Chapter 7: Precursors and Indirect Emissions

CHAPTER 7

PRECURSORS AND INDIRECTEMISSIONS

2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

7.1

Volume 1: General Guidance and Reporting

Authors
Klaus Radunsky (Austria), Michael Gillenwater (USA)7.2

2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

Chapter 7: Precursors and Indirect Emissions

Contents
7

Precursors and Indirect Emissions ................................................................................................................ 7.4
7.1

Introduction ............................................................................................................................................ 7.4

7.2

Precursor emissions ................................................................................................................................ 7.4

7.2.1

Inventory of precursors ................................................................................................................... 7.5

7.2.2

Link to relevant methodology chapters in the EMEP/CORINAIR Emission Inventory Guidebook7.8

7.3

Indirect N2O emissions from the atmospheric deposition of nitrogen in NOx and NH3 ......................... 7.8

7.3.1

Methodology ................................................................................................................................... 7.8

7.3.2

Quality Assurance/Quality Control, Reporting and Documentation ............................................... 7.9

References .......................................................................................................................................................... 7.10
Annex 7A.1

Practical examples for carbon emitted in gases other than CO2 ................................................ 7.11

Equations
Equation 7.1

N2O emissions from atmospheric deposition of NOx and NH3 ...................................... 7.8

TablesTable A7.1 (New)

Non-Biogenic sources of CO2 from the atmospheric oxidation of CH4, CO, and
NMVOCs ..................................................................................................................... 7.11

Table A7.2 (New)

Examples of NMVOCs from the different source categories ....................................... 7.13

Table A7.3 (New)

Carbon content of various materials (percent carbon by mass, PC) and percent of totalsolvent NMVOC emissions (by mass, PU) .................................................................. 7.14

2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

7.3

Volume 1: General Guidance and Reporting

7 PRECURSORS AND INDIRECT EMISSIONS
Users are expected to go to Mapping Tables in Annex 1, before reading this chapter. This is required to correctly
understand both the refinements made and how the elements in this chapter relate to the corresponding chapter
in the 2006 IPCC Guidelines.

7.1

INTRODUCTION

This chapter addresses the calculation of emissions of precursors of greenhouse gases and of indirect emissions
that have not been addressed in Volumes 2-5 and that may be reported in greenhouse gas inventories.
Although they are not included in global warming potential-weighted greenhouse gas emission totals, directemissions of carbon monoxide (CO), nitrogen oxides (NOx), non-methane volatile organic compounds (NMVOCs),and sulphur dioxide (SO2) are also reported in greenhouse gas inventories. Carbon monoxide, NOx and NMVOC
as well as CH4 in the presence of sunlight contribute to the formation of the greenhouse gas ozone (O3) in the
troposphere and are therefore often called ‘ozone precursors’. Furthermore, NOx emission plays an important rolein the Earth’s nitrogen cycle and is an aerosol precursor. Sulphur dioxide emissions lead to formation of sulphate
particles, which also play a role in climate change. Ammonia (NH3) is an aerosol precursor with increasing
contribution to ambient particulate matter concentrations in several regions, in part due to decreasing SO2
emissions. The majority of the carbon emitted in the form of non-CO2 species (i.e., CH4, CO, and NMVOCs)
eventually oxidizes to CO2 in the atmosphere and this amount can be estimated from the emissions of these nonCO2 gases.
The guidance of this chapter is consistent with the use of any radiative forcing metric (e.g., Global Warming
Potential or Global Temperature change Potential) included in assessment reports of the IPCC so far and follows
the principle to avoid double counting (see Section 7.2.1.5). However, it does not provide guidance to estimate theoverall radiative forcing resulting from emissions of greenhouse gases, precursors and indirect emissions.
Section 7.2 addresses the estimation and reporting of the precursors for national inventories. The methodologies
for ambient air quality emission inventories have been elaborated in detail in the EMEP 1/EEA 2 Emission Inventory
Guidebook (Guidebook), and these methodologies for CO, NOx, NMVOCs, and SO2 emissions are referenced inthis chapter rather than to be included in the 2006 IPCC Guidelines. Exceptions are for sources not well coveredby the Guidebook.
Section 7.3 addresses nitrous oxide (N2O) emissions that result from the deposition of the nitrogen emitted as NOx
and NH3. Nitrous oxide is produced in soils through the biological processes of nitrification and denitrification.
Simply defined, nitrification is the aerobic microbial oxidation of ammonium to nitrate and denitrification is theanaerobic microbial reduction of nitrate to nitrogen gas (N2). Nitrous oxide is a gaseous intermediate in the reaction
sequence of denitrification and a by-product of nitrification that leaks from microbial cells into the soil atmosphere.
One of the main controlling factors in this reaction is the availability of inorganic nitrogen in the soil and therefore
deposition of nitrogen resulting from NOx and NH3 will enhance emissions. Nitrous oxide emissions will also beenhanced if nitrogen is deposited in the ocean or in lakes. For this reason, the 2006 IPCC Guidelines include
guidance for estimating N2O emissions resulting from nitrogen deposition of all anthropogenic sources of NOx andNH3. Only agricultural sources of nitrogen were considered in the Revised 1996 IPCC Guidelines (IPCC 1997).
Guidance is provided in Section 7.3 on estimating N2O emissions from atmospheric deposition resulting from all
categories except agricultural soil management and manure management. Section 7.3 provides information on NOx
emissions. Countries may use national methodologies to estimate emissions of NH3 not originating fromagriculture. NH3 emissions are also covered in the EMEP/EEA Emission Inventory Guidebook.

