Consultative Group Of Experts (CGE) – National GHG Inventory

consultative group of experts (cge) – national ghg inventory handbook waste sector consultative group of experts on national communicatio

Consultative Group of Experts (CGE) – National GHG Inventory Handbook
Waste Sector
Consultative Group of Experts on National Communications from Parties
not included in Annex I to the Convention
(CGE)

Handbook on the
Waste Sector
CONTENTS
Box 6.1 Framework of the tier structure 13
IPCC good practice guidance approach 17
Improvement suggested 17
IPCC good practice guidance approach 17
Improvement suggested 17
IPCC good practice guidance approach 17
Improvement suggested 17
Revised 1996 IPCC Guidelines category 25
10 CH4 Emissions from Solid Waste Disposal Sites 17
10.1 Issues in estimating CH4 emissions from Solid Waste Disposal
Sites 17
10.1.1 Methodological issues or problems relating to this category 17
10.1.2 Issues relating to activity data and emission factors 18
10.2 Addressing issues relating to activity data 18
10.3 Addressing issues relating to emission factors 18
10.4 Sources of activity data and emission factors 18
11 Emissions from Wastewater Handling 18
11.1 Issues in estimating CH4 emissions from wastewaters and N2O from
human sewage 18
11.1.1 Methodological issues or problems relevant to this category 19
11.1.2 Issues related to activity data and emission factors
11.2 Addressing issues relating to activity data 19
11.3 Addressing issues relating to emission factors 19
11.4 Sources of activity data and emission factors 20
12 Emissions from Waste Incineration 20
12.1 Issues in estimating CO2 and N2O from waste incineration 20
12.1.1 Methodological issues or problems relevant to this category
12.1.2 Issues related to activity data and emission factors
12.2 Addressing issues relating to activity data 20
12.3 Addressing issues relating to emission factors 20
12.4 Source of activity data and emission factors 21
13 Emissions from Waste Incineration 21
13.1 Method of estimating and combining uncertainties 21
13.2 Quality assurance and quality control 22
13.2.1 QC procedures 22
13.2.2 QA review procedures 23
14 Emission Factor Database 23
14.1 Features of the EFDB 23
14.2 Steps involved in using the EFDB 24
14.3 Status of the EFDB 24
15 Conclusions and Strategy for Future 24
16 Glossary 26
ABBREVIATIONS
AD – Activity Data
EF – Emission Factor
NAI – Non-Annex I
GHG – Greenhouse Gas
EFDB – Emission Factor Database
1. Background
Article 4, paragraph 1, and Article 12, paragraph 1 of the United
Nations Framework Convention on Climate Change (UNFCCC) establish that
each Party shall develop, periodically update, publish and make
available to the Conference of Parties (COP), information on its
emissions by sources and removals by sinks of all Greenhouse Gases
(GHGs), not controlled by the Montreal Protocol (GHG inventories), as
a component of National Communications.
The COP adopted guidelines for the preparation of initial National
Communications at its second session, by decision 10/CP.2. These
guidelines were used by 106 non-Annex I (NAI) Parties to prepare their
initial communications. At its fifth session, the COP initiated a
process to revise those guidelines. New UNFCCC guidelines were adopted
by the COP, at its eighth session, by decision 17/CP.8.
UNFCCC decision 17/CP.8 provides improved guidelines for preparing GHG
inventory, which is reflected in ,
to encourage the preparation and reporting of GHG inventory in an
accurate, consistent, transparent, comparable and flexible manner. The
UNFCCC has prepared a “UNFCCC User Manual for the Guidelines on
National Communications from NAI Parties” to assist NAI Parties on the
latest UNFCCC guidelines for National Communications, particularly in
the preparation of GHG inventory.
More than 100 NAI Parties have used the Revised IPCC 1996 Guidelines
for National Greenhouse Gas Inventories (hereinafter referred to as
the Revised 1996 IPCC Guidelines) in preparing their GHG inventory.
However, compilation and synthesis reports of NAI inventories have
highlighted several difficulties and limitations in using the Revised
1996 IPCC Guidelines (e.g. FCCC/SBI/1999/11, FCCC/SBI/2003/13 and
FCCC/SBSTA/2003/INF.10). The Intergovernmental Panel on Climate Change
(IPCC) Good Practice Guidance and Uncertainty Management in National
Greenhouse Gas Inventories (2000) (hereinafter referred to as the IPCC
good practice guidance) has to some extent addressed some of the
limitations and also provided guidelines for reducing the uncertainty.
This Handbook aims to assist NAI Parties in using the UNFCCC “User
Manual for the Guidelines on National Communications from NAI Parties”
and also provides an overview of the tools and methods available for
inventory in the waste sector, as well as the UNFCCC inventory
software for non-Annex I Parties.
2. Purpose of the Handbook
For the primarily biological sectors (two of the three waste
subcategories) the GHG inventory is characterized by methodological
limitations, lack of data or low reliability of existing data, leading
to higher uncertainty. This Handbook aims to assist the NAI Parties in
preparing GHG inventory using the Revised 1996 IPCC Guidelines and the
IPCC good practice guidance, particularly in the context of UNFCCC
decision 17/CP.8, focusing on:
*
The need to move to IPCC good practice guidance and to higher
Tiers or methods to reduce uncertainty;
*
A complete overview of the tools and methods;
*
Use of the UNFCCC inventory software and the IPCC emission factor
database (EFDB);
*
Review of activity data (AD) and emission factors (EFs), and
options to reduce uncertainty;
*
Use of key source category analysis, methodologies and decision
trees.
The Handbook also addresses many of the problems encountered by the
NAI experts during the course of using Revised 1996 IPCC Guidelines.
These problems have been reflected in many documents of the Subsidiary
Body for Implementation (SBI) (e.g. FCCC/SBI/1999/11,
FCCC/SBI/2003/13) and the Subsidiary Body for Scientific and Technical
Advice (SBSTA) (e.g. FCCC/SBSTA/2003/INF.10). The approach adopted to
address these problems is as follows:
*
The problems are reviewed and categorized into: i) methodological
issues, ii) AD, and iii) EFs;
*
The approach adopted by IPCC good practice guidance to overcome
some of these problems is presented;
*
Strategies for improvement in the methodology, AD and EF are
presented;
*
IPCC good practice guidance strategy for AD and EF, according to
the three-tier approach is presented;
*
The sources of data for AD and EF, including EFDB are presented.
