Environment Counts | Greenhouse Gas Emissions from Industrial Processes and Waste
Author: Wendy Aritenang – Published At: 2012-10-06 12:09 – (1031 Reads)
The Industrial Processes and Product Use (IPPU) sector covers the greenhouse gas emissions resulting from various industrial activities that that do not involve primary energy generation. Examples include the release of CO2 as by-product of cement production and the use of fossil fuel as a feedstock in ammonia production. The IPPU sectors accounts for about 7% of total green house gas emission from Annex 1 countries, and about 6% of total green house gas emission for non-Annex 1 countries. The waste sector accounts for about 3 percent of the total from Annex I countries and about 4 percent of the total from non-Annex I countries. GHG emissions, primarily methane, from waste include emissions from solid waste disposal and wastewater treatment and discharge. UNFCCC Inventories of Industrial Processes and Waste
Among the sources of non-energy GHG emissions from the advanced economies, agriculture is the largest, followed by waste and industrial processes. Gross nonenergy emissions are estimated to be 15.4% of all GHG emissions from the advanced economies in 2010. The relative importance of gross non-energy emissions in total GHG emissions is tending to decline because of the slow growth in emissions from waste and agriculture. Ainsley Jolley, Climate Change Working Paper No. 10, 2006
Industrial processes producing GHG emissions
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. 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, CH 4) 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.
Estimating CO2 emissions for the IPPU sector
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 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 emission factors. The key source of uncertainty for lime production is incomplete data; reported lime production statistics often omit non marketed lime production, potentially resulting in order-of-magnitude underestimates.
GHG emissions from waste
The waste sector accounts for only about 3 percent of the total from Annex I countries and about 4 percent of the total from non-Annex I countries. GHG emissions from waste include emissions from solid waste disposal, biological treatment of solid waste, burning of waste, and wastewater treatment and discharge.
Methane (CH4) emissions
The primary greenhouse gas emitted from the waste sector is CH4, which accounts for about 90 percent of the total in Annex I countries.
CH4 from solid waste disposal sites
The degradation of organic material under anaerobic conditions at solid waste disposal sites (SWDS) is the principal source of CH4 emissions. Methane emissions from SWDS are calculated using the First Order Decay method, which assumes that the rate of CH4 production is directly proportional to the amount of degradable organic carbon (DOC) remaining in the waste. The quantity of CH4 that is oxidized in the landfillâ€™s top layer and/or is recovered and combusted is then subtracted from the calculated emissions value.
The key source of uncertainty in estimates of CH4 from SWDS is the activity data relating to the quantities and composition of the waste disposed (several decades of historical data are required). For many countries, data on waste amounts and composition (particularly historical data) are not available and default activity data must be used. The major uncertainties in the emission factors include the DOC values assigned to different waste types (e.g., municipal) and materials (e.g., paper, food), the fraction of DOC that is ultimately degraded and released from SWDS, and the half-life of the DOC, which is difficult to measure in real solid waste disposal sites. Also highly uncertain are the emission factors used to determine the fraction of CH4 that is oxidized in the landfillâ€™s top layer, which depends on whether the SWDS is managed or unmanaged and also varies considerably with conditions at the site.
CH4 from wastewater
The other significant source of CH4 emissions within the waste sector is the anaerobic treatment or disposal of wastewater. The Intergovernmental Panel on Climate Change (IPCC) provides a means of estimating the quantity of domestic wastewater generated as well as default values for biological oxygen demand for selected regions and countries. Similarly, the IPCC provides default values for quantities of industrial wastewater generated and the chemical oxygen demand for various industry types.
Reliable estimates of the quantity of CH4 released from wastewater discharge are particularly difficult to obtain for developing countries due to uncertainties in the fraction of domestic wastewater that is removed by sewers (as opposed to being treated in latrines), the fraction of sewers that are open, and the degree to which these open sewers are anaerobic.