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CGE Greenhouse Gas Inventory Hands-on Training Workshop WASTE SECTOR. Overview. Introduction IPCC 1996GL ( Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories ) and GPG2000 ( Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories )

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Presentation Transcript
  • Introduction
  • IPCC 1996GL (Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories) and GPG2000 (Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories)
  • Reporting framework
  • Key source category analysis and decision trees
  • Tier structure, selection and criteria
  • Review of problems
    • Methodological issues
    • Activity data
    • Emission factors
  • IPCC 1996GL category-wise assessment and GPG2000 options
  • Examination and assessment of activity data and emission factors: data status and options
  • Uncertainty estimation and reduction
  • COP2 adopted guidelines for preparation of initial national communications (decision 10/CP.2)
  • IPCC guidelines used by 106 NAI Parties to prepare national communications
  • New UNFCCC guidelines adopted at COP8 (decision 17/CP.8) provided improved guidelines for preparing GHG inventory
  • UNFCCC User Manual for guidelines on national communications to assist NAI Parties in using latest UNFCCC guidelines
  • Review and synthesis reports of NAI inventories highlighted several difficulties and limitations of using IPCC 1996GL (FCCC/SBSTA/2003/INF.10)
  • GPG2000 addressed some of the limitations and provided guidelines in order to reduce uncertainties
purpose of this handbook
Purpose of this Handbook
  • GHG inventories are mostly biological sectors, such as Waste, and characterized by:
    • methodological limitations
    • lack of data or low reliability of existing data
    • high uncertainty
  • This handbook aims at assisting NAI Parties in preparing GHG inventories using the IPCC 1996GL, particularly in the context of UNFCCC decision 17/CP.8, focusing on:
    • the need to shift to GPG2000 and higher tiers/methods to reduce uncertainty
    • complete overview of the tools and methods
    • use of IPCC inventory software and EFDB
    • review of AD and EF and options to reduce uncertainty
    • use of key sources, methodologies and decision trees
target groups
Target groups
  • NAI inventory experts
  • National GHG inventory focal points
nai country examples
NAI country examples
  • Review of national communications: Argentina, Colombia, Chile , Cuba and Panama
  • GHG inventories show that the Waste sector may be significant in NAI countries
  • Commonly a significant source of CH4
  • In some cases a significant source of N2O
  • Solid waste disposal sites (SWDS) frequently a key source of CH4 emissions
  • Waste emissions – Includes GHG emissions resulting from waste management activities (solid and liquid waste management, excepting CO2 from organic matter incinerated and/or used for energy purposes).
  • Source – Any process or activity that releases a GHG (such as CO2, N2O, CH4) into the atmosphere.
definitions 2
Definitions (2)
  • Activity Data – Data on the magnitude of human activity, resulting in emissions during a given period of time (e.g. data on waste quantity, management systems and incinerated waste).
  • Emission Factor – A coefficient that relates activity data to the amount of chemical compound that is the source of later emissions. Emission factors are often based on a sample of measurement data, averaged to develop a representative rate of emission for a given activity level under a given set of operating conditions.
ipcc 1996gl and gpg2000

