 150 psig system. estimate in the annual report.
Distribution any size burst plate and pressure rating (e.g., 8,000 scf/minute for a 2-inch burst plate operating at
150 psig). Calculate emissions reductions using the following equation:
ER = 500 Mcf/plate/hour · AF · OF
References:
Replace Burst Plates with Secondary Relief Valves PRO Where,
http://www.epa.gov/gasstar/documents/replaceburst.pdf ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (plates burst)
OF = Operation factor (hours/year of unblocked venting avoided)
Assumes a 2-inch burst plate for a system at 150 psig
References:
Replace Burst Plates with Secondary Relief Valves PRO
http://www.epa.gov/gasstar/documents/replaceburst.pdf
Test and repair pressure Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
safety valves
Measurement may be done with an organic vapor analyzer or high volume sampler while pressure Partners report fugitive emissions from pressure safety valves can be characterized by an Natural Gas STAR encourages partners to identify other
Production safety valves are in service to calculate an annual emissions rate from a leaking valve. Emissions emissions factor of approximately 57.5 Mcf/year/valve. methods to quantify methane emissions reductions. Please
Processing reductions are the difference between leak rates before and after the repairs. identify the basis for any alternate emissions reduction
Transmission Calculate emissions reductions using the following equation: estimate in the annual report.
Distribution References: ER = 57.5 Mcf/year/valve · AF
Test and Repair Pressure Safety Valves PRO
http://www.epa.gov/gasstar/documents/testandrepairpressuresafetyvalves.pdf Where,
ER = Total annual emission reductions from repairing leaking blowdown valves (Mcf/year)
AF = Activity Factor (number of leaking valves repaired)
References:
Test and Repair Pressure Safety Valves PRO
http://www.epa.gov/gasstar/documents/testandrepairpressuresafetyvalves.pdf
Valves 6
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Valves
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Test gate station pressure Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
relief valves with nitrogen
Determining the proper pressure settings for pressure relief valves requires routine testing. Determining the proper pressure settings for pressure relief valves requires routine testing. Based Natural Gas STAR encourages partners to identify other
Production Substituting pressurized nitrogen for natural gas when testing accounts for methane savings. on partner surveys, 8 Mcf/year of methane can be saved by 100 valves using pressurized nitrogen methods to quantify methane emissions reductions. Please
Processing Monitor the pressure change in the pressurized nitrogen cylinders to determine the volume of to test the valves rather than natural gas. identify the basis for any alternate emissions reduction
Transmission nitrogen that was used in tests. Multiply this by the methane content of the natural gas that would estimate in the annual report.
Distribution have been used during testing to determine emissions reductions. Calculate emissions reductions using the following equation:
ER = 0.08 Mcf/year/valve test · AF
References:
Test Gate Station Pressure Relief Valves with Nitrogen PRO Where,
http://www.epa.gov/gasstar/documents/testgatestationpressurereliefvalveswithnitrogen.pdf ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (number of valve tests/year)
References:
Test Gate Station Pressure Relief Valves with Nitrogen PRO
http://www.epa.gov/gasstar/documents/testgatestationpressurereliefvalveswithnitrogen.pdf
Use of YALE closures for Emissions Factor Partner Quantified Methane Emissions Reductions
ESD testing
The Department of Transportation requires annual tests for emergency shutdown systems (ESD) at Natural Gas STAR encourages partners to identify other methods to quantify methane emissions
Processing compressor stations. YALE closures make it possible to test individual valves cost-effectively reductions. Please identify the basis for any alternate emissions reduction estimate in the annual
Transmission without having to blowdown the entire system. One partner reports saving 1,800 Mcf/ESD test with report.
Distribution YALE closures for a "typical" compressor station with eight compressors, with ten 8-inch ESD
valves, operating at 500 psig.
Calculate emissions reductions using the following equation:
ER = 1,800 Mcf/ESD test with YALE closures · AF
Where,
ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (ESD tests with YALE closures/year)
Assumes eight compressors with ten 8-inch ESD valves operating at 500 psig
References:
Use YALE Closures for ESD Testing PRO
http://www.epa.gov/gasstar/documents/useofyale.pdf
Valves 7
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Valves
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Use ultrasound to identify Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
leaks
Measurement of leak rates from shutoff valves that prevent high-pressure gas leakage to the Partners report leaking valves on open-ended lines emit 20 Mcf/year/valve. Natural Gas STAR encourages partners to identify other
Production atmosphere through open-ended lines may require the use of ladders or a bucket-truck to access methods to quantify methane emissions reductions. Please
Processing the vent stack. Bagging techniques, rotameters, or a high volume sampler may be used to quantify Calculate emissions reductions using the following equation: identify the basis for any alternate emissions reduction
Transmission the leak rate and calculate the annual emissions from a leaking valve. ER = 20 Mcf/year/valve · AF estimate in the annual report.
