National Atmospheric Emissions Inventory

National Atmospheric Emissions Inventory

Appendix 1

The Methodology of the National Atmospheric Emissions Inventory

2. Estimation of Emission Sources

2.1 Introduction
The previous sections have defined the fuels and source categories used in the NAEI. The aim of this section is to describe in detail the methodology used to estimate the emissions for each source category.

It would be impossible to measure every emission source in the UK directly; therefore, the majority of emissions are estimated from other information such as fuel consumption, distance travelled or some other statistical data related to the emissions. Estimates are calculated by applying an emission factor to an appropriate statistic. That is:

Emission = Factor × Statistic

The emission factors have been derived from measurements on a number of installations representative of the source and the resulting factor is assumed to apply to all installations in that source.

For certain sectors, emission data are available for individual sites from databases such as the Environment Agency's Chemical Release Inventory (CRI). Hence the emission for a particular sector can be calculated as the sum of the emissions from these point sources. That is:

Emission = S Point Source Emissions

However it is necessary to make an estimate of the fuel consumption associated with these point sources, so that the emissions from non-point sources can be estimated from fuel consumption data without double counting.

Section 2.2 discusses the base combustion module which corresponds to the more straight forward combustion emissions. Subsequent sections discuss the other modules which are based on more complex models or require further explanation.

2.2 Base Fuel Combustion Module
For the pollutants and sources discussed in this section the emission results from the combustion of fuel. The statistics used to calculate the emission are fuel consumption statistics taken from DTI (1997).

Emissions are calculated according to the equation:

E(p,s,f) = A(s,f) × e(p,s,f)

where


E(p,s,f) = Emission of pollutant p from source s from the combustion of fuel f (Kg)
A(s,f) = Consumption of fuel f by source s (kg or therms)

e(p,s,f) = Emission factor of pollutant p from source s from combustion of fuel f(kg/kg or kg/therm)

The sources covered by this module are:

Domestic

Miscellaneous

Other Non-Industrial

Public Service

Refineries

Iron & Steel

Iron & Steel Other

Flaring (of coke oven gas and blast furnace gas)

Other Industry

Autogenerators

Gas Production

Town Gas Production

Collieries

Production of Nuclear Fuel

Railways

Coastal Shipping

Shipping Naval

Aircraft Military

Fishing

Agriculture

Ammonia: Combustion

Cement & Lime: Fuel

The fuels covered are listed in Table A2, though not all fuels occur in all sources.

Tables A3 to A6 list the emission factors used in this module. Emission factors are expressed in terms of kg pollutant/ t for solid and liquid fuels and g/therm for gases. This differs from the IPCC approach which expresses emission factors as tonnes pollutant/ TJ based on the net calorific value of the fuel. For gases, the NAEI factors are based on the gross calorific value of the fuel. This approach is used because the gas consumption data in DTI, (1997) are reported in terms of energy content on a gross basis. It should be noted that gross calorific values of fuels are higher than net calorific values. For straw and wood, emission factors are given as g/GJ gross. This is because the activity data in DTI(1997) is given in energy units, and the calorific values of wood and straw required to convert the emission factor to a mass basis are rather uncertain.

The sulphur dioxide emission factors are updated each year where possible. For liquid fuels they are based on data published by the Institute of Petroleum (1997). Prior to 1995, the sulphur dioxide emission factors for coal were based on data supplied by British Coal on the sulphur contents of coals sold into different sectors in the UK. Since then, similar sulphur content and sales data has been gathered from the four main UK coal producers and sectoral averages estimated. The estimates take account of coal imports which tend to have a lower sulphur content than home produced coal though most of this coal is used in power stations and for coking.

For most of these categories, the emission is estimated from a fuel consumption reported in DTI (1997) and an emission factor appropriate to the type of combustion e.g. commercial gas fired boiler. However the DUKES category 'Other Industries' covers a range of sources and types, so the Inventory disaggregates this category into a number of sub-categories:

Other Industry

Ammonia Combustion:- See Section 2.5.10

Other Industry Off-Road:- See Section 2.9.4

Ammonia & Feedstock (natural gas only):- See Section 2.5.10

Cement & Lime Fuel (Combustion in cement and lime kilns) :- See Section 2.5.4

The NAEI category Other Industry refers to stationary combustion in boilers and heaters. The other categories are estimated by more complex methods discussed in the sections indicated. The fuel consumption of Other Industry is estimated so that the total fuel consumption of these sources is consistent with DUKES, (DTI, 1997).

