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GHG Accounting
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This Module (Independent components of Isometric Certified Protocols which are transferable between and applicable to different Protocols.) describes greenhouse gas (Those gaseous constituents of the atmosphere, both natural and anthropogenic (human-caused), that absorb and emit radiation at specific wavelengths within the spectrum of terrestrial radiation emitted by the Earth’s surface, by the atmosphere itself, and by clouds. This property causes the greenhouse effect, whereby heat is trapped in Earth’s atmosphere (CDR Primer, 2022).) (GHG) accounting requirements for all Carbon Dioxide Removal (CDR) (Activities that remove carbon dioxide (CO₂) from the atmosphere and store it in products or geological, terrestrial, and oceanic Reservoirs. CDR includes the enhancement of biological or geochemical sinks and direct air capture (DAC) and storage, but excludes natural CO₂ uptake not directly caused by human intervention.)Projects (An activity or process or group of activities or processes that alter the condition of a Baseline and leads to Removals or Reductions.). Credits (A publicly visible uniquely identifiable Credit Certificate Issued by a Registry that gives the owner of the Credit the right to account for one net metric tonne of Verified CO₂e Removal or Reduction. In the case of this Standard, the net tonne of CO₂e Removal or Reduction comes from a Project Validated against a Certified Protocol.) issued under the Isometric Standard are contingent on the conservative (Purposefully erring on the side of caution under conditions of Uncertainty by choosing input parameter values that will result in a lower net CO₂ Removal or GHG Reduction than if using the median input values. This is done to increase the likelihood that a given Removal or Reduction calculation is an underestimation rather than an overestimation.) accounting of all GHG emissions (The term used to describe greenhouse gas emissions to the atmosphere as a result of Project activities.) related to project activities (The steps of a Project Proponent’s Removal or Reduction process that result in carbon fluxes. The carbon flux associated with an activity is a component of the Project Proponent’s Protocol.), including leakages (The increase in GHG emissions outside the geographic or temporal boundary of a project that results from that project's activities.).
This Module applies to all CDR pathways (A collection of Removal or Reduction processes that have mechanisms in common.), ensuring a consistently rigorous standard in how GHG emissions are quantified and reported between different CDR Projects and approaches.
This Module will be adapted as science evolves and will be reviewed at a minimum every 2 years.
Projects credited under the Isometric Standard must use project-level consequential analysis (The analysis of specific Uncertainties, hazards and scenarios inherent in complex systems such as the natural and engineered environment, aiming to describe how systems-level environmentally relevant flows will change in response to possible decisions.) to determine net CO2e (The amount of CO₂ emissions that would cause the same integrated radiative forcing or temperature change, over a given time horizon, as an emitted amount of GHG or a mixture of GHGs. One common metric of CO₂e is the 100-year Global Warming Potential.)removals (The term used to represent the CO₂ taken out of the atmosphere as a result of a CDR process.) associated with project activities. Project emissions and removals must be assessed against a baseline (A set of data describing pre-intervention or control conditions to be used as a reference scenario for comparison.) scenario of The Project not taking place. When submitting Claimed Removals (A Removal which has been submitted by a Project Proponent, but which has not yet been Verified.), The Project's emissions ([math: CO_2e_{Emissions}]), removals ([math: CO_2e_{Stored}]) and counterfactual (An assessment of what would have happened in the absence of a particular intervention – i.e., assuming the Baseline scenario.) ([math: CO_2e_{Counterfactual}]) must be presented together in net metric tonnes of CO2e as part of a GHG Statement (A document submitted alongside Claimed Removals and/or Reductions that details the calculations associated with a Removal or Reduction, including the Project's emissions, Removals, Reductions and Leakages, presented together in net metric tonnes of CO₂e per Removal or Reduction.).
All Projects must follow GHG accounting requirements as set out by the relevant Protocol (A document that describes how to quantitatively assess the net amount of CO₂ removed by a process. To Isometric, a Protocol is specific to a Project Proponent's process and comprised of Modules representing the Carbon Fluxes involved in the CDR process. A Protocol measures the full carbon impact of a process against the Baseline of it not occurring.). Protocols set out the system boundary (GHG sources, sinks and reservoirs (SSRs) associated with the project boundary and included in the GHG Statement.) to be followed, which details the GHG Sources (Any process or activity that releases a greenhouse gas, an aerosol, or a precursor of a greenhouse gas into the atmosphere.), Sinks (Any process, activity, or mechanism that removes a greenhouse gas, a precursor to a greenhouse gas, or an aerosol from the atmosphere.) and Reservoirs (A location where carbon is stored. This can be via physical barriers (such as geological formations) or through partitioning based on chemical or biological processes (such as mineralization or photosynthesis).) (SSRs) that must be considered by Projects as part of the GHG Statement (A document submitted alongside Claimed Removals and/or Reductions that details the calculations associated with a Removal or Reduction, including the Project's emissions, Removals, Reductions and Leakages, presented together in net metric tonnes of CO₂e per Removal or Reduction.).
GHG SSRs are grouped into three categories: Controlled, Related and Affected. Controlled GHG SSRs (Sources, Sinks and Reservoirs that are under the direction and influence of the Project Proponent. Typically includes removals, reductions and emissions that occur at the project site.) relate to operations that are under the direction and influence of the GHG Project Proponent (The organization that develops and/or has overall legal ownership or control of a Removal or Reduction Project.), and typically include removals and emissions that directly occur at the project site. Related GHG SSRs (Sources, Sinks, and Reservoirs that are not under the direction and influence of the Project Proponent. Typically occur upstream or downstream of the project site.) typically occur upstream or downstream of the project site. Controlled and Related GHG SSRs collectively cover emissions associated with Project Establishment, Operations, and End-of-Life and are referred to as Project emissions in Section 2.4.1. Affected GHG SSRs (Sources, Sinks and Reservoirs that are affected by the Project activities through changes in market demand or supply for associated products or services, or through physical displacement. Also referred to as leakage.) include increases in GHG emissions as a result of the project displacing emissions or causing a secondary effect that increases emissions elsewhere and are referred to as leakage (The increase in GHG emissions outside the geographic or temporal boundary of a project that results from that project's activities.) in this Module (See Section 2.4.2). This Module is applicable to the quantification of emissions sources (Any process or activity that releases a greenhouse gas, an aerosol, or a precursor of a greenhouse gas into the atmosphere.), whereas the quantification of removals ([math: CO_2e_{Stored}]) is outlined in the relevant Protocol.
In some instances, project activities may be integrated into existing activities, such as biochar spreading while tilling agricultural lands. Activities that were already occurring and would continue to occur without the project may be omitted from the system boundary, if evidence that the activity was already occurring and would have continued to occur in the absence of the project can be provided.
Note that while project-level consequential analysis is the overarching methodology adopted in Isometric Protocols, elements of attributional analysis (Analysis aiming to describe the environmentally relevant physical flows to and from a life cycle and its subsystems.) are also widely used for GHG accounting. See Appendix C for more information on Isometric’s approach to project-level consequential analysis.
This Module aligns with the six overarching principles proposed in ISO (International Organization for Standardization) 14064-2: 2019 that underpin all aspects of the accounting, quantification and reporting of CDR projects. These are repeated below:
The following information must be submitted as part of the verification (A process for evaluating and confirming the net Removals and Reductions for a Project, using data and information collected from the Project and assessing conformity with the criteria set forth in the Isometric Standard and the Protocol by which it is governed. Verification must be completed by an Isometric approved third-party (VVB).) of every Claimed Removal (The term used to represent the CO₂ taken out of the atmosphere as a result of a CDR process.):
Project Proponents (The organization that develops and/or has overall legal ownership or control of a Removal or Reduction Project.) are responsible for collecting sufficient documentation to support the above information.