7.2

PRECURSOR EMISSIONSNo refinement.

1 Cooperative programme for the monitoring and evaluation of the long-range transmission of air pollutants in Europe (EMEP).
2 Up until 2007 this EMEP/EEA Guidebook was formally called the EMEP/CORINAIR Emission Inventory Guidebook.

7.4

2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

Chapter 7: Precursors and Indirect Emissions

7.2.1

Inventory of precursors

7.2.1.1

E NERGY

For most countries, road transportation will be a major source of NOx, CO, and NMVOC emissions. Public
electricity and heat production will likely be the major source of SO2 emissions in countries where coal is used
extensively, and also an important source of NOx emissions. Industrial combustion will also be a source of SO2,
NOx and CO emissions and residential combustion a source of CO emissions. Oil production will likely be a sourceof NMVOC, NOx, and, CO emissions in countries that produce oil and gas.
Most NOx emissions resulting from fuel combustion are typically ‘fuel-NOx’ that is formed from the conversionof chemically bound nitrogen in the fuel. The content of nitrogen in different fuel varies. Depending on the
combustion temperature, thermal-NOx and prompt-NOx can also be formed from nitrogen contained in the
combustion intake air (e.g., in pulverized coal combustion).
Carbon monoxide and NMVOCs are generated during under-stoichiometric combustion conditions and are
dependent on a variety of factors, including fuel type and combustion conditions.
Emissions of sulphur oxides (SOx) are primarily related to the sulphur content of the fuel, although some sulphur
can be retained in the ash. Abatement in stationary and mobile (e.g., marine) combustion can reduce the amountemitted; desulphurization of fuels can reduce SO2 emissions in transport related emissions.

7.2.1.2

I NDUSTRIAL PROCESSES AND PRODUCT USE

No refinement.

7.2.1.3

A GRICULTURE , F ORESTRY AND O THER L AND U SE

The burning of crop residues emits NOx, as does the addition of nitrogen to the soils from nitrogen fertilizers andother nutrients. Carbon monoxide and SO2 are emitted when biomass is burned. The primary sources of the
NMVOC emissions are burning of crop residues and other plant wastes, and the anaerobic degradation of livestock
feed and animal excreta. Plants, mainly trees (e.g. oil palm trees) and cereals, also contribute to NMVOC
concentrations in the atmosphere.
The EMEP/EEA Guidebook does not fully cover emissions from burning of biomass, therefore additional guidanceis given in Agriculture, Forestry and Other Land Use (AFOLU) Volume, Chapter 4, Section 4.2.4 for Non-CO2
emissions from biomass burning from forest, Chapter 5, Sections 5.2.4 and 5.3.4 for Non-CO2 emissions frombiomass burning in Cropland, and Chapter 6, Sections 6.2.4 and 6.3.4 for Non-CO2 emissions from biomassburning in Grassland (CO, CH4, N2O, NOx). Biomass burning when forest and grasslands are converted to otheruses, forest fires, and biomass burning due to forest management practices are discussed in these chapters ofVolume 4 for AFOLU sector.