The target readers for this Handbook waste include:
*
NAI inventory experts;
*
CGE group members;
*
National GHG inventory team leaders.
Even where waste emissions are not explicitly requested by Table II of
the former UNFCCC Guidelines (decision 10/CP.2), they have been
reported by most NAI Parties because in some cases they may be the
largest source of methane emissions and even the largest source from
the inventory as a whole.
3. Organization of the Handbook and Background Resources
The Handbook has adopted the following approach and outline.
*
Revised 1996 IPCC Guidelines; approach and steps
*
IPCC good practice guidance; approach and steps
*
Key source category analysis and decision trees according to IPCC
good practice guidance
*
Reporting framework for the waste sector under Revised 1996 IPCC
Guidelines and IPCC good practice guidance
*
Choice of methods – tier structure, selection and criteria
*
Review of the problems encountered in using Revised 1996 IPCC
Guidelines and how these are addressed in IPCC good practice
guidance
*
Methodological issues
*
AD
*
EFs
*
Revised 1996 IPCC Guidelines category-by-category assessment of
problems and IPCC good practice guidance options to address them
*
Review and assessment of AD and EFs; data status and options
*
Uncertainty estimation and reduction.
The resources for the Handbook and for users of the Handbook involved
in preparing the GHG inventory include:
*
Revised 1996 IPCC Guidelines for National Greenhouse Gas
Inventories
*
Good Practice Guidance and Uncertainty Management in National
Greenhouse Gas Inventories
*
EFDB – emissions factor database
*
Subsidiary Body for Implementation (SBI)
and Subsidiary Body for Scientific and Technical Advice (SBSTA)
documents.
The Handbook will focus on the approach for the preparation of the GHG
inventory in the waste sector adopted by the Revised 1996 IPCC
Guidelines. However, the Handbook attempts to incorporate the elements
provided in the IPCC good practice guidance to address many of the
problems in inventory preparation and to reduce uncertainty.
4. Global Carbon and Nitrogen Cycle and the Waste Sector
Global carbon cycle: Carbon in the form of inorganic and organic
compounds, as the greenhouse gases carbon dioxide (CO2) and methane
(CH4), is cycled between the atmosphere, the oceans and the biosphere.
The largest natural exchange occurs between the atmosphere and
terrestrial biosphere, but human influence keeps growing, particularly
since the industrial era.
Plants withdraw CO2 from the atmosphere through the process of
photosynthesis. Carbon dioxide is returned to the atmosphere by the
respiration of living creatures and the decay or incineration of
organic matter; fossil fuel burning and land-use change being the main
anthropogenic processes that release CO2 to the atmosphere. The mean
annual global aggregate carbon emissions from anthropogenic sector for
the 1990s have been estimated to be around 7.9 GtC. The waste sector
contributes to CO2 emissions through waste incineration of inorganic
matter when there is no energy recovery and it is a rather infrequent
key source.
Some 10–23 per cent (IPCC, 2001) of annual global anthropogenic CH4
produced and released into the atmosphere is a by-product of the
anaerobic decomposition of land-filled wastewater treatment may
account for another 10 per cent of anthropogenic methane emissions,
both from domestic and industrial waste sources. Industrial sources,
pulp and paper as well as food and beverages processing industries
account for most of the emissions.
Global nitrogen cycle: Nitrogen in the form of inorganic and organic
compounds, as in the greenhouse gas nitrous oxide (N2O), is cycled
between the atmosphere, the oceans and the biosphere. The largest
natural exchange occurs between the atmosphere and terrestrial
biosphere, but human influence keeps growing, particularly since the
industrial era (due to the use of fossil fuels, particularly in motors
and urea production for agriculture).
Nitrous oxide emissions from human sewage or waste incineration are
not generally considered important. For both of the above-mentioned
sectors they represent less than 1 per cent of global anthropogenic N2O
emissions.
Contribution of the waste sector: Changes due to waste management
mainly affect CH4 emissions. The contribution of the waste sector to
global CH4 emissions was estimated to be around 90 Mt annually during
the 1990s. Solid waste management is usually the major source of
methane emission from the waste sector.
The contribution of other gases is commonly smaller. These include: N2O,
CO2 and Non-Methane Volatile Organic Compounds (NMVOCs).
A review of the National Communications of three developing countries
– Cuba, Panama and Chile –which have prepared inventories in
accordance with the Revised 1996 IPCC Guidelines for the year 1994
showed that the waste sector has significant impact on national CH4
emissions in developing countries (depending on the agricultural and
land-use change and forestry emissions sectors) and could be a
significant source of N2O.
5. Revised 1996 IPCC Guidelines
5.1 The approach adopted by the Revised 1996 IPCC Guidelines
The Revised 1996 IPCC Guidelines provide approaches, methodologies and
technical guidance for preparing GHG inventories for the waste sector.
The fundamental basis for the inventory methodology rests upon three
assumptions; i) the flux of CH4 to the atmosphere is assumed to be
equal to the sum of emissions from solid waste disposal sites,
wastewater treatment and emissions from waste incineration (considered
to be negligible); ii) the flux of N2O to the atmosphere is assumed to
be equal to the sum of emissions from wastewater treatment and
emissions from waste incineration; and iii) CO2 can be estimated by
first establishing the rates of organic content in waste incinerated.
This requires the estimation of the amounts and composition of waste
and wastewater produced and treated each year, and the conditions in
which the treatment is applied.
The Revised 1996 IPCC Guidelines provide a default approach,
methodology and default data for the GHG inventory of the waste
sector. The default approach involves estimating emissions using three
categories, namely:
*
Solid waste disposal on land – the most important effects of
humans in terms of waste production are considered in a single
broad category, which includes household, yard/garden and
commercial/market as well as industrial waste if it is
significant.Which subcategories are significant;
*
Wastewater handling – the CH4 emissions from activities that
should be calculated separately are from domestic and commercial
wastewater, as well as industrial wastewater, including sludge
streams.
