compendium of greenhouse gas emissions estimates

8/2/2019 Compendium of Greenhouse Gas Emissions Estimates

1/6

Compendium of Greenhouse Gas

Emissions Estimation Methodologies forthe Oil and Gas Industry

Errata

February 2005


2/6

4.0COMBUSTION EMISSIONS ESTIMATION METHODS

4.1.1 Steam/Heat Utility Emissions

Imported steam/heat or steam/heat generated onsite results in GHG emissions due to combustionthat occurs to produce the steam. If the method of generation for the steam/heat is known, then theapproach to estimate combustion emissions given in Section 4.1 can be used. However, if noinformation about the steam/heat generation method is known, then a simple approach of assumingthat the steam/heat was generated in a natural gas boiler is suggested. A thermal based emissionfactor for this approach can be developed by dividing a boiler emission factor on a lower heatingvalue (LHV) basis by an assumed boiler efficiency. For example, the LHV natural gas combustionemission factors given in Table 4-1 for CO 2 and Table 4-4a for CH 4 and N 2O (controlled ) can beconverted to a thermal basis by dividing by an assumed 92% boiler efficiency, as shown below:

(Corrected the following emission factors.)

Lbasis,energyt(steam/heaBtuO/10Ntonne103.26 0.92

Btutonne/10103.0 FactorEmissionON

LHbasis,energyt(steam/heaBtu /10CHtonne101.20 0.92

Btutonne/10101.1 FactorEmissionCH

LHV)basis,energyt(steam/heaBtu /10COtonne0.0641 0.92

Btutonne/100.0590 FactorEmissionCO

62

767-2

64

666-

4

62

6

2

==

=

=

==

4-51 February 2005


3/6

4.7.3 Allocation of Cogeneration Emissions

Work Potential Allocation Approach

This approach assigns the emissions to the energy streams in proportion to their contribution to the

total work potential, or exergy. The work potential for steam is calculated from the specificenthalpy (H) and specific entropy (S) of the stream. This approach sums the work potential of allstreams and allocates the total emissions to the individual streams.

As with the UK ETS method, the first step is to calculate the total direct CO 2 emissions from thecombustion of natural gas at the cogeneration facility. The second step is to calculate the work potential of the steam, using 212 F (100 C) saturated water as the reference basis, and 700F (371C) and 600 psia (4,137 kilo Pascal) for the process steam. The enthalpy and entropy of the steamcan be determined from a steam table at the reference and actual conditions. The work potential of

the steam is calculated using the following equations.In US units:

)S(S460)(T)H(H(Btu/lb)potentialwork Steam ref iref ref i += (Equation 4-11)

and in SI units:)S(S)273(T)H(HJ/tonne)(10potentialwork Steam ref iref ref i9 += (Equation 4-12)

where:H i = specific enthalpy of the process steam (BTU/lb or 10 3 J/kilogram)H ref = specific enthalpy at the reference conditions (BTU/lb or 10 3 J/kilogram)

Tref = reference temperature (F or

C)Si = specific entropy of the process steam (BTU/lb R or 10 3 J/kilogram K)

Sref = specific entropy at the reference conditions (BTU/lb R or 10 3 J/kilogram K)

4-63 February 2005


4/6

6.0FUGITIVE EMISSIONS ESTIMATION METHODS

Table 6-1. Facility-Level Average Fugitive Emission Factors

SourceEmission FactorOriginal Units

Precision( %) a

Gas ContentBasis of Factor

Emission Factor b Converted Units

ProductionOnshore gas production 44 78.8 mole % 2.595E-02 tonnes CH 4 / 10

6 scf 57.21 lb CH 4 /106scf

produced CH 4 9.164E-01 tonnes CH 4 / 106 m3

Offshore gas production Not 78.8 mole % 1.038E-02 tonnes CH 4 / 106 scf 22.88 lb CH 4 /10

