PCS TR 001 Landfill Methane Capture_v1.0

Document Control

Document identification

• Document code: PCS-TR-001

• Title: Landfill Methane Capture Methodology

• Scope: Landfill methane capture projects installing new systems or expanding/improving existing systems, where methane capture/destruction or productive use is the primary mitigation purpose.

• Crediting outcome: Emission reductions (tCO₂e) through capture and destruction or productive use of methane from landfill waste.

Version history and change log

Table DC-1. Revision history

Version	Date	Status	Summary of changes	Prepared by	Approved by
v1.0	TBD	Draft	Release for public consultation	PCS	TBD

Superseded versions

No superseded versions for v1.0.

Governance note on versioning and archiving

Only the latest approved version of this methodology shall be used for new project registrations. Superseded versions shall be archived and retained for traceability, including for projects registered under earlier versions where applicable, consistent with PCS governance rules.

Purpose and scope summary

Purpose

This methodology establishes the procedures required to quantify emission reductions resulting from the capture and destruction or productive use of methane from landfill waste, including baseline determination, boundary definition, additionality demonstration, calculation procedures, monitoring requirements, QA/QC, and reporting.

Scope summary

This methodology applies to projects that install new landfill gas collection systems or expand/improve existing systems to achieve measurable increases in methane capture.

It excludes waste incineration and other thermal treatment processes that fundamentally alter the waste stream rather than capturing landfill-generated methane.

Methodology overview (how the quantification works)

Emission reductions are generated by comparing methane emissions under the baseline scenario with emissions under the project scenario after methane capture, destruction, oxidation, and (where relevant) displacement of fossil fuel energy by recovered landfill gas.

Conservative quantification is supported through first-order decay modeling, direct measurement of gas flows where applicable, prescribed monitoring frequencies, treatment of oxidation in cover materials, and performance requirements for methane destruction devices.

Normative references

The methodology is grounded in recognized technical sources including IPCC Guidelines for National Greenhouse Gas Inventories and the UNFCCC CDM framework.

In addition, the landfill methane capture quantification tool and its user guide operationalize calculation and evidence expectations for application of PCS-TR-001.

Table NR-1. Normative references

Document / Source	Title	Role in this methodology
IPCC Guidelines	National GHG Inventories	Technical basis for landfill methane generation concepts and conservative treatment
UNFCCC CDM	CDM framework	Reference basis for methodological structure and integrity framing
PCS-TA-010 / Guide	Landfill Methane Capture Tool and User Guide	Calculation workflow, evidence trail expectations, cross-references to PCS-TR-001 requirements

Chapter 1 - Introduction

1. Landfills are significant anthropogenic sources of methane, a greenhouse gas with a global warming potential substantially higher than carbon dioxide over a 100-year timeframe. In unmanaged disposal sites, organic waste undergoes anaerobic decomposition, producing methane that typically escapes to the atmosphere. Landfill methane capture projects mitigate these emissions by installing engineered systems that collect and destroy or utilize landfill gas. These systems may include vertical or horizontal wells, gas collection piping, flares, enclosed oxidizers, or gas-to-energy facilities.

2. This methodology establishes the procedures required to quantify emission reductions resulting from the capture and destruction or productive use of methane from landfill waste. It provides guidance for baseline determination, project boundary definition, additionality demonstration, calculation of project and baseline emissions, monitoring requirements, data quality assurance, and reporting. The methodology draws on open scientific and regulatory sources including the Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories and the UNFCCC Clean Development Mechanism framework.

3. The methodology applies to projects that install new landfill gas collection systems or expand existing systems where improved operational practices lead to measurable increases in methane capture. It does not apply to waste incineration, advanced thermal treatment technologies, or systems primarily designed for energy recovery unless methane capture is their primary purpose.

4. Emission reductions are generated by comparing the methane emitted under the baseline scenario with emissions occurring under the project scenario. The baseline scenario represents unmanaged or sub-optimally managed landfill conditions that would persist in the absence of the project. The project scenario reflects emissions after methane capture, destruction, oxidation, or displacement of fossil fuel energy by recovered landfill gas.

5. This methodology may be applied to existing landfills, controlled dumpsites transitioning to sanitary landfill operations, and newly designed landfill cells where methane capture is feasible. The methodology does not govern landfill siting or waste acceptance procedures; however, it requires that project developers demonstrate compliance with applicable environmental, health, and safety regulations.

6. The methodology incorporates requirements for conservative quantification of methane generation using first-order decay models, direct measurement of gas flows, and specified monitoring frequencies. It also provides procedures for estimating oxidation in landfill cover materials and for adjusting capture efficiency where direct measurement is not available. The results must be supported by evidence that the project activities are additional, that the systems are maintained, and that methane destruction devices meet minimum performance standards.

7. This chapter establishes the purpose and scope of the methodology. Subsequent chapters describe applicability conditions, project boundary, baseline selection, additionality criteria, emission reduction calculations, leakage assessment, monitoring requirements, and data handling procedures.

Chapter 2 - Scope And Applicability

1. This methodology applies to activities that capture, control, destroy, or utilize methane generated from the anaerobic decomposition of solid waste in landfills. It is designed for use across a range of landfill typologies, including controlled dumps, open dumps undergoing rehabilitation, engineered landfills, and sanitary landfills with active or closed waste cells. The methodology may be applied to both existing landfills where landfill gas (LFG) capture systems are absent or inadequate, and to newly constructed landfill cells where methane capture is integrated into the design.

2. The methodology is applicable only where project developers demonstrate that methane emissions in the baseline scenario are significant and uncontrolled. Sites where regulatory requirements mandate methane capture, flare installation, or gas-to-energy systems, without the possibility of demonstrating additionality, fall outside the scope of this methodology. The methodology does not apply to waste incineration, pyrolysis, gasification, or other thermal treatment processes that fundamentally alter the waste stream rather than capturing landfill-generated methane.

3. Eligible project activities may include installation of vertical or horizontal extraction wells, passive or active gas collection systems, manifolds and piping, condensate management systems, blowers, enclosed or open flares, high-temperature oxidation units, or landfill gas utilization facilities such as internal combustion engines, turbines, or boilers. Projects may also expand or rehabilitate an existing gas collection system, provided that quantifiable and verifiable improvements in collection efficiency or methane destruction can be demonstrated.

4. The methodology is applicable to landfills receiving municipal solid waste, commercial waste, industrial non-hazardous waste, or other biodegradable waste streams. Hazardous waste landfills are excluded due to differing gas generation characteristics and regulatory controls. Where the landfill includes mixed waste streams, the project developer must define and document the composition of the degradable organic carbon fraction using representative sampling or established national waste composition studies.

5. This methodology may be applied to projects that destroy methane via flaring, thermal oxidizers, or oxidation units, or that use methane as a renewable energy source in electricity or heat generation. The methodology covers emission reductions from both destruction and displacement mechanisms, provided that energy generation systems meet applicable performance and monitoring requirements. The displacement of fossil fuel-based electricity or heat must be calculated in accordance with approved grid emission factors or fuel-specific emission factors based on publicly available national or international datasets.

6. The methodology applies to projects implemented by private, public, or municipal entities, including public–private partnerships. It may also be applied in concession-based landfill operation models where long-term operational control of the site is contractually assigned.

7. In cases where the landfill is partly closed and partly active, the project developer must specify which portion of the site is included in the project boundary. Projects may include both closed and active cells provided that gas collection systems are installed or upgraded in each included area. Where the landfill is in the process of closure, the methodology remains applicable during the post-closure phase as long as methane generation remains significant and capture systems remain operable.