*
Nitrous oxide from human sewage – which uses a method developed
for the agriculture sector.
The Revised 1996 IPCC Guidelines briefly described general issues and
methodological approaches for other possible categories, such as waste
incineration, in which an indication is provided that if waste is used
directly as fuel or converted into a fuel, the emissions should be
calculated and reported under the energy sector. Carbon dioxide
emissions from the decomposition of organic materials are assigned to
the agriculture and Land Use, Land-Use Change and Forestry (LULUCF)
sector. There is also a recognition that no method is provided to
calculate emissions related to NMVOCs. Thus the inventory estimates:
*
CH4 emissions in the first two categories above;
*
N2O from human sewage.
5.2 Steps in the preparation of an inventory using the Revised 1996
IPCC Guidelines
The approach, methodology and the steps involved in estimating
emissions in waste sector, particularly for the NAI Parties using the
IPCC default methods, are as follows:
*
Step 1: Conduct a key source category analysis for the waste
sector, where the sector is compared with others such as energy,
industrial processes, agriculture, and LULUCF. Estimate the share
of waste sector to national GHG inventory. Key source
identification could be adopted by Parties which have already
prepared their initial National Communications and have the
inventory estimates. Parties which have not prepared the initial
National Communications can use inventories prepared under other
programmes (such as US Country Studies Program, ALGAS, UNEP etc.).
Parties that have not prepared any inventory, may not be able to
carry out the key source analysis.
*
Step 2: Select the relevant categories, conditions and management
systems.
*
Step 3: Assemble the required AD depending on the tier selected,
from local, regional, national and global databases, including the
EFDB.
*
Step 4: Collect EFs, depending on the tier level selected from
local, regional, national and global databases, including EFDB.
*
Step 5: Select the method of estimation based on the tier level
and quantify the emissions for each category;
*
Step 6: Estimate the uncertainty involved.
*
Step 7: Adopt quality assurance/quality control (QA/QC) procedures
and report the results.
*
Step 8: Report GHG emissions and removals, according to Revised
1996 IPCC Guidelines, Table 7.1.
*
Step 9: Report all the procedures, equations and sources of data
adopted for the preparation of the GHG inventory.
6. IPCC Good Practice Guidance
6.1 Broad approach and steps
The IPCC good practice guidance covers the waste sector and activities
as described in Chapter 6 of the Revised 1996 IPCC Guidelines,
creating a whole new section for emissions from waste incineration.
The IPCC good practice guidance adopted a decision tree-based approach
to organize the methodologies and good practices to prepare the GHG
inventory and its uncertainties. Adoption of the IPCC good practice
guidance approach involves reporting emissions from all categories and
for all relevant GHGs, excluding NMVOCs. The approach for adopting the
IPCC good practice guidance for preparation of the GHG inventory would
involve the following steps:
1.
Account for all categories and subcategories, all gases, depending
on the key source category analysis;
2.
Conduct a key category analysis;
3.
Select the appropriate tier level/methodology for the key
categories and subcategories and gases based on the key category
analysis, as well as resources available for the inventory
process;
4.
Assemble the required AD, depending on the tier/methodology
selected, from regional, national and global databases;
5.
Collect EFs, depending on the tier selected, from regional,
national and global databases, waste inventories, national
greenhouse gas inventory studies, field studies and surveys and
the EFDB;
6.
Select the method of estimation (equations), based on the tier
level/methodology selected, and quantify the emissions for each
category and gas. Adopt the default worksheet provided in the
Revised 1996 IPCC Guidelines;
7.
Estimate uncertainty;
8.
Adopt QA/QC procedures and report the results;
9.
Report the GHG emissions using the reporting tables;
10.
Document and archive all information used to produce the
inventory, including all the AD, EFs, sources of data, methods
used, QA/QC procedures adopted for different categories and
management systems and gases.
6.2 Waste categories and GHGs
The IPCC good practice guidance adopted two major advances over
Revised 1996 IPCC Guidelines. They are:
i.
Introduction of hierarchical tiers of methods that range from
default data and simple equations to use of country-specific data
and models to accommodate national circumstances;
ii.
Inclusion of the waste incineration category.
The IPCC good practice guidance adopted three categories to ensure
consistent and complete representation of main waste management
categories, covering all the geographic area of a country:
*
CH4 emissions are estimated for all the categories (in waste
incineration, emissions are considered to be negligible);
*
N2O emissions are estimated for human sewage (no improvement since
the Revised 1996 IPCC Guidelines) and waste incineration (new);
*
CO2 emissions are estimated only for waste incineration (and only
for organic material of fossil origin not used for energy
purposes);
*
NMVOC, remaining unaddressed.
6.2.1 Revised 1996 IPCC Guidelines and IPCC good practice guidance
categories:
*
There is a one-to-one linkage, or correspondence, between the
Revised 1996 IPCC Guidelines categories and the IPCC good practice
guidance categories.
*
Additional categories (for waste incineration) are included in the
IPCC good practice guidance.
6.3 Methodological choice – identification of key (source) categories
The IPCC good practice guidance identifies a key source category as
“one that is prioritized within the national inventory system because
its estimate has a significant influence on a country’s total
inventory of direct GHGs in terms of absolute level of emissions, the
trends in emissions, or both”. In this section, the term key category
is used to represent the sources. Key category analysis helps a
country to achieve the highest possible levels of certainty while
using the limited resources for the inventory process. The decision
about what tier to use and where to allocate resources for inventory
improvement should take into account the key category analysis. Key
category analysis is required to identify the following:
*
Which categories are critical;
*
Which subcategories are significant;
*
Which gases are significant.
A GHG subcategory is significant if its contribution to the GHG
emissions accounts for between 25 and 30 per cent of the overall waste
sector inventory. The key category analysis given in IPCC good
practice guidance is directly applicable to the categories used in the
Revised 1996 IPCC Guidelines.