Distribution
References: Where,
Use Ultrasound to Identify Leaks PRO ER = Total annual emission reductions from repairing leaking valves on open-ended lines
http://www.epa.gov/gasstar/documents/useultrasound.pdf (Mcf/year)
AF = Activity Factor (number of leaking valves repaired)
References:
Use Ultrasound to Identify Leaks PRO
http://www.epa.gov/gasstar/documents/useultrasound.pdf
Valves 8
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Wells
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Connect casing to vapor Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
recovery unit
Casinghead gas collects in the annular space between the tubing and casing of an oil well. Casinghead gas collects in the annular space between the tubing and casing of an oil well. Methane emission reductions from connecting casing to
Production Typically casinghead gas is vented to the atmosphere when the wellhead pressure drops below gas Typically casinghead gas is vented to the atmosphere when the wellhead pressure drops below gas vapor recovery units are highly variable. Factors such as
sales line pressure. Use an orifice meter to measure the volume of gas vented from casings. sales line pressure. Vapor recovery units can recover 95% of this vapor. Emissions factors have production composition, well production rate, well depth, and
These can be used to estimate the volume of vapors that would otherwise be vented to the been developed for the amount of methane emitted from venting these casingheads. well pressure will affect methane emission reductions for
atmosphere. Multiply by the methane content of the gas and by the estimated 95% vapor recovery each specific application. Natural Gas STAR encourages
rate. Calculate emissions reductions from the following equation: partners to identify other methods to quantify methane
ER = AF · EF · 95% emissions reductions. Please identify the basis for any
References: alternate emissions reduction estimate in the annual report.
Connect Casing to Vapor Recovery Unit PRO Where,
http://www.epa.gov/gasstar/documents/connectcasingtovaporrecoveryunit.pdf ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (number of casings connected to VRUs/given year)
API. Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Gas Industry. Pg 5-
66. API, February 2004. Active wells casings
EF = 1.03 Mcf/well
Suspended wells casings
EF = 0.56 Mcf/well
References:
Connect Casing to Vapor Recovery Unit PRO
http://www.epa.gov/gasstar/documents/connectcasingtovaporrecoveryunit.pdf
API Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Gas Industry. Page
5-68. API, February 2004.
Wells 1
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Wells
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Install smart lift automated Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
systems on gas wells
Methane is vented to the atmosphere during liquid unloading operations to restore production to One partner reported reducing approximately 50% of well venting emissions leading to a methane Natural Gas STAR encourages partners to identify other
Production gas wells. Savings are determined by comparing before and after unloading volumes and their savings of 2.3 Bcf by using "smart" automation on 2,200 wells in New Mexico's San Juan basin methods to quantify methane emissions reductions. Please
frequency when "smart" automation is utilized. Orifice meters can be used to establish gas (both plunger lift and blowdown wells). This is an average of 1,045 Mcf/year/well producing with a identify the basis for any alternate emissions reduction
blowdown flow rates and volumes for each type of well condition and formation resulting in robust "smart" automation system to maximize efficiency and recovery of gas and liquids during well estimate in the annual report.
volume estimates. Multiply by the methane content of produced gas to determine emissions unloading. It is important to note that methane emissions reductions will vary from site-to-site
savings. depending on the well depth, pressure, and frequency of blowdowns.
References: Calculate emissions reductions using the following equation:
Gas Well "Smart" Automation System PRO ER = 1,045 Mcf/year/well · AF
http://www.epa.gov/gasstar/documents/smart_automation.pdf
Where,
Installing Plunger Lift Systems in Gas Wells Lessons Learned ER = Emissions Reductions (Mcf/year)
http://www.epa.gov/gasstar/documents/ll_plungerlift.pdf AF = Activity Factor (wells producing with "smart" automation system)
References:
Gas Well "Smart" Automation System PRO
http://www.epa.gov/gasstar/documents/smart_automation.pdf
Installing Plunger Lift Systems in Gas Wells Lessons Learned
http://www.epa.gov/gasstar/documents/ll_plungerlift.pdf
Optimize gas well Direct Measurement Partner Quantified Methane Emissions Reductions
unloading times
Use an orifice meter to determine the rate of gas vented during blowdowns. Multiply this by the Methane emission reductions from optimizing gas well unloading time are highly variable. Factors
Production quantity of blowdown time reduced in a year by optimizing unloading times, and then multiply by the such as production composition, gas production rate, liquids production rate, well depth, and well
methane content of the gas to determine emissions reductions. pressure will affect methane emission reductions for each specific application. Natural Gas STAR
encourages partners to identify other methods to quantify methane emissions reductions. Please
References: identify the basis for any alternate emissions reduction estimate in the annual report.