The System boundary must include all relevant GHG Sources, Sinks (Any process, activity, or mechanism that removes a greenhouse gas, a precursor to a greenhouse gas, or an aerosol from the atmosphere.) and Reservoirs (A location where carbon is stored. This can be via physical barriers (such as geological formations) or through partitioning based on chemical or biological processes (such as mineralization or photosynthesis).) (SSRs) relevant to The Project, including but not limited to the SSRs set out in the relevant Protocol. These can be categorised into Project emissions (Controlled and Related SSRs) and Leakage (Affected SSRs).
The Project Proponent must consider all GHGs associated with SSRs, in alignment with the United States Environmental Protection Agency’s definition of GHGs, which includes: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and fluorinated gasses such as hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6) and nitrogen trifluoride (NF3). For CO2 stored, only CO2 shall be included as part of the quantification. For all other activities all GHGs must be considered. For example, the release of CO2, CH4, and N2O is expected during diesel consumption.
All GHGs must be quantified and converted to CO2e in the GHG Statement using the 100-year Global Warming Potential (GWP) (A measure of how much energy the emissions of 1 tonne of a GHG will absorb over a given period of time, relative to the emissions of 1 ton of CO₂.) for the GHG of interest, based on the most recent volume of the IPCC Assessment Report (currently the Sixth Assessment Report).
Project emissions can occur on the project site, as well as upstream and downstream from the project site. For SSRs happening on the project site, the Project Proponent typically has direct control over the GHG emissions or removals that occur. For SSRs happening upstream or downstream from the GHG Project, these can occur either on or off the project site, and the Project Proponent typically has less control over the generation of these GHG emissions.
Project emissions include all SSRs set out in the relevant Protocol including over the Project Establishment, Operations and End-of-Life Phases of a project.
Ancillary activities are GHG Sources that do not have a direct relationship with the generation of Credits, but are instead required to keep the business operational, or for research and development purposes. These can include activities such as research and development, or corporate activities associated with organizational processes. It is recommended that Project Proponents track and manage these emissions, but they may be excluded from the system boundary.
Leakage include increases in GHG emissions as a result of the project displacing emissions or causing a secondary negative effect that increases emissions elsewhere.
Projects may generate positive impacts on GHG emissions that extend beyond the system boundary defined in the relevant Protocol. For instance, secondary sequestrations may occur when reforestation practices foster ecological benefits outside the project area, or when biochar application enhances soil carbon storage (Describes the addition of carbon dioxide removed from the atmosphere to a reservoir, which serves as its ultimate destination. This is also referred to as “sequestration”.). Under this conservative accounting framework, secondary reductions in GHG emissions or secondary sequestrations are not accounted for. The only exception is through the “substitution method” which allows for the consideration of multifunctionality in emissions accounting, for which conservative guardrails are in place (See Section 6.1). Multifunctionality in this instance refers to Projects which produce co-products (Products that have a significant market value and are planned for as part of production.) as well as CDR.
Leakage (The increase in GHG emissions outside the geographic or temporal boundary of a project that results from that project's activities.) that results in increases in GHG emissions are addressed under [math: CO_2e_{Leakage}], with further details provided in the relevant Protocol.
This section sets out the data quality hierarchy and the data quality principles that must be considered for every input parameter.
Project Proponents must use data that best represents the activity included in the GHG Statement and is aligned to data quality hierarchy and principles as outlined in Section 3.4.
The quality of data used in GHG accounting underpins the accuracy of results. GHG accounting as a practice is inherently uncertain as it is based on estimated data, unless emissions are measured directly (such as in flue gas measurements). Emissions that are not measured directly are quantified using activity (An activity or process or group of activities or processes that alter the condition of a Baseline and leads to Removals or Reductions.) data multiplied by emission factors (An estimate of the emissions intensity per unit of an activity.) as set out in Equation 1:
[math: Activity \;GHG \;Emissions \; = \; Activity \; * \; Emission \;Factor]
(Equation 1)
where:
Emission factors are an estimate of emissions associated with a given activity, not a direct measurement of emissions that occurred.
This Module defines three types of data:
Requirements for direct CO2e measurements are set out in Protocols. For all other data points, primary data must always be used over secondary data when collecting activity data, as secondary data carries more uncertainty than primary data. This is especially important for emission sources which are likely to be material for the GHG Statement.
Section 3.4 provides guidance on the data quality hierarchy to be followed for both activity data and emission factors.
As mentioned above, emission factors are considered secondary data as they are derived from existing studies, databases, or industry averages.
Emission factors used by Project Proponents must:
Examples of Reputable Source (A source that would be widely considered trustworthy based on the process undertaken (e.g., peer review) or origin of the information (e.g., government body).) for emission factors include: Argonne National Laboratory GREET Model1, California Air Resources Board modified GREET model (CA-GREET)2, Department for Energy and Net Zero Conversion factors for company reporting of GHGs3, Ecoinvent database4, US Federal Life Cycle Inventory database or LCA Commons5, and similar databases used in common life cycle analysis (An analysis of the balance of positive and negative emissions associated with a certain process, which includes all of the flows of CO₂ and other GHGs, along with other environmental or social impacts of concern.) practices or tools (such as OpenLCA, SimaPro, or GaBi).
Further requirements for emission factors for embodied and transportation emissions are set out in Appendix A. Further requirements for emission factors for energy use are set out in the Embodied Emissions Accounting v1.0, Energy Use Accounting Module v1.36 and Transportation Emissions Accounting v1.1 Modules.
Data must follow the requirements set out in the relevant Protocols and Modules. Whenever specific data quality requirements are included in a Protocol or relevant Module(s), for example storage (Describes the addition of carbon dioxide removed from the atmosphere to a reservoir, which serves as its ultimate destination. This is also referred to as “sequestration”.) Modules or emissions accounting Modules, they must be followed.
Where direct measurements are not available for the SSRs relevant to the system boundary, the Project Proponent must gather the highest quality data available to estimate emissions, following the principles and quality hierarchies outlined in this section.
Each data should be selected considering the following data quality criteria: Reliability, Completeness, Age, Geography, and Technology. A brief description of these criteria is provided in Table 1, while Table 2 and Table 3 provide high level descriptions of what constitutes high, medium, and low quality for each criteria for both activity data and emission factors, respectively. Detailed descriptions of these criteria are provided in Appendix A.
The data quality hierarchy serves as a guide for Project Proponents to distinguish between high and low-quality data, enhance the transparency of the GHG Statement, and encourage the continuous pursuit of the best available data. Project Proponents who must use data that is not ideal (e.g., global instead of geography-specific, or older than eight years) will not be penalized if no better alternatives are available.
Where high quality data is not available to a Project Proponent, justification for using medium or low quality data for the relevant SSR must be provided either within the GHG Statement, or as part of the GHG Statement Report (at the verification (A process for evaluating and confirming the net Removals and Reductions for a Project, using data and information collected from the Project and assessing conformity with the criteria set forth in the Isometric Standard and the Protocol by which it is governed. Verification must be completed by an Isometric approved third-party (VVB).) stage) or the Project Design Document (PDD) (The document that clearly outlines how a Project will generate rigorously quantifiable Additional high-quality Removals or Reductions.) (at the validation (A systematic and independent process for evaluating the reasonableness of the assumptions, limitations and methods that support a Project and assessing whether the Project conforms to the criteria set forth in the Isometric Standard and the Protocol by which the Project is governed. Validation must be completed by an Isometric approved third-party (VVB).) stage).
Justification must include:
Justification may also include:
Justification must be assessed during every verification event, though it may remain unchanged if circumstances have not evolved. The ongoing acceptance of medium or low-quality data will be determined by the verifier, based on conservatism, scope, materiality, as well as project-specific factors. For one-time emissions, typically related to Project Establishment and End-of-Life activities, which can be amortized over multiple Reporting Periods, justifications provided and deemed acceptable at the first verification event do not require any further action.
