GHG Emissions Taxonomy

Definition

A GHG Emissions Taxonomy is any well organized, comprehensive Taxonomy of GHG Emissions sources. In the language of GHG Accounting the elements of the taxonomy are sometimes denoted as Sectors, not to be confused with Business Sector.

IPCC Sectors

The 2006 Guidelines group emissions and removals categories into five main sectors.

• Energy
• Industrial Processes and Product Use (IPPU)
• Agriculture, Forestry and Other Land Use (AFOLU)
• Waste
• Other

Each sector comprises individual categories (e.g., transport) and sub-categories (e.g., cars). Ultimately, countries will construct an inventory from the sub-category level because this is how IPCC methodologies are set out, and total emissions calculated by summation. A national total is calculated by summing up emissions and removals for each gas. An exception is emissions from fuel use in ships and aircraft engaged in international transport which is not included in national totals, but is reported separately.

In order to calculate a national total it is necessary to choose an approach to include harvested wood products (HWP).

Reporting is generally organised according to the sector actually generating emissions or removals. There are some exceptions to this practice, such as CO2 emissions from biomass combustion for energy, which are reported in AFOLU Sector as part of net changes in carbon stocks. Where CO2 emissions are captured from industrial processes or large combustion sources, emissions should be allocated to the sector generating the CO2 unless it can be shown that the CO2 is stored in properly monitored geological storage sites.

GHG Corporate Accounting Standard

The GHG Protocol corporate accounting identifies the following high level categories:

• Stationary Combustion: combustion of fuels in stationary equipment such as boilers, furnaces, burners, turbines, heaters, incinerators, engines, flares, etc.
• Mobile Combustion: combustion of fuels in transportation devices such as automobiles, trucks, buses, trains, airplanes, boats, ships, barges, vessels, etc.
• (Industrial) Process Emissions: emissions from physical or chemical processes such as CO₂ from the calcination step in cement manufacturing, CO₂ from catalytic cracking in petrochemical processing, PFC emissions from aluminum smelting, etc.
• Fugitive Emissions: intentional and unintentional releases such as equipment leaks from joints, seals, packing, gaskets, as well as fugitive emissions from coal piles, wastewater treatment, pits, cooling towers, gas processing facilities, etc.

GHG Project Accounting Standard

Under the GHG Project Protocol, there are five general GHG source categories :

• Combustion Emissions from generating grid-connected electricity;
• Combustion Emissions from generating energy or off-grid electricity, or from flaring;
• Industrial Process Emissions - e.g., carbon dioxide (CO2) from the production of clinker for cement;
• Fugitive Emissions - e.g., GHG leaks from pipelines; and
• Waste Emissions - e.g., GHG emissions from landfills.

GPC Cities Accounting Standard

Under the Global Protocol for Community-Scale Greenhouse Gas Inventories, there are six general GHG source sectors :

• Stationary Energy
• Transportation
• Industrial Process Emissions (IPPU) - e.g., carbon dioxide (CO2) from the production of clinker for cement;
• Agriculture, Forestry and Other Land Use (AFOLU)
• Waste Emissions - e.g., GHG emissions from landfills.
• Any other emissions occurring outside the Geographic GHG Boundary as a result of city activities (Scope 3 GHG Emissions)

Emissions from these sectors shall be sub-divided into subsectors and may be further sub-divided into sub-categories.

GHG Emissions by Source Geometry

GHG Emissions Sources can be categorized by geometry as follows:

• Point Source GHG Emissions where emission can be idealized as occuring from a wikipedia:Point source
• Linear Source GHG Emissions where emissions can be idealized as occuring from a wikipedia:Linear source
• Areal Source GHG Emissions where emissions can be idealized as occuring from a wikipedia:Area source (pollution)

The above geometrical classification depends heavily on the spatial and temporal resolution of emissions measurement.