7.2.1.4

W ASTE

Open burning, as well as incineration of municipal and other solid wastes and sludge from wastewater treatment,
produces emissions of NOx, CO, and SO2. NMVOC emissions can originate from wastewater treatment plants andsolid waste disposal on land.

7.2.1.5

C ARBON EMITTED IN GASES OTHER THAN CO 2

The 2006 IPCC Guidelines estimate carbon emissions in terms of the species that are emitted. The majority of the
carbon emitted in the form of non-CO2 species (i.e., CH4, CO, and NMVOCs) eventually oxidizes to CO2 in theatmosphere and this amount can be estimated from the emissions estimates of the non-CO2 gases (Seinfeld and2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

7.5

Volume 1: General Guidance and Reporting

Pandis 1998; Boucher et al. 2009). This section provides guidance on calculating CO2 inputs to the atmospherefrom emissions of carbon-containing compounds that are not included under other emission categories. 3
In national GHG inventories, inputs of CO2 from the atmospheric oxidation of CH4, CO, and NMVOCs are
typically included in inventories for some source categories, correctly excluded for some other categories, andlikely require estimating separately for yet other categories. The source categories falling into these first two groups
are as follows (Gillenwater 2008):•

Fossil fuel combustion and fuelling activities including the atmospheric oxidation of CH4, CO, and NMVOCs
to CO2 is accounted for by the methodology used by most countries to calculate CO2 emissions from fossil
fuel combustion. 4 This methodology is based on fuel consumption statistics, data on the carbon content ofeach fuel, and oxidation factors; IPCC default carbon content or CO2 emission factors assume that except thesmall fraction of carbon remaining as un-oxidized solids, for example soot or ash (IPCC 1997; IPCC 2000),
all carbon in the fuel is oxidized to CO2 in the combustion process or atmosphere. 5 For most countries thatuse common CO2 factors, these inputs to the atmosphere of CO2 from fossil fuel combustion related emissionsof CH4, CO, and NMVOCs are already accounted for under the Energy sector category 1A. 6•

Several managed sources of biogenic carbon (e.g., livestock) also emit CH4, CO, and NMVOCs. The carbon
in these gases is derived from rapidly cycling (non-fossil) sources. For example, the carbon content of CH4
from enteric fermentation is derived from plant matter, which has converted atmospheric CO2 to organic
compounds. The atmospheric oxidation of CH4 merely completes a natural cycle and is not treated as a net
anthropogenic contribution to the atmosphere's CO2 burden. Any net changes in the biogenic carbon stocks
found in plant matter are assumed to be captured under the AFOLU sector through estimates of CO2 emissions
and removals from land-use and land-use changes and forestry (i.e., biogenic carbon stock changes).

Methane, CO, or NMVOCs are also emitted as fugitives from fossil fuel production activities such as coal mining
as well as petroleum and natural gas exploration, processing and storage. The carbon emitted in the form of CH4,
CO, or NMVOCs from these fugitive emission source categories is not typically captured in fuel combustion
activity data because these emissions occur prior to the collection of data on fossil fuel consumption. Therefore,
CO2 inputs to the atmosphere from the oxidation of these fugitive emissions are typically not estimated elsewhere
in national GHG inventories, although fugitive CH4 emissions are reported separately in GHG inventories.
Some industrial processes in which carbon from fossil fuel sources is used as a production feedstock (e.g.,
petrochemical production) may also lead to CO2 inputs to the atmosphere. The carbon emitted in the form of CH4,
CO, or NMVOCs from these industrial processes may be included in a country’s non-energy use of fossil fuelstatistics or they may be estimated separately. 7 Carbon dioxide emissions from industrial processes that use carbon
feedstock as reducing agents (e.g., iron and steel production) are typically included in GHG inventories based on
the assumption that the carbon in the reducing agent is fully oxidized. Depending on the assumptions and methods
used to estimate storage and emissions from those non-energy use and feedstock categories (e.g., solvent use), CO2
resulting from emissions of CH4, CO, and NMVOCs may or may not be included elsewhere in GHG inventories.
Two options are possible to address inputs of CO2 from CH4 of fossil origin. Countries may apply the methods
described below to calculate the mass of CO2 oxidised. If countries use a metric for CH4 that includes the inputs of
CO2 from CH4 of fossil origin (such as GWP and GTP for fossil methane provided in Table 8.A.1 of Appendix
8.A in IPCC 2013), they should not estimate separately the amount of CO2 from atmospheric oxidation of CH4 offossil origin to avoid double counting the warming impact. If countries choose to apply a metric which does nottake into account the conversion of CH4 into CO2, countries should apply the methods described below to calculate
the amount of CO2 from CH4. Countries should transparently document which option used.
The methodologies for calculating CO2 from the atmospheric oxidation of CH4, CO, and NMVOCs are simple andfor countries that already have detailed inventories of CH4, CO, and NMVOC emissions, no additional activity
3 The contents of Box 7.2 from the 2006 IPCC Guidelines have been elaborated and included in the text of this section.
4 This includes evaporative emissions of NMVOCs associated with immediate fuelling activities for mobile or stationary