IPCC 1996GL andGPG2000

Approach and steps

emissions from waste management
Emissions from waste management
  • Decomposition of organic matter in wastes (carbon and nitrogen)
  • Waste incineration (these emissions are not reported when waste is used to generate energy)
decomposition of waste
Decomposition of waste
  • Anaerobic decomposition of man-made waste by methanogenic bacteria
    • Solid waste
      • Land disposal sites
    • Liquid waste
      • Human sewage
      • Industrial waste water
  • Nitrous oxide emissions from waste water are also produced from protein decomposition
land disposal sites
Land disposal sites
  • Major form of solid waste disposal in developed world
  • Produces mainly methane at a diminishing rate taking many years for waste to decompose completely
  • Also carbon dioxide and volatile organic compounds produced
  • Carbon dioxide from biomass not accounted or reported elsewhere
decomposition process
Decomposition process
  • Organic matter into small soluble molecules (including sugars)
  • Broken down to hydrogen, carbon dioxide and different acids
  • Acids are converted to acetic acid
  • Acetic acid with hydrogen and carbon dioxide are substrate for methanogenic bacteria
methane from land disposal
Methane from land disposal
  • Volumes
    • Estimates from landfills: 20–70 Tg/yr
    • Total human methane emissions: 360 Tg/yr
    • From 6% to 20% of total
  • Other impacts
    • Vegetation damage
    • Odours
    • May form explosive mixtures
characteristics of the methanogenic process
Characteristics of the methanogenic process
  • Highly heterogeneous
  • However, relevant factors to consider:
    • Waste management practices
    • Waste composition
    • Physical factors
waste management practices
Waste management practices
  • Aerobic waste treatment
    • Produces compost that may increase soil carbon
    • No methane
  • Open dumping
    • Common in developing regions
    • Shallow, open piles, loosely compacted
    • No control for pollutants, scavenging frequent
    • Anecdotal evidence of methane production
    • An arbitrary factor, 50% of sanitary land filling, is used
waste management practices ii
Waste management practices (II)
  • Sanitary landfills
    • Specially designed
    • Gas and leakage control
    • Scale economy
    • Continued methane production
waste composition
Waste composition
  • Degradable organic matter can vary
    • Highly putrescible in developing countries
    • In developed countries, due to higher paper and card content, less putrescible
  • This affects stabilization and methane production
    • Developing countries: 10–15 years
    • Developed countries: more than 20 years
physical factors
Physical factors
  • Moisture essential for bacterial metabolism
    • Factors: initial moisture content, infiltration from surface and groundwater, as well as decomposition processes
  • Temperature: 25–40°C required for a good methane production
physical factors ii
Physical factors (II)
  • Chemical conditions
    • Optimal pH for methane production: 6.8 to 7.2
    • Sharp decrease of methane production below 6.5 pH
    • Acidity may delay the onset of methane production
  • Conclusion
    • Data availability is too poor to use these factors for national or global methane emissions estimates
methane emissions
Methane emissions
  • Depend on several factors
  • Open dumps require other approaches
  • Availability and quality of relevant data
waste water treatment
Waste-water treatment
  • Produces methane, nitrous oxide and non-methane volatile organic compounds
  • May lead to storage of carbon through eutrophication
methane emissions from waste water treatment
Methane emissions from waste-water treatment
  • From anaerobic processes without methane recovery
  • Volumes
    • 30–40 Tg/yr
    • About 8%–11% of anthropogenic methane emissions
    • Industrial emissions estimated at 26–40 Tg/yr
    • Domestic and commercial estimated at 2 Tg/yr
factors for methane emissions
Factors for methane emissions
  • Biochemical oxygen demand (BOD) (+/+)
  • Temperature ( >15°C)
  • Retention time
  • Lagoon maintenance
    • Depth of lagoon ( >2.5 m, pure anaerobic; less than 1 m, not expected to be significant, most common facultative 1.2 to 2.5 m – 20% to 30% BOD anaerobically)
biochemical oxygen demand
Biochemical oxygen demand
  • Is the organic content of waste water (“loading”)
  • Represents O consumed by waste water during decomposition (expressed in mg/l)
  • Standardized measurement is the “5-day test” denoted as BOD5
  • Examples of BOD5:
    • Municipal waste water 110–400 mg/l
    • Food processing 10 000–100 000 mg/l
main industrial sources
Main industrial sources
  • Food processing:
    • Processing plants (fruit, sugar, meat, etc.)
    • Creameries
    • Breweries
    • Others
  • Pulp and paper
waste incineration
Waste incineration
  • Waste incineration can produce:
    • Carbon dioxide, methane, carbon monoxide, nitrogen oxides, nitrous oxides and non-methane volatile organic compounds
  • Nevertheless, it accounts for a small percentage of GHG output from the waste sector
emissions from waste incineration
Emissions from waste incineration
  • Only the fossil-based portion of waste to be considered for carbon dioxide
  • Other gases difficult to estimate
    • Nitrous oxide mainly from sludge incineration
ipcc 1996gl
  • Basis of inventory methodology for waste sector is:
    • Organic matter decomposition
    • Incineration of fossil origin organic material
  • Does not include concrete calculations for the latter
  • Organic matter decomposition covers:
    • Methane from organic matter in both liquid and solid wastes
    • Nitrous oxide from protein in human sewage
    • Emissions of non-methane volatile organic compounds are not covered
ipcc default categories
IPCC default categories
  • Methane Emissions from Solid Waste Disposal Sites
  • Methane Emissions from Wastewater treatment
    • Domestic and Commercial Wastewater
    • Industrial Wastewater and Sludge Streams
  • Nitrous oxide from Human Sewage
inventory preparation using ipcc 1996gl
Inventory preparation using IPCC 1996GL
  • Step 1: Conduct key source category analysis for Waste sector where:
    • Sector is compared to other source sectors such as Energy, Agriculture, LUCF, etc.
    • Estimate Waste sector’s share of national GHG inventory
    • Key source sector identification adopted by Parties that have already prepared an initial national communication, have inventory estimates
    • Parties that have not prepared an initial national communication can use inventories prepared under other programs/projects
    • Parties that have not prepared any inventory, may not be able to carry out the key source sector analysis
  • Step 2:Select the categories
inventory preparation using ipcc 1996gl 2
Inventory preparation using IPCC 1996GL (2)
  • Step 3: Assemble required activity data depending on tier selected from local, regional, national and global databases, including EFDB
  • Step 4: Collect emission/removal factors depending on tier level selected from local/regional/national/global databases, including EFDB
  • Step 5: Select method of estimation based on tier level and quantify emissions/removals for each category
  • Step 6: Estimate uncertainty involved
  • Step 7: Adopt quality assurance/control procedures and report results
  • Step 8: Report GHG emissions
  • Step 9: Report all procedures, equations and sources of data adopted for GHG inventory estimation
calculation of methane from solid waste disposal
Calculation of methane from solid waste disposal
  • For sanitary landfills there are several methods:
    • Mass balance and theoretical gas yield
    • Theoretical first order kinetics methodologies
    • Regression approach
  • Complex models not applicable for regions or countries
  • Open dumps considered to emit 50%, but should be reported separately
mass balance and theoretical gas yield
Mass balance and theoretical gas yield
  • No time factors
  • Immediate release of methane
  • Produces reasonable estimates if amount and composition of waste have been constant or slowly varying, otherwise biased trends
  • How to calculate:
    • Using empirical formulae
    • Using degradable organic content
empirical formulae
Empirical formulae
  • Assumes 53% of carbon content is converted to methane
  • If microbial biomass is discounted it reduces the amount emitted
  • 234 m3 of methane per tonne of wet municipal solid waste
using degradable organic content base of tier 1
Using degradable organic content (Base of Tier 1)
  • Calculated from the weighted average of the carbon content of various components of the waste stream
  • Requires knowledge of:
    • Carbon content of the fractions
    • Composition of the fractions in the waste stream
  • This method is the basis for the Tier I calculation approach
  • Methane emission =