8. The methodology is not applicable if the project claims emission reductions for activities unrelated to methane capture, such as composting, anaerobic digestion of external waste streams, or landfill cover improvements that do not contribute to measurable methane oxidation. However, the methodology allows oxidation factors to be applied where scientifically supported and monitored.

9. The applicability conditions below must be met:

Requirement	Applicability Condition
Baseline emissions	Methane is emitted to the atmosphere in the absence of the project.
Regulatory environment	No mandatory regulation requires methane capture beyond what already exists.
Technology	Project installs or upgrades methane capture, destruction, or utilization systems.
Waste type	Landfill contains biodegradable waste capable of generating methane.
Operational control	Project developer has authority to install, operate, and maintain LFG systems.
Monitoring feasibility	Equipment is available to measure flow, methane content, and destruction efficiency.

1. This chapter defines the scope of eligible project activities and establishes the conditions under which the methodology can be applied. The next chapter describes the project boundary, including physical, temporal, and greenhouse gas boundaries.

Chapter 3 - Project Boundary

3.1 Overview of the Project Boundary

1. The project boundary identifies all physical areas, equipment, processes, and greenhouse gas (GHG) emission sources that are affected by the landfill methane capture project. The boundary includes both the landfill waste mass where methane is generated and the engineered systems used to capture, transport, treat, destroy, or utilize landfill gas (LFG). The boundary is defined to ensure that all relevant baseline and project emissions are quantified and no significant sources are omitted.

3.2 Physical Boundary

1. The physical boundary encompasses all areas of the landfill where waste decomposition occurs and where methane can be generated or emitted. This includes active disposal cells, closed or capped cells, and any areas undergoing rehabilitation. The boundary also includes all methane collection infrastructure such as vertical wells, horizontal collectors, headers, condensate traps, blowers, flares, engines, turbines, or boilers used for methane destruction or utilization.

2. The physical boundary may include multiple discrete landfill areas within a single operational facility, provided that the project developer demonstrates control over gas management systems in each included area. Areas outside the landfill footprint, such as energy distribution networks or grid interfaces, are not part of the physical boundary but may influence the quantification of displacement emissions.

3.3 Temporal Boundary

1. The temporal boundary begins on the project start date, defined as the date when the project becomes operational and capable of capturing methane. This typically corresponds to commissioning of the gas collection and destruction equipment. The temporal boundary includes:

• The crediting period, during which emission reductions are claimed.

• Any post-closure period in which methane capture and destruction continues.

• Periods where gas capture temporarily ceases due to maintenance or operational interruptions.

1. The project developer must provide evidence for the exact commissioning date and document any periods of downtime to ensure emissions are conservatively quantified.

3.4 Greenhouse Gas Boundary

1. The greenhouse gas boundary includes all GHGs relevant to methane generation, capture, and destruction. These include:

3.4.1 Baseline Emissions Sources

• Methane emissions released directly from landfill surfaces in the absence of a capture system.

• Methane oxidation occurring naturally in landfill cover materials (considered for adjustment).

• Carbon dioxide from biogenic waste decomposition is excluded, as per IPCC guidance.

3.4.2 Project Emissions Sources

• Residual methane emissions from landfill that are not captured by the project system.

• Methane fugitive emissions from collection wells, piping, joints, connectors, blowers, and treatment units.

• Methane slip from flares, engines, turbines, or boilers.

• Carbon dioxide and nitrous oxide emissions from combustion of landfill gas in energy systems.

• Indirect emissions from electricity consumption of gas blowers and monitoring equipment (optional, depending on PCS rules).

3.4.3 Leakage Emissions

1. Leakage is generally negligible for landfill methane projects. However, leakage may arise if:

• Fossil fuel use increases at the site due to the project.

• Waste diversion or operational changes outside the site boundary increase methane emissions elsewhere.

1. If leakage risks are identified, they must be quantified or conservatively set to zero.

3.5 Spatial Boundary Table

1. The following table summarizes the spatial inclusion of key components:

Component	Included in Boundary	Description
Landfill waste body	Yes	Source of methane from anaerobic decomposition.
Gas extraction wells	Yes	Physical infrastructure for methane capture.
Gas transport system	Yes	Manifolds, pipes, condensate traps, blowers.
Gas destruction devices	Yes	Flares, thermal oxidizers, power generation units.
Leachate treatment system	No	Not directly influencing methane capture.
Composting or AD facilities	No	Outside scope unless integrated with LFG system.
Grid infrastructure	No	Considered only for emission factor inputs.

Chapter 4 - Baseline Scenario

4.1 Overview of the Baseline Scenario

1. The baseline scenario represents the most plausible situation in which the landfill would continue to operate in the absence of the project activity. Under typical conditions—especially in developing or transitioning waste sectors—landfills lack active gas collection or utilize systems with limited operational effectiveness. Methane generated from decomposing waste therefore escapes passively into the atmosphere through surface cracks, cover soils, or engineered vents.

2. This chapter establishes the procedures for determining the baseline conditions, including methane generation potential, landfill operational practices, and regulatory context.

4.2 Baseline Conditions at Landfills

1. Baseline conditions at eligible landfills generally fall into one of the following categories:

4.2.1 Uncontrolled Methane Emissions

1. Most unmanaged or minimally managed landfills do not install gas extraction systems. Methane emissions occur diffusely from the entire landfill surface. Methane oxidation through cover layers may occur but is generally limited, varies spatially, and must be conservatively accounted for.

4.2.2 Existing but Ineffective Gas Collection Systems

1. Some landfills may have partial, degraded, or poorly operated methane capture systems. In these cases, the baseline scenario is not the physical presence of infrastructure but the level of gas collection actually achieved in the absence of the project. The baseline scenario must therefore reflect realistic, measurable performance rather than theoretical system capacity.

4.2.3 Mandatory Regulations and Their Implications

1. If national or local regulations require methane capture or destruction at the site, and enforcement can be demonstrated, the baseline scenario must incorporate those requirements. Projects cannot claim emission reductions for actions that are mandatory under enforceable law.

2. If regulations exist but are not enforced, project developers must document the historical compliance levels to justify a baseline that reflects real-world conditions.

4.3 Baseline Methane Generation and Emissions

1. Baseline methane emissions represent the quantity of methane that would be released to the atmosphere in the absence of the project. Methane generation is calculated using a scientifically recognized model—typically the IPCC First-Order Decay (FOD) model—unless robust, long-term historical gas collection data allow direct estimation.

2. The baseline methane emission calculation requires the following elements:

• Methane generated in the landfill during year y (CH₄_{gen,bsl,y}).

• Fraction of methane released to the atmosphere after adjusting for oxidation in the cover material (CH₄_{rel,bsl,y}).

• Methane oxidized in the landfill cover (OX_{bsl,y}).

• Global Warming Potential (GWP₁₀₀) for methane consistent with the PCS vintage rule.

Baseline emissions (BE_y) are therefore estimated using these components.

4.3.1 Baseline Methane Generation (FOD Model)

1. The IPCC First-Order Decay model expresses methane generation as a function of the degradable organic content of the waste and its decomposition over time. Methane generated in year y from all past waste deposits is calculated using terms for waste mass deposited in each year, DOC, DOC_f, MCF, F, k, and the decay function e^{-k(y-x)}.

2. Parameter values must be conservative and supported by site-specific or national studies where available, or by IPCC defaults when no better data exist.

4.3.2 Baseline Methane Released to Atmosphere

1. Total methane released in the baseline is the methane generated minus the portion oxidized in the landfill cover:

BE_y = CH₄_gen,y − OX_{bsl,y}

Where OX_{bsl,y} = methane oxidized in the aerobic cover layers.