sources where the mass of carbon associated with these emissions is accounted for in the fuel consumption activity data usedin the combustion-related emission estimates for CO2.

5 If a direct measurement method is used to estimate CO

2 emissions from fuel combustion then CO2 emissions from theatmospheric oxidation of CH4, CO, and NMVOCs will not be included and must be estimated separately.

6 If a country uses a country-specific CO emission factor based on direct measurement data to estimate emissions then CO
2
2from the atmospheric oxidation of CH4, CO, and NMVOCs would not be included in emission estimates for fossil fuelcombustion, as the direct measurement occurs prior to the atmospheric oxidation process.

7 Non-energy products from fossil fuels include industrial applications of fossil carbon material such as in the manufacture ofammonia from natural gas.

7.6

2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

Chapter 7: Precursors and Indirect Emissions

data collection should be necessary. Input of CO2 to the atmosphere are calculated by converting previously
estimated mass emissions of CH4, CO, or NMVOCs to CO2 based on the carbon content of each gas. For example,
the activity data used to estimate CO2 inputs from the oxidation of emissions coal mining is already collected toestimate CH4 for that category (1.B.1).
Methane, CO, or NMVOC emissions will eventually be oxidised to CO2 in the atmosphere. These CO2 inputs
could be included in national inventories. They can be calculated from emissions of methane, CO and NMVOCs.
The basic calculation principles are:From CH4:

InputsCO2 = EmissionsCH4 • OF • 44/16

From CO:InputsCO2 = EmissionsCO • OF • 44/28

From NMVOC: InputsCO2 = EmissionsNMVOC • C • OF • 44/12
Where,
InputsCO2 are the added CO2 to the atmosphere from the oxidation of CH4, CO, and NMVOCs that are notaccounted for already under other categories.
EmissionsCH4, EmissionsCO, and EmissionsNMVOC are the emission estimates taken from other relevant emission
categories (e.g., CO, NMVOC, CH4 from oil and gas systems, 1.B.2).
C is the fraction carbon in NMVOC by mass (default = 0.6 for solvent use and 0.85 for other source categories;
see Tables A7.2 and A7.3 and Gillenwater 2008).
OF is the oxidation factor of the carbon to carbon dioxide as a fraction. The default assumption is a value of 1. For
open burning of waste in Volume 5, Chapter 5 a default value of 0.71 for OF is specified (see Table 5.2).
The carbon content in NMVOCs will vary depending on the source. Therefore, an inventory based on thespeciation of the NMVOC compounds gives more accurate results.
In making these estimates inventory compilers should assess each category to ensure that this carbon is not alreadycovered by the assumptions and approximations made in estimating CO2 emissions.
See Table A7.1 for a list of the source categories relevant to the estimation of CO2 from atmospheric oxidation.
When identifying categories for which these CO2 inputs are to be estimated, it is good practice to prevent double
counting or omitting of carbon emitted to the atmosphere as CO2.
NMVOCs do not represent a single molecular species, but instead a broad range of volatile hydrocarbon species
with varying molecular weights and carbon contents. Therefore, an accurate estimate of emissions of CO2 fromthe atmospheric oxidation of NMVOCs requires a chemical speciation profile of the constituent NMVOCs(Gillenwater 2008).
To estimate CO2 atmospheric inputs from NMVOC emissions the following steps may be used:
Separate the portion of national NMVOCs emissions resulting from biogenic materials from the portion of
NMVOC emissions resulting from petroleum or other fossil fuel products.
Identify the portion of the fossil-based NMVOC emissions resulting from relevant energy and industrial processsource categories (as determined using Table A7.2).
For the portion of these NMVOC emissions resulting from solvent use, determine the average carbon content (ona mass basis) based on a chemical speciation profile (see Table A7.3 for example). If information on the speciation
profile is not available, assume a default average carbon content of 60 percent by mass. For the remaining portionof relevant NMVOC emissions from other source categories, determine carbon content values using a chemical
speciation profile. If information on the speciation profile is not available, assume an average default carbon
content of 85 percent by mass (Gillenwater 2008, and see Table A7.3).
There is scientific uncertainty regarding the degree to which all CH4 and NMVOCs are completely oxidised to
CO2 in the atmosphere. There is very low uncertainty in this assumption for CO emissions. Boucher et al. 2009
assumes 95 percent of emitted CH4 is oxidised, with a range of 51 to 100 percent. NMVOCs include a wide rangeof chemical species with atmospheric lifetimes that primarily range from minutes to months. Although, the fate of
NMVOCs emitted to the atmosphere is generally oxidation to CO2 through complex chemical and photochemical
reactions, the fate of a fraction of some NMVOC species can be dry or wet deposition to the Earth’s surface, where
the carbon they contain may escape complete oxidation to CO2. The above equations assume a complete oxidationof NMVOCs, CO and CH4 to CO2 in the atmosphere, however countries may apply oxidation factors less than 1,
based on scientific evidence.