Materiality may be used as a justification for applying lower-quality data when an emission source accounts < 1% of net removals (See Section 4). Emission sources using this justification must collectively represent < 1% of net removals. If the cumulative total of these SSRs exceeds 1%, Project Proponents should seek higher-quality data, starting with the SSRs that have the highest contribution.
Table 1. Data quality criteria descriptions7. Refer to Appendix A for further detail.
| Criteria | Description |
|---|---|
| Reliability | The proficiency of the entities that gathered, calculated, and or reviewed the data and whether the process of generating the data is reproducible. |
| Completeness | The degree to which the data are statistically representative of the relevant activity. Completeness includes the percentage of locations for which data is available and used out of the total number that relate to a specific activity. Completeness also addresses seasonal and other normal fluctuations in data. |
| Age | The degree to which the data reflects the actual time (e.g., year) or age of the activity. |
| Geography | The degree to which the data reflects the actual geographic location of the activity (e.g., country or site). |
| Technology | The degree to which the data reflects the actual technology(ies) used. |
Table 2. Data quality hierarchy for activity data7 . Refer to Appendix A for further detail.
| Criteria | High quality | Medium quality | Low quality |
|---|---|---|---|
| Reliability | Data is measured and verified. | Activity data are inferred from high quality benchmarks/proxies, such as internal proxies, or benchmarks from official sources. | Activity data are inferred from low quality benchmarks, proxies from non qualified sources, or spend data is used. |
| Completeness | Data is complete (or with minimal extrapolations) for the Reporting Period. | Data is mostly complete, with some estimates, however is still a good representation. | Data is mostly incomplete, and significant proxy (A measurement which correlates with but is not a direct measurement of the variable of interest.) estimations are required. |
| Age | Data is fully representative of the Reporting Period. | Some activity data are from previous time periods, but are a good representation of the Reporting Period. | Some activity data are from previous time periods and are a poor representation of the Reporting Period. |
| Geography | Data is fully representative of the location where the activity took place. | Data is representative at a minimum of the country where the activity took place. | Data is either regional (e.g. Europe) or global. |
| Technology | Data description is highly specific, broken down by all (or for the most relevant) key factors. | Data is well described at a high level. | Data description is generic. |
Table 3. Data quality hierarchy for emission factors. Refer to Appendix A for further detail
| Criteria | High quality | Medium quality | Low quality |
|---|---|---|---|
| Reliability | Emission factors are from the most authorative source available for that activity, which is a Reputable Source. | Generic emission factors (excl. expenditure-based emission factors) are provided by a database which is a Reputable Source. | Emission factors are extrapolated from non-official sources, or from an expenditure based database (even if this is a reputable source, e.g. USEPA or EXIOBASE). |
| Completeness | The emission factor represents the whole life cycle of the activity. | The emission factor is mostly complete, but is missing some life cycle stages. | The emission factor is an approximation, or no information is provided for life cycle stages. |
| Age | Emission factor is updated and published for the same year as the Reporting Period, or is the most up to date available. | Emission factors are a maximum of six years old. | Emission factors are more than six years old. |
| Geography | The emission factor used is representative of the activity location. | The emission factor is an acceptable representation of the activity location. | The emission factor is a poor representation of the activity location. |
| Technology | The emission factor is specified by all or at least the most relevant components. | The emission factor is well described at a high level. | The emission factor is generic. |
Once the highest quality data have been identified based on the above criteria, the Project Proponent must also consider Scope and Conservativeness (Table 4). Scope refers to the degree to which the data is representative of the relevant activity. Conservativeness refers to the degree to which the data is conservative.
Table 4. Scope and Conservativeness
| Criteria | Description |
|---|---|
| Scope | How well the emission factor represents the activity data, plus the suitability of any proxy data used. In some cases, highly specific and recent emission factors may be less appropriate than older less specific emission factors if they better match the activity data. |
| Conservativeness | The most conservative value must always be chosen when selected between multiple input parameters equal in all other aspects of data quality . Further information on the principle of conservativeness is provided below. |
Conservative values and assumptions are those that are more likely to underestimate than overestimate net CO2e removals.
Conservative input parameters must be selected when determining which data to use. For example, there may be instances where there are multiple emission factors for an activity type and no indication from activity data on which might be the most appropriate to select. In this instance the highest, and therefore most conservative, emission factor should be selected. Or, if there is a gap in natural gas consumption data and different values are available from previous years for a similar period, the more conservative value should be used to fill the gap.
Conservative estimates of input parameters must be made in any cases where there is more than one possible input parameter to select from, and all options are equal in all other aspects of data quality. However, if a less conservative input parameter is more representative, it should be selected. This applies to all data types.
For each input parameter, including emission factors selected or assumptions made on activity data, justification for how the input parameter is conservative must be included in the PDD.
Improving the quality of activity data used by moving up the activity data quality hierarchy typically will reduce the number of conservative assumptions required in GHG accounting, therefore likely leading to an increase in net CO2e removals.
It is advisable for the Project Proponents to create a data collection tracker that can be shared internally and with third parties to record data requests, dates when raw data is received, data format, data limitations, and links to where data is stored. Keeping track of data in this way increases traceability and transparency of reporting and can be used as evidence as part of validation and verification. In some cases, it may be necessary to have a discussion with third parties to understand what might be available in the absence of measured primary data and to build assumptions together. Those carrying out the activity will have a better understanding of the processes and associated emissions that take place as part of the activity.
The following sections outline GHG accounting considerations for specific categories of emission sources that commonly occur in relation to CDR projects. These categories of emission sources are not mutually exclusive to project phases and may occur as part of [math: CO_2e_{Establishment}] , [math: CO_2e_{Operations}] , [math: CO_2e_{End-Of-Life}] or [math: CO_2e_{Leakage}].
Embodied emissions refer to the life cycle GHG impacts associated with the production of materials, consumables, equipment, buildings and infrastructure related to the Project. Full life cycle emissions from raw materials extraction through to product end-of-life must be considered for all embodied emissions. Embodied emissions must be considered as part of the assessment for all GHG SSRs relevant to the project, as set out in the relevant Protocol.
Embodied emissions calculations must include all life cycle stages of the product, consumable, building or infrastructure asset, as defined by ISO (A worldwide federation (NGO) of national standards bodies from more than 160 countries, one from each member country.) 21930 8 and EN15804 and as referenced in the GHG Protocol supplement 9, including:
The anticipated design life of equipment must be based on manufacturer information or best practice industry guidance.
Equipment, infrastructure and vehicles that must be included in the life cycle GHG emissions calculations includes all equipment produced, constructed, utilized and disposed of for the CDR project. Where appropriate, this includes all equipment and support systems related to storage monitoring (see the relevant Protocol's Storage Module for further details). Where equipment, infrastructure or vehicles are not utilized explicitly for the CO2 removal process, a proportional approach to emissions accounting can be taken.
Embodied emissions accounting for shared infrastructure must be undertaken in alignment with Section 6.1.
The data quality requirements in Section 3 and supplementary information in Appendix A, Section 10.1.1: Embodied emissions must be considered for embodied emissions.
The emissions associated with the transportation of goods must be calculated when any mode of transportation is used to move goods between sites as part of project operations. This includes transportation by trucks, rail, ships, pipeline and aircraft. For a CDR project, the transportation of goods includes, but is not limited to, the transportation of CO2, feedstocks (Raw material which is used for CO₂ Removal or GHG Reduction.), consumables and waste.