Table A3 Emission Factors for the Combustion of Liquid Fuels (kg/t)

Fuel Source C CH₄ N₂O NO_x CO NMVOC SO₂ PM₁₀ BS^q

ATF Aircraft Military 859^a 0.0825^d 0.1^e 23.7^d 4.0^d 0.667^d 0.8^g - 0.98

Burning Oil Domestic 859^a 0.309^b 0.0265^e 2.21^b 0.16^f 0.133^b 0.6^g 0.014^r 0.007

Burning Oil(P) Domestic 859^a 0.309^b 0.0265^e 2.21^b 0.16^f 0.133^b <0.1^g 0.014^r 0.007

Burning Oil Agriculture, Railways, Other Industry, Public Service 859^a 0.0432^b 0.0265^e 2.84^m 0.16^f 0.0865^b 0.6^g 0.014^r 0.007

Gas Oil Agriculture 857^a 0.225^b 0.026^e 2.84^m 0.71^f 0.128^k 2.8^g 0.25^r 0.75

Gas Oil Domestic 857^a 0.303^b 0.026^e 2.16^b 0.24ⁱ 0.13^b 2.8^g 0.25^r 0.75

Gas Oil Fishing;Coastal Shipping 857^a 0.1^c 0.2^d 70^h 10.0^h 7.9^l 19.4^h 1.07^r 1.35

Gas Oil Shipping Naval 857^a 0.288^p 0.2^d 57.0^d 7.4^d 2.11^p 19.4^h 1.07^r 1.35

Gas Oil Other Industry, Iron & Steel 857^a 0.0432^b 0.026^e 3.46^b 0.24ⁱ 0.0865^b 2.8^g 0.25^r 0.75

Gas Oil Other Non-Industrial 857^a 0.0432^b 0.026^e 2.84^b 0.24ⁱ 0.0865^b 2.8^g 0.25^r 0.75

Gas Oil Railways 857^a 0.166^d 1.2^e 35^b 19.3^f 13.1^k 2.8^g 0.25^r 0.75

Gas Oil Refineries 857^a 0.0432^b 0.026^e 3.46^b 0.24ⁱ 0.0865^b 2.8^g 1.07^r 0.75

Gas Oil Town Gas Production 857^a 0.0432^b NE 3.46^b 0.24ⁱ 0.0865^b - ^o 1.07^r 0.75

Fuel Oil Agriculture; Other Non-Industrial 850^a 0.122^b 0.0243^e 6.99^m 0.5ⁱ 0.122^b 42.9^g 1.032^r 1.0

Fuel Oil Fishing;Coastal Shipping 850^a 0.1^c 0.2^d 70^h 10^h 7.9^l 56.4^h 1.032^r 1.35

Fuel Oil Domestic 850^a 0.303^b 0.0243^e 6.99^m 0.5ⁱ 0.13^b 42.9^g 1.032^r 1.0

Fuel Oil Other Industry, Iron & Steel, Railways 850^a 0.122^b 0.0243^e 7.54ⁱ 0.5ⁱ 0.122^b 42.9^g 1.032^r 1.0

Fuel Oil Refineries 850^a 0.122^b 0.0243^e 6.1^b 0.5ⁱ 0.122^b 42.9^g 1.032^r 1.0

Fuel Oil Cement & Lime Fuel 850^a 0.0406^d NE 21.4^b 3.37^d 0.122^b 23.6^d 1.032^r 1.0

Fuel Oil Town Gas Production 850^a 0.122^b NE 7.54ⁱ 0.5ⁱ 0.122^b -^o 1.032^r 1.0

Naphtha Refineries 940^a 0.122^j NE 7.54^j 0.5^j 0.122^j 42.9^j 1.07^s 1.0

Miscellaneous Refineries 800^a 0.122^j NE 7.54^j 0.5^j 0.122^j 42.9^j 1.07^r 1.0

Petrol Refineries 855^a 0.0432ⁿ NE 3.46ⁿ 0.24ⁿ 0.0865ⁿ 0.8^g 0.204^r 1.0

Waste Oils Cement & Lime Fuel 859^a 0.0406^j NE 21.4^j 3.37^j 0.122^j 23.6^j NE 1.0