2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

7.7

Volume 1: General Guidance and Reporting

7.2.2

Link to relevant methodology chapters in the
EMEP/CORINAIR Emission Inventory Guidebook

No refinement.

7.3

INDIRECT N 2 O EMISSIONS FROM THE
ATMOSPHERIC DEPOSITION OF NITROGENIN NO X AND NH 3

No refinement.

7.3.1

Methodology

All anthropogenic NH3 or NOx emissions are potential sources of N2O emissions 8. Specific guidance on estimating
N2O emissions from that portion of nitrogen compounds associated with the volatilisation of NOx and NH3 from
(1) manure management systems and applied sewage sludge and (2) synthetic and organic nitrogen input tomanaged soils, and urine and dung nitrogen deposited by grazing animals, are provided in Section 10.5 of Chapter
10, Emissions from livestock and manure management, and Section 11.2.2 of Chapter 11, N2O emissions frommanaged soils and CO2 emissions from lime and urea application, of Volume 4 of AFOLU.
This section provides guidance on estimating N2O emissions from the atmospheric deposition of nitrogencompounds from all other sources of NOx and NH3 emissions, such as fuel combustion, industrial processes, andburning of crop residues and agricultural wastes. The method needs only to be applied where data on NOx andNH3 emissions from these sources are available, e.g., from the inventories identified Section 7.2.
Equation 7.1 and EF4 from Table 11.4, Chapter 11 of Volume 4 can be used to estimate N2O emissions from theatmospheric deposition of nitrogen resulting from NOx and NH3.
EQUATION 7.1
N2O EMISSIONS FROM ATMOSPHERIC DEPOSITION OF NOX AND NH3

( NOx − N (i ) ) + ( NH 3 − N (i ) )  • EF4 • 44 / 28
N 2O(i=)

Where:
N2O(i)=
N2O produced from atmospheric deposition of N from NOx and NH3 emissions fromsource i, in Gg

nitrogen content of NOx emissions from source i assuming that NOx is reported in NO2
NOx-N(i) =equivalents (Gg NOx-N or Gg NO2 • 14/46)
NH3-N(i) =EF4nitrogen content of NH3 emissions from source i (Gg NH3-N or Gg NH3 • 14/17)=
emission factor for N2O emissions from atmospheric deposition of N on soils and water
surfaces (kg N2O-N/kg NH3-N or NOx-N emitted)

The activity data NOx-N(i) and NH3-N(i) are taken from the inventories as identified in Section 7.2, if
available.
This method assumes that N2O emissions from atmospheric deposition are reported by the country that produced
the original NOx and NH3 emissions. In reality, the ultimate formation of N2O may occur in another country due
to atmospheric transport of emissions. The method also does not account for the probable lag time between NOx
and NH3 emissions and subsequent production of N2O in soils and surface waters. This time lag is expected to besmall relative to an annual reporting cycle.
8

In addition to being redeposited on soils and surface waters, NH3 can also lead to the formation of N2O from atmosphericchemical reactions. However, there is currently no method available for estimating conversion of NH3 to N2O in theatmosphere.