The key category analysis should be performed at the level of IPCC
source categories (i.e. at the level at which the IPCC methods are
described). The analysis should be performed using CO2 equivalent
emissions calculated using the global warming potentials. The key
category evaluation should be performed for each of the gases
separately because the methods, EFs and related uncertainties differ
for each gas. For each key category, the inventory agency should
determine whether certain sub categories are particularly significant
(i.e. represent a significant share of the emissions).
In this section a generic approach to key category analysis is given
based on decision trees. As an illustration, a decision tree is
presented to select which tier to apply on key source determination:

6.4 Tier structure: selection and criteria
The Revised 1996 IPCC Guidelines introduced different levels of
complexity at which national experts can work depending on the
importance of the source category, availability of data and other
capabilities. The IPCC good practice guidance provides users with
methodological tiers for estimating GHG emissions for each source. The
tiers defined by the IPCC good practice guidance nearly correspond to
the levels of complexity given in the Revised 1996 IPCC Guidelines,
though they were not referred to as ‘tiers’ (Revised 1996 IPCC
Guidelines, Reference Manual). Tiers correspond to a progression from
the use of simple equations or methods with default data through to
country-specific data in more complex national systems. The tiers are
summarized in Box 6.1. Tiers implicitly progress from least to
greatest levels of certainty in estimates as a function of:
*
Methodological complexity;
*
Regional specificity of model parameters;
*
Extent of AD.
Box 6.1
Framework of the tier structure
Tier 1 approach employs the basic default method provided for the
waste sector in the Revised 1996 IPCC Guidelines. Tier 1 methodologies
usually use AD that are coarse, such as nationally available estimates
of AD such as aggregate waste and wastewater statistics. Similarly the
EFs could be sourced from global or regional databases.
Tier 2 is only applied in waste for CH4 emissions from solid waste
disposal sites using a different methodological approach (First Order
Decay Method) as Tier 1 and applying AD and EFs which are obtained
from national sources for several years.
Regardless of the tier level, countries should document which tiers
were used for various categories as well as the EFs and AD used to
prepare the estimate. For higher tiers, inventory agencies may need to
provide additional documentation to support decisions to use more
sophisticated methodologies or country-defined parameters. Moving from
lower to higher tiers will usually require increased resources, and
institutional and technical capacity. Higher tiers should be adopted
for key categories, wherever possible.
7. Comparison Between the Revised 1996 IPCC Guidelines and the IPCC
good practice guidance
The IPCC good practice guidance is aimed at:
i.
Overcoming the methodological limitations of Revised 1996 IPCC
Guidelines;
ii.
Preparing an accurate, consistent, complete, comparable and
transparent inventory;
iii.
Reducing uncertainty in the GHG inventory.
However, there is a difference between the Revised 1996 IPCC
Guidelines and the IPCC good practice guidance with respect to:
*
Methodological approach;
*
Categories included;
*
AD and EFs required.
In this section, the advancement or the differences between IPCC good
practice guidance and Revised 1996 IPCC Guidelines are presented.
7.1 Approach and methods adopted
The difference in the approach and methods adopted by the Revised 1996
IPCC Guidelines compared with the IPCC good practice guidance are
briefly presented in Table 7.1.
Table 7.1
Comparison of methods adopted in the IPCC good practice guidance and
Revised 1996 IPCC Guidelines
IPCC good practice guidance
Revised 1996 IPCC Guidelines
First Order Decay method for solid waste disposal sites, based on real
world conditions of decomposition
Based on the last year of waste entering to the disposal sites. Good
approximation, only for long-term stable conditions. The First Order
Decay method is mentioned without specific calculations
Includes a “check method” for countries with difficulties in
calculating the emissions from domestic wastewater handling
Keeps a separation between:
*
Domestic wastewaters
*
Industrial wastewaters
Human sewage is indicated as an area for further development and no
improvement is presented to Revised 1996 IPCC Guidelines
Calculation made on the basis of an approximation developed for the
agriculture sector
New section including emissions from waste incineration. Covers:
*
CO2 emissions
*
N2O emissions
No detailed methodologies were included.
Some references were provided
7.2 Key activity data required
Table 7.2 provides some examples of the differences in AD required for
adopting the IPCC good practice guidance and Revised 1996 IPCC
Guidelines. However, common AD required for both are not given in
Table 7.2.
Table 7.2
Examples of AD required for IPCC good practice guidance and Revised
1996 IPCC Guidelines
IPCC good practice guidance
Revised 1996 IPCC Guidelines
*
Disposal activity for solid waste for several years
*
Less requirements with the check method for CH4 emissions from
domestic wastewater
*
Top down modification for Revised 1996 IPCC Guidelines recommended
due to high costs
*
Incineration amounts, composition (carbon content and fossil
fraction) required for CO2
*
Emission measurements recommended for N2O
*
Disposal activity for current year, default values or a per capita
approach
*
Wastewater flows and wastewater treatments data required
*
Industrial specific data very detailed required
*
No specific methodology specified
*
No specific methodology specified
7.3 Key emission factors required
There are a number of EFs common to both the Revised 1996 IPCC
Guidelines and IPCC good practice guidance, such as: Methane
Generation Potential for solid waste disposal sites, Human Sewage and
Methane Conversion Factor.
However, there are additional EFs required for the IPCC good practice
guidance approach, as in the Tier 2 method for the CH4 emissions from
solid waste disposal sites using the First Order Decay method, e.g.
the k value (no specific calculation methods or default values where
provided by the Revised 1996 IPCC Guidelines).