Table A3: Notes
a        UKPIA (1989)
b        CORINAIR (1992)
c        Methane factor estimated as 1.25% of total hydrocarbon emission factor taken from EMEP (1990)
d        EMEP/CORINAIR (1996)
e        IPCC(1997)
f        USEPA (1977)
g        1996 emission factor based on Institute of Petroleum, (1997)
h        EMEP (1990)
i        Walker et al. (1985)
j        As fuel oil
k        NMVOC emission factor estimated as 98.75% of total hydrocarbon emission factor taken from USEPA (1977).
l        NMVOC emission factor estimated as 98.75% of total hydrocarbon emission factor taken from EMEP(1990)
m        USEPA(1995)
n        As gas oil
o        Source no longer exists
p        EMEP/CORINAIR (1996) for THC assuming 12% methane according to IPCC(1997)
q        Keddie et al. (1978); Timmis et al. (1988)
r        USEPA (1995)
s        USEPA (1995b)

Table A4 Emission Factors for Combustion of Coal (kg/t)

C CH₄ N₂O NO_x CO NMVOC SO₂ PM₁₀ BS^t

Agriculture 659.6^a 0.287^b 0.155^e 4.31^b 4.1^g 0.575^b 22.5^h 2.5^k 1.0^j

Town Gas Production 710^a 0.286^b NE 5.15^b 4.1^g 0.572^b - ⁱ 2.5^k 1.0^j

Collieries 659.6^a 0.252^b 0.061^e 4.53^b 4.1^g 0.503^b 24.2^h 2.5^k 1.0^j

Domestic 676.8^a 7.7^c 0.119^e 1.42^b 45.0^f 11.7^c 24.1^h 10.4^k 40.0^j

Iron & Steel 659.6^a 0.276^b 0.0704^e 4.97^b 4.1^g 0.552^b 22.5^h 2.5^k 1.0^j

Miscellaneous, Public Service 659.6^a 0.264^b 0.143^e 3.96^b 4.1^g 0.529^b 22.5^h 2.5^k 1.0^j

Other Industry 659.6^a 0.258^b 0.213^e 4.65^b 4.1^g 0.516^b 22.5^h 2.5^k 1.0^j

Railways 659.6^a 0.295^b 0.0753^e 5.04^b 4.1^g 0.591^b 22.5^h 20^k 20.0^j

Autogenerators 659.6^a 0.258^b 0.0658^e 4.65^b 4.1^g 0.516^b 22.5^h 2.5^k 1.0^j

Cement & Lime Fuel 659.6^a 0.0258^d 0.108^e 13.6^d 2.84^d 0.516^b 11.9^d 2.5^k 1.0^j

SSF Production 710^a 0.28^b NE 5.04^b 4.1^g 0.56^b 14.9^h NE 1.0^j

Notes for Table A4

a        British Coal (1989)
b        CORINAIR (1992)
c        Coal Research Establishment (1993)
d        EMEP/CORINAIR (1996)
e        Fynes et al. (1994)
f        USEPA (1977)
g        Walker et al. (1985)
h        1996 emission factor based on Data provided by RJB Mining (1997), Celtic Energy (1997), Scottish Coal (1997), Tower (1997)
i        Source no longer exists
j        Keddie et al. (1978); Timmis et al. (1988)
k        USEPA (1995)

Table A5 Emission Factors for Combustion of Solid Fuels (kg/t)

C CH₄ N₂O NO_x CO NMVOC SO₂ PM₁₀ BS

Anthracite Domestic 813.4^a 7.3^e 0.14^h 1.6^b 45.0^f 0.8^e 13.8^k 3.59^p 5.6^o

Coke Agriculture 795.4^a 0.267^b NE 4.0^b 4.1ⁱ 0.534^b 19.0^l 0.288^p 0.225^o

Coke Coke Production; SSF Productn 820^a 0.267^b NE 4.8^b 4.1ⁱ 0.534^b 19.0^l 0.288^p 0.225^o

