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Emission Estimation & Regulatory Reporting

Emission Estimation is the method for evaluation of atmospheric emissions produced by its activities. The methodology would be complete, consistent, and transparent method to estimate the quantity of specific pollutants emitted into air. The following emissions are considered :

  • Direct emissions from the usage of fuels.
  • Indirect emissions produced by purchased electricity.
  • Indirect emissions produced by air business trips.

The present Criteria provides a complete, consistent, and transparent method to estimate the quantity of specific pollutants emitted into air.

Once the data is reported, the emission estimation methodology is applied automatically by the software Prometheus and Dashboard, giving emissions as output. Prometheus and Dashboard were included in the scope of the audit and their correct functioning is certified as well.

In order to obtain a representative and up-to-date emission estimation methodology, published literature databases have been assessed. For major details please refer to external reference par.1.4.2.

Methodology to improve and refine existing scope 1 & 2 Emission calculation

In developing the inventory, it is necessary that completeness, consistency and comparability and accuracy of the data is necessary. Based on the inventory a compilation of the inventory which includes data collection, uncertainty assessment, category analysis, time series consistency, QA/QC of the data is very important.

  • Direct emissions from the usage of fuels.
  • Indirect emissions produced by purchased electricity.
  • Indirect emissions produced by:
  • well to tank emission of fuel acquired;
  • transmission and distribution electricity loss;
  • well to tank emission of fuel produced for electricity generation;
  • fresh water supply;
  • water treatment;
  • material use;
  • waste disposal;
  • air business travel;
  • well to tank emission of fuel used on air business travel;
  • emissions of cars provided to employees;
  • freighting goods;
  • hotel stay.

As a part of activity, it is important to define the type of emissions and common quantifying methodology, that is to be applied across assets.

Since direct measurement of emissions from all sources is not possible, the United Nations Framework Convention on Climate Change requires that countries develop, update, publish and maintain national inventories using internationally approved and comparable emissions and removals estimation methods for 7 GHGs (carbon dioxide, methane, nitrous oxide, sulphur hexafluoride, perfluorocarbons, hydrofluorocarbons and nitrogen trifluoride). The asset emissions would be grouped as per the United Nations Framework Convention on Climate Change Inventory Reporting Guidelines for Annex I Parties, which require the use of the 2006 methodological guidance developed by the Intergovernmental Panel on Climate Change. The Intergovernmental Panel on Climate Change guidelines are based on the best available science and developed through an international process that involves testing of methods through ongoing inventory development, country studies, technical and regional workshops, and national and international expert’s consultations.

Quality assurance and quality control procedures are an essential requirement of the GHG inventory development and submission process. Quality assurance and quality control procedures ensure and improve transparency, consistency, comparability, completeness and confidence in the national emissions for the purpose of meeting OQ's and Oman and its subsidiaries reporting requirements based on the United Nations Framework Convention on Climate Change.

Uncertainty analysis helps to prioritize improvements and to guide decisions on methodological choices. An uncertainty assessment for shall be carried out for estimating GHG emissions. Further details on uncertainty related to specific sectors shall be done separately.

Activities description

International Guidelines can be used by companies for voluntary reporting of atmospheric emission. These guidelines offer the possibility to estimate a wide range of company emissions, with methods of different accuracy. However, all the methods use the same emission estimation formula, to be applied for each pollutant:

Activity Data is the measurement of a human activity that generates air emissions. Examples of Activity Data are tons of fuel utilized, kWh of energy purchased, km travelled, etc.

Emission Factors are coefficients specific for each pollutant, that quantify their emissions per unit of Activity Data. In the less accurate emission estimation methods, the same Emission Factor could be used for an entire Activity Data, while for more advanced methods the same Activity Data can have multiple Emission Factors, depending on multiple boundary conditions.

The obtained data would be analysed for gaps, which would include

  1. Filling in gaps
  2. Time series
  3. Compensating for old data by Incorporating improved data
  4. Filling in incomplete data

In addition to the pollutant listed under primary, secondary, CO2, CH4 and N2O can be accounted together through their GWP (source IPCC Fifth Assessment Report), to obtain the total GHGs emitted in terms of CO2 equivalent, with the formula:


Accordingly, to international standards CO2 equivalent its considered the main indicator of air pollution of a company, and therefore its calculation represent a major relevance for OQ.

Calculation and Verification of SCOPE 1 & 2 Emissions

All the pollutants described can be emitted directly or indirectly by companies’ activities. Those emissions can be categorized in 3 main groups:

Scope 1 emissions are related to direct emissions occurring from sources that are owned or controlled by the company; for example, emissions from combustion in owned or controlled boilers, generators, vehicles, etc.; emissions from chemical production in owned or controlled process equipment.

Scope 2 emissions accounts for emissions from the generation of purchased electricity consumed by companies. Purchased electricity is defined as electricity that is purchased or otherwise brought into the organizational boundary of the company. Scope 2 emissions physically occur at the facility where electricity is generated. They can be accounted with a Location Based approach (reflecting the average emissions intensity of grids on which energy consumption occurs) or with a Market Based approach (reflecting emissions from electricity that companies have purposefully chosen).

Emission Scope

The Scope 1 would be direct emissions and the Scope 2 GHG emissions related to the purchase of electric energy (with a location-based approach) and the Scope 3 GHG emission related to air business travel.

In this new methodology Consultant decided to expand the boundaries of its accounting, including:

  • The estimation of Scope 2 GHG with the market base approach, an alternate and more accurate system to estimate them.

Recalculations are performed annually on Asset’s previously reported greenhouse gas emissions estimates to reflect updates to source data and estimation methodology. Chapter 8 of the National Inventory Report provides a summary of the recalculations that occurred due to methodological changes and/or refinements since the previous submission. The summary includes:

  1. brief description, justification and summary of individual impacts on previously reported emission estimates
  2. details on specific inventory improvements implemented in 2022 as well as planned improvements

Task 2: Methodology to account Scope 3 emissions:

Scope 3 accounts all indirect emissions (not included in Scope 2) that occur in the value chain of the reporting company. Those emissions cover a wide range of activities, as they include the emissions to produce, ship and dispose of every good used by the company. Also, the commuting and business travels of employees are included in Scope 3.

The methodological approaches to estimate emissions can be divided in three different Tiers, according to the quantity of information required, and the degree of analytical complexity:

  • Tier 1 employs gain-loss methods and it is the easiest approach, where the Emission Factors depend exclusively on the type of fuel combusted (or other Activity Data). The use of a Tier 1 emission estimation requires data on the amount of fuel combusted and a default Emission Factor for each pollutant. The Emission Factor is therefore the same one for each Activity Data, independently of the technology used.
  • Tier 2 generally uses the same methodological approach as Tier 1 but requires an intermediate level of complexity and locally specific data. Generally, the use of a Tier 2 approach requires data on the amount of fuel combusted and a country-specific or technologic-specific Emission Factor for each pollutant.
  • Tier 3 standards are the most complex and require the most specific data, but properly implemented these methods can provide estimates of greater certainty than lower tiers. A Tier 3 approach splits the fuel combustion statistics according to several variables and uses Emission Factors that are dependent upon various factors like: data on the amount of fuel combusted, a country-specific Emission Factor for each pollutant, combustion technology, operating conditions, control technology, quality of maintenance, age of the equipment used to burn the fuel.
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