7.4 Additional efforts and the rationale needed for adopting the IPCC
good practice guidance
The adoption of the IPCC good practice guidance approach will lead to:
an improved GHG inventory; reduced uncertainty; full and consistent
representation of all emission categories; and consideration of all
the relevant gases (based on key category analysis). This requires AD
and EFs for the additional categories and gases included. However,
adoption of the IPCC good practice guidance approach helps to use the
limited inventory resources more efficiently by concentrating efforts
only on the identified key (or significant) categories, gases and the
relevant AD and EFs. The rationale for adopting the IPCC good practice
guidance approach is justified by the following:
*
Addresses most of the methodological limitations and inadequacies
of the Revised 1996 IPCC Guidelines;
*
Adopts key category analysis, which enables dedication of limited
inventory resources to key source categories and gases;
*
Enables the estimation of emissions for all the relevant sources;
*
Reduces uncertainty in GHG estimates.
8. Reporting of GHG Inventory in the Waste Sector
8.1 Mapping or linkage between Revised 1996 IPCC Guidelines and IPCC
good practice guidance
The IPCC good practice guidance uses the same tables as were provided
by the Revised 1996 IPCC Guidelines, which is based on the same
categories.
9. Methodological Issues and Problems in the GHG Inventory for Waste
Using the Revised 1996 IPCC Guidelines
More than 100 non-Annex I Parties have used the Revised 1996 IPCC
Guidelines when preparing their GHG inventory and have reported as a
part of their National Communications. UNFCCC (SBI and SBSTA) has been
periodically compiling and synthesizing the information contained in
National Communications from Parties not included in Annex I to the
Convention. These compilation reports have periodically highlighted
several problems related to methodological issues, AD and EFs as well
as the approach adopted by the Revised 1996 IPCC Guidelines. The
problems related to methodological issues, AD and EF are compiled and
presented in sections 9.1 and 9.2 below, based on information from
UNFCCC documents (FCCC/SBI/1999/11, FCCC/SBI/2000/15,
FCCC/SBI/2001/14, FCCC/SBI/2002/16 and FCCC/SBI/2003/13 and
FCCC/SBSTA/2003/INF.10).
9.1 Problems relevant to methodological issues
The methodological issues largely relate to the following:
*
Methodologies that are not covered, such as: sludge spreading and
composting; the use of burning under conditions not reflected
properly in the waste incineration section; the tropical condition
of many non-Annex 1 Parties for Solid Waste Disposal Sites’
methane generation; the use of open dumps instead of landfills;
the lack of a proper calculation method for human sewage in the
case of island countries or countries with prevailing coastal
population; and complexity of the methodology.
The following paragraphs present the methodological issues listed
above and the approach adopted by the IPCC good practice guidance,
along with additional options for improvement. Adoption of IPCC good
practice guidance significantly reduces the problems related to the
methodological issues. However, the problems related to AD and EFs
remain for Revised 1996 IPCC Guidelines as well as IPCC good practice
guidance approaches.
Problem 1: Lack of coverage of waste management methodologies that
reflect national circumstances.
The approach adopted by IPCC good practice guidance to overcome this
problem and potential improvements are presented below.
IPCC good practice guidance approach
------------------------------------
Improvement suggested
---------------------
*
The IPCC good practice guidance does not cover composting and
sludge spreading, which are common practices in NAI countries
*
Burning and open dump processes are not well covered by IPCC good
practice guidance and are frequent practices in NAI Parties
- Initiate field studies to generate methodologies, or use approaches
proposed by Annex I Parties for these categories
- Expand the relevant sections to reflect the conditions prevailing in
many NAI Parties
Problem 2: Different conditions than those presented in the
methodologies
IPCC good practice guidance approach
------------------------------------
Improvement suggested
---------------------
- The IPCC good practice guidance does not cover conditions for
tropical countries and their management practices in both solid wastes
and wastewaters
- The approximation used to calculate nitrous oxide emissions from
human sewage in the IPCC good practice guidance (the same as in the
Revised 1996 IPCC Guidelines) does not reflect properly the situation
of coastal/island areas
- Initiate field studies to expand the methodology
- Adopt the proposed methodologies covered in the agriculture sector,
differentiating according to geographical reality
Problem 3: Complexity of methodology
IPCC good practice guidance approach
------------------------------------
Improvement suggested
---------------------
- The methodologies presented for Solid Waste Disposal Sites and Waste
Incineration require data that is not commonly available in NAI
Parties
- Methods similar to the Check method for wastewater shall be provided
to enhance completeness of reporting
9.2 Problems relevant to activity data and emission factors
An examination of the problems encountered by the NAI experts relevant
to AD and EF, as reported in several Compilation and Synthesis Reports
of SBI and SBSTA are referred to in this section. The problems largely
related to absence of data, lack of access to data, lack of processes
to validate the data and high uncertainty. Some examples of the
problems relevant to AD and EFs are listed below.
Examples: Activity Data
Examples: Emission Factors
Lack of data on generated solid waste
Inappropriate default values given in Revised 1996 IPCC Guidelines
Lack of time-series data for waste generation
Default data not suitable for national circumstances
Lack of availability of disaggregated data
Lack of EF at disaggregated level
Lack of data on composition of solid waste
Lack of availability of Methane Conversion Factors (MCF) for certain
NAI regions
Lack of data on oxidation conditions
Low reliability and high uncertainty of data
Extrapolations based on past data used to apply Tier 2 for Solid waste
Disposal Sites CH4 generation
Lack of EF for:
*
Waste incineration in Revised 1996 IPCC Guidelines (covered by
IPCC good practice guidance)
Low reliability and high uncertainty of data
Default data commonly provides upper value, leading to over estimation
Approach adopted in IPCC good practice guidance: To minimize the
uncertainty involved in inventory estimation originating from AD and
EFs, the IPCC good practice guidance has provided multiple approaches:
*
Key category analysis enables focusing of inventory efforts on the
identified key categories, incorporating AD and EFs;
*
Selective approach for choice of AD and EFs;
*
Additional default values for EFs;
*
Provision of improved sources of data, including EFDB.
The AD and EFs relevant to each of the Revised 1996 IPCC Guidelines
categories are considered separately in sections 10–12, below. Higher
tiers are recommended for key AD and EFs to reduce uncertainty and use
the limited resources efficiently.