Oxidation only applies where the landfill has any form of soil cover; no oxidation is assumed for uncovered dumpsites.

4.3.3 Methane Oxidation in the Baseline

1. Methane oxidation occurs when methane passes through aerobic cover layers where methanotrophic bacteria convert CH₄ to CO₂. The oxidation factor applied in the baseline must reflect scientifically defensible estimates of site conditions.

2. PCS requirements:

• Oxidation must not exceed 10% for unmanaged landfills unless supported by field measurements.

• Oxidation may be up to 20% for sites with enhanced cover systems such as thick soil layers or compost-amended biocovers, provided robust evidence exists.

• Any deviation from IPCC defaults must be justified with site-specific measurements, studies, or verified engineering assessments.

1. The oxidation factor must always be conservative, ensuring that baseline emissions are not overstated.

4.4 Selection of Baseline Option

1. Project developers must select the appropriate baseline condition from the options below and justify the selection with evidence.

Baseline Option	Description	Applicability
Option 1: No gas collection system	All methane generated is released minus oxidation.	Unmanaged or minimally managed landfills.
Option 2: Existing system with poor performance	Baseline emissions correspond to measured historical capture efficiency or gas collected.	Landfills with partial systems or degraded infrastructure.
Option 3: Regulatory requirement scenario	Baseline includes methane capture or destruction mandated by enforceable regulation.	Jurisdictions with enforced methane control laws.

1. Option 1 is the most common baseline in low- and middle-income waste sectors.

4.5 Evidence Requirements for Baseline Determination

1. Project developers must provide documentation to support the baseline scenario selection. Acceptable evidence includes:

• Historical landfill operational records

• Site inspection reports

• Aerial or satellite imagery

• Waste deposition data

• Regulatory texts and enforcement records

• Field measurements of methane flux (if available)

• Waste composition studies

1. All evidence must be catalogued in the Evidence_Reference sheet of the tool (created later in Step C).

4.6 Baseline Scenario Summary Table

Element	Baseline Condition
Gas collection	Absent or ineffective in most eligible cases
Methane destruction	Zero in most cases; limited if poor flaring exists
Methane oxidation	Limited; apply conservative default unless measured
Regulatory requirement	Only included if demonstrably enforced
Evidence	Site-specific documentation required

Chapter 5 - Additionality

5.1 Purpose of Additionality Assessment

1. Additionality ensures that emission reductions generated by landfill methane capture projects represent real and credible climate benefits that would not have occurred without the project. This methodology requires project developers to demonstrate that the installation, expansion, or improvement of methane capture systems is not mandated by regulation, not common practice, and not financially viable without carbon revenue.

2. The assessment must be transparent, evidence-based, and consistent with PCS rules for proving regulatory, financial, technological, and implementation barriers.

5.2 Regulatory Additionality

1. Regulatory additionality determines whether the project activity is legally required. A landfill methane capture project is considered non-additional if:

• National, provincial, or municipal laws mandate gas collection, flaring, or energy recovery at the landfill;

• Regulations specify minimum gas capture efficiencies, gas-to-energy requirements, or flare installation;

• Enforcement agencies have a documented history of ensuring compliance at comparable sites.

1. A project may still be additional if:

• Regulations exist but are not enforced, and the developer provides evidence of long-term non-compliance at similar sites;

• Regulations require “environmental best practice” or “mitigation measures” but do not explicitly mandate methane capture systems;

• Compliance is optional, incentive-based, or tied to voluntary environmental certification.

1. Required Evidence Examples

• Copies of relevant environmental and waste management regulations

• Records of enforcement actions (or absence thereof)

• Historical operations at similar landfills with no methane control

• Official letters clarifying regulatory expectations

1. All evidence must be entered in the Evidence_Reference register.

5.3 Financial Additionality

1. Financial additionality evaluates whether the methane capture system would be implemented without carbon credit revenue. Many landfill operators—especially municipal ones—lack the capital to install or upgrade gas systems due to high upfront costs, operational expenditure, and limited revenue streams.

2. Projects must demonstrate one or more of the following:

5.3.1 Investment Barrier

1. The project faces high capital costs (e.g., drilling wells, installing blowers, flares, or engines) that the landfill operator cannot justify under normal operations.

5.3.2 Lack of Revenue Streams

• No existing tariffs or incentives for renewable electricity from landfill gas.

• Electricity sales alone cannot offset operating costs (common where power purchase agreements or feed-in tariffs do not exist).

5.3.3 Negative or Low Internal Rate of Return (IRR)

1. A financial analysis must show that the project yields a negative or sub-threshold IRR without carbon revenue, but becomes viable with carbon revenue.

Evidence Examples

• Feasibility studies

• CAPEX and OPEX estimates

• IRR/NPV calculations

• Financial statements

• Electricity tariff documentation

5.4 Technological and Implementation Additionality

1. In many regions, the implementation of landfill gas capture systems is constrained by limited technical experience, lack of skilled contractors, or absence of institutional capacity.

2. Additionality is supported if:

• Comparable landfills in the region do not operate methane capture systems.

• The proposed technology (e.g., enclosed flares, high-efficiency blowers, gas engines) is not common practice.

• Operators lack historical experience managing gas systems safely and effectively.

Evidence Examples

• Surveys of similar facilities

• National waste sector technology assessments

• Documentation of limited technical capacity or supply-chain constraints

5.5 Common Practice Analysis

1. A project must demonstrate that landfill methane capture is not widespread in the region. The common practice test considers:

• Number of landfills operating gas collection systems

• Proportion of waste sector emissions controlled by comparable systems

• Whether existing systems were built only in response to mandatory regulations or donor-funded programs

1. If fewer than 20% of comparable sites implement methane capture, the project passes the common practice screen.

Evidence Examples

• National waste sector reports

• Academic or governmental studies

• Inventory of operating landfills

5.6 Additionality Demonstration Summary Table

Additionality Type	Requirement	Evidence Examples
Regulatory	Methane capture not legally mandated or enforced	Regulations, enforcement records
Financial	Project not viable without carbon revenue	Financial model, CAPEX/OPEX, tariffs
Technological	Limited technical capacity or experience	Sectoral assessments
Common Practice	Capture not widespread in the region	National landfill datasets

5.7 Additionality Conclusion

1. A project is additional if:

• It is not required by regulation;

• It faces financial, technical, or implementation barriers;

• Methane capture is not common practice in the project’s regional context.

1. A clear written justification must be included in the Project Description document and all supporting documentation must be cross-referenced in the evidence register.

Chapter 6 - Emission Reduction Calculations

6.1 Overview of Emission Reduction Quantification

1. Emission reductions (ERs) are calculated as the difference between baseline methane emissions and project scenario emissions, adjusted for methane oxidation, destruction efficiency, and any leakage attributable to the project.

2. This chapter establishes the equations, parameters, and procedural steps required to conservatively quantify emission reductions from landfill methane capture projects. The fundamental relationship is:

ER_y = BE_y − PE_y − LE_y

Where:

• ER_y = Emission reductions in year y

• BE_y = Baseline emissions in year y

• PE_y = Project emissions in year y

• LE_y = Leakage emissions in year y

1. Leakage is typically zero unless conditions in Section 6.10 apply.

6.2 Baseline Emissions (BEᵧ)

1. Baseline emissions represent the methane released to the atmosphere in the absence of project activity.

BE_y = CH₄_gen,y − OX_bsl,y

Where:

• CH₄_gen,y = Methane generated in year y (via IPCC FOD model or measured baseline)

• OX_bsl,y = Methane oxidized in cover material

• GWP_CH₄ = Global warming potential for methane (PCS default vintage)

6.2.1 Methane Generation (CH₄_gen,y)

1. Methane generation is estimated using the IPCC First-Order Decay (FOD) model unless site-specific measurements exist.

2. The FOD model uses parameters including waste mass (Wₓ), degradable organic carbon (DOC), methane correction factor (MCF), methane fraction (F), decay rate constant (k), and DOC fraction decomposed (DOC_f).