Total municipal solid waste (MSW) generated (Gg/yr) x

Fraction landfilled x

Fraction degradable organic carbon (DOC) in MSW x

Fraction dissimilated DOC x

0.5 g C as CH4/g C as biogas x

Conversion ratio (16/12) ) – Recovered CH4

  • Only urban populations in developing countries need be considered; rural areas produce no significant amount of emissions
  • Fraction dissimilated was assumed from a theoretical model that varies with temperature: 0.014T + 0.28, considering a constant 35°C for the anaerobic zone of a landfill, this gives 0.77 dissimilated DOC
  • No oxidation or aerobic process included
  • Waste generated 235 Gg/yr
  • % landfilled 80
  • % DOC 21
  • % DOC dissimilated 77
  • Recovered 1.5 Gg/yr
  • Methane =(235*0.80*0.21*0.77*0.5*16/12) – 1.5 =19 Gg/yr
  • Main:
    • No time factor
    • No oxidation considered
  • DOC dissimilated too high
  • Delayed release of methane under increasing waste landfilled conditions leads to significant overestimations of emissions
  • Oxidation factor may reach up to 50% according to some authors, a 10% reduction is to be accounted
default method tier 1
Default method – Tier 1
  • Includes a methane correction factor according to the type of site (waste management correction factor). Default values range from 0.4 for shallow unmanaged disposal sites (> 5m) to 0.8 for deep (<5m) unmanaged sites; and 1 for managed sites. Uncategorized sites given a correction factor of 0.6
  • The former DOC dissimilated was reduced from 0.77 to 0.5 - 0.6, due to the presence of lignin
default method tier 11
Default method – Tier 1
  • The fraction of methane in landfill gas was changed from 0.5 to a range between 0.4 and 0.6, to account for several factors, including waste composition
  • Includes an oxidation factor. Default value of 0.1 is suitable for well managed landfills
  • It is important to remember to subtract recovered methane before applying an oxidation factor
default method tier 1 good practice
Default method – Tier 1 Good Practice
  • Emissions of methane (Gg/yr) =