At minimum, GHG emissions from the direct combustion of fuels in vehicles, as well as the upstream emissions associated with the production and distribution of the fuel and/or electricity must be accounted for. Furthermore, a full cradle-to-grave (Considering impacts at each stage of a product's life cycle, from the time natural resources are extracted from the ground and processed through each subsequent stage of manufacturing, transportation, product use, and ultimately, disposal.)GHG assessment (The process by which all emissions associated with a Project's Removal or Reduction process, including leakages, are accounted for.) is required for vehicles and infrastructure produced, constructed, and utilized for the CO2 removal project, in line with Section 4.1.
Transportation should be calculated by using one of the following two approaches:
The Energy Usage Method must always be prioritized. Where it is not possible to use the Energy Usage Method due to lack of data and this is appropriately evidenced, the Distance-Based Method may be used. Other approaches may be allowable on a case-by-case basis in agreement with Isometric.
The Data Quality requirements in Section 3 and supplementary information in Appendix A, Section 10.1.2: Transportation emissions must be considered for transportation emissions.
Emissions are calculated as follows:
[math: {CO}_{2}^{}e_{Transportation,\ j}^{}\ = \ F_{j}^{}\ \times \ {EF}_{Fuel,\ Transportation,\ j}^{}]
(Equation 2)
Where:
[math: {CO}_{2}^{}e_{Transportation,\ j}^{}] = the total GHG emissions associated with the transportation journey of a product, [math: j], in tonnes of CO2e
[math: F_{j}^{}] = the quantity of fuel or electricity consumed during the transportation journey, [math: j], from one location to another including other induced transportation, in appropriate units e.g. litres
[math: {EF}_{Fuel,\ Transportation,\ j}^{}] = the relevant fuel or electricity-based full life cycle emission factor, in appropriate units e.g. kg CO2e/litre
Equation 2 is analogous to Equation 6 in Section 6.0 of the Energy Use Accounting Module v1.36 when considered at a Removal level.
Emissions are calculated as follows:
[math: {CO}_{2}^{}e_{Transportation,\ j}^{}\ = \ D_{j}^{}\ \times \ W_{j}^{}\ \times \ {EF}_{Transportation,\ j}^{}]
(Equation 3)
Where:
[math: D_{j}^{}] = the distance traveled for the transportation journey, [math: j], from one location to another, in appropriate units e.g. km
[math: W_{j}^{}] = the mass of material transported as part of the transportation journey, [math: j], from one location to another, in appropriate units e.g. tonnes
[math: {EF}_{Transportation,\ j}^{}] = the weight- and distance-based emission factor for transportation for a specific vehicle type, or infrastructure asset where available, provided in appropriate units e.g. kg CO2e/tonne-km
The Energy Use Accounting Module v1.36,11 describes how energy-related emissions must be calculated for CDR projects, including the use of both electricity and stationary fuel. The The Energy Use Accounting Module v1.36 sets out the calculation methods to follow, as well as eligibility criteria for low-carbon power procurement of Book-and-Claim Unit procurement.
SSRs that are not applicable to the project (i.e, not part of project emissions or leakage), or not relevant to the Reporting Period, may be excluded from the system boundary.
Project Proponents may also exclude SSRs where the total emissions for that SSR, and all excluded SSRs collectively, are expected to be negligible. Negligible SSRs are those which fall below a Materiality threshold based on environmental significance of < 1% of net CO2e removals. The purpose of the Materiality threshold is to save resources being expended on GHG accounting for negligible SSRs, in a manner that is proportional to the principle of scientific rigor and evaluation of uncertainty that underpins the Isometric Standard.
A Materiality Assessment should be undertaken for any SSRs that are suspected to be negligible. The Materiality Assessment is a comparison between estimated total net CO2e removal for a Reporting Period or batch, and estimated emissions for the SSR suspected to be negligible for a Reporting Period or batch.
The Materiality assessment should be undertaken as follows:
[math: M_{SSR} = \frac{CO_2e_{SSR\;Estimated,\;RP}}{CO_2e_{Removal\;Estimated,\;RP}} * 100]
(Equation 4)
Where:
If [math: M_{SSR}] is < 1%, then the emissions associated with the SSR may be excluded from the system boundary, provided that the total exclusions make up < 1% collectively. If the sum of SSRs that individually are < 1% becomes > 1%, then the SSRs with the highest Materiality must be included in the system boundary until the sum of SSRs becomes < 1%. It is not necessary to calculate emissions related to SSRs that are < 1% using more accurate data if the emission calculations for the Materiality assessment were conducted using a high-level approach, e.g., using expenditure data (see below). Full details of the Materiality assessment must be provided as part of the GHG Statement.
The Materiality assessment should be undertaken for complete categories of SSRs, as defined in the relevant Protocol and set out in the system boundary, as they relate to a Reporting Period. A complete category of SSRs refers to a grouping of all related activities and described at the Protocol level. examples of such categories include:
Buffer pools (A common and recognized insurance mechanism among Registries allowing Credits to be set aside (in this case by Isometric) to compensate for Reversals which may occur in the future.) should not be considered when performing the Materiality assessment (see Section 5.6.2 of the Isometric Standard for more information on Buffer Pools.) .
The Materiality Assessment must be repeated when any of the following conditions are met:
The estimated SSR emissions, [math: CO_2e_{SSR\;Estimated}], should be determined via a high level, conservative assessment of the emissions associated with the SSR. This may be based on high level information that was easily obtainable for The Project, such as emails, plot areas, mapping and testimonials, or it may be based on the financial expenditure-based emissions methodology. The latter is a common approach for estimating emissions at a high level. This method uses financial expenditure data in combination with Environmentally-Extended Input-Output (EEIO) emission factor models. EEIO emission factors are provided by organizations such as US EPA1112 and EXIOBASE1213.
The spend-based method should be used as a screening tool to efficiently assess emission sources that are expected to be negligible, thereby avoiding disproportionate effort in data collection for low-impact categories. It is particularly suited for assessing the Materiality of sources suspected to have a low impact, such as staff travel and similar activities.
Where information is readily available for an SSR, regardless of its Materiality, the Materiality should be assessed using the readily available information. Information is deemed to be readily available if there are limited steps required to obtain the data. For example the Project Proponent may own the data, or a third party may have the data available and ready to share without any intermediate steps or additional information required.
The estimated total net CO2e Removal, [math: CO_2e_{Removal\;Estimated}], should be calculated using actual data and following all required methodologies for SSRs considered to be material. Estimated data, following the calculation criteria set out for calculating [math: CO_2e_{SSR\;Estimated}] should be used for any SSRs which have the potential to be negligible. Calculation of [math: CO_2e_{Removal\;Estimated}] must include all SSRs applicable to The Project.
An example of how the Materiality Assessment should be applied is set out in Appendix B.
The CDR process may result in the production of co-products, either as a direct result of the CDR process, or because the CDR process is integrated into a wider system. Co-products are products that are produced intentionally and in a controlled manner alongside the main product in a production process, and have a significant market value. By-products (Materials of value that are produced incidentally or as a residual of the production process.) are products that are produced as a secondary or unintended result of the production process, and typically have lower market value than the main product. Co-products and by-products that are outputs of the Project’s processes are treated the same under the allocation rules outlined in the procedures in this section.
Emissions accounting for by-products that are inputs to the CDR system are considered in Section 6.4. These may be physical products or energy outputs, such as electricity and heat.
To allocate Project emissions associated with CDR and the co-product, the Project Proponent may apply the procedures outlined below according to the following rules. The subdivision method (Procedure 2) and the substitution method (Procedure 3) are mutually exclusive and cannot be combined within the same assessment. For example, if shared processes exist up to a certain stage of the Project, but later the CDR and the co-product can be tracked separately, it is not permitted to allocate emissions separately to the divided processes (Procedure 2) and apply the substitution method (Procedure 3) to the shared processes. Instead, Project Proponents must select one method only. However, the carbon mass balance method (Procedure 4) can be used in combination with either Procedure 1, 2 or 3, provided the Project leads to the production of multiple CDR products where the co-product also leads to crediting.