Coke Domestic 803.6^a 6.4^e NE 1.33^b 45^j 1.2^e 16.0^l 0.288^p 5.6^o

Coke I&S Blast Furnaces 820^a 0.267^b NE 4.8^b 4.1ⁱ 0.534^b 0 2.75^p 0.225^o

Coke I&S Other; Other Industry; Railways; Town Gas Production 795.4^a 0.267^b NE 4.8^b 4.1ⁱ 0.534^b 19.0^l 0.288^p 0.225^o

Coke Miscellaneous; Other Non-Industrial; Public Service 795.4^a 0.267^b NE 4.0^b 4.1ⁱ 0.534^b 19.0^l 0.288^p 0.225^o

Petro- Coke Refineries 800^c 0.267ⁿ NE 8.0^b 4.1ⁱ 0.534ⁿ 19.0ⁿ NE 0.225^o

SSF Agric; Miscellaneous; Public Service 766.3^a 0.264^b NE 3.96^b 4.1ⁱ 0.528^b 19.0^l 0.23^p 0.225^o

SSF Domestic 774.2^a 6.4^e NE 1.32^b 45^j 1.2^e 16.0^l 5.6^p 5.6^o

SSF I&S Blast Furnaces 766.3^a 0.264^b NE 4.75^b 4.1ⁱ 0.528^b 0 0.23^p 0.225^o

SSF I & S Other, Other Industry, Railways 766.3^a 0.264^b NE 4.75^b 4.1ⁱ 0.528^b 19.0^l 0.23^p 0.225^o

Scrap Tyres Cement & Lime Fuel 832^d 0.0258ⁱ NE 13.6ⁱ 2.84ⁱ 0.516ⁱ 11.9ⁱ NE 1.0ⁱ

Wood Domestic; Other Industry - - - - - - 0.037^m - -

(kg/GJ gross)

Straw Agriculture NE 0.167^g 0.0033^g 0.119^g 3.5^g NE 0 NE NE

Wood Domestic NE 0.38^b 0.0041^g 0.076^b 6.0^g 0.57^b - NE NE

Wood Other Industry NE 0.0285^b 0.0041^g 0.19^b 0.189^g 0.0475^b - NE NE

Notes for Table A5

a        British Coal (1989)
b        CORINAIR (1992)
c        UKPIA (1989)
d        Estimate based on data in Ogilvie(1995)
e        Coal Research Establishment (1993)
f        USEPA (1977)
g        IPCC (1995)
h        Fynes et al. (1994)
i        As coal
j        As anthracite
k        1996 emission factor based on Data provided by BJC Mining (1997), Celtic Energy (1997), Scottish Coal (1997), Tower (1997)
l        Munday (1990)
m        USEPA(1995)
n        As coke
o        Keddie et al. (1978); Timmis et al. (1988)
p        USEPA (1995)

Table A6 Emission Factors for the Combustion of Gaseous Fuels (g/therm)

Fuel Source C CH₄ N₂O NO_x CO NMVOC SO₂ PM₁₀

BF Gas Flaring, I & S Blast Furnaces, Iron & Steel 6273^a 11.8^d 0.211^d 8.3^d 4.17^d 0.591^d 0 0.1^r

BF Gas Coke Production 6273^a 0.0317^d 0.211^d 11^d 15.8^d 0.317^d 0 0.1^r

BF Gas Collieries 6273^a 11.8^d 0.211^d 8.3^d 4.17^d 0.591^d 0 0.56^r

Coke Oven Gas Domestic 1599^a 0.791^b+ NE 4.75^b 0.25^g 1.85^b+ 41.1^k 0.602^r

Coke Oven Gas Flaring, Collieries, Iron & Steel, Other Industry, Town Gas Prod 1599^a 0.791^b+ NE 8.55^b 0.25^g 1.85^b+ 41.1^k 0.135^r

Coke Oven Gas Coke Production 1599^a 0.791^b+ NE 52.8^k 22.8^k 1.85^b+ 41.1^k 0.135^r

LPG Domestic 1874^c 0.0971^h 0.0095^j 4.85^b 0.863^g 0.194^h 0 0.393^r

LPG Gas Prodn; Town Gas Prodn 1874^c 0.0971^h NE 9.4^h 0.25^g 0.194^h 0 0.295^r

LPG I&S; Other Industry; Refineries 1874^c 0.0971^h 0.0095^j 9.4^h 0.25^g 0.194^h 0 0.295^r