Improvements for the future: NAI Parties may have to initiate
dedicated inventory programmes and provide infrastructural and
technical support for sustained inventory processing. This may involve
organizing periodic inventories, development of nationally relevant
emission factors. It is likely that many countries may not have the
resources needed to initiate these researches. Such countries may
obtain data from other environmental or social studies. The limited
resources could be efficiently utilized to minimize the uncertainty
through adoption of key source category analysis.
10. CH4 Emissions from Solid Waste Disposal Sites
10.1 Issues in estimating CH4 emissions from Solid Waste Disposal
Sites
10.1.1 Methodological issues or problems relevant to this category
This category is commonly a key source in many countries and in
several cases is the main source of CH4 in the country. Accordingly,
the Tier 2 methodology should be applied, but this approach is
infrequent due to problems with AD, as discussed below.
Another problem relates to the fact that some common practices in NAI
Parties, such as the use of open dumps or open incineration in the
waste disposal sites, are not well reflected in either the Revised
1996 IPCC Guidelines or in the IPCC good practice guidance. The fact
that recycling (commonly of wood and paper but even of organic waste)
is a common practice in NAI Parties, which occurs in many cases in an
informal manner, needs to be reflected in future assessments preparing
new guidelines.
10.1.2 Issues related to activity data and emission factors
The main constraint for using Tier 2 is the lack of AD, both for the
present and the required time series, for the waste flows and waste
composition. It is worth to remember that the Revised 1996 IPCC
Guidelines present default AD for only 10 NAI Parties. Also, the
values reflected for a critical parameter for the application of the
First Order Decay method, namely k, do not reflect the tropical
conditions of temperature and humidity which prevail in many NAI
Parties. The higher k value presented in the IPCC good practice
guidance is 0.2 and the k value in the Revised 1996 IPCC Guidelines is
0.4.
The proposed Methane Correction Factor (MCF) even using the lesser
value, 0.4, may lead to overestimations, due to the conditions of
shallowness and the rather frequent practices of burning as a
pretreatment in disposal sites.
10.2 Addressing issues related to activity data
The provision of default values suitable for use by NAI Parties or a
simplified methodology that is less data intensive will enhance both
completeness and comparability. Some NAI Parties have prepared their
own methodologies and those experiences may be shared.
10.3 Addressing issues related to emission factors
There is a need to develop parameter k values in NAI Parties. However,
due to economic constraints, this will be more feasible if it is
associated with projects or programmes for CH4 recovery that will give
additional inputs for the development of such research.
10.4 Sources of activity data and emission factors
The sources of AD for solid waste disposal in NAI Parties are not just
related to the national or local governments that are dealing with the
issue. Non-governmental organizations related to social or
environmental work frequently address this theme and are a valuable
source of AD in both quantities and composition. Academic or research
institutions related to environmental, health or social issues are
also frequently a good source of AD and, possibly, EFs.
11. Emissions from Wastewater Handling
11.1 Issues in estimating CH4 emissions from wastewaters and N2O from
human sewage
11.1.1 Methodological issues or problems, relevant to this category
Wastewater is a source of both CH4 and N2O emissions. For CH4
emissions from domestic wastewater handling, the IPCC good practice
guidance presents a simplified method called “check method” which, in
most cases, will be enough to avoid the complexities inherent in the
Revised 1996 IPCC Guidelines. In NAI Parties, the availability of
national methods or parameters, and even of AD is problematic. For CH4
emissions from industrial wastewater handling, the IPCC good practice
guidance presents an example where these emissions represent a key
source, recommending the selection of 3 or 4 key industries. For human
sewage emissions of N2O, no improvements have been achieved since the
Revised 1996 IPPC Guidelines, and this methodology presents several
limitations that have made several NAI declare it as “inapplicable”
11.1.2 Issues related to activity data and emission factors
As it is mentioned above, the lack of availability of AD and EFs is
common in NAI Parties for CH4 emissions from domestic wastewater, and
the “check method” may help to overcome this issue; even if it is not
the case, the IPCC good practice guidance has provided some
improvements by identifying the potential CH4 emissions. If industrial
wastewater CH4 emissions is a key source category, it is feasible to
work only with the largest industries. For N2O emissions from human
sewage, the AD needed are relatively simple and easy to obtain.
11.2 Addressing issues related to activity data
Sources of AD and EFs in this sector are complex and scarce, as well
as difficult to be obtained due to the differences in treatment,
wastewater and conditions. The use of simplified methods – less data
intensive is “check method” for CH4 emissions from domestic
wastewater, top-down approach for industrial wastewaters and human
sewage N2O emissions – are therefore recommended.
11.3 Addressing issues related to emission factors
IPCC good practice guidance has provided a significant improvement by
differentiating the Bo (maximum methane producing capacity) value for
Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD) in
the case of CH4 emissions from domestic wastewater, even when, in NAI
Parties, it is difficult to obtain data for any of those values. For
this reason, the MCF remains the most complex issue to solve. Methane
and N2O generation conditions for discharges into natural water bodies
needs to be addressed in the future. In addition, the EF for human
sewage N2O emissions needs to be carefully applied taking into account
the fact that it represents a combination of two parameters:
discharges to rivers and to estuaries.
11.4 Sources of activity data and emission factors
A close collaboration with water quality/wastewater management
authorities may provide data for the CH4 emissions from domestic
wastewater. For the CH4 emissions from industrial wastewaters, a close
collaboration with the experts calculating emissions from industry is
highly recommendable. For human sewage N2O emissions, AD such as
population and protein consumption are commonly available from
national and international statistics.
12. Emissions from Waste Incineration
12.1 Estimating CO2 and N2O from waste incineration
12.1.1 Methodological issues or problems relevant to this category
This category was only very briefly introduced in the Revised 1996
IPCC Guidelines, but is fully developed in the IPCC good practice
guidance. In NAI Parties, the incineration of waste for purposes other
than to destroy clinical waste is relatively uncommon, due to the high
costs associated with incineration. The differentiation between CO2
and N2O is made because the former is calculated with a mass balance
approach and the later depends on operating conditions.