6scf produced available CH 4 3.665E-01 tonnes CH 4 / 10

6 m3

Onshore oil production Not 78.8 mole % 2.342E-04 tonnes CH 4 /bbl0.5164 lb CH 4 /bblproduced available CH 4 1.473E-03 tonnes CH 4 /m3

Offshore oil production Not 78.8 mole % 9.371E-05 tonnes CH 4 /bbl0.2066 lb CH 4 /bblproduced available CH 4 5.894E-04 tonnes CH 4 /m

3

Gas processing plants 69 87 mole % 2.918E-02 tonnes CH 4 / 106 scf 64.32 lb CH 4 /10

6scf processed CH 4 1.030E+00 tonnes CH 4 / 10

6 m3

Gas storage stations 1,489,000 lb CH 4 /station 57 93.4 mole %CH 4

6.754E+02 tonnes CH 4 /station

Gas transmission pipelinesCH 4 from pipeline leaks 7,923 lb CH4/mile-yr 84 93.4 mole % 3.594E+00 tonnes CH 4 /mile-yr

CH 4 2.233E+00 tonnes CH 4 /km-yrCO 2 from oxidation

c 7.59 lb CO 2 /mile-yr 65 2 mole % 3.443E-03 tonnes CO 2 /mile-yrCO 2 2.139E-03 tonnes CO 2 /km-yr

CO 2 from pipeline leaks 466.7 lb CO 2 /mile-yr 84 2 mole % 2.117E-01 tonnes CO 2 /mile-yrCO 2 1.315E-01 tonnes CO 2 /km-yr

Crude transmission pipelines Negligible NegligibleGas distribution pipelines

CH 4 from pipeline leaks 3,551 lb CH 4 /mile-yr 48 93.4 mole % 1.611E+00 tonnes CH 4 /mile-yrCH 4 1.001E+00 tonnes CH 4 /km-yr

CO 2 from oxidationc 1,237 lb CO 2 /mile-yr 69 2 mole % 5.611E-01 tonnes CO 2 /mile-yr

CO 2 3.486E-01 tonnes CO 2 /km-yrCO 2 from pipeline leaks 235.6 lb CO 2 /mile-yr 45 2 mole % 1.069E-01 tonnes CO 2 /mile-yr

CO 2 6.640E-02 tonnes CO 2 /km-yrRefining d 0.53 kg THC/m 3 crude

feedstock Notavailable

8.43E-05 tonnes THC/bblfeedstock 5.30E-04 tonnes THC/m 3 feedstock

Source: Shires, T.M. and C.J. Loughran. GHGCalc Version 1.0 Emission Factor Documentation , Draft, Gas TechnologyInstitute (GTI), January 2002, Tier 1 fugitive emission factors from Table 4-26.a Precision is based on a 90% confidence interval from the data used to develop the original emission factor.b The CH 4 emission factors can be adjusted based on the relative concentrations of CH 4 and CO 2 to estimate CO 2 emissionsc A portion of CH 4 emitted from underground pipeline leaks is oxidized to form CO 2.

6-5 February 2005


5/6

Table 62. Fugitive Emission Factors for Onshore Natural Gas ProductionEquipment

Equipment BasisReference Emission Factor,

Original Units Precision

( %) aEmission Factor b ,Converted Units

Gas wellheads 8,208 scfy CH 4 /well 22 1.80E-05 tonne CH 4 /well-hrSeparators 20,171 scfy CH 4 /separator 73 4.42E-05 tonne CH 4 /separator-hrGas Heaters 20,978 scfy CH 4 /heater 145 4.59E-05 tonne CH 4 /heater-hrSmall reciprocating gascompressor

97,043 scfy CH 4 /compressor 106 2.12E-04 tonne CH 4 /compressor-hr

Large reciprocating gascompressor c

5.55 106 scfy CH 4 /compressor 169 1.22E-02 tonne CH 4 /compressor-hr

Large reciprocating gascompressor stations c

3.088 106 scfy CH 4 /station 102 6.59E-03 tonne CH 4 /station-hr

Meters/piping 16,072 scfy CH 4 /meter 133 3.52E-05 tonne CH 4 /meter-hrDehydrators 32,551 scfy CH 4 /dehydrator 37 7.13E-05 tonne CH 4 /dehydrator-hrGathering pipelines 825 lb CH 4 /mile-yr 108 4.27E-05 tonne CH 4 /mile-hr