6.2.2 Baseline Oxidation (OX_bsl,y)

1. The oxidation factor accounts for methane oxidized in the cover layer. Typical defaults:

• 10% for daily soil cover

• Up to 20% for engineered biocovers (requires evidence)

• 0% for uncovered dumpsites

1. Oxidation must never be overstated.

6.3 Project Emissions (PEᵧ)

1. Project emissions include all greenhouse gas emissions resulting from project activity, including methane that is not captured, fugitive emissions, and emissions associated with combustion or electricity consumption.

6.3.1 Uncaptured Methane (PE_uncaptured,y)

PE_uncaptured,y = (1 − CE_y) × (CH₄_gen,y − OX_prj,y)

Where:

• CE_y = Collection efficiency in year y

• OX_prj,y = Oxidation in project scenario (typically 10–20%, rarely higher)

1. Collection efficiency must be based on measurement or conservative defaults (see table below).

System Condition	Default CE (%)
New engineered system	60–75
Intermediate cover	50–60
Poorly managed system	< 40
Direct flow measurement available	Use measured values

6.3.2 Fugitive Emissions (PE_fugitive,y)

1. Includes methane escaping through:

• Leaks in wells, condensate traps, or joints

• Over-pressurization events

• Temporary shutdowns

1. If direct leak quantification is unavailable, a conservative default of 3–7% of captured methane may be applied.

6.3.3 Combustion Emissions (PE_comb,y)

1. These include CO₂ and N₂O from LFG combustion in flares or engines.

2. Methane slip from enclosed flares is usually <1%.

6.3.4 Electricity Consumption (PE_elec,y)

1. Electricity used for blowers, controls, condensate pumps, and monitoring contributes to project emissions if the grid is fossil-dominated.

If renewable electricity is used, PE_elec,y may be zero.

6.4 Methane Captured and Destroyed

1. Captured methane is calculated using measured flow and methane fraction:

CH₄_captured,y = Flow_y × CH₄%_y × Density_CH₄ (corrected to STP)

1. Destroyed methane:

CH₄_destroyed,y = CH₄_captured,y × DE

Where DE is destruction efficiency (typical ranges):

• Open flares: 90–98%

• Enclosed flares: ≥ 99%

• Engines/turbines: 96–99%

6.5 Emission Reductions from Methane Destruction

Project ERs from destruction are the baseline methane that would have been emitted minus uncaptured methane and residual emissions after destruction; the methodology ensures conservative accounting using measured or default efficiencies.

6.6 Emission Reductions from Electricity Generation (Displacement Projects Only)

1. If landfill gas is used for electricity:

ER_elec,y = E_gen,y × EF_grid

Where:

• E_gen,y = electricity generated

• EF_grid = fossil grid emission factor

1. Only grid-connected systems may claim displacement benefits.

6.7 Avoided Venting or Flaring

1. If the baseline includes partial flaring:

“Additional captured methane” is methane captured beyond the historical baseline.

Calculations must account only for incremental capture attributable to the project.

6.8 Total Project Emission Reductions

Total ERs combine avoided methane emissions from destruction and any displacement benefits, less project emissions and leakage:

ER_y = (BE_y − PE_uncaptured,y − PE_fugitive,y − PE_comb,y − PE_elec,y) − LE_y

(Expressions above detail components for computation.)

6.9 Key Parameters Used in the Methodology

Parameter	Description	Units	Notes
DOC	Degradable organic carbon	Fraction	Waste composition dependent
MCF	Methane correction factor	Fraction	Depends on landfill type
k	Decay rate constant	yr⁻¹	Climate-dependent
CE	Collection efficiency	Fraction	Based on system condition
DE	Destruction efficiency	Fraction	Based on device type
EF_grid	Grid emission factor	tCO₂/MWh	Must be from public sources
FUG_rate	Fugitive emission factor	Fraction	Conservative default 3–7%

6.10 Leakage Emissions (LEᵧ)

1. Leakage is generally zero for landfill methane capture. Leakage must be included only if:

• Fossil fuel use increases at the landfill because of the project;

• Waste is diverted to uncontrolled dumpsites outside the boundary;

• Energy displacement causes upstream emissions above baseline levels.

1. If no leakage source is identified, LE_y is set to zero (documented and justified).

6.11 Summary Equation

1. The consolidated emission reduction equation brings together methane generation, capture, destruction, combustion emissions, fugitive losses, electricity consumption, displacement, and leakage as summarized above.

Chapter 7 - Monitoring Requirements

7.1 Overview of Monitoring Requirements

1. Monitoring ensures that emission reductions reported under this methodology are based on accurate, transparent, and verifiable measurements. The monitoring system must collect all data required to quantify baseline methane generation, project methane capture, destruction efficiency, fugitive emissions, and other parameters.

2. The monitoring framework must be implemented throughout the crediting period and maintained to ensure data integrity, consistency, and traceability.

7.2 Monitoring Responsibilities

1. The project developer must designate technical staff or contracted operators who are responsible for:

• Operating and maintaining the gas collection and destruction systems

• Ensuring continuous monitoring of gas flow, methane concentration, and combustion conditions

• Recording downtime and operational anomalies

• Maintaining calibration certificates and logbooks

• Implementing data quality checks

1. A monitoring plan must be included in the Project Description and updated if system modifications occur.

7.3 Monitoring of Project Methane Capture

1. Quantification of project methane capture requires continuous or near-continuous measurement of gas flow and methane concentration at a central monitoring point.

7.3.1 Gas Flow Measurement

1. Gas flow meters must be:

• Installed downstream of the blower or at a representative location

• Capable of measuring volumetric or mass flow

• Resistant to landfill gas corrosive conditions (moisture, H₂S)

1. The following parameters must be monitored:

Parameter	Unit	Requirement
Flow rate (Flow_y)	m³/hr or kg/hr	Measured continuously or at ≥ 15-minute intervals
Temperature	°C	Required for density correction
Pressure	kPa	Required for conversion to standard conditions

1. Measured flow must be corrected to standard temperature and pressure.

7.3.2 Methane Concentration Measurement

1. Methane fraction of landfill gas must be measured using:

• Portable gas analyzers, or

• Continuous online gas analyzers

1. Minimum specifications:

Requirement	Description
CH₄ accuracy	±1–2% absolute
Calibration	Manufacturer recommendation or every 6 months
Data recording	Automatic data logger preferred

7.4 Monitoring of Methane Destruction

1. Methane destruction must be demonstrated for flares, gas engines, turbines, or boilers.

7.4.1 Flares

1. For enclosed and open flares:

• Temperature must exceed 500–600°C for effective oxidation

• Continuous temperature monitoring is required

• Automatic shutoff must occur if flame-out or low temperature conditions are detected

1. Parameters:

Parameter	Unit	Requirement
Combustion temperature	°C	Continuous monitoring
Flare uptime	hours	Record operational hours
Methane slip (if measured)	%	Optional unless required by local law

7.4.2 Gas-to-Energy Systems

1. For engines and turbines:

• Methane destruction efficiency must be ≥ 96% unless justified otherwise

• Electricity generation meters must comply with national standards

1. Parameters:

Parameter	Unit	Requirement
Electricity generated	MWh	Continuous metering with revenue-grade meters
Engine/turbine runtime	hours	Record downtimes
CH₄ slip	ppm or %	If measured

7.5 Monitoring of System Performance and Downtime

1. Project developers must document:

• Gas system maintenance events

• Shutdown periods

• Blower failures

• Condensate trap blockages

• Surface monitoring results (if performed)

1. Downtime must be conservatively accounted for in emission reduction calculations. When capture or combustion systems are not functioning, methane is considered emitted.