12.1.2 Issues related to activity data and emission factors
IPCC good practice guidance recognizes the difficulties in finding AD
to differentiate the four proposed categories (municipal, hazardous,
clinical and sewage sludge) and does not request differentiation if
data are not available if it is not a key source category (which, as
stated above, is infrequent).
12.2 Addressing issues related to activity data
In NAI Parties, the main AD required is incineration from clinical
waste. However, due to the high costs associated with collection of
data, this is often not accomplished even when legally required, and
this fact may lead to overestimations in this category. It is
recommended that Parties associate these emissions with pollution
emissions that are commonly monitored.
12.3 Addressing issues related to emission factors
IPCC good practice guidance establishes EFs for different types of
waste and incineration plants, but default values are only established
for 5 out of 12 possible combinations and none of these cover the case
of clinical waste, the most relevant category for NAI Parties.
12.4 Sources of activity data and emission factors
Health authorities may be very relevant to the collection of AD,
considering that for NAI Parties clinical waste is the most important
category. For N2O emissions, direct measurements will be the most
appropriate for NAI Parties.
13. Uncertainty Estimation and Reduction
The good practice approach for inventories requires that the estimates
of GHG inventories should be accurate in the sense that they are
neither over- nor underestimated as far as can be judged, and the
uncertainties are reduced. The causes of uncertainty could include:
unidentified sources, lack of data, quality of data, lack of
transparency, etc. Uncertainty analysis involves:
*
Identifying the types of uncertainties (measurement error, lack of
data, sampling error, missing data, model limitations, etc.);
*
Reducing uncertainties (improving representativeness, using
precise measurement methods, correct statistical sampling method,
etc.);
*
Quantifying uncertainties (sources of data and information,
techniques for quantifying uncertainty);
*
Combining uncertainties (simple propagation of errors and Monte
Carlo analysis).
The estimates of emissions arising from waste activities have
uncertainties associated with:
*
AD on quantities and composition;
*
EFs;
*
Management practices, etc.
13.1 Methods of estimating and combining uncertainties
The IPCC good practice guidance describes two methods for the
estimation of combined uncertainties, namely Tier 1, simple
propagation of errors and Tier 2, Monte Carlo analysis. The details of
these two methods are given in IPCC good practice guidance. Use of
either Tier 1 or Tier 2 uncertainty estimation provides insight into
how individual categories and GHGs contribute to uncertainty in the
total emissions in a given year. It is important to note that Tier 1
and Tier 2 methods of uncertainty assessment are different from the
methods or Tiers (1 or 2) of inventory estimation. For example, a Tier
1 uncertainty assessment could be used by Parties adopting any of the
tiers or methods for inventory estimation.
Tier 1 methods: The uncertainty associated with Tier 1 methods is
likely to be high, because the suitability of the available default
parameters to a country’s circumstances is not known. The application
of default data in a country or region that has different
characteristics from those of the source of the data can lead to large
systematic errors. Ranges of uncertainty estimates for the emission
factors are given in Chapter 5 of IPCC good practice guidance. Tier 1
is spreadsheet-based and easy to apply. Thus, all countries could
undertake uncertainty analysis according to Tier 1 of uncertainty
estimation, irrespective of which method or tier is used in the
inventory process.
Examples:
*
Degradable Organic Carbon: –50 per cent to +20 per cent
uncertainty;
*
Methane Generation Rate Constant: Uncertainty between –40 per cent
and +300 per cent;
*
BOD/person: Uncertainty between –30 per cent and +30 per cent.
Tier 2 methods – Estimating uncertainties by category using Monte
Carlo analysis: This analysis is suitable for detailed
category-by-category Tier 2 uncertainty assessment. In this method,
country-specific data are used. These data are often only broadly
defined. It is possible to assess the uncertainties involved due to
the national circumstances, based on a few national level studies or
direct measurements. Statistical packages are readily available for
adopting the Monte Carlo algorithm.
Tier 3 methods: Extensive and representative country-specific
information is used to estimate the emissions. The uncertainty with
respect to AD, EFs (such as DOC, BOD) and the models adopted can be
estimated using the methods described in the IPCC good practice
guidance. The uncertainty of the GHG inventory estimate is likely to
be low for countries adopting Tier 3 inventory methods; however the
cost of implementing Tier 3 methods is likely to be very high.
13.2 Quality assurance) and quality control
The IPCC good practice guidance as well as the Revised 1996 IPCC
Guidelines provide definitions and guideline for QA and QC, keeping in
mind the need to enhance transparency and accuracy of the estimates of
GHG inventory.
*
QC is a system of routine technical activities to measure and
control the quality of the inventory as it is being developed, and
is designed to:
*
Provide routine and consistent checks to ensure data integrity,
correctness and completeness;
*
Identify and address errors and omissions;
*
Document and archive inventory material and record all QC
activities.
*
QA is a planned system of review procedures conducted by personnel
not directly involved in the inventory compilation/development
process.
13.2.1 QC procedures
Tier 1 - General QC procedures: It is good practice to implement the
generic Tier 1 QC checks as outlined in IPCC good practice guidance.
The general methods focus on the processing, handling, documenting,
archiving and reporting procedures. An example of QC activity and
procedure involves the following:
*
Check the integrity of database files:
*
Confirm the appropriate data processing steps are correctly
represented in the database;
*
Confirm the data relationships are correctly represented in the
database;
*
Ensure that data fields are properly labeled and have the correct
design specifications;
*
Ensure adequate documentation of database and model structure.
Tier 2 – Source category-specific QC procedures: Tier 1 QC checks
relate to data processing, handling and reporting, whereas Tier 2
relates to category-specific procedures for key categories. Tier 2 QC
procedures are directed at specific types of data used in the methods
and require knowledge of:
*
Source category;
*
Type of data available;
*
Parameters associated with emissions.
Tier 2 QC procedures should focus on the following types of checks
(these are only examples; refer to Chapter 8 of IPCC good practice
guidance for details):
*
Check that no double counting or omissions have occurred;
*
Ensure completeness of source categories;
*
Check consistency of time series AD;
*
Check sampling and extrapolation protocols adopted.