Natural Gas Agriculture; 1501^e 0.38^b 0.0095^j 4.88^h 0.25ⁱ 0.38^b 0 0.604^r

Natural Gas Coke Production; SSF Productn 1501^e 0.38^b 0.0095^j 9.5^b 0.25ⁱ 0.38^b 0 0.108^r

Natural Gas Domestic 1501^e 0.285^b 0.0095^j 4.85^l 0.863^p 0.665^b 0 0.482^r

Natural Gas Gas Prodn, Iron & Steel, Other Industry, Refineries, Nuclear Fuel Prodn, 1501^e 0.38^b 0.0095^j 9.5^b 0.25ⁱ 0.38^b 0 0.108^r

Natural Gas Cement & Lime Fuel 1501^e 0.105^d NE 106^d 11.4^d 0.38^b 0 0.108^r

Natural Gas Collieries 1501^e 0.38^b 0.0095^j 9.5^b 0.25ⁱ 0.38^b 0 0.604^r

Natural Gas Miscellaneous 1501^e 0.38^b 0.0095^j 4.88^h 0.25ⁱ 0.38^b 0 0.108^r

Natural Gas Public Service 1501^e 0.38^b 0.0095^j 4.88^h 0.25ⁱ 0.38^b 0 0.514^r

Natural Gas Railways 1501^e 0.38^b 0.0095^j 9.5^b 0.25ⁱ 0.38^b 0 NE

Natural Gas Autogenerators 1501^e 0.579^m 0.0095^j 4.69ⁿ 0.019^q 0.38^b 0 0.108^r

Natural Gas Ammonia Combustion 1501^e 0.38^b 0.0095^j 58.7^o 0.25ⁱ 0.38^b 0 NE

Natural Gas Town Gas Production 1501^e 0.38^b NE 9.5^b 0.25ⁱ 0.38^b 0 0.108^r

Table A6 Emission Factors for the Combustion of Gaseous Fuels Continued (g/therm)

Town Gas Domestic 1599^f 0.285^g NE 4.85^g 0.863^g 0.665^g 0 0.602^r

Town Gas Miscellaneous; Public Service 1599^f 0.38^g NE 4.88^g 0.25^g 0.38^g 0 0.755^r

Town Gas Gas Production, Iron & Steel 1599^f 0.38^g NE 9.5^g 0.25^g 0.38^g 0 0.135^r

Town Gas Other Industry 1599^f 0.38^g NE 9.5^g 0.25^g 0.38^g 0 0.755^r

OPG Refineries, Other Industry, Gas Production 1627^c 0.324^b+ NE 13.6^b 0.25^g 0.647^b+ 0 0.295^r

OPG Town Gas Production 1627^c 0.324^b+ NE 13.6^b 0.25^g 0.647^b+ 0 0.393^r

Colliery CH₄ Collieries 1501^g 0.38^g 0.0095^g 9.5^g 0.25^g 0.38^g 0 0.604^r

Colliery CH₄ Coke Prodn, Gas Prodn, Other Industry 1501^g 0.38^g 0.0095^g 9.5^g 0.25^g 0.38^g 0 0.108^r

Sewage Gas Public Services NE 64.9^h NE 94.6^h 17.4^h 4.99^h 0 0.612^r

Landfill Gas Miscellaneous NE 64.9^h NE 94.6^h 17.4^h 4.99^h 0 0.612^r

Notes for Table A6

a        British Coal (1989)
b        CORINAIR (1992)
b+        Derived from CORINAIR(1992) assuming 30% of total VOC is methane
c        UKPIA (1989)
d        EMEP/CORINAIR (1996)
e        British Gas (1992)
f        British Gas (1988)
g        As natural gas
h        USEPA(1995)
i        Walker et al. (1985)
j        IPCC(1997)
k        Emission factor derived from emissions reported in the CRI
l        British Gas (1994)
m        IPCC (1995)
n        PowerGen (1997); National Power (1997)
o        Data provided by ICI (1997), Kemira (1997)
p        USEPA (1977)
q        Powergen (1994)
r        USEPA (1995)