Gas Well Unloading Time Optimization PRO
http://www.epa.gov/gasstar/documents/unloading_time508.pdf
Wells 2
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Wells
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Green completions/perform Direct Measurement Engineering Calculation Partner Quantified Methane Emissions Reductions
reduced emissions
completions Use an orifice meter to measure the volume of gas vented to the atmosphere during well After hydraulic fracture jobs, green completions use portable equipment to treat gas normally lost Natural Gas STAR encourages partners to identify other
completions of similar wells in the same reservoir. Partners report after hydraulic fracture jobs, during completions and make it useable in sales. methods to quantify methane emissions reductions. Please
Production green completions save approximately 50% of this vented gas by cleaning it sufficiently for sales identify the basis for any alternate emissions reduction
rather than venting it to the atmosphere. Multiply by the methane content of recovered gas to Calculate emissions reductions using the following equation: estimate in the annual report.
estimate the emissions reductions. ER = Q · OF · η · XCH4
References: Where,
Green Completions PRO ER = Emissions Reductions (Mcf/year)
http://www.epa.gov/gasstar/documents/greencompletions.pdf Q = Flowrate during gas completions (Mcf/hour)
OF = Operating factor (hours of completions/year)
Reduced Emissions Completions (Green Completions) presentation η = Recovery rate (% of volume recovered) - default is 50% (typically between 50 and 70%)
http://epa.gov/gasstar/documents/vincent.pdf XCH4 = Mole fraction of methane in the gas (decimal) - default is 0.788 (Production)
References:
Green Completions PRO
http://www.epa.gov/gasstar/documents/greencompletions.pdf
Reduced Emissions Completions (Green Completions) presentation
http://epa.gov/gasstar/documents/vincent.pdf
Wells 3
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Wells
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Install compressors to Direct Measurement Emissions Factor Partner Quantified Methane Emissions Reductions
capture casinghead gas
Casinghead gas collects in the annular space between the tubing and casing of an oil well. Casinghead gas collects in the annular space between the tubing and casing of an oil well. Methane emission reductions from installing compressors to
Production Typically casinghead gas is vented to the atmosphere when the wellhead pressure drops below gas Typically casinghead gas is vented to the atmosphere when the wellhead pressure drops below gas capture casinghead gas are highly variable. Factors such as
sales line pressure. Use an orifice meter to measure the volume of gas vented from casings before sales line pressure. Emissions factors have been developed for the amount of methane emitted production composition, well production rate, well depth, and
and after installing compressors to route gas to sales. These can be used to estimate the volume from venting these casingheads. well pressure will affect methane emission reductions for
of vapors that would otherwise be vented to the atmosphere. Multiply by the methane content of each specific application. Natural Gas STAR encourages
the gas. Calculate emissions reductions from the following equation: partners to identify other methods to quantify methane
ER = AF · EF · OF emissions reductions. Please identify the basis for any
References: alternate emissions reduction estimate in the annual report.
Install Compressors to Capture Casinghead Gas PRO Where,
http://www.epa.gov/gasstar/documents/installcompressors.pdf ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (number of casings connected to VRUs/given year)
OF = Operating factor of compressor - default is 95%
Active wells casings
EF = 1.03 Mcf/well
Suspended wells casings
EF = 0.56 Mcf/well
References:
Install Compressors to Capture Casinghead Gas PRO
http://www.epa.gov/gasstar/documents/installcompressors.pdf
API Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Gas Industry. Page
5-68. API, February 2004.
Wells 4
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Wells
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Install downhole separator Engineering Calculation Partner Quantified Methane Emissions Reductions
pumps
The methane savings from installing downhole separator pumps are due to avoiding the handling of Methane emission reductions from installing downhole separator pumps are highly variable. Factors
Production produced water from which dissolved methane flashes to the atmosphere. such as production composition, well production rate, and well pressure will affect methane
emission reductions for each specific application. Natural Gas STAR encourages partners to
Calculate emissions reductions using the following equation: identify other methods to quantify methane emissions reductions. Please identify the basis for any
ER = WP · XM alternate emissions reduction estimate in the annual report.
Where,
ER = Emissions Reductions (Mcf/year)
WP = Water production rate (thousand barrels/year)
XM = Methane emissions from each barrel of water
From 50psi separator
XM = 0.078 Mcf/thousand barrels water
From 250psi separator
XM = 0.738 Mcf/thousand barrels water
From 1,000psi separator
XM = 2.642 Mcf/thousand barrels water
References:
Install Downhole Separator Pumps PRO
http://www.epa.gov/gasstar/documents/installdownholeseparatorpumps.pdf
API Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Gas Industry. Page
5-46. API, February 2004.
