addressing uncertainty in oil and natural gas industry greenhouse

6 6
⎛40×10 scf 928 Btu ⎞ ⎛ 2×10 Btu 24 hr 343 days ⎞
V = ⎜ × ⎟+ ⎜3 Units× × × ⎟
⎝ yr scf ⎠ ⎝ hr-unit day yr ⎠
6
V = 86,512 ×10 Btu/yr
The uncertainty for the boiler activity factor is calculated by applying Equation 4-6 and using the relative
uncertainty values.
2 2 2 2
boiler AF AF Heating Value
( )
Urel ( ) = U( rel) +U( rel ) = 15 + 4 =± 15.5% Btu/yr
Uncertainty for heater/reboilers: (Equation 4-6, relative uncertainties)
U ( rel) = U( rel) +U( rel) +U( rel)
2 2 2
heater Units Capacity Days
Urel = + + =±
( )
2 2 2
( )
heater
0 5 2 5.39% Btu/yr
The uncertainty for the combined activity factor is calculated by applying Equation 4-4 and using the
absolute uncertainty values.
U ( abs) = (U( abs) +U( abs)
U abs
2 2
AF Boiler Heater
6 2 6 2 6
( )
AF
= (0.155× 37,120× 10 ) + (0.0539× 49,392× 10 ) = 6,347×
10 Btu/yr
6
6,347×10 Btu/yr
AF 6
( )
Urel ( ) = 100% × =± 7.34% Btu/yr
86,512×10 Btu/yr
As stated previously, the uncertainty in the emissions factor for N 2 O is determined by engineering judgment
to be 150%. The uncertainty in the emissions factor for methane is 25% based on expert judgment. The
uncertainty for emissions is calculated by applying Equation 4-6 and using the relative uncertainty values.
Because it is not possible to have negative emissions, the lower bound uncertainty will be truncated at zero.
As a result, the lower and upper bound uncertainties are estimated separately.
6
-6
86,512 × 10 Btu 1.0 × 10 tonne CH
4
E
CH
: × = 0.0865 tonnes CH
4
6
4
/yr
yr
10 Btu
( )
Urel ( ) = U( rel) +U( rel ) = 7.34 + 25 =± 26.1% tonnes CH /yr)
2 2 2 2
emissions AF EF 4
6
-7
86,512 × 10 Btu 2.8 × 10 tonne N2O
E
NO= × = 0.0242 tonnes N
2
6
2O/yr
yr
10 Btu
( )
U( rel) = U( rel) +U( rel ) = 7.34 + 150 =+ 150%, − 100% tonnes N O/yr
2 2 2 2
emissions AF EF 2
Pilot Version, September 2009 F-8