7.8

2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

Chapter 7: Precursors and Indirect Emissions

7.3.2

Quality Assurance/Quality Control, Reporting andDocumentation

No refinement.

2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

7.9

Volume 1: General Guidance and Reporting

References
References copied from the 2006 IPCC Guidelines
EEA (2001). EMEP/CORINAIR Emission Inventory Guidebook, third ed. Technical report No. 30, European
Environmental Agency (EEA). http://reports.eea.eu.int/technical_report_2001_3/en.
IPCC (1997). Revised 1996 IPCC Guidelines for National Greenhouse Inventories, Volume 1-3. Houghton J.T.,
Meira Filho L.G., Lim B., Tréanton K., Mamaty I., Bonduki Y., Griggs D.J. and Callander B.A. (Eds).
Intergovernmental Panel on Climate Change (IPCC), IPCC/OECD/IEA, Paris, France.

References newly cited in the 2019 Refinement
Boucher O., Friedlingstein P., Collins B. & Shine K. P. (2009) The indirect global warming potential and global
temperature change potential due to methane oxidation. Environmental Research Letters 4: 5.
EEA (2016) EMEP/EEA air pollutant emission inventory guidebook 2016. EEA Report No 21/2016.
(https://www.eea.europa.eu/publications/emep-eea-guidebook-2016).
Gillenwater, M. (2008) Forgotten carbon: Indirect CO2 in greenhouse gas emission inventories. Environmental
Science and Policy 11: 8.
IPCC (1997). Revised 1996 IPCC Guidelines for National Greenhouse Inventories, Houghton, J.T., Meira Filho,
L.G., Lim B., Tréanton, K., Mamaty, I., Bonduki, Y., Griggs, D.J. and Callander, B.A. (Eds). Intergovernmental
Panel on Climate Change (IPCC), IPCC/OECD/IEA, Paris, France.
IPCC (2000). Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories,
Penman, J., Kruger, D., Galbally, I., Hiraishi, T., Nyenzi, B., Emmanuel, S., Buendia, L., Hoppaus, R.,
Martinsen, T., Meijer, J., Miwa, K. and Tanabe, K. (Eds). Intergovernmental Panel on Climate Change (IPCC),
IPCC/OECD/IEA/IGES, Hayama, Japan.
IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth
Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner,
M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University
Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.
Seinfeld, J.H., Pandis, S.N., 1998 Atmospheric Chemistry and Physics: From Air Pollution to Climate Change.
Wiley-Interscience, New York, NY.

7.10

2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

Chapter 7: Precursors and Indirect Emissions

Annex 7A.1 Practical examples for carbon emitted in gases other than CO2
TABLE A7.1 (NEW)NON-BIOGENIC SOURCES OF CO2 FROM THE ATMOSPHERIC OXIDATION OF CH4, CO, AND NMVOCS
NMVOC

1.

FossilOriginCO2 included inexisting category
emission
estimates?

ExplanationxYes(d)

Yes

Fossil fuel combustion emission estimates calculated with use of carbon content and oxidation
factors are more likely to include emissions of CO2 from atmospheric oxidation of CH4, CO andNMVOC (i.e., if they assume complete oxidation of carbon except for that remaining as soot or
ash solids).

x

Yes

No

x

Yes

x

Yes

x

x

Yes

(c)

x

x

Yes

(c)

x
x
x
x

Yes
Yes
Yes
Yes

(c)
(c)
(c)
(c)

CO

Source Category(IPCC reporting format)

CH4

Gases Emitted(a)EnergyA. Fuel Combustion Activities(b)xx

B. Fugitive Emissions from Fuels
1. Solid Fuels
a. Coal Miningx

2. Oil and Natural Gas

2.

a. Oilxb. Natural Gasxx

No (except
flaring)
No (except
flaring)

The carbon in fugitive emissions of CH4 and NMVOCs is fossil in origin, but the CO2 from theatmospheric oxidation of this carbon is not typically included in emissions estimates from anyother source category. However, the carbon in NMVOC emissions from fuelling stations would
more likely be captured in fossil fuel consumption activity data and therefore in emissions from
1.A. For flaring, emission estimates with use of carbon content factors are more likely to include
emissions of CO2 from atmospheric oxidation of CH4, CO and NMVOC.