[(MSWT*MSWF*L0) -R]*(1-OX) where

MSWT= Total municipal solid waste

MSWF= Fraction disposed at SWDS

L0 = Methane generation potential

R = Recovered methane (Gg/yr)

OX = Oxidation factor (fraction)

methane generation potential
Methane generation potential

L0 = (MCF*DOC*DOCF*F*16/12 (GgCH4/Gg waste))


MCF = Methane correction factor (fraction)

DOC = Degradable organic carbon

DOCF = Fraction of DOC dissimilated

F = Fraction by volume of methane in landfilled gas

16/12 = Conversion from C to CH4

other approaches
Other approaches
  • Include a fraction of dry refuse in the equation
  • Consider a waste generation rate (1 kg per capita per day for developed countries, half of that for developing countries)
  • Use gross domestic product as an indicator of waste production rates
theoretical first order kinetics methodologies tier 2
Theoretical first order kinetics methodologies (Tier 2)
  • Tier 2 considers the long period of time involved in the organic matter decomposition and methane generation
  • Main factors:
    • Waste generation and composition
    • Environmental variables (moisture content, pH, temperature and available nutrients)
    • Age, type and time since closure of landfill
base equation
Base equation
  • QCH4 = L0R(e-kc - e-kt)

QCH4 = methane generation rate at year t (m3/yr)

L0 = degradable organic carbon available for

methane generation (m3/tonne of waste)

R = quantity of waste landfilled (tonnes)

k = methane generation rate constant (yr-1)

c = time since landfill closure (yr)

t = time since initial refuse placement (yr)

good practice equation
Good practice equation
  • Time t is replaced by t-x, normalization factor that corrects for the fact that the evaluation for a single year is a discrete time rather than a continuous time estimate
  • Methane generated in year t (Gg/yr) = Sx [(A*k*MSWT(x)*MSWF(x)*L0(x)) * e-k(t-x) ] for x = initial year to t
  • Sum the obtained results for all years (x)
good practice equation1
Good practice equation
  • Where:

t = year of inventory

x = years for which input should be added

A = (1-e-k)/k; normalisation factor which corrects the summation

k = Methane generation rate constant

MSWT (x)= Total municipal solid waste generated in year x (Proportional to total or urban population if no rural waste collection)

L0(x) = Methane generation potential

methane generation rate constant
Methane generation rate constant
  • The methane generation rate constant k is the time taken for the DOC in waste to decay to half its initial mass (half-life)
  • k = ln2/t½
  • This requires historical data. Data for 3 to 5 half lives in order to achieve an acceptable result. Changes in management should be taken into account
methane generation rate constant1
Methane generation rate constant
  • Is determined by type of waste and conditions
  • Measurements go from 0.03 to 0.2 per year, equivalent to half lives from 23 to 3 years
  • More degradable material and humidity lower half life
  • Default value: 0.05 per year, or a half life of 14 years
methane generation potential1
Methane generation potential

L0(x) = (MCF(x)*DOC(x)*DOCF*F*16/12 (GgCH4/Gg waste))


MCF(x) = Methane correction factor in year x (fraction)

DOC (x) = Degradable organic carbon in year x

DOCF = Fraction of DOC dissimilated

F = Fraction by volume of methane in gas generated from landfill

16/12 = Conversion from C to CH4

methane emitted
Methane emitted
  • Methane generated minus methane recovered and not oxidized
  • Equation:

Methane emitted in year t (Gg/yr) = (Methane generated in year t (Gg/yr) - R(t))*(1 - Ox)


R(t) = Methane recovered in year t (Gg/yr)

Ox = Oxidation factor (fraction)

practical applications
Practical applications
  • Base for Tier 2 approach
  • Applied earlier in:
    • United Kingdom
    • The Netherlands
    • Canada
regression approach
Regression approach
  • From empirical models
  • Statistical and regressional analysis applied
uncertainties in calculations
Uncertainties in calculations
  • Methane actually produced
    • Are old landfills covered?
  • Quantity and composition of landfilled waste
    • Is there historical data on waste composition?
  • Methane actually produced
    • Are landfill and waste management practices well known?
calculations of emissions from waste water treatment
Calculations of emissions fromwaste-water treatment
  • Calculations for industrial and domestic and commercial waste water are based on biochemical oxygen demand (BOD) loading
  • Standard methane conversion factor 0.22 Gg CH4/Gg BOD is recommended
  • For nitrous oxide and methane it is possible to base calculation on total volatile solids and apply the simple method used in the agriculture sector
methane from domestic and commercial waste water
Methane from domestic and commercial waste water
  • Simplified approach
  • Data:
    • BOD in Gg per 1000 persons (default values)
    • Country population in thousands
    • Fraction of total waste water treated anaerobically (0.1–0.15 as default)
    • Methane emission factor(default 0.22 Gg CH4/Gg BOD
    • Subtract recovered methane
  • Methane emission =

Population (103) x

Gg BOD5/1000 persons x

Fraction anaerobically treated x

0.22 Gg CH4/Gg BOD –

Methane recovered

good practice guidance check method
Good practice guidance – Check method
  • WM = P*D*SBF*EF*FTA*365*10-12 , where:

WM = country’s annual methane emissions from domestic waste water

P = population (total or urban in developing countries)

D = organic load (default 60 g BOD/person/day)

SBF = fraction of BOD that readily settles, default = 0.5

EF = emission factor (g CH4/ g BOD), default =0.6 or 0.25 g CH4/ g COD (chemical oxygen demand) when using COD

FTA = part of BOD anaerobically degraded, default = 0.8

check method rationale
Check method rationale
  • SBF is related to BOD from non-dissolved solids, which account for more than 50% of BOD. Settling tanks remove 33% and other methods 50%
  • Fraction of BOD in sludge that degrades anaerobically (FTA) is related to the processes, aerobic or anaerobic. Aerobic processes and sludge non-methane producing procedures may lead to FTA = 0
check method rationale1
Check method rationale
  • Emission factor is expressed in BOD, however COD is used in many places
  • COD is 2 to 2.5 times higher than BOD, so the default values are 0.6 g CH4/ g BOD or 0.25 g CH4/ g COD
  • Emission factor is calculated from the methane producing factor stated above and the weighted average of methane conversion factor (MCF)
methane conversion factor
Methane conversion factor
  • IPCC guidelines recommends to separate calculations for waste water and sludge. This influences the detailed approach calculation
  • Excepting sludge sent to landfills or for agriculture, this is not necessary
  • If no data are available, expert judgement of sanitation engineers may be incorporated: Weighted MCF = Fraction of BOD anaerobically degrades
detailed approach
Detailed approach
  • Considers two additional factors:
    • Different treatment methods used and total waste water treated using each method
    • MCF for each treatment
  • The final result is the sum of the fractions calculated by the simplified approach, less the recovered methane
  • Domestic and commercial waste-water emissions =