2.65E-05 tonne CH 4 /km-hrCO 2 from oxidation d 84.5 lb CO 2 /mile-yr 66 4.38E-06 tonne CO 2 /mile-hr

2.72E-06 tonne CO 2 /km-hr112.9 lb CO 2 /mile-yr 107 5.85E-06 tonne CO 2 /mile-hrCO 2 from pipeline

leaks 3.63E-06 tonne CO 2 /km-hr

Source: Shires, T.M. and C.J. Loughran. GHGCalc Version 1.0 Emission Factor Documentation , Draft, GasTechnology Institute, January 2002. Cite data from Sections 4.2.1 and 4.3.1.

Notes:a Precision is based on a 90% confidence interval from the data used to develop the original emission factor.b Emission factors converted from scfy are based on 60 F and 14.7 psia. The average CH 4 concentration associatedwith these emission factors is 78.8 mole %; the average CO 2 concentration (for buried pipelines) is 2 mole %. If theactual concentration differs from the default value, the emission factors shown above can be adjusted by the ratio of the site concentration to the default concentration.c Large compressors are those with more than 3 stage of compression. Large compressor stations are those with fiveor more compressors.d A portion of CH 4 emitted from underground pipeline leaks is oxidized to form CO 2.

6-9 February 2005


6/6

Table 63. Fugitive Emission Factors Gas Distribution Equipment

Equipment BasisReference Emission Factor,

Original Units Precision

( %) aEmission Factor b ,Converted Units

Customer Meters 129.15 scf/meter-yr 22 2.83E-07 tonne CH 4 /meter-hrDistribution Meter/Reg. Stations 207,018 scf/station-yr 90 4.53E-04 tonne CH 4 /station-

hrDistribution Pipelines 1,357 lb CH 4 /mile-yr 69 7.03E-05 tonne CH 4 /mile-hr

4.37E-05 tonne CH 4 /km-hr1,205 lb CO 2 /mile-yr 71 6.24E-05 tonne CO 2 /mile-hrCO 2 oxidation EF for

distribution pipeline c 3.88E-05 tonne CO 2 /km-hr105.7 lb CO 2 /mile-yr 63 5.47E-06 tonne CO 2 /mile-hrCO 2 leaks from distribution

pipeline 3.40E-06 tonne CO 2 /km-hrDistribution Services 1,067 lb CH 4 /mile-yr 142 5.52E-05 tonne CH 4 /mile-hr

3.43E-05 tonne CH 4 /km-hr54.0 lb CO 2 /mile-yr 114 2.79E-06 tonne CO 2 /mile-hrCO 2 oxidation EF for

distribution services c 1.74E-06 tonne CO 2 /km-hr

63.9 lb CO 2 /mile-yr 142 3.31E-06 tonne CO 2 /mile-hrCO 2 leaks from distributionservices 2.06E-06 tonne CO 2 /km-hr

Source: Shires, T.M. and C.J. Loughran. GHGCalc Version 1.0 Emission Factor Documentation , Draft, GasTechnology Institute, January 2002. Cites data from multiple tables.

Notes:a Precision is based on a 90% confidence interval from the data used to develop the original emission factor.b Emission factors converted from scfy are based on 60 F and 14.7 psia. The average CH 4 concentration associatedwith these emission factors is 93.4 mole %; the average CO 2 concentration (for buried pipelines) is 2 mole %. If theactual concentration differs from the default value, the emission factors shown above can be adjusted by the ratio of the site concentration to the default concentration. c A portion of CH 4 emitted from underground pipeline leaks is oxidized to form CO 2.

6-13 February 2005

compendium of greenhouse gas emissions estimates

Documents