Install pumpjacks or rod Direct Measurement Partner Quantified Methane Emissions Reductions
pumps on gas wells
Use an orifice meter to determine the volume of gas vented during a blowdown. Multiply this by the Methane emission reductions from installing pumpjacks are highly variable. Factors such as
Production number of blowdowns reduced in a year by installing pumpjacks removing liquids downhole, and production composition, gas production rate, liquids production rate, well depth, and well pressure
then multiply by the methane content of the gas to determine emissions reductions. will affect methane emission reductions for each specific application. Natural Gas STAR
encourages partners to identify other methods to quantify methane emissions reductions. Please
References: identify the basis for any alternate emissions reduction estimate in the annual report.
Install Pumpjacks on Low Water Production Gas Wells PRO
http://www.epa.gov/gasstar/documents/gaswells.pdf
Wells 5
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Wells
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Install velocity tubing Direct Measurement Partner Quantified Methane Emissions Reductions
strings
Use an orifice meter to determine the volume of gas vented during a blowdown. Multiply this by the Methane emission reductions from installing velocity tubing strings are highly variable. Factors such
Production number of blowdowns reduced in a year by installing tubing strings to remove liquids, and then as production composition, gas production rate, liquids production rate, well depth, and well
multiply by the methane content of the gas to determine emissions reductions. pressure will affect methane emission reductions for each specific application. Natural Gas STAR
encourages partners to identify other methods to quantify methane emissions reductions. Please
References: identify the basis for any alternate emissions reduction estimate in the annual report.
Install Velocity Tubing Strings PRO
http://www.epa.gov/gasstar/documents/installvelocitytubingstrings.pdf
Install plunger lift systems Emissions Factor: Avoiding blowdowns Emissions Factor: Replacing beam lifts (avoiding workovers) Partner Quantified Methane Emissions Reductions
Production Installing plunger lifts saves methane emissions by avoiding blowdowns. Mobil measured When installing plunger lifts replace beam lifts, well workovers for mechanical repairs, to remove Natural Gas STAR encourages partners to identify other
approximately 640 Mcf/well/year of blowdown of emissions reductions. Direct measurement of debris and cleanout perforations, to remove mineral scale and paraffin deposits from the sucker methods to quantify methane emissions reductions. Please
emissions volumes before and after plunger lift installment can be done using an orifice meter. rods, emissions can be avoided. identify the basis for any alternate emissions reduction
estimate in the annual report.
Calculate emissions reductions using the following equation: Calculate emissions reductions using the following equation:
ER = AF · 640 Mcf/well/year ER = AF · EF
Where, Where,
ER = Emissions Reductions (Mcf/year) ER = Emissions Reductions (Mcf/year)
AF = Activity Factor (well blowdowns) AF = Activity Factor (workovers/year)
EF = Emissions Factor (Mcf/workover) - default is 2 Mcf/workover
References:
Installing Plunger Lift Systems in Gas Wells Lessons Learned References:
http://www.epa.gov/gasstar/documents/ll_plungerlift.pdf Installing Plunger Lift Systems in Gas Wells Lessons Learned
http://www.epa.gov/gasstar/documents/ll_plungerlift.pdf
Lower heater-treater Partner Quantified Methane Emissions Reductions
temperature
Methane emission reductions from lowering heater treater temperatures are highly variable. Factors
Production such as production composition, well production rate, and process details will affect methane
emission reductions for each specific application. Natural Gas STAR encourages partners to
identify other methods to quantify methane emissions reductions. Please identify the basis for any
alternate emissions reduction estimate in the annual report.
References:
Lower Heater-Treater Temperature PRO
http://epa.gov/gasstar/documents/lowerheatertreatertemp.pdf
Wells 6
Natural Gas STAR Recommended Technologies and Practices - Quantification Methods
Wells
Technology/
Practice and Quantification Method 1 Quantification Method 2 Quantification Method 3
Applicable Sector(s)
Use foaming agents to Direct Measurement Partner Quantified Methane Emissions Reductions
reduce blowdown
frequency Use an orifice meter to determine the volume of gas vented during a blowdown. Multiply this by the Methane emission reductions from using foaming agents are highly variable. Factors such as
number of blowdowns reduced in a year by using foaming agents to form gas-water foam that can production composition, gas production rate, liquids production rate, well depth, and well pressure
Production be lifted to the surface, and then multiply by the methane content of the gas to determine emissions will affect methane emission reductions for each specific application. Natural Gas STAR
reductions. encourages partners to identify other methods to quantify methane emissions reductions. Please
identify the basis for any alternate emissions reduction estimate in the annual report.
References:
Use Foaming Agents PRO
http://www.epa.gov/gasstar/documents/usefoamingagents.pdf
Wells 7
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