(Si Methane calculated by simplified approach x

Fraction waste water treated using method i x MCF for method i) - methane recovered

methane emissions from industrial waste water
Methane emissions from industrial waste water
  • Industrial waste water may be treated in domestic sewer systems or on site
  • Only on-site calculations are covered in this section, the rest should be added to domestic waste-water loading
  • Most estimates used are for point sources
  • Focus on key industries is required and default values are provided
emissions from industrial waste water treatment
Emissions from industrial waste-water treatment
  • Simplified approach:
      • Determine relevant industries (wine, beer, food, paper, etc.)
      • Estimate waste-water outflow (per tonne of product, or default)
      • Estimate BOD5 concentration (or default)
      • Estimate the fraction treated
      • Estimate methane emission factor (default 0.22 Gg CH4/Gg BOD )
      • Subtract any methane recovered
  • Industrial waste-water emissions =

(Siwaste-water outflow by industry (Ml/yr) x

kg BOD5/I x

Fraction waste water treated anaerobically x 0.22) - Methane recovered

detailed approach1
Detailed approach
  • Similar to the used for estimating methane emissions from domestic and commercial waste water
  • Requires knowledge of:
    • Specific waste-water treatments
    • MCF for each factor
  • Industrial waste-water Emissions =

(SiWaste-water outflow by industry (Ml/yr) x

kg BOD5/l x

Fraction waste water treated using method i x MCF for method i) - Methane recovered

uncertainties in calculations1
Uncertainties in calculations
  • Lack of information about volumes, treatments and recycling
  • Discharge into surface waters:
    • Not anaerobic (default 0%)
    • Anaerobic (default 50%)
  • Septic tanks (long retention times: more than 6 months)
    • Long retention of solids (default 50%)
    • Short retention of solids (default 10%)
  • Open pits and latrines (default 20%)
  • Other limitations: BOD, temperature, pH and retention time
emissions from waste incineration1
Emissions from waste incineration
  • For carbon dioxide, only fossil fraction counts not biomass
  • Only accounted under waste sector when no energy is recovered
  • IPCC guidelines include a simple method
    • It is good practice to disaggregate waste into waste types and take into account burn-out efficiency of incinerator
equation for carbon dioxide
Equation for carbon dioxide

CO2 emission (Gg/yr) = Si(IWi*CCWi*FCFi*Efi*44/12)

where i = MSW, HW, CW, SS

MSW municipal solid waste, HW hazardous waste, CW clinical waste and SS sewage sludge

IWi = Amount of incinerated waste type i

CCWi = Fraction of C content in waste type i

FCFi =Fraction of fossil C in waste type i

EF = Burn-out efficiency of combustion of incinerators for waste type i (fraction)

44/12 = Conversion from C to CO2

equation for nitrous oxide
Equation for nitrous oxide

N2O emission (Gg/yr) = Si(IWi*Efi)*10-6where

IWi = Amount of incinerated waste type i (Gg/yr)

EFi = Aggregate emission factor for waste type i (kg N2O/Gg) or

N2O emission (Gg/yr) = Si(IWi*ECi*FGVi)*10-9

IWi = Amount of incinerated waste type i (Gg/yr)

ECi =N2O emission concentration in flue gas from waste of type i (mg N2O /Mg)

FGVi = Flue gas volume by amount of incinerated waste type i (m3/Mg)