13.2.2 QA review procedures
QA review procedures require an expert review to assess the quality of
the inventory and to identify areas where improvements are necessary.
The Tier 1 QA procedure involves basic expert peer review by inventory
agencies. Apply the review process to all source categories,
particularly the key categories.
A Tier 2 QA procedure involves expert peer review, which includes:
Review calculations or assumptions;
Identify if the major models used have undergone peer review;
Assess documentation of models, input data and other assumptions.
14. Emission Factor Database
The EFDB has the objective to provide a variety of users, in
particular the inventory compilers of the Parties to the UNFCCC, with
current and well-documented EFs and other parameters, as well as to
establish a communication platform for distributing and commenting on
new research and measurement data. The EFDB is designed to be a
recognized data repository where users can find EFs and other
parameters with background documentation or technical references. EFDB
is a database on various parameters to be used in calculation of
anthropogenic emissions by sources and removals by sinks of GHGs.
14.1 Features of the EFDB
Some of the key features of EFDB are as follows:
*
EFDB is an online database;
*
It is continuously updated with data that is reviewed by a panel
of experts;
*
It is menu driven and user-friendly;
*
It requires use of Internet Explorer version 5.0 or Netscape
Navigator version 6.0 or higher coupled with Microsoft Office 97
for generating outputs in Word or Excel
*
It has multiple options such as:
*
Step-by-step search using IPCC source category and gas;
*
Full text search using key words;
*
Find emission factor using unique ID.
However, the responsibility of using this information appropriately
will always remain with the end users.
14.2 Steps involved in using EFDB
*
Step 1: Selection of the sector, e.g. Waste (6)
*
Step 2: Selection of gases e.g. CO2, CH4, N2O
*
Step 3: Display the results
*
Step 4: Set the filter giving the conditions such as gas,
parameter/condition, region, etc.
Results are displayed along with the following details;
*
EF ID, gas, description, technologies/practices,
parameters/conditions, region/regional conditions,
abatement/control technologies, other properties, value, unit,
data provider, source of data.
14.3 Status of the EFDB for the waste sector
The EFDB is an emerging database, initiated in 2002. EFDB expects all
experts to contribute to the database. Currently (year-2004), the EFDB
has limited information for the waste sector EFs (Table 14.1). In
future, with contribution from experts around the world, the EFDB is
likely to become a reliable source of data for emission/removal
factors for GHG inventory.
Table 14.1
Status of EFDB for waste sector – Number of records of emission
factors
Revised 1996 IPCC Guidelines category
=====================================
Emission factor records
Solid Waste Disposal on Land (6A)
115
Wastewater Handling (6B)
191
Waste Incineration (6C)
47
Other (6D)
0
Total
353
15. Conclusions and Strategy for the Future
Over 100 NAI Parties have used the Revised 1996 IPCC Guidelines.
Capacity-building has occurred in non-Annex-I Parties in using Revised
1996 IPCC Guidelines. NAI experts, as well as compilation and
synthesis by UNFCCC have identified a number of issues and problems in
using the Revised 1996 IPCC Guidelines. Some broad issues identified
are:
i.
Lack of clarity and inadequacies of the methods;
ii.
Lack of AD and EFs;
iii.
Low quality or reliability of AD and EFs;
iv.
High uncertainty of AD and EFs, leading to uncertainty in
inventory estimates;
v.
Non-suitability of default AD and EFs to national circumstances.
The IPCC good practice guidance attempted to overcome some of the
methodical issues and problems involved in using the Revised 1996 IPCC
Guidelines and suggested methods to reduce uncertainty. IPCC good
practice guidance has not merely attempted to provide good practice
guidance to the Revised 1996 IPCC Guidelines methods, but has gone
beyond and suggested new methods. Adoption of the IPCC good practice
guidance approach will lead to:
*
Efficient use of limited inventory resources by adopting key
category analysis;
*
Reduction in uncertainty.
Thus adoption of the IPCC good practice guidance approach and
methodology would be a significant advancement in making accurate and
reliable estimates of GHG inventory, and to meet the requirements of
CP8 decisions. IPCC good practice guidance contributes to overcoming
the methodological problems. However, the problems relevant to AD and
EFs may remain. The Parties may have to adopt twin strategies, namely:
*
Firstly, build technical capacity and adopt the IPCC good practice
guidance;
*
Secondly, initiate the generation of a nationally derived database
(for AD and EFs) and its validation (through QA/QC procedures) to
help inventory process.
It is important to state that most of the AD and EFs required for the
GHG inventory process are also required for environmental management
and development programmes (e.g. monitoring of solid waste generated,
domestic and industrial wastewater generation and incinerated waste,
etc.). The NAI Parties could initiate measures to shift from Tier-1
methods to Tier-2 for Solid Waste Disposal Sites CH4 Generation, based
on nationally derived AD and EF, to reduce uncertainty.
*
Adoption of IPCC good practice guidance helps to shift to higher
tiers by the adoption of higher tiers for key categories and gases
only;
*
Limited national resources could be allocated to key categories,
to increase the efficiency of the use of limited resources;
*
Focusing limited resources on generating nationally relevant key
identified AD and EF.
The initiatives that are likely to contribute to the adoption of the
IPCC good practice guidance approach and improved national GHG
inventories of NAI Parties include:
*
Development of Inventory Software for IPCC good practice guidance
initiated by UNFCCC;
*
Development of EFDB by IPCC and individual experts;
*
Capacity building activities for NAI in using IPCC good practice
guidance and generation of AD and EF;
*
Preparation of IPCC 2006 Guidelines.
16. Glossary
Waste Emissions – This includes GHG emissions resulting from waste
management activities (involving solid and liquid waste management,
excepting carbon dioxide from incineration of organic matter and/or
used for energy purposes).
Source – Any process or activity which releases a greenhouse gas (such
as CO2, N2O and CH4) into the atmosphere.
Activity Data – Data on the magnitude of human activity, resulting in
emissions taking place during a given period of time. For example,
data on waste quantity, management systems, and incinerated waste.
Emission Factor – A coefficient that relates activity data to the
amount of chemical compound which 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.

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