7.6 Monitoring of Waste Inputs (Optional for FOD Calibration)

1. If the FOD model is used, projects may monitor waste disposal quantities and composition to improve accuracy. Monitoring includes:

• Tonnes of waste disposed each year

• Waste composition sampling

• Moisture content and degradable organic carbon (DOC)

This step is optional but recommended for large or long-lived landfills.

7.7 Monitoring of Electricity Consumption

1. If project electricity use must be included in project emissions:

• Electricity meters must be installed on blowers, pumps, and monitoring stations

• Monthly readings must be recorded

• Meters must comply with local calibration requirements

7.8 Monitoring of Fugitive Emissions (If Applicable)

1. Fugitive methane emissions can be monitored using:

• Periodic surface flux measurements

• OGI (Optical Gas Imaging) surveys

• Soap-bubble tests on fittings and joints

• Portable methane detectors

1. If direct monitoring is not feasible, a conservative default (3–7% of captured methane) must be applied.

7.9 Calibration Requirements

1. All monitoring equipment must be calibrated according to manufacturer or national standards.

Minimum Calibration Frequencies

Equipment	Frequency
Flow meters	1 year
Methane gas analyzers	6 months
Temperature sensors	6–12 months
Pressure sensors	6–12 months
Electricity meters	National standard

1. Calibration records must be retained for auditing.

7.10 Data Logging and Storage

1. The project developer must ensure:

• Automated logging where possible

• Manual logs for downtime and maintenance

• Secure digital storage for minimum 7 years after crediting period

• Backup systems to prevent data loss

1. All raw data must be accessible for verification.

7.11 Summary of Monitored Parameters

Parameter	Unit	Method	Frequency
Gas flow rate	m³/hr	Flow meter	Continuous / 15-min
Methane concentration	%	Gas analyzer	Continuous / 15-min
Temperature	°C	Thermocouple	Continuous
Pressure	kPa	Pressure sensor	Continuous
Flare/engine uptime	hours	Logbook or SCADA	Continuous
Electricity generated	MWh	Revenue meter	Continuous
Electricity consumed	kWh	Meter	Monthly
Waste disposed (optional)	tonnes	Weighbridge	Daily
Fugitive CH₄ (optional)	g/m²/hr	Flux chamber/OGI	Quarterly/annually

7.12 Monitoring Plan

1. A monitoring plan must be included in the Project Description and must describe:

• Monitoring points and equipment

• Data collection methods

• QA/QC procedures

• Backup and redundancy measures

• Maintenance schedules

• Data integrity protocols

1. The monitoring plan must be updated if:

• New landfill cells are added

• Capture systems are modified

• Additional treatment units are installed

Chapter 8 - Data, Parameters, And QA/QC Requirements

8.1 Overview

1. This chapter defines all data and parameters required to calculate emission reductions under the PCS Landfill Methane Capture Methodology. It distinguishes between:

• Monitored parameters: Measured during project implementation.

• Static parameters: Fixed or externally sourced values (e.g., IPCC defaults, national factors).

• Calculated parameters: Derived from formulas.

1. The chapter also sets out QA/QC procedures to ensure accuracy, traceability, and integrity of monitoring data throughout the project duration.

8.2 Data and Parameters Not Monitored (Static / Externally Sourced)

1. These parameters remain constant during each monitoring period unless updated by national authorities or approved scientific sources.

Table 8.1 — Static Parameters

Parameter	Unit	Source	Description
GWP_CH₄	tCO₂e/tCH₄	IPCC AR (PCS vintage)	Global warming potential of methane.
MCF	Fraction	IPCC 2006/2019	Methane correction factor based on landfill type.
DOC	Fraction	National waste studies or IPCC default	Degradable organic carbon in waste.
DOC_f	Fraction	IPCC	Fraction of DOC decomposed.
k	yr⁻¹	IPCC climate region defaults	Waste decay rate constant.
F	Fraction	IPCC	Fraction of decomposed carbon converted to methane.
OX_bsl	Fraction	IPCC default or site measurements	Baseline oxidation factor.
EF_grid	tCO₂/MWh	Public national grid factors	Used if claiming displacement benefits.
Density_CH₄	kg/m³	Standard reference	For converting volume to mass.

1. Static parameters must be justified and referenced in the Evidence_Reference sheet.

8.3 Data and Parameters to Be Monitored

1. These parameters are collected during the crediting period.

Table 8.2 — Monitored Parameters

Parameter	Unit	Measurement Requirement	Frequency
Flow_y	m³/hr	Flow meter (corrected to STP)	Continuous or ≥15 min interval
CH₄%	%	Gas analyzer	Continuous or ≥15 min interval
Temperature	°C	Thermocouple	Continuous
Pressure	kPa	Pressure sensor	Continuous
Flare uptime	hours	SCADA/logbook	Continuous
Combustion temperature	°C	Temperature probe	Continuous
Electricity generated	MWh	Revenue-grade meter	Continuous
Electricity consumed	kWh	Meter	Monthly
Fugitive emissions (optional)	g/m²/hr or % captured	Flux chamber/OGI/Leak surveys	Quarterly/annual
Waste disposed (optional)	tonnes	Weighbridge	Daily

1. Monitored data must be stored in digital form, backed up, and secured from tampering.

8.4 Calculated Parameters

1. These values are derived from static and monitored inputs.

Table 8.3 — Calculated Parameters

Parameter	Unit	Description
CH₄_gen,y	tonnes CH₄/yr	Methane generated using IPCC FOD model.
CH₄_captured,y	tonnes CH₄/yr	From flow × CH₄% × density.
CH₄_destr,y	tonnes CH₄/yr	Captured methane × destruction efficiency.
CH₄_uncaptured,y	tonnes CH₄/yr	Methane not collected by system.
PE_uncaptured,y	tCO₂e	Project emissions from uncaptured methane.
PE_fugitive,y	tCO₂e	Fugitive emissions (measured or default).
ER_des,y	tCO₂e	Emissions avoided by methane destruction.
ER_elec,y	tCO₂e	Displacement-based reductions.

1. Calculated parameters must be traceable to raw inputs.

8.5 Data Management and Storage Requirements

1. The project developer must:

• Maintain a centralized digital database for all monitored parameters.

• Store raw monitoring files in read-only formats (CSV, TXF, instrument logs).

• Maintain calibration logs, maintenance logs, and validation files.

• Retain all data for minimum 7 years after crediting period expiration.

1. Backups must be created at least monthly and stored in a separate secure location.

8.6 Quality Assurance (QA) Procedures

1. QA procedures ensure monitoring system reliability and data accuracy. These include:

8.6.1 Equipment Procurement and Installation

• Use equipment certified to international standards (ISO, ASTM, EPA).

• Verify correct installation through commissioning tests.

