mETHODOLOGIES

CDM- Article 6.4 Methodologies

Methodologies define how greenhouse gas emission reductions or removals are established, quantified, monitored, verified, and issued as Certified Emission Reductions. Many CDM methodologies reference approved methodological tools. These tools address cross-cutting technical elements such as: additionality testing, baseline identification, leakage assessment, grid emission factor calculation, sampling and uncertainty analysis. These ensure methodological consistency across sectors and reduce duplication of complex calculations.

Active methodologies

What Are CDM Methodologies?

CDM methodologies are approved baseline and monitoring frameworks that specify:
  • How to define a credible baseline scenario (what would happen in the absence of the project)
  • How to demonstrate additionality
  • How to quantify emission reductions or net removals
  • How to monitor, report, and verify project performance over time
They ensure environmental integrity, comparability of emission reductions, and confidence in issued CERs. Without an approved methodology, a CDM project cannot be registered or issue CERs.
Each approved methodology explains:
  • Typical project types
  • Applicability conditions
  • Eligible GHG mitigation actions
  • Key monitored parameters
  • Baseline and project scenario

Categories of Methodologies

CDM methodologies are formally classified into five categories:

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Large scale project

This covers utility-scale and industrial projects such as grid-connected renewable power plants, large energy efficiency retrofits, fuel switching in industry, and gas destruction facilities implemented at significant operational and emission reduction scale.

Small scale project

These apply to small, dispersed project types including household renewable energy systems, efficient cookstoves, small biogas units, mini-grids, and community-level energy efficiency measures with limited individual emission volumes.

Large scale A/R

This includes extensive afforestation or reforestation projects such as plantation forestry, large restoration programmes, and land-use conversion activities that generate carbon removals across wide, contiguous land areas.

Small scale A/R

These methodologies cover smallholder and community-driven tree planting activities, agroforestry systems, and local restoration projects implemented on limited land areas, often involving multiple landowners or community groups.

Carbon Capture & Storage

CCS methodologies are intended for large industrial projects capturing CO₂ from power generation or industrial processes and permanently storing it in geological formations, such as depleted oil and gas reservoirs or deep saline aquifers.
activities and technology

Choosing a right methodology

The are two other complementary classification systems to support methodology selection.
— Mitigation activity type
According to sectoral scope and mitigation logic. Selection based on activity is particularly useful during early project conceptualization. Representative activities include:

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Renewable and low-carbon electricity

Grid-connected solar photovoltaic parks, onshore and offshore wind farms, run-of-river and reservoir hydropower plants, geothermal power stations, and biomass-based electricity generation using agricultural or forestry residues.

Energy efficiency

 Industrial process optimisation in cement, steel, and chemicals; efficient boilers and furnaces; waste heat recovery systems; high-efficiency motors; building-level efficiency retrofits; and efficient public lighting programmes.

Fuel and feedstock switching

Replacement of coal or heavy fuel oil with natural gas, biomass, or waste-derived fuels in industry; switching from diesel to electricity in transport fleets; and alternative raw materials in cement and clinker production.

GHG destruction

Methane capture and flaring or utilisation at landfills, wastewater treatment plants, and coal mines; destruction of nitrous oxide in nitric acid plants; and abatement of high‑GWP industrial gases.

GHG emission avoidance

Improved waste management systems, composting facilities, recycling infrastructure, and technologies that prevent methane generation through aerobic treatment processes.

GHG removal by sinks

Afforestation, reforestation, and revegetation activities that sequester carbon in biomass and soils over long project lifetimes.
— TECHONOLOGY type
Methodologies evolved around specific technologies. This approach is ideal when a project technology has already been selected. Representative technology pathways include:

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Grid-connected renewables:

Utility-scale solar PV plants, concentrated solar power, wind power clusters, hybrid renewable installations, and grid-scale battery integration projects.

Industrial energy efficiency:

Kiln upgrades, efficient grinding systems, cogeneration units, compressed air optimisation, and digital energy management systems.

Waste and wastewater:

Anaerobic digesters, landfill gas recovery systems, biogas upgrading plants, municipal wastewater methane capture, and organic waste composting facilities.

Transport systems

Bus rapid transit corridors, metro and light rail systems, electric vehicle charging infrastructure, modal shift programmes, and fuel efficiency improvements in freight transport.

Household and community technologies

Includes clean cookstove distribution programmes, household solar home systems, small biogas digesters, solar water heaters, and efficient household appliances.
CDM Methodology Booklet (Fourteenth Edition, updated to EB 116)
A concise reference featuring one-page summaries of all approved CDM methodologies, including project types, applicability conditions, baseline and monitoring logic, and visual flow diagrams for rapid screening.

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