Figure 1 outlines the stepwise process for co-products emissions allocation. Examples for each procedure are provided in Appendix D.
Figure 1 Flowchart for co-product allocation
Procedure 1: Allocate all emissions to CDR
Projects may opt to allocate all Project emissions to CDR. The co-product(s) must still comply with all relevant emission accounting regulations and requirements, for example if emissions accounting for the co-product are regulated under construction product regulations or as part of an emissions trading scheme. This may mean emissions are double counted. Removals must not be double counted. This is the most conservative approach to take.
Procedure 2: Divide the process into sub-processes
Where processes, or aspects of processes, are physically separable and dedicated exclusively to either the CDR product or the co-product, the process may be divided into sub-processes. This means that only sub-processes that can be clearly separated and are physically distinct in their entirety can undergo division. Sub-processes that are physically separable and do not contribute to CDR may be excluded from the GHG Statement boundary.
Furthermore, if the CDR process is being introduced as a retrofit (The introduction of new materials, products or technologies to an existing process or facility.) to an existing facility, and the original facility was operational prior to the introduction of the CDR process, the CDR process may be considered a new sub-process of the facility. In this case, only the emissions directly associated with the CDR process should be allocated to it.
Eligibility criteria, evidence requirements and system boundary considerations for dividing the process into sub-processes are set out in Table 5. At least one of EC1 or EC2 must be satisfied in order to divide the process into sub-processes.
Table 5. Procedure 2 Eligibility Criteria, EC1 and EC2
| Eligibility Criteria | Description | Documentation required |
|---|---|---|
| EC1 | The CDR process is a retrofit to an existing facility that was operable prior to the introduction of the CDR process. A retrofit is defined as the introduction of new materials, products or technologies to an existing process or facility. Prior to the retrofit the existing facility must have been operational for purposes other than CDR. | Records of existing facility activities dating back three years prior to the CDR Project start date must be provided for infrastructure projects where a planning application was required. For all other projects, records of the existing facility activities dating back one year is required. The distinction for infrastructure projects that require a planning application is to ensure that the CDR process is indeed a retrofit, given that major infrastructure project construction may be staged over many years. The system boundary in this case is limited to materials and processes necessary for the retrofit and processes that directly contribute to the CDR process. This includes existing processes at the facility that are operated at increased capacity to provide for the CDR process as well as any additional load bearing structures. Evidence of fractional differences in inputs, for example the step-change in energy requirements for the CDR process as a retrofit to an existing facility, must be evidenced in full. Any reduction in efficiency of energy production as a result of the CDR process must be included in the system boundary as part of the assessment of leakage. |
| EC2 | The process has components and operations that are physically separate from one another. | Evidence of separation should be provided, for example engineering diagrams showing separate equipment or electricity metering systems for separate components of the process. Sub-processes that can be isolated from the CDR process and do not contribute to CDR may be excluded from the system boundary. |
Procedure 3: "Substitution method"
Project Proponents may use the “substitution method” to account for the avoided emissions associated with the production of a co-product where it is not possible to divide processes. This approach expands the system boundary to include the co-product, allowing the emissions that were avoided through the market displacement of another product to be subtracted from certain project emissions. This is sometimes referred to as the "expanding the system boundary" or “avoided burden” approach1314.
When undertaking this approach, the full facility GHG emissions must be included within the system boundary before applying the substitution method.
The application of the substitution method is subject to eligibility and implementation criteria to ensure its use is conservative, transparent, and does not disincentivise the decarbonisation of project activities.
Eligibility Criteria
Eligibility criteria for application of the substitution method are set out in Table 6. Both EC3 or EC4 must be satisfied in order to apply the substitution method.
Table 6. Procedure 3 Eligibility Criteria, EC3 and EC4
| Eligibility Criteria | Description | Documentation required |
|---|---|---|
| EC3 | Demonstrated net negativity: The Project must demonstrate net negative CO₂e removals before the application of the substitution method. This ensures that the substitution method does not enable the crediting of net emitting processes. | GHG Statement calculations prior to application of the substitution method. |
| EC4 | No double counting of environmental attributes: In line with Section 5.7 the Isometric Standard, the environmental attributes which are included as part of the CDR Credit, including [math: CO_2e_{Stored}] and the avoided burden (the substituted emissions) must not be double counted. This includes as part of the carbon accounting for the co-product, for example in the development of an Environmental Product Declaration, and in any marketing claims associated with the co-product. The environmental attribute of carbon removal and durable storage, and the substituted emissions that are considered as part of this, belong to the Credit owner. The co-product should still comply with all relevant emission accounting regulations and requirements, which may mean [math: CO_2e_{Emissions}] are double counted (once for CDR and once for product accounting compliance where required). | Statement confirming that the environmental attributes which are included as part of the CDR Credit, including [math: CO_2e_{Stored}] and the avoided burden (the substituted emissions) have not been double counted. |
Implementation Criteria
When using the substitution method, the following implementation procedure must be followed:
The Project Proponent must report the quantity and type for all marketed co-products. The substitution method may only be applied to one co-product. The quantity and type of substituted product may be informed by the following hierarchy:
a) Confirmation from the co-product purchaser regarding application of the co-product and that the alternative product (the substituted product) would have been used in its absence. Evidence provided to support this will depend on the Project and context, but may include:
b) If information from the co-product purchaser is unavailable, a default conservative assumption for the substituted product may be used, whereby the substituted product is a highly similar product to the co-product. For example:
Substituted emissions must be calculated via the following process:
a) Determine differences in efficiencies between the co-product and the substituted product through the identification of a substitution ratio.
b) Determine the emission intensity of the substituted product, [math: EF_{Substituted}]. The emission intensity of the substituted product must be conservative (meaning the emissions intensity of the displaced product is underestimated), from a Reputable Source and approved by Isometric. Specifically:
c) Multiply the quantity of the substituted product by the emission intensity of the substituted product to determine the Substituted Emissions.
d) Apply a conservative uncertainty discount to the Substituted Emissions. The default value for the uncertainty factor is 50%. Projects may propose a lower discount, which must be justified with supporting evidence, such as verified product displacement data or binding statements from co-product buyers.
e) Downstream emissions associated with the co-product (for example emissions associated with transportation of the co-product to the end-user, or emissions associated with use of the co-product by the end-user) must be quantified and subtracted from Substituted Emissions if they are anticipated to be higher than those of the substituted product. These downstream emissions may be excluded from the deduction if the Project Proponent can reasonably demonstrate that transport distances and use-phase emissions for the co-product are equal to or lower than those of the counterfactual product.
Substituted Emissions may be subtracted from residual emissions only. Residual emissions are defined as hard-to-abate emissions for which no technically or economically feasible decarbonisation options are available to the Project at the time of assessment. To support the identification of project emissions as residual, projects must submit a Decarbonisation Statement that:
Equation 5 sets out the calculation procedure to be followed to apply the substitution method.
[math: CO_{2e,Emissions} = \max \Bigg(0,\;\Big[CO_2e_{Establishment}^{Residual}+CO_2e_{Operations}^{Residual} + CO_2e_{EndOfLife}^{Residual}\Big]- \Big[Q_{CoProduct} * EF_{Substituted} * SR *U-CO_2e_{CoProduct}\big]\Bigg)+\Big[CO_{2e,Establishment}^{Non-Residual}+CO_2e_{Operations}^{Non-Residual}+CO_2e_{EndOfLife}^{Non-Residual}+ CO_2e_{Leakage}\Big]]
(Equation 5)
Where:
[math: CO_2e_{Establishment}] , [math: CO_2e_{Operations}] , [math: CO_2e_{End-Of-Life}] and [math: CO_2e_{Leakage}] are as defined in the relevant Protocol. Where identified in the equation, these terms reflect residual emissions, or non-residual emissions.