8.6.2 Personnel Training

1. Operators responsible for monitoring must be trained in:

• Gas collection system operations

• Data recording and validation

• Safety procedures for high-methane environments

• Emergency response protocols

1. Training records must be preserved.

8.7 Quality Control (QC) Procedures

1. QC focuses on routine checks to prevent data errors.

8.7.1 Routine Checks

• Verify flow meter readings visually each shift.

• Check analyzer calibration drift weekly.

• Inspect flares for flame-out or temperature drops.

8.7.2 Data Validation

1. Cross-check:

• Flow vs. blower operational hours

• CH₄% vs. expected landfill gas composition

• Electricity generation vs. captured gas volume (if generating energy)

8.7.3 Handling Missing Data

• If interruptions < 48 hours, interpolate using conservative assumptions.

• If interruptions > 48 hours, assume zero gas capture for that period.

• Document all equipment failures.

8.8 Calibration Requirements

1. Calibration must follow manufacturer guidelines or national standards.

2. Minimum requirements:

Equipment	Calibration Frequency
Flow meters	Annually
Methane analyzers	Every 6 months
Temperature sensors	6–12 months
Pressure sensors	6–12 months
Electricity meters	As per national metering code

1. Calibration certificates must be kept on file.

8.9 Uncertainty Management

1. Uncertainty must be minimized through:

• Use of high-precision instruments

• Replicate measurements during commissioning

• Conservative default factors where measurement uncertainty is high

• Documentation of uncertainty assumptions in the Monitoring Report

1. If uncertainty exceeds acceptable PCS limits, the project developer must apply conservative adjustments to estimated emission reductions.

8.10 Summary Table of QA/QC Requirements

Category	Requirement
Data collection	Continuous monitoring with automated logging
Verification	Cross-checking raw data against operational logs
Calibration	Regular calibration of all sensors and meters
Personnel	Training for operators and monitoring technicians
Record-keeping	Minimum 7-year secure storage of all data
Backup	Monthly backup to independent medium
Missing data	Conservative treatment following PCS rules

Chapter 9 - Environmental And Social Safeguards

9.1 Introduction

1. Landfill methane capture projects must be implemented in a manner that protects environmental quality, public health, worker safety, and community well-being. This chapter establishes safeguard requirements aligned with internationally recognized frameworks such as the UNFCCC CDM environmental assessment guidelines, the IFC Environmental and Social Performance Standards, and IPCC Good Practice principles. The safeguards apply throughout the design, construction, operation, and monitoring phases of the project.

9.2 Environmental Safeguards

1. Environmental safeguards ensure that project activities do not create or exacerbate environmental risks. The installation and operation of landfill gas collection systems, blowers, flares, and energy recovery units may introduce localized air emissions, noise, and disturbances to the landfill surface. These impacts must be identified, assessed, and mitigated through an environmental management plan.

2. Methane destruction devices may emit combustion by-products such as carbon dioxide, carbon monoxide, nitrogen oxides, and particulates. These emissions must comply with national air quality regulations and be monitored where required. Flaring systems must be designed to minimize visible smoke, odour, and incomplete combustion. Landfill gas extraction may affect subsurface pressure conditions; therefore, operators must monitor for excessive vacuum that could induce air intrusion, fires, or surface instability.

3. Leachate and stormwater management must remain fully functional and must not be adversely affected by gas system installation. Any excavation for well installation should include measures to prevent leachate release, slope instability, or exposure of waste layers to rainfall. Projects implemented in active landfills must ensure that waste placement continues safely and without interference from installed gas infrastructure.

9.3 Social Safeguards

1. Social safeguards focus on protecting nearby communities, waste pickers, and onsite workers who may be affected by project activities. Projects must comply with all relevant labor, occupational health and safety, and community protection regulations.

2. A social impact assessment should identify potential risks such as increased traffic from equipment delivery, temporary restrictions on landfill access, or changes in odor levels due to modifications in landfill ventilation patterns. Where informal waste pickers operate on the landfill, the project developer must ensure that activities do not inadvertently displace livelihoods without adequate engagement or transition planning. Engagement with affected communities should be meaningful, informed, and documented, with grievance procedures established to receive and respond to concerns.

3. Noise levels from blowers and generators, especially during nighttime operations, must remain within acceptable limits. If the landfill is near residential areas, additional mitigation such as acoustic shielding may be required. Emergency preparedness protocols must be communicated to relevant community representatives, especially in regions with heightened fire or explosion risks.

9.4 Health and Safety Requirements

1. Landfill gas projects involve inherent hazards due to the presence of methane, hydrogen sulfide, volatile organic compounds, and combustible mixtures. Worker safety must therefore be prioritized through a structured health and safety management system. This system must include procedures for confined space entry, lock-out tag-out, fire prevention, personal protective equipment, and safe handling of condensate and leachate.

2. Workers must be trained in hazard recognition and emergency response. Procedures for addressing fire outbreaks, gas migration, equipment failure, or accidental emissions must be documented and tested periodically. Operation of flares and engines must be restricted to trained personnel, and access to high-temperature or high-pressure equipment should be controlled. Gas detectors and alarms should be installed in areas where explosive mixtures may occur. All incidents, near-misses, and corrective actions must be logged and reviewed.

9.5 Compliance with Local and National Regulations

1. Projects must demonstrate compliance with applicable environmental permits, zoning requirements, labor laws, and waste management regulations. Where environmental impact assessments (EIAs) are mandated, the project developer must submit the approved EIA report or exemption documentation. Any conditions imposed by regulators, such as buffer zones, emission limits, groundwater monitoring, or leachate protections, must be fully integrated into project implementation.

2. Regular reporting to authorities may be required depending on the jurisdiction. Project developers must maintain communication with regulatory bodies and update permits when expansions, modifications, or operational changes occur.

9.6 Safeguards Monitoring and Reporting

1. Safeguards performance must be monitored throughout the crediting period. Monitoring may include recording noise levels, tracking complaints, verifying worker training records, and documenting any environmental incidents. Safeguard information must be included in the Monitoring Report submitted for verification, especially where impacts have occurred or mitigation actions were taken.

2. Records of any community grievances and their resolution must be maintained. If corrective actions are required, they should be described clearly, including timelines and responsibilities.

9.7 Summary Table of Safeguard Requirements

Safeguard Area	Key Requirement
Environmental protection	Prevention of harmful emissions, surface instability, and adverse impacts to leachate/stormwater systems
Social protection	Community engagement, livelihood considerations, and grievance mechanisms
Health and safety	Worker training, emergency procedures, hazard controls
Regulatory compliance	Alignment with all applicable permits, EIAs, and national laws
Safeguard monitoring	Ongoing documentation of impacts and mitigation measures

Chapter 10 - Uncertainty And Conservativeness

10.1 Introduction

1. Uncertainty is inherent in landfill methane generation and capture processes due to the heterogeneity of waste composition, variability in environmental conditions, and operational fluctuations in gas collection systems. This chapter outlines the methodological requirements for identifying, quantifying, and reducing uncertainty at each stage of the emission reduction calculation process. Conservativeness principles ensure that uncertainty always results in downward-adjusted emission reductions, preventing overestimation of climate benefits.

10.2 Sources of Uncertainty in Landfill Methane Capture Projects

1. Uncertainty arises from several domains. Waste composition and degradable organic carbon fractions vary by region, season, and socioeconomic conditions. The rate at which waste decomposes depends on climate conditions, moisture availability, and waste depth. Gas collection efficiency fluctuates with operational practices, well spacing, waste settlement, and surface integrity. Measurements of methane flow, concentration, temperature, and pressure involve instrument precision limitations. Combustion efficiency of flares and engines may vary over time due to temperature control, maintenance, and wear.