emission factors and activity data for carbon dioxide
Emission factors and activity data for carbon dioxide
  • C content varies: sewage sludge, 30%; municipal solid waste, 40%; hazardous waste, 50%; and clinical waste, 60%.
  • It is assumed that there is very little <<virtually no>> fossil carbon in sewage sludge, 0%; high content in clinical and municipal, 40%; and very high content in hazardous waste, 90%
  • The efficiency of combustion is 95% for all waste streams, except hazardous, which is 99.5%
emission factors and activity data for nitrous oxide
Emission factors and activity data for nitrous oxide
  • Emission factors differ with facility type and type of waste
  • Default factors can be used
  • Consistency and comparability are difficult due to heterogeneous waste types across countries
general reporting recommendations
General reporting recommendations
  • It is good practice to document and archive all information required to produce the national inventory estimates
  • See GPG2000, Chapter 8, Quality Assurance and Quality Control, Section 8.10.1, Internal Documentation and Archiving
  • Transparency in activity data and the possibility to retrace calculations are important
report quality assurance quality control
Report quality assurance/quality control
  • Transparency can be improved through clear documentation and explanations
    • Estimate using different approaches
    • Cross check emission factors
    • Check default values, survey data and secondary data preparation for activity data
    • Cross check with other countries
  • Involve industry and government experts in review processes
reporting for methane from solid waste disposal sites
Reporting for methane from solid waste disposal sites
  • If Tier 2 is applied, historical data and k values should be documented, and closed landfills should be accounted for
  • Distribution of waste (managed and unmanaged) for MCF should be documented
  • Comprehensive landfill coverage, including industrial, sludge disposal, construction and demolition waste sites is recommended
reporting for methane from solid waste disposal sites1
Reporting for methane from solid waste disposal sites
  • If methane recovery is reported an inventory is desirable. Flaring and energy recovery should be documented separately
  • Changes in parameters should be explained and referenced
  • Time series should apply the same methodology; if there are changes it is required to recalculate the entire time series to achieve consistency in trends (See GPG2000, Chapter 7,, Alternative recalculation techniques)
reporting for methane from domestic waste water handling
Reporting for methane from domestic waste-water handling
  • Function of human population and waste generation per person, expressed as biochemical oxygen demand
  • If in rural areas, only aerobical disposal; only urban population is accounted for
  • COD*2.5 = BOD
  • Recalculate whole time series
  • Calculations need to be retraced, particularly if there are changes to MCFs
reporting for methane from industrial waste water handling
Reporting for methane from industrial waste-water handling
  • Industrial estimates are accepted if they are transparent and consistent with QA/QC
  • Recalculations need to be consistent over time
  • Default data for industrial waste water is in GPG2000, Chapter 5, Table 5.4
  • Sectoral tables and a detailed inventory report are necessary to provide transparency
reporting nitrous oxide emissions from waste water
Reporting nitrous oxide emissions from waste water
  • Based on IPCC Guidelines, Chapter 4, Agriculture, Section 4.8, Indirect N2O emissions from nitrogen used in agriculture
  • Future work on data, approaches and calculations is needed
reporting for waste incineration
Reporting for waste incineration
  • All waste incineration is to be included
  • Avoid double counting with energy recovery, even when waste is used as a substitute fuel (e.g. cement and brick production)
  • Default ranges for emission estimates are provided in GPG2000, Chapter 5, Tables 5.6 and 5.7
  • Support fuel, generally little, shall be reported in Energy sector; maybe important for hazardous waste
key emission factors required for ipcc 1996gl and gpg2000
Key emission factors required for IPCC 1996GL and GPG2000
  • Most emission factors are common to both:
    • Methane generation potential for SWDS
    • Human sewage conversion factor
    • Methane conversion factor
  • New emission factors related to:
    • Tier 2 for SWDS, particularly k value
    • Waste incineration (lack of some default values)
link between ipcc 1996gl and gpg2000
Link between IPCC 1996GL and GPG2000
  • GPG2000 uses the same tables as were provided in IPCC 1996GL, based on the same categories
problems addressed
Problems addressed
  • Problems found by NAI experts in using IPCC 1996GL
  • Problems categorized into:
    • Methodological issues
    • Activity data (AD)
    • Emission factors (EF)
  • GPG2000 addresses some deficiencies found in IPCC 1996GL
    • Strategies for improvement in methodology, AD and EF
    • Strategy for AD and EF – tier approach
    • Points to sources of data for AD and EF, including EFDB
methodological issues
Methodological issues
  • Methodologies that are not covered :
    • Sludge spreading and composting,
    • Use of burning under conditions not reflected properly in the waste incineration section
    • Tropical conditions of many NAI Parties vis-à-vis methane generation
    • Use of open dumps instead of landfills