Industrial Processes and Product Use

B. Chemical Industryx

C. Metal Industry
D. Non-Energy Use of Fuels
1. Lubricant Use
2. Asphalt Paving of Roads and Roofs
3. Paraffin Waxes Use
4. Solvents and other Petroleum Product Usex2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

The carbon in emissions of CH4 and NMVOCs from chemical and metallurgical processes islikely to be of fossil in origin. The CO2 from the atmospheric oxidation of this carbon may or may
not be included in emissions estimates from these source categories or from non-energy uses offossil fuels as feedstock.
The carbon in emissions of CH4 and NMVOCs occurring from the use of non-energy products isof fossil origin and does lead to CO2 emissions. The Oxidized During Use (ODU) factors applied
for estimating emissions from these source categories in most cases will include CO2 emissions.

7.11

Volume 1: General Guidance and Reporting

TABLE A7.1 (NEW) (CONTINUED)
NON-BIOGENIC SOURCES OF CO2 FROM THE ATMOSPHERIC OXIDATION OF CH4, CO, AND NMVOCS
Gases Emitted(a)NMVOC

FossilOriginCO

CO2 included inexisting category
emission
estimates?

CH4

Source Category(IPCC reporting format)

A. Solid Waste Treatment and disposal

x

x

x

No

-

B. Wastewater Treatment and discharge

x

x

x

No

-

C. Incineration and open burning of waste(b)

x

x

x

Yes

Yes

5.

Explanation

Waste
The vast majority of the carbon in CH4, CO, and NMVOC emissions is likely to be of biogenic
origin.
The carbon in CH4, CO, and NMVOC emissions is of both biogenic and fossil origin. Estimatesof CO2 emissions from the fossil carbon portion of waste materials include the emissions of CO2
from atmospheric oxidation of CH4, CO and NMVOCs when carbon content factors are used.

(a) Only gases listed are those relevant to the estimation of CO2 emissions from atmospheric oxidation of CH4, CO and NMVOCs. Emission factors for CO and NMVOC can be found in the EMEP/EEA
Emission Inventory Guidebook and for CH4 see the relevant chapters/volumes of this 2019 Refinement.
(b) Assumes that CO2 emissions are estimated using data on the carbon content of fuels or waste materials, not direct measurement.
(c) CO2 emissions from atmospheric oxidation of CH4, CO and NMVOCs may or may not be accounted for depending on the Oxidized During Use factor assumptions under non-energy use of fuels (2.D).
(d) Assumes biofuels are reported separately.
Reference: Gillenwater (2008).

7.12

2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

Chapter 7: Precursors and Indirect Emissions

Waste
Treatment andDisposal

Total

Nature (Forests)

Solvent Use















Acetone









74-86-2

Acetylene

0.923









71-43-2

Benzene

0.923











106-97-8

Butane

0.827











74-84-0Ethane

0.799









64-17-5

Ethanol

0.521

74-85-1Ethylene

0.856



















110-54-3

Hexane

0.835





















75-28-5

Isobutane

0.827





















78-78-4

Isopentane

0.832



















108-38-3m-xylene

0.905























95-47-6o-xylene

0.905

























109-66-0

Pentane

0.832























74-98-6

Propane

0.817



















115-07-01

Propylen

0.621







106-42-3p-xylene

0.905

108-88-3

Toluene0.913

Unspeciated mixtures of m-, o- and p-xylene

0.905



Total



(OtherTransport)(5)67-64-1

0.620

OtherTran
sp & Mach

0.533

Other
Transport
ation andMachinery, Off Road

2-propanol

107-98-2

RoadTransport(Evaporati)
Road
Transport(PETROL)

Road
Transport(DERV)



Combustion inIndustry

Industrial
Processes

WASTE

EnergyProduction

Transport

AFOLU

Commerci
al andResidential

Stationary Combustion

IPPU
Extraction &Distribution of
Fossil Fuels

ENERGY
Carbon content

CAS number

NMVOC Species

TABLE A7.2 (NEW)EXAMPLES OF NMVOCS FROM THE DIFFERENT SOURCE CATEGORIES















































































































































































Source: Data in table compiled from various references by Kristina Saarinen, Finnish Environment Institute.