2. These uncertainties must be recognized, quantified where possible, and treated conservatively where quantification is impractical.

10.3 Conservativeness in Baseline Methane Generation

1. Baseline methane generation often contributes the largest share of uncertainty because the model depends on assumptions regarding DOC, decay rates, methane correction factors, and historical waste quantities. To maintain conservativeness:

• DOC values should prioritize site-specific data when available; otherwise, lower-end IPCC defaults must be used.

• The decay constant (k) must be selected from the lower range of scientifically justified values for the local climate regime.

• The methane correction factor must not exceed values associated with the landfill’s actual management level. Open dumps and semi-controlled landfills must use conservative MCF values consistent with IPCC guidance.

• Historical waste deposition values must be validated through at least two independent sources where possible.

1. Conservative selections reduce the risk of overstating baseline emissions.

10.4 Conservativeness in Project Scenario Quantification

1. Project methane capture and destruction involve direct measurements, which reduce uncertainty but do not eliminate it. Gas flow meters may drift over time, methane analyzers may fluctuate with temperature and humidity, and system downtime may temporarily interrupt data collection.

2. To maintain conservativeness, any missing or invalid data must be replaced with the lowest plausible values for captured methane. If data loss occurs for more than 48 hours, capture is assumed to be zero during the affected period. If flare temperature records are missing, destruction must not be credited for those intervals. For energy recovery systems, electricity generation readings must be cross-checked against gas flow to detect inconsistencies.

3. Combustion efficiency must be assumed at the lowest documented performance level for the device unless higher efficiencies are validated through testing or manufacturer certification.

10.5 Uncertainty in Fugitive Emissions and Oxidation Factors

1. Fugitive emissions are difficult to measure directly and often represent an important uncertainty source. Projects may use periodic leak surveys or flux chamber measurements, but when such measurements are unavailable or incomplete, conservative defaults must be applied. These defaults typically represent upper-bound estimates of fugitive losses.

2. Similarly, oxidation factors reflect the extent to which methane is consumed in aerobic cover layers. Oxidation varies spatially and seasonally; therefore, projects may not assume high oxidation rates without field evidence. Default IPCC oxidation factors are intentionally conservative to avoid overstating methane mitigation. Only direct measurements or peer-reviewed research applicable to similar landfill conditions may justify higher oxidation values.

10.6 Instrumentation Uncertainty

1. Flow meters, pressure sensors, temperature probes, and gas analyzers have defined accuracy ranges. The cumulative effect of these uncertainties must be considered. Calibration records must demonstrate that devices remain within their allowable error ranges. If instruments exceed calibration tolerances or show drift beyond acceptable thresholds, affected data must either be corrected using traceable calibration coefficients or replaced with conservative estimates.

2. Projects should document instrument specifications, calibration methods, and any corrective actions taken when devices malfunction. Measurement uncertainty should be minimized by selecting high-quality instruments that are appropriate for corrosive landfill gas environments.

10.7 Uncertainty in Model-Based Parameters

1. Parameters such as the decay rate constant (k), DOC, and DOC_f rely on empirical studies, laboratory analyses, or default literature values. Where uncertainty is high, the methodology requires selection of the most conservative values consistent with the local waste sector.

• The decay constant must reflect the slowest plausible decomposition rate.

• DOC must be based on the lower confidence interval if a range of values is available.

• DOC_f must follow IPCC default unless defensible site-specific evidence indicates otherwise.

1. These adjustments ensure that model-based uncertainty reduces baseline emissions rather than project emissions, preserving methodological conservativeness.

10.8 Aggregated Uncertainty and Its Treatment

1. Where multiple sources of uncertainty interact, projects must consider aggregated effects. This does not require full statistical propagation unless specified by PCS rules. Instead, projects must identify all high-uncertainty parameters and apply additional conservativeness adjustments where their combined effect could materially inflate emission reductions.

2. Examples of aggregated uncertainties include simultaneous uncertainty in gas flow measurement and methane concentration, or combined uncertainty in waste composition and decay rates. In such cases, project developers may reduce final emission reductions by an additional percentage as a conservativeness buffer if required by verifiers.

10.9 Conservativeness for Missing or Invalid Data

1. Missing data must always default to conservative assumptions:

• Gas capture must be recorded as zero for periods without valid flow or methane concentration data.

• Combustion must not be credited for periods lacking temperature or uptime records.

• Electricity generation data must be excluded if meters malfunction and readings cannot be validated.

1. Narrative documentation of the root cause, duration, and corrective actions must be included in the Monitoring Report.

10.10 Summary Table of Conservativeness Requirements

Parameter Area	Conservativeness Requirement
Baseline methane generation	Use lower-end DOC, MCF, and k values; validate waste deposition.
Project methane capture	Replace missing data with zero capture; apply minimum device efficiency.
Fugitive emissions	Apply upper-bound default if direct measurement is unavailable.
Oxidation factors	Use IPCC default unless site data justify higher values.
Instrumentation	Apply conservative correction or exclude data if calibration is out of range.
Aggregated uncertainty	Apply additional adjustment if multiple uncertainties could overstate ERs.

10.11 Conclusion

1. Uncertainty and conservativeness principles ensure that emission reductions are not overstated and that credit issuance reflects real, verifiable climate benefits. The methodology prioritizes empirical measurement where feasible and mandates conservative assumptions where uncertainty cannot be directly measured or reduced. This approach maintains the environmental integrity of the PCS crediting system and ensures alignment with international best practices.

Chapter 11 - Leakage Assessment

11.1 Introduction

1. Leakage refers to increases in greenhouse gas emissions that occur outside the project boundary as a direct result of implementing the landfill methane capture project. Although landfill gas projects typically exhibit low leakage potential, this methodology requires a systematic assessment to ensure that any unintended emissions are identified and addressed. Leakage must be quantified when it is measurable and attributable to the project; when uncertainties are high, conservative assumptions must be applied.

11.2 Potential Sources of Leakage

1. Landfill methane capture projects may influence emissions beyond the physical project boundary in several ways. The installation of methane destruction or gas-to-energy systems may require electricity or fossil fuels to operate equipment, though these internal emissions are treated as project emissions rather than leakage. Leakage instead concerns changes in emissions outside the defined project boundary.

2. One potential source arises when project implementation alters waste management practices at nearby sites. If waste is diverted from the project landfill to uncontrolled dumps or open burning locations due to changes in site accessibility or tipping fees, additional methane or combustion emissions may occur elsewhere. Another potential source is increased fossil fuel use by external entities triggered by the project’s electricity exports or supply disruptions. Additionally, if energy users depend on waste heat or steam from landfill gas systems that did not exist pre-project, and an interruption forces them to switch to fossil fuels, leakage may occur.

3. In most circumstances, these situations do not arise or have negligible impact. However, they must be evaluated to ensure methodological completeness.

11.3 Conditions Where Leakage Must Be Quantified

1. Leakage must be quantified when any of the following conditions apply:

• Waste Diversion Outside the Project Boundary: If the project indirectly causes waste to be deposited at uncontrolled sites or burned openly due to operational changes, waste volume changes, or altered tipping structures, the resulting methane or combustion emissions must be estimated.

• Increased Fossil Fuel Consumption by External Parties: If external users rely on landfill gas for thermal or electrical energy and the project limits or disrupts their supply, requiring them to revert to fossil fuels, the incremental emissions must be considered.

• Upstream or Downstream Emissions from Equipment Procurement or Disposal: Normally excluded due to their minimal impact, but in exceptional cases—such as procurement of high-emitting equipment transported over large distances—verifiers may request justification for excluding such emissions.