    • Lack of a proper calculation method for human sewage in the case of island countries or countries with prevailing coastal populations, and complexity of the methodology.
methodological issues1
Methodological issues
  • Use of open dumps or open incineration
  • Recycling, commonly of wood and paper but even of organic waste
activity data and emission factors
Activity data and emission factors
  • Lack of activity data, both for the present and the required time series, for the waste flows and their composition
  • Default activity data for only 10 NAI countries
  • Values reflected for k parameter for the application of the First Order Decay method do not reflect tropical conditions of temperature and humidity. The higher k value in GPG2000 is 0.2 and the one in IPCC 1996GL is 0.4
  • The proposed Methane Correction Factor, even using the lesser value, 0.4, may lead to overestimations, due to shallowness and the frequent practice of burning as a pretreatment at disposal sites
methodological issues2
Methodological issues
  • For CH4 emissions from domestic waste-water handling, GPG2000 presents a simplified method called the “check method” avoiding the complexities in IPCC 1996GL
  • In NAI countries, national methods or parameters, or even activity data, may by available only infrequently
  • For CH4 emissions from industrial waste-water handling, GPG2000 presents a “best practice” for cases where these emissions represent a key source, recommending the selection of 3 or 4 key industries
  • For emissions of N2O from human sewage, no improvements were made in GPG2000 over IPPC 1996 GL. This methodology has several limitations that have caused several NAI countries to declare it “inapplicable”
activity data and emission factors1
Activity data and emission factors
  • Availability of activity data and emission factors is uncommon in NAI countries for CH4 emissions from domestic waste water, and the “check method” may help to overcome this issue. In any case, GPG 2000 is an improvement in that it identifies potential CH4 emissions
  • For CH4 emissions from industrial waste water, in cases where it is a key source, it is feasible to work only with the largest industries
  • For N2O emissions from human sewage, the activity data needed are relatively simple and easy to obtain
methodological issues3
Methodological issues
  • This source category was only briefly introduced in the IPCC 1996GL, but is fully developed in the GPG2000
  • In NAI countries, incineration of waste (other than clinical waste) is uncommon due to high costs
  • Differentiation is made between CO2 and N2O because the former is calculated with a mass balance approach and the latter depends on operating conditions
activity data and emission factors2
Activity data and emission factors
  • GPG2000 recognizes the difficulties in finding activity data to differentiate the four proposed categories (municipal, hazardous, clinical and sewage sludge)
  • Do not request differentiation if data are not available when it is not a key source category
status of efdb for the waste sector
Status of EFDB for the Waste sector
  • EFDB is an emerging database
  • All experts are expected to contribute to EFDB.
  • Currently it contains only limited information on Waste sector emission factors
  • In future, with contributions from experts around the world, EFDB should become a reliable source of data for emission factors for GHG inventory
uncertainty estimation and reduction1
Uncertainty estimation and reduction
  • The good practice approach requires that estimates of GHG inventories be accurate
    • they should neither be over- nor underestimated as far as can be judged
  • Causes of uncertainty could include:
    • unidentified sources
    • lack of data
    • quality of data
    • lack of transparency
reporting uncertainties from solid waste disposal sites
Reporting uncertainties from solid waste disposal sites
  • Main uncertainty sources:
      • Activity data (total municipal waste MSWT and fraction sent to disposal sites MSWF)
      • Emission factors (methane generation rate constant)
  • Other factors listed in GPG2000, Table 5.2:
      • Degradable organic carbon, fraction of degradable organic carbon, methane correction factor, fraction of methane in landfill gas
      • Possibly also methane recovery and oxidation factor
reporting uncertainties from domestic waste water handling
Reporting uncertainties from domestic waste-water handling
  • Uncertainties are related to BOD/person, maximum methane producing capacity and fraction treated anaerobically (data for population has little uncertainty (+5%))
  • Default ranges are:
    • BOD/person and maximum methane producing capacity (+ 30%)
  • For fraction treated anaerobically use expert judgement
reporting uncertainties from industrial waste water treatment
Reporting uncertainties from industrial waste-water treatment
  • Uncertainties are related to industrial production, COD/unit waste water (from -50% to +100%), maximum methane producing capacity and fraction treated anaerobically
  • Default ranges are:
    • industrial production (+ 25%)
    • maximum methane producing capacity (+ 30%)
  • For fraction treated anaerobically use expert judgement
reporting uncertainties from waste incineration
Reporting uncertainties from waste incineration
  • Activity data uncertainty on amount of incinerated waste assumed to be low (+5%) in developed countries. Some wastes, such as clinical waste, may be higher
  • Major uncertainty for CO2 is fossil carbon fraction
  • For N2O default values, uncertainty is as high as 100%