[math: Q_{Co-product}] is the quantity of the co-product produced, in appropriate units.
[math: EF_{Substituted}] is the emission factor for the substituted product, in tonnes CO2e per unit.
[math: SR] is the conversion ratio for the substituted product to account for efficiency differences between the co-product and the substituted product.
[math: U] is the Uncertainty Factor. The default for this value is 0.5.
Equation 5 requires an adjustment to the equations for [math: CO_2e_{Emissions}] as they are set out in the requisite Protocol. When allocation procedures are undertaken, Equation 5 supersedes the relevant equation in the requisite Protocol.
The assumptions underpinning the Substituted Emissions value, the Decarbonisation Statement, and all supporting evidence must be updated and revalidated annually to account for changes in market conditions.
Procedure 4: Carbon mass balance if the co-product leads to Crediting
Physical allocation based on carbon mass balance shall be used in instances where the co-product leads to Crediting for CDR with Isometric, for example if the process produces both biochar and bio-oil (A mixture of water, organic acids, aldehydes, ketones, sugars, phenols, and other organic compounds derived from the thermal breakdown of biomass. Thermal breakdown of biomass is achieved via thermochemical processes, such as pyrolysis, which heat biomass in low- or no-oxygen environments to high temperatures (~e.g. 350-650°C). Bio-oil is often also referred to as pyrolysis oil or bio-crude.) that is injected underground, and the CDR co-products have different durability (The amount of time carbon removed from the atmosphere by an intervention – for example, a CDR project – is expected to reside in a given Reservoir, taking into account both physical risks and socioeconomic constructs (such as contracts) to protect the Reservoir in question.). This is so that emissions are distributed according to the CO2 balance output of the system. The requirement for Crediting to be with an Isometric Project ensures that co-product allocation can be traced and verified appropriately and according to the same set of allocation and emissions accounting requirements. The co-product allocation between CDR products can be made after process subdivision and substitution has taken place. The calculation process to be followed is:
[math: CO_2e_{Emissions} = F_{Allocation} \;*\; ( CO_2e_{Establishment} \;+ \;CO_2e_{Operations} \;+ \;CO_2e_{End-Of-Life} \;+ \;CO_2e_{Leakage})]
(Equation 6)
Where:
[math: CO_2e_{Establishment}] , [math: CO_2e_{Operations}] , [math: CO_2e_{End-Of-Life}] and [math: CO_2e_{Leakage}] are as defined in the relevant Protocol.
[math: F_{Allocation}] is the fraction of emissions assigned to the CDR product, represented as:
[math: F_{Allocation} = \frac {CO_2e_{Stored \;[CDR product],\; RP}}{CO_2e_{Stored \;[Total], \;RP}}]
(Equation 7)
Where:
[math: CO_2e_{Stored \;[CDR \;product],\; RP}] is the total CO2 stored over a Reporting Period for the CDR Project in question, as calculated in the relevant Protocol, in tonnes CO2e.
[math: CO_2e_{Stored \;[Total], \;RP}] is the total CO2 stored across all CDR methods over the same representative Reporting Period, as calculated by requisite Protocols, in tonnes CO2e.
Equation 6 requires an adjustment to the equations for [math: CO_2e_{Emissions}] as they are set out in the requisite Protocol. When allocation procedures are undertaken, Equation 6 supersedes the relevant equation in the requisite Protocol.
It is noted that calculation of [math: CO_2e_{Stored \;[Total], \;RP}] may require adjustments where the Reporting Period for different Projects do not align. Adjustments may be made where necessary, provided that total [math: CO_2e_{Stored}] reported is still the equivalent of the sum of [math: CO_2e_{Stored}] reported under different Projects.
In some cases CO₂ may be stored in a product, for example when CO2 is stored in concrete via carbonation.
When this occurs, the co-product allocation requirements in Section 6.1 must be followed. Furthermore, it should be noted that [math: CO_2e_{Stored}] must not be double counted, regardless of the production of Environmental Product Declarations(EPD)1415. The product should still comply with all relevant emission accounting regulations and requirements, which may mean [math: CO_2e_{Emissions}] are double counted (once for CDR and once for EPD compliance where required), however removals ([math: CO_2e_{Stored}]) must not be double counted in the EPD and may only be reported as part of Crediting for CDR. This is the most conservative approach to take. Crediting claims must be transparently reported and must not form part of marketing for a separate product. The product must not be marketed as carbon negative if it is used as a storage mechanism for the generation of Credits. This practice ensures that a single carbon removal is not counted twice (e.g., once for the Credit and again as a product attribute), in alignment with the prohibition against double counting in Section 5.7 of the Isometric Standard.
Embodied emissions associated with system inputs considered to be waste products (An output of a process that has no intended value to the producer.) can be excluded from the accounting of the system boundary provided the appropriate criteria are met. A waste product is defined as an output of a process that has no intended value to the producer.
For waste energy inputs, including the use of waste heat, refer to the Energy Use Accounting Module v1.36. Eligibility criteria described in the Energy Use Accounting Module v1.36 must be satisfied in order to exclude GHG emissions associated with production of the heat. Any activities specifically developed inside the Project gate to handle and utilize waste heat must be accounted for in the life cycle analysis.
For waste biomass feedstocks (Raw material which is used for CO₂ Removal or GHG Reduction.), refer to the Biomass Feedstock Accounting Module v1.2. Eligibility criteria described in the Biomass Feedstock Accounting Module v1.2 must be satisfied in order to exclude biomass sourcing emissions from the system boundary. Emissions relating to any processing and transport of biomass feedstock for the CDR process must be included in the system boundary.
For all other waste products used as inputs, the following criteria must be considered.
If EC3 or both EC4 and EC5 are satisfied, then embodied and leakage emissions associated with the waste input may be excluded from the system boundary. This is further detailed below.
If EC5 in Table 7 is satisfied, embodied emissions associated with the waste product used as input can be excluded from the system boundary. Market leakage emissions associated with waste inputs may also be excluded from the system boundary, as compliance with EC5 would result in no change to the waste producer behavior (i.e. no market leakage) and indicates there are no alternative users of the waste product (i.e. no replacement emissions (Any emissions that occur to compensate for biomass that was previously serving another purpose and is now being used for carbon removal or GHG reduction. For example, if agricultural waste was previously left on a field to decompose - fertilizer production to replace those nutrients need to be accounted for.).
Table 7. Waste input emissions exclusion criteria, EC5
| Criteria | Description | Documentation required |
|---|---|---|
| EC5 | No payment was made for the material, or only a “tipping fee” | Purchase or removal records between Project Proponent and material supplier demonstrating price paid, amount, Buyer (An entity that purchases Removals or Reductions, often with the purpose of Retiring Credits to make a Removal or Reduction claim.), seller and date. Affidavit that no in-kind compensation was made. Not applicable if the material was produced by the Project Proponent. |
If EC6 and EC7 in Table 8 are both satisfied, embodied emissions associated with the waste product input can be excluded from the system boundary. Market leakage emissions associated with waste inputs may also be excluded from the system boundary, as compliance with EC6 and EC7 would result in no significant change to the waste producer behavior (i.e. no market leakage) and there are no alternative use cases for the waste product (i.e. no replacement emissions).