• Changes in Landfill Cover or Management Outside the Project: If the project influences management practices at adjacent landfill cells or facilities not included in the boundary, and these changes alter methane emissions, leakage may arise.

1. Leakage quantification is required only when such conditions can be shown to be causally linked to project activities.

11.4 Leakage Quantification Methods

1. When leakage is present, emissions must be quantified using conservative, evidence-based approaches.

11.4.1 Waste Diversion Leakage

1. If waste diversion occurs, the methane generation potential of diverted waste is estimated using the IPCC FOD model or a simplified methane emission factor, adjusted for the characteristics of the receiving disposal site. If waste is burned, emission factors for open burning must be applied. All calculations must use conservative assumptions regarding decay rates and oxidation.

11.4.2 Fossil Fuel Substitution Leakage

1. If displacement or interruption of landfill gas supply causes external entities to consume additional fossil fuels, leakage is estimated by multiplying fuel volumes with appropriate emission factors from national inventories or IPCC defaults. Only the incremental portion attributable to the project is included.

11.4.3 Negligible or De Minimis Leakage

1. When potential leakage sources are demonstrated to contribute less than one percent of project emission reductions, and no causal chain exists linking project activity to those emissions, the methodology permits classification as negligible. In such cases, leakage is set to zero but must be justified.

11.5 Evidence Requirements

1. Projects must provide documentation supporting conclusions about leakage presence or absence. Evidence may include:

• Historical waste disposal patterns and contract structures

• Gate fee schedules, waste acceptance policies, and operational plans

• Records of energy users and their supply arrangements

• Interviews or written statements from landfill operators or energy customers

• Satellite imagery confirming that nearby dump sites have not experienced increased activity

• Metering data from external energy systems

1. Evidence must be consolidated in the Evidence_Reference register.

11.6 Conservativeness in Leakage Treatment

1. Where leakage is uncertain or difficult to measure directly, conservativeness requires adopting upper-bound estimates or applying default emission factors associated with uncontrolled sites or fossil fuels. If evidence is inconclusive, leakage must not be assumed zero. Projects should avoid assumptions that credit improvements at external sites unless those benefits are directly measurable and attributable, which this methodology does not allow.

11.7 Reporting and Verification of Leakage

1. Leakage assessment must be included in each Monitoring Report. The assessment should summarize:

• Whether leakage sources exist

• Whether conditions changed since the prior reporting period

• Evidence supporting the conclusion

• Quantified leakage values (if applicable)

• Any corrective actions taken

1. Verifiers must examine the evidence and confirm that leakage, if present, has been conservatively quantified and subtracted from emission reductions.

11.8 Summary Table of Leakage Requirements

Leakage Category	Requirement
Waste diversion	Quantify if waste shifts to uncontrolled sites or burning due to project activities
Fossil fuel substitution	Quantify if external parties revert to fossil fuels because of project
Upstream/downstream impacts	Normally negligible unless evidenced otherwise
Evidence	Must demonstrate presence or absence of leakage
Conservativeness	Apply upper-bound defaults when uncertainty exists

11.9 Conclusion

1. Leakage is typically minimal in landfill methane capture projects, but it must be assessed rigorously to ensure the integrity of emission reductions. The methodology requires evidence-based evaluation, conservative quantification where applicable, and transparent reporting. When no leakage occurs, this must be demonstrated, not assumed.

Chapter 12 - Annexes

This chapter compiles all supporting material needed to apply the methodology correctly, including equations, parameter references, default values, and a sample calculation framework. Annexes are intended to ensure consistency, transparency, and ease of use when implementing landfill methane capture projects under PCS.

Annex A - Equations And Formulas

A1. Methane Generation (IPCC First-Order Decay Model)

1. This equation estimates methane generation from waste disposed in year x during year y using terms for waste disposed (W_x), DOC, DOC_f, MCF, F, k, and the decay function e^{-k(y-x)}.

A2. Baseline Methane Emissions

Baseline emissions are methane generated minus baseline oxidation (OX_bsl).

A3. Captured Methane

Captured methane is calculated from volumetric flow (corrected to STP), methane concentration, and methane density.

A4. Methane Destroyed

Destroyed methane equals captured methane multiplied by destruction efficiency (DE).

A5. Project Methane Emissions (Uncaptured)

Uncaptured methane is a function of collection efficiency (CE) and project oxidation factor.

A6. Fugitive Emissions

Fugitive emissions are calculated using measured leak data or a FUG_rate default (typically 0.03–0.07).

A7. Combustion Emissions

Combustion emissions depend on CH₄ slip values for flares/engines and combustion of landfill gas (CO₂, N₂O).

A8. Electricity Consumption

Project electricity consumption is metered and may contribute to PE_elec,y if grid emissions are non-zero.

A9. Electricity Displacement Benefits

Applicable for gas-to-energy systems using E_gen and EF_grid.

A10. Total Emission Reductions

Consolidated annual ER equation combines all components: baseline generation, capture/destruction, project emissions, displacement, and leakage.

Annex B - Default Parameters And Sources

B1. IPCC Default Parameters (2006 Guidelines)

Parameter	Default Values	Notes
DOC	0.08–0.21	Depends on waste composition
DOC_f	0.5	Standard for unmanaged landfills
MCF	0.4–1.0	Higher values for controlled sites
F (CH₄ fraction)	0.5	Assumes equal CH₄/CO₂ composition
k	0.03–0.17 yr⁻¹	Varies with climate
OX	0–0.1	Up to 0.2 for engineered biocovers
GWP_CH₄	28 or 34	Based on IPCC AR5 or AR6 vintage

PCS will define the applicable GWP vintage in the project’s reporting period.

B2. Destruction Efficiency Defaults

Device Type	Default DE
Enclosed flare	≥ 0.99
Open flare	0.90–0.98
IC engine	0.96–0.98
Turbine	0.98–0.99

If site-specific testing shows lower performance, measured values must be used.

B3. Collection Efficiency Reference Ranges

System Condition	Typical CE Range
Well-designed active system	0.60–0.75
Intermediate cover	0.50–0.60
Poor management or large settlement areas	< 0.40

Upper values must not be used without supporting data.

Annex C - Sample Calculation Framework

This annex provides a structured example without numerical values.

C1. Step 1 — Estimate Methane Generation

Using historical waste deposition and IPCC model parameters, calculate:

• DOC (using composition data)

• k (climate-based default)

• CH₄_gen,y for each year

Produces time-series of methane generation.

C2. Step 2 — Determine Baseline Emissions

Compute baseline methane released (CH₄_gen,y minus OX_bsl,y).

C3. Step 3 — Calculate Captured Methane

From monitored flow and concentration, derive CH₄_captured,y.

C4. Step 4 — Calculate Methane Destroyed

Apply DE to CH₄_captured,y.

C5. Step 5 — Calculate Project Emissions

Include uncaptured methane, fugitive emissions, methane slip, and electricity consumption.

C6. Step 6 — Final Emission Reductions

Subtract project emissions and leakage from baseline emissions to obtain ER_y.

Annex D - Documentation And Reporting Checklist

A textual checklist to support project developers:

• Confirm landfill boundary and gas system layout are documented with maps and diagrams.

• Provide historical waste deposition records and reference studies used for DOC and k values.

• Include raw monitoring data, calibration certificates, maintenance logs, and downtime logs.

• Provide evidence for destruction efficiency, engine/flaring performance, and oxidation assumptions.

• Document leakage assessment and justification.

• Ensure all equations, parameters, and data sources are properly referenced.