2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

7.13



Volume 1: General Guidance and Reporting

TABLE A7.3 (NEW)CARBON CONTENT OF VARIOUS MATERIALS (PERCENT CARBON BY MASS, PC) AND PERCENT OF TOTAL SOLVENT NMVOC EMISSIONS (BY MASS, PU)

7.14

Material

PC

PU

Methane75.0-

Carbon monoxide

42.9

-

PC

PU

United States

Austria

Hungary18

Solvent NMVOCs1

Solvent NMVOCs

Solvent NMVOCs

Methylene chloride

14

2

Perchloroethylene

14

1

Trichloroethane

18

1

Trichloroethylene

181

Residuals

25

Methanol38

Glycols50

Alcohols

52

Ester

59

PC

PU

Methyl alcohol

381Ethylene glycol

391

Propylene glycol solvents2

47

1

Ester solvents

49

1

Ethyl alcohol

52

24

Butanediol derivatives353

7

Ester acetate455

19

Other ethylene oxide solvents5

55<1

Glue, etc.

57-

Propyl acetate

59

2

Waste base paint

57-

Isopropyl alcohol60

10Propyl alcohol60

2E-series ether solvents661<1

Alcohols/propanols

602019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

Chapter 7: Precursors and Indirect Emissions

TABLE A7.3 (NEW) (CONTINUED)CARBON CONTENT OF VARIOUS MATERIALS (PERCENT CARBON BY MASS, PC) AND PERCENT OF TOTAL SOLVENT NMVOC EMISSIONS (BY MASS, PU)
Material

PC

PU

Methane75.0-

Carbon monoxide

42.9

-

PC

PU

PC

United States

Austria

Hungary18

Solvent NMVOCs1

Solvent NMVOCs

Solvent NMVOCs

Acetone62

2

Acetone

Butyl acetate

62

62

<1

Other propylene oxide-derived solvents7

62<1

Furfural solvents863

2

Other chlorinated solvents964<1Ether solvents10

65

1

Ether

Other alcohol solvents11

65

65

2

Methyl ethyl ketone

67

Tetrahydrofuran solvents12

1

Ketones

67

67

1

Aldehydes

67

Methyl isobutyl ketone72

1

Other ketone solvents13

72

2

Special napthas14

84

12

Solvent naphta

D-Limonene solvents15

88<1

Pinene solvents16

88

PU

Other paint, lack, etc.

80

-

86

Solvent based paint

81.4

-

Cyclic hydrocarbons

86

Solvent

81.6

-

1

Paraffins86

Aromates

91

Toluene91<1

Xylene91<1

Benzene92<1

Solvent weighted average17

56.3

2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

60 to 66

76 to 80

7.15

Volume 1: General Guidance and Reporting

TABLE A7.3 (NEW) (CONTINUED)CARBON CONTENT OF VARIOUS MATERIALS (PERCENT CARBON BY MASS, PC) AND PERCENT OF TOTAL SOLVENT NMVOC EMISSIONS (BY MASS, PU)
Source: Pu values taken from National Inventory Reports submitted in 2004. <http://unfccc.int/national_reports/annex_i_ghg_inventories/national_inventories_submissions/items/3473.php/>.
Pc values as noted below.
1) Except where noted, values from CRC Handbook of Chemistry and Physics. CRC Press, 1995.
2) Assumed to be "propylene glycol".
3) Assumed to be 1,3-butanediol.
4) Assumed to be "ethyl acetate".
5) Assumed to be "ethylene oxide".
6) Assumed to be "ethylene glycol n-butyl ether" (trade name "Dowanol EB").
7) Assumed to be "propylene oxide".
8) Assumed to be "furfural" (2-furaldehyde).
9) Assumed to be "chlorobenzene".
10) Assumed to be "diethyl ether".
11) Assumed to be "butyl alcohol".
12) Assumed to be "tetrahydrofuran" (THF) (1,4-Epoxybutane).
13) Assumed to be methyl isobutyl ketone (MIBK).
14) Assumed to be "hexane".
15) Assumed to be "limonene" (1-methyl-4-(1-methylethyl)cyclohexene).
16) Assumed to be "alpha pinene" (bicylc(3.1.1)hept-2-ene,2,6,6-trimethyl).
17) USA value is for 1998, Austria and Hungary values vary from year to year based on mix of solvent chemicals used.
18) Values apply only to the solvent portion of each material. The solvent content of each material assumed was as follows: solvent based paint 50%, water based paint 5-6%, other paint 25%, glue 8%,
and solvent 100%.

7.16

2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories