Appendix A
UNFCCC Inventories of Industrial Processes and Waste

INDUSTRIAL PROCESSES AND PRODUCT USE

The industrial processes and product use (IPPU) sector covers the greenhouse gas emissions resulting from various industrial activities that produce emissions not directly the result of energy consumed during the process and the use of man-made greenhouse gases in products (IPCC, 2006). Examples include the release of CO2 as a by-product of cement production and the use of fossil fuel (primarily natural gas) as a feedstock in ammonia production. The IPPU sector accounts for about 7 percent of total greenhouse gas emissions from Annex I countries (UNFCCC, 2008) and about 6 percent of total greenhouse gas emissions for non-Annex I countries (UNFCCC, 2005).

Carbon Dioxide

Carbon dioxide (CO2) is the most important greenhouse gas emitted by the IPPU sector, comprising about 69 percent of total emissions (in terms of CO2 equivalents) from the sector for Annex I countries (UNFCCC, 2005). The main sources of CO2 in this sector are the production of cement, lime, glass, ammonia, iron, steel, and aluminum. The calcination of limestone produces lime, which may then be combined with silica compounds to produce clinker (an ingredient of cement). Both processes result in CO2 emissions. Glass production emits CO2 during the melting and fusion of limestone, dolomite, and soda ash. The principal source of CO2 emissions from ammonia production is the steam reforming of natural gas (methane, CH4) to produce hydrogen (H2). Iron and steel production yields CO2 emissions through the use of metallurgical coke to convert iron ore to pig iron in a blast furnace. Similarly, CO2 is emitted during the smelting process from the use of carbon to reduce alumina to aluminum.

The CO2 emissions from mineral, chemical, and metal production can be estimated simply by applying appropriate emission factors to national-level production data. The major source of uncertainty in emissions from the mineral industry is typically the activity data (IPCC, 2006; EPA, 2008) because the chemistry of the processes involved is known. For cement production, CO2 emissions should ideally be estimated using national-level data on clinker production, the lime content of the clinker, and the fraction of lime from limestone. However, national statistics on cement and/or clinker production may not be complete for countries in which a substantial part of production comes from numerous small kilns, for which data are difficult to obtain. If clinker production data are not available, they are inferred from information on the quantities of cement produced (correcting for imports and exports) and the types and clinker fraction of the cement. For lime and glass production, CO2 emissions can be estimated using national-level data on the types and quantities of lime or glass produced (or, less preferably, total lime or glass production figures) and default emission factors. The key source of uncertainty for lime production is incomplete data; reported lime production statistics often omit nonmarketed lime production, potentially resulting in order-of-magnitude underestimates. For glass production, activity data uncertainties



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Appendix A UNFCCC Inventories of Industrial Processes and Waste INDUSTRIAL PROCESSES AND PRODUCT duce hydrogen (H2). Iron and steel production yields USE CO2 emissions through the use of metallurgical coke to convert iron ore to pig iron in a blast furnace. Similarly, The industrial processes and product use (IPPU) CO2 is emitted during the smelting process from the sector covers the greenhouse gas emissions resulting use of carbon to reduce alumina to aluminum. from various industrial activities that produce emissions The CO2 emissions from mineral, chemical, and not directly the result of energy consumed during the metal production can be estimated simply by applying process and the use of man-made greenhouse gases in appropriate emission factors to national-level produc- products (IPCC, 2006). Examples include the release tion data. The major source of uncertainty in emissions of CO2 as a by-product of cement production and the from the mineral industry is typically the activity data use of fossil fuel (primarily natural gas) as a feedstock (IPCC, 2006; EPA, 2008) because the chemistry of in ammonia production. The IPPU sector accounts for the processes involved is known. For cement produc- about 7 percent of total greenhouse gas emissions from tion, CO2 emissions should ideally be estimated using Annex I countries (UNFCCC, 2008) and about 6 per- national-level data on clinker production, the lime cent of total greenhouse gas emissions for non-Annex content of the clinker, and the fraction of lime from I countries (UNFCCC, 2005). limestone. However, national statistics on cement and/or clinker production may not be complete for Carbon Dioxide countries in which a substantial part of production comes from numerous small kilns, for which data are Carbon dioxide (CO 2) is the most important difficult to obtain. If clinker production data are not greenhouse gas emitted by the IPPU sector, compris- available, they are inferred from information on the ing about 69 percent of total emissions (in terms of quantities of cement produced (correcting for imports CO2 equivalents) from the sector for Annex I countries and exports) and the types and clinker fraction of the (UNFCCC, 2005). The main sources of CO2 in this cement. For lime and glass production, CO2 emissions sector are the production of cement, lime, glass, ammo- can be estimated using national-level data on the types nia, iron, steel, and aluminum. The calcination of lime- and quantities of lime or glass produced (or, less prefer- stone produces lime, which may then be combined with ably, total lime or glass production figures) and default silica compounds to produce clinker (an ingredient of emission factors. The key source of uncertainty for lime cement). Both processes result in CO2 emissions. Glass production is incomplete data; reported lime produc- production emits CO2 during the melting and fusion of tion statistics often omit nonmarketed lime production, limestone, dolomite, and soda ash. The principal source potentially resulting in order-of-magnitude underesti- of CO2 emissions from ammonia production is the mates. For glass production, activity data uncertainties steam reforming of natural gas (methane, CH4) to pro- 

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 APPENDIX A are magnified where glass production is measured in a consumption of a chemical in a specific application or variety of units. subapplication (production plus imports minus exports In the chemical and metal industries, reliable pro- minus destruction of the chemical) and then applying duction data are available for most countries, so the an emission factor(s) to the net consumption. For the emission factors present the greatest source of uncer- mass-balance approach, emissions are estimated as tainty, particularly for iron and steel production. For the sum of the sales of a chemical and, for equipment ammonia production, CO2 emissions can be estimated containing this chemical, the total charge of retired using national-level data on ammonia production (or, equipment minus the total charge of new equipment. less preferably, ammonia production capacity) and The major source of uncertainty in national estimates of default values for the quantity of fuel (typically natural HFC emissions is the lack of activity data on chemical gas) required as feedstock per unit of output, the carbon production or sales in countries where suppliers treat content of the fuel, and the carbon oxidation factor. the information as confidential. This barrier to the pro- Any CO2 recovered for purposes of urea production duction of reliable national estimates is being reduced is also accounted for. For iron and steel production, with the development of regional and global databases the CO2 emissions are estimated by applying the of ozone-depleting substances. For example, databases appropriate emission factors to national statistics on that track the phase-out of ozone-depleting substances the amount of steel produced by each method and the are directly relevant for estimating the phase-in of HFC total amount of pig iron produced that is not processed substitutes (IPCC, 2006). into steel. Similarly, the estimation of CO2 emissions in Emissions of HFC-23 can be calculated by apply- aluminum production requires national-level produc- ing a default emission factor to the quantity of HCFC- tion data by process type (i.e., Søderberg or Prebake) 22 produced. Given the known variability in emissions to which the appropriate default emission factor can from different HCFC-22 manufacturing facilities, the then be applied. uncertainty in the emission factor far outweighs the uncertainty in the activity data (IPCC, 2006). Hydrofluorocarbons Nitrous Oxide Hydrofluorocarbons (HFCs) comprise about 18 percent of total emissions (in terms of CO2 equivalents) Emissions of nitrous oxide (N2O) from nitric acid from the IPPU sector for Annex I countries.1 The use and adipic acid production comprise about 7 percent of HFCs as substitutes for ozone-depleting substances of total emissions from the IPPU sector in Annex I countries.2 Nitric acid production emits N2O as a by- in a variety of industrial applications is by far the largest source of HFC emissions, accounting for about 86 per- product during the catalytic oxidation of ammonia, and cent of total emissions from the sector, and their usage adipic acid production (most of which takes place in a is growing rapidly. A smaller, but significant source of few plants in the United States and Europe) generates HFC emissions is the generation of trifluoromethane N2O as a by-product during a process involving the (HFC-23) as a by-product during the production of oxidation of nitric acid. Emissions of N2O from both chlorodifluoromethane (HCFC-22). sources can be estimated by multiplying production by Actual emissions of HFCs are estimated using a default emission factor. For nitric acid production, the either an emission-factor or a mass-balance approach major source of uncertainty in N2O emissions is the (IPCC, 2006). Both methods can use activity data activity data. Nitric acid production is often underesti- collected at either the application level (e.g., refrig- mated because nitric acid is formed as part of a larger eration) or the subapplication level (e.g., equipment production process and is never sold on the market. or product type); the latter is expected to yield higher- For adipic acid production, neither the default emission accuracy estimates. For the emission-factor approach, factor nor the activity data are significant sources of HFC emissions are calculated by determining the net uncertainty (IPCC, 2006). The default emission factor 1 See 2 See . .

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 APPENDIX A is derived from a well-understood chemical reaction decades of historical data are required), although some (i.e., nitric acid oxidation), and only a small number of of the emission factors can also be highly uncertain. For adipic acid plants exist. many countries, data on waste amounts and composi- tion (particularly historical data) are not available and default activity data must be used. The major uncertain- WASTE ties in the emission factors include the DOC values The waste sector is not a significant source of assigned to different waste types (e.g., municipal) and greenhouse gas emissions, accounting for only about 3 materials (e.g., paper, food), the fraction of DOC that percent of the total from Annex I countries (UNFCCC, is ultimately degraded and released from SWDS, and 2008) and about 4 percent of the total from non-Annex the half-life of the DOC, which is difficult to measure I countries (UNFCCC, 2005). This sector covers the in real solid waste disposal sites. Also highly uncertain greenhouse gas emissions from solid waste disposal, are the emission factors used to determine the frac- biological treatment of solid waste, burning of waste, tion of CH4 that is oxidized in the landfill’s top layer, and wastewater treatment and discharge (IPCC, 2006). which depends on whether the SWDS is managed or Waste sector reporting includes neither the greenhouse unmanaged and also varies considerably with condi- gas emissions resulting from the use of waste mate- tions at the site. rial as fuel nor the CO2 emissions resulting from the The other significant source of CH4 emissions decomposition or burning of organic biomass. These within the waste sector is the anaerobic treatment or emissions are accounted for under the energy sector disposal of wastewater. The CH4 emitted from waste- and the agriculture, forestry, and other land-use sector, water handling depends on the amount of degrad- respectively. able organic material, measured by biological oxygen demand in domestic wastewater and chemical oxygen demand in industrial wastewater. The Intergovernmen- Methane tal Panel on Climate Change (IPCC) provides a means The primary greenhouse gas emitted from the of estimating the quantity of domestic wastewater waste sector is CH4, which accounts for about 90 generated as well as default values for biological oxy- percent of the total (in terms of waste sector CO2 gen demand for selected regions and countries. Simi- equivalents) in Annex I countries.3 The degradation larly, the IPCC provides default values for quantities of organic material under anaerobic conditions at solid of industrial wastewater generated and the chemical waste disposal sites (SWDS) is the principal source of oxygen demand for various industry types. Reliable CH4 emissions. The potential of SWDS to generate estimates of the quantity of CH4 released from waste- CH4 depends on the degradable organic carbon (DOC) water discharge are particularly difficult to obtain for content of the waste, which is a function of the amount developing countries due to uncertainties in the frac- and composition of the waste disposed, and on the tion of domestic wastewater that is removed by sewers waste management practices. Methane emissions from (as opposed to being treated in latrines), the fraction SWDS are calculated using the First Order Decay of sewers that are open, and the degree to which these method, which assumes that the rate of CH4 produc- open sewers are anaerobic (IPCC, 2006). tion is directly proportional to the amount of DOC remaining in the waste. The quantity of CH4 that is Carbon Dioxide oxidized in the landfill’s top layer and/or is recovered and combusted is then subtracted from the calculated Carbon dioxide is a relatively minor source of emissions value. g reenhouse gas emissions from the waste sector, The key source of uncertainty in estimates of CH4 accounting for about 4 percent of total emissions (in from SWDS is the activity data relating to the quanti- terms of CO2 equivalents) from the sector for Annex I Parties.4 The predominant source of these emissions, ties and composition of the waste disposed (several 3 See 4 See . .

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 APPENDIX A comprising about 97 percent of total CO2 emissions effluent into aquatic environments are sources of N2O from this sector, is the incineration and open burn- emissions, the latter is typically a far more significant ing of waste containing fossil carbon (e.g., plastics, source. Emissions of N2O from wastewater effluent certain textiles). The practice of waste incineration is discharged to aquatic environments are determined currently more common in developed countries, while using national statistics on population and annual open burning of waste occurs predominantly in the per capita protein consumption to estimate the total developing world. However, the basic approach recom- amount of nitrogen discharged in wastewater effluent, mended by the IPCC for estimating CO2 emissions and a default emission factor for the N2O emitted per from these two sources is the same: the quantity of unit of wastewater effluent nitrogen content (IPCC, waste incinerated and/or open-burned is multiplied by 2006). Large uncertainties are associated with estimates default values for the dry matter content, total carbon of N2O emissions from wastewater handling, and the content, fossil carbon fraction, and oxidation factor for major source of uncertainty is the default emission fac- the waste (IPCC, 2006). The major source of uncer- tor for N2O from the effluent. tainty is the estimation of the fossil carbon fraction of the waste, which is directly related to uncertainties REFERENCES regarding waste composition. Where country-specific EPA (Environmental Protection Agency), 2008, Inventory of U.S. data regarding quantities of waste incinerated and/or Greenhouse Gas Emissions and Sinks: 0-00, EPA 430-R- open-burned are not available, large uncertainties are 08-005, Office of Atmospheric Programs, Washington, D.C., also associated with the waste amounts determined available at . IPCC (Intergovernmental Panel on Climate Change), 2006, 00 management. IPCC Guidelines for National Greenhouse Gas Inventories, H.S. Eggleston, L. Buendia, K. Miwa, T. Ngara, and K. Tanabe, eds., prepared by the National Greenhouse Gas Inventories Nitrous Oxide Programme, Institute for Global Environmental Strategies, Hayama, Kanagawa, Japan, 5 volumes. Nitrous oxide emissions comprise about 6 percent UNFCCC (United Nations Framework Convention on Climate of total emissions (in terms of CO2 equivalents) from Change), 2005, Sixth compilation and synthesis of initial na- the waste sector for Annex I countries.5 The major tional communications from Parties not included in Annex I to the Convention, prepared by the UNFCCC Secretariat, October source, comprising about 82 percent of total N2O emis- 2005, available at . emitted from the degradation of nitrogen components UNFCCC, 2008, Report on national greenhouse gas inventory in the wastewater (e.g., urea, nitrate, protein). Although data from Parties included in Annex I to the Convention for the period 1990-2006, prepared by the UNFCCC Secretariat, both wastewater treatment plants and the discharge of November 2008, available at . 5 See .