Table 8. Waste input emissions exclusion criteria, EC6 and EC7
| Criteria | Description | Documentation required |
|---|---|---|
| EC6 | The amount of the waste product used by the CDR Project was not already being utilized as a valuable product by another party for non-CDR uses. Therefore, the producer of the waste product has no alternative use case for the waste product. | Purchase or removal records between Project Proponent and material supplier demonstrating price paid, amount, Buyer, seller and date. Plus an affidavit from the waste supplier identifying that there are no alternative use cases for the waste product. |
| EC7 | Payments received for the waste product must not exceed 5% of the total annual revenue generated from the waste producer’s upstream operations | Purchase or removal records between Project Proponent and material supplier demonstrating price paid, amount, Buyer, seller and date. Plus an affidavit from the waste supplier that documents that payments from the Project do not constitute a large share of upstream operations revenue. |
Projects utilizing waste inputs must validate and demonstrate compliance with eligibility requirements according to the following rules.
For waste inputs that are used once within the scope of a project (for example, enhanced weathering feedstocks, or construction materials), validation and compliance with eligibility requirements demonstrated at the time of initial use is sufficient. The Project Proponent must document and retain evidence demonstrating that the waste input met eligibility requirements at the time of its use.
For waste inputs that are used on an ongoing basis throughout the Project:
Material changes that trigger revalidation include, but are not limited to:
Projects should consider revalidating waste input eligibility at their discretion in response to broader market developments that could affect the characterization of the input as waste (e.g., increased media scrutiny, emerging regulatory changes, or shifts in market dynamics).
Inputs to a CDR process, such as feedstocks, may be by-products or co-products under a separate system. Where a life cycle analysis specific to the sub-process is not available, Projects may seek to undergo emissions allocation to determine an appropriate emissions factor for the input material, following a stepwise process. Allocation refers to the partitioning of the inputs or outputs of a process or product system between the product system under study and one or more other product systems.
Projects must follow best practice guidance to undertake allocation of other product systems, such as:
Where it is possible to undertake more than one emission allocation approach, the results of all approaches must be documented. Evidence must be provided to determine why the selected approach is acceptable and how it is conservative in line with Isometric uncertainty requirements.
Emissions amortization (The term used to describe allocation of Project emissions to multiple Removals or Reductions.) refers to the process of allocating project emissions to removals on a temporal or per product output basis. As set out in the relevant Protocol, Project [math: CO_2e_{Establishment}] and [math: CO_2e_{End-of-Life}] emissions, which are estimated upfront during the initial project assessment, may be amortized. Unless set out otherwise in the relevant Protocol1718, emission amortization may be undertaken:
Project Proponents choosing to amortize emissions must report the residual emission debt at every verification. Projects that initially choose to amortize emissions over time (options 2 or 3) may later elect to deduct the remaining unamortized emissions in full from a subsequent removal verification, thereby transitioning to a one-time deduction approach (option 1). This provides flexibility for projects that wish to simplify reporting or consolidate emissions accounting at a later stage.
The anticipated Project lifetime or total gross CO2 sequestration should be justified as part of The Project Design Document (PDD), to be assessed as part of Project validation. Project Proponents must provide justification to support the chosen Project lifetime or total gross CO2 sequestered, which should be evidenced appropriately with Project specific documentation. The anticipated design life of equipment must be based on manufacturer information or best practice industry guidance. Any additional requirements related to amortization, anticipated Project lifetime, or total gross CO2 sequestrations are set out in the relevant Protocols.
Where emissions are amortized over the Project lifetime (2) or tonne of CO2 removed (3), this must be reviewed as part of verification at the end of year 1, year 3, year 5, and at each subsequent Crediting Period (The period of time over which a Project Design Document is valid, and over which Removals or Reductions may be Verified, resulting in Issued Credits.) renewal.
Where initial estimates prove to be unattainable or unlikely, adjustments to the emissions allocation schedule are permitted. Emissions must be adjusted to subtract the amount already covered by Credits from earlier Reporting Periods, and the remaining emissions should be reassigned to future verifications. If significant changes occur in the emissions amortization schedule (for example, if the emission allocation to each Reporting Period was greatly underestimated) the acceptance of an updated emissions amortization schedule will be down to the Validation and Verification Body's (Third-party auditing organizations that are experts in their sector and used to determine if a project conforms to the rules, regulations, and standards set out by a governing body. A VVB must be approved by Isometric prior to conducting validation and verification.) discretion. The adjustment mechanism exists to maintain alignment between emissions allocation and actual project performance, ensuring accuracy and integrity in reporting.
In addition to the review schedule set out above, if the Project Proponent is not able to comply with the allocation schedule described in the PDD, for example due to changes in delivered volume or anticipated Project lifetime, the Project Proponent must notify Isometric as soon as the change is identified in order to adjust the allocation schedule for future removals. If that is not possible, the Reversal (The escape of CO₂ to the atmosphere after it has been stored, and after a Certificate has been Issued. A Reversal is classified as avoidable if a Project Proponent has influence or control over it and it likely could have been averted through application of reasonable risk mitigation measures. Any other Reversals will be classified as unavoidable.) process will be triggered in accordance with the Isometric Standard (Section 5.6.1), to account for any remaining embodied emissions.
In situations where storage infrastructure is shared among multiple entities, the Project Proponent must allocate embodied emissions of that storage infrastructure to the Project proportionally, based on the mass of stored material for The Project relative to the total storage capacity. The amortization schedule should follow Options 1, 2 or 3. If new information becomes available, such as an updated storage capacity of the shared infrastructure, this should be taken into account and the amortization schedule adjusted as needed if this results in an increase to allocated emissions.
Isometric would like to thank following reviewer of this Module:
Tables A1 (Activity data) and Table A2 (Emission factors) provide examples for what constitutes high, medium, and low quality data under each criteria. The data and assumptions used in the GHG Statement will ultimately be dependent on The Project, and the tables below are meant to serve as guidance only.
Table A1: Detailed data quality hierarchy for activity data
| Criteria | High quality | Medium quality | Low quality |
|---|---|---|---|
| Reliability | Data are based on measurements and have been verified; they represent high-quality direct consumption data. Examples: Transport Actual fuel quantities from invoices Embodied Actual mass or quantity of goods purchased, as shown on supplier invoices, bill of quantities, equipment specifications or purchase agreements. Energy Energy consumption data from meter readings | Activity data are inferred from high-quality benchmarks or proxies, such as internal proxies or benchmarks from official sources. Examples: Transport Fuel usage estimated based on distance travelled and the specific efficiencies of vehicles that covered the distance Embodied Mass or quantity of materials estimated using dimensions of actual equipment on site and manufacturing specifications of similar equipment showing material weights and build up. Energy Energy usage based on manufacturer details of energy efficiency of equipment Fuel consumption expenditure data converted into fuel quantities using average price per litre from governmental sources | Activity data are inferred from low-quality benchmarks and proxies from non-qualified sources, or expenditure data is used for emissions calculations. Examples: Transport Expenditure data related to travel converted into fuel usage using non-official sources Embodied Expenditure data used as the primary basis for estimating emissions Energy Expenditure data used as the primary basis for estimating emissions |
| Completeness | Data is complete for the Reporting Period; there is no missing data or extrapolation, or if present, these gaps are very minor. Examples: Transport Data is complete for all trips that took place within the Reporting Period Embodied Data is complete for all materials and equipment used Energy Data is complete for electricity consumed by The Project | Some data is missing, and estimates have been used; however, it still provides an acceptable representation of the Reporting Period. Examples: Transport Data for one trip in the Reporting Period is missing from transportation logs. A conservative estimate is used for the missing trip based on the data available for other similar trips. Embodied Data for some minor pieces of equipment and materials are missing. Conservative estimates are used based on typical equipment requirements for the process. Energy Electricity consumption data is missing for one month out of 12 in non-intensive facilities, with activities remaining consistent across the Reporting Period. In this case, an average of the other months is used to estimate the missing consumption. | Data is mostly incomplete, requiring proxy estimations, and the result is likely to be a poor representation of the Reporting Period. Examples: Transport Data for multiple trips in the Reporting Period are missing from transportation logs. A conservative estimate is used for the missing trip based on the data available for other similar trips. Embodied Data for major equipment and materials are missing. Expenditure data is used to estimate embodied emissions. Energy Natural gas data is missing for three months out of 12, with no data available from previous years. An average of the other months is used, which is not a good representation as gas consumption fluctuates throughout the year. |
| Age (If using a benchmark to estimate quantities for a specific activity, the benchmark must be assessed instead of the activity data) | Data are fully representative, or are up to one year out, but are still an excellent representation of the Reporting Period. Examples: Transport Assumptions used for transportation are based on data published within the last year Embodied Assumptions used for embodied emissions are based on data published within the last year Energy A benchmark for electricity consumption associated with an activity is sourced from an industry report published within the last year. | Some activity data are from previous years (max three years out), but are a good representation of the Reporting Period. Examples: Transport Assumptions used for transportation are based on data published within the last three years Embodied Assumptions used for embodied emissions are based on data published within the last three years Energy A benchmark for electricity consumption associated with an activity is sourced from an industry report published within the last three years. | Some activity data are from previous years, and are a poor representation of the reporting year. Examples: Transport Assumptions used for transportation are based on data published within the last six years Embodied Assumptions used for embodied emissions are based on data published within the last six years Energy A benchmark for electricity consumption associated with an activity is sourced from an industry report published over three years ago. |
| Geography (If using a benchmark to estimate quantities for a specific activity, the benchmark must be assessed instead of the activity data) | Data is representative exactly of the location where the activity took place. The minimum boundary is the same region within a country (e.g. Southeast England). Examples: Transport Typical freight transport mode is assumed based on regional data. Embodied Assumptions for waste management are based on regional estimates. Energy Electricity usage at third party sites is estimated based on regional averages for electricity consumption for the activity type. | Data is representative at a minimum of the country where the activity took place (e.g. UK) Examples: Transport Typical freight transport mode is assumed based on regional data. Embodied Assumptions for waste management are based on national estimates. Energy Electricity usage at third party sites is estimated based on national averages for electricity consumption for the activity type. | Data is either regional (e.g. Europe) or global. Examples: Transport Typical freight transport mode is assumed based on global data. Embodied Assumptions for waste management are based on global estimates. Energy If no better data is available, electricity usage at third party sites is estimated based on global averages for electricity consumption for the activity type. |
| Technology | The description of activity data is highly specific and is broken down by all relevant components. Examples: Transport The fuel efficiency of the vehicle used is known for each trip for both outbound and return legs. The type of vehicle is described e.g. HGV (diesel) Articulated (>3.5 - 33t). Embodied Quantities of exact product with manufacturing specification is available, with an accompanying Environmental Product Declaration from the manufacturer. At a minimum, the goods or materials should be well described (e.g., hot rolled steel, Portland cement). Energy The type of fuel used is well-described e.g. Diesel (average biofuel blend) | Data is well described at a high level. Examples: Transport The type of vehicle is described at a high level e.g. HGV. Embodied Goods or materials are described at a high level e.g. steel, cement Energy The type of fuel used is described at a high level e.g. Diesel | Data is generic; activities have been grouped into generic descriptions. Examples: Transport The mode of transport is not known, e.g. land transport The mode of transport is known (road), but the type of vehicle is unknown. Embodied Goods or materials descriptions are generic e.g. metals, construction materials Energy The type of fuel used is not known. |
Table A2: Detailed data quality hierarchy for emission factors
| Criteria | High quality | Medium quality | Low quality |
|---|---|---|---|
| Reliability | Emission factors are provided by the best source available for that activity. Examples: Transport Emission factor is from a recognised database such as GLEC, US EPA, DESNZ. Embodied Independently verified life cycle analysis for the material or product completed in accordance with ISO 14040 or similar guidelines. An environmental product declaration (EPD) for a material or product completed and independently verified in accordance with ISO 14025, ISO 2193 0, EN 15804 or equivalent standards Emission factor for materials are from peer-reviewed databases such as ecoinvent, ICE Energy Emission factor is from a reliable source such as Green-e, AIB (for residual mix), DESNZ (for average EF) Diesel emission factor is from a recognised database such as DESNZ, US EPA | Emission factors are provided by a database considered generic for certain emission sources and are taken from an approved list. Examples: Transport Emission factor is taken from an industry report. Embodied Emission factor is taken from an industry report. Energy Emission factor is taken from an industry report. | Emission factors are extrapolated from non official sources, or from an expenditure based database. Examples: Transport Emission factors are extrapolated from an academic research paper. Emission factor from EXIOBASE. Embodied Emission factors are extrapolated from an academic research paper. Emission factor from EXIOBASE. Energy Emission factors are extrapolated from an academic research paper. Emission factor from EXIOBASE. |
| Completeness | The emission factor represents the whole life cycle of the activity. Examples: Transport Emission factor covers Combustion + WTT + embodied vehicle Embodied independently verified life cycle analysis or environmental product declaration (EPD) prepared for the specific material or product covering all life cycle stages Energy Emission factor represents Generation + T&D Losses + WTT | The emission factor is mostly complete, but is missing some life cycle stages. Examples: Transport Combustion only (No WTT) Embodied Only emissions related to life cycle modules A1-A3 is available from LCA / EPD Energy Emission factor represents Generation + T&D Losses (no WTT) | The emission factor is an approximation. Examples: Transport Life cycle stages covered are not declared. Embodied Life cycle stages covered are not declared. Energy Life cycle stages covered are not declared. |
| Age | The emission factor is updated and published in the Reporting Period year or is, at minimum, the most up-to-date available database (e.g., Green-e factors reflect the grid from two years prior). | The emission factors are max 6 years older than the Reporting Period year. | The emission factors are more than 6 years older than the Reporting Period year. |
| Geography | The emission factor used is a great representation of the location. | The emission factor is at a minimum representative of the country where the activity takes place. | The emission factor is a poor representation of the location. The emission factor is global. |
| Technology | The emission factor is specified by all or at least the most relevant components. | The emission factor is well described at the high level. | The emission factor is generic. |
Embodied emissions should be calculated based on quantities of materials, equipment or products and representative embodied emission factors for the specific components.
Examples of high quality activity data are:
Examples of high quality emission factors are:
The calculations should utilize approaches outlined in the Sector Supplement for Measuring and Accounting for Embodied Emissions in the Built Environment: A Guide for measuring and reporting embodied emissions using the Greenhouse Gas Protocol version 1.1 - November 2021, specifically:
For the Energy Usage Method, emission factors must:
For the Distance-Based Method, emissions factors must:
GHG emissions from transportation sources must be evaluated for all transportation completed between facilities, from the gate of one facility to the gate of the next facility, including return journeys. Primary measurements considered in calculation of emissions are:
The fuel consumed, [math: F_{j}^{}] , can be determined by one of the following methods:
The distance traveled, [math: D_{j}^{}], can be determined by one of the following methods:
Distance traveled and fuel usage must consider:
Evidence must be provided showing the distance of every trip to the next destination if the second option is used. When no onwards journey information is available, the full round trip must be assumed in calculations.
Calculations shall be completed separately for each leg of the trip associated with a removal, with total emissions calculated by the sum of emissions from each leg.
Weight of the material being shipped, [math: W_{j}^{}], should be determined as loaded gross vehicle weight measured at facility gate of departure minus vehicle gross weight upon facility entry, as determined by calibrated a weigh scale.
Required records for each transportation leg calculated using the Energy Usage Method include:
Required records for each transportation leg calculated using the Distance-Based Method include:
Any use of book and claim mechanisms to reduce reported transportation emissions should be transparently disclosed, in line with the Energy Use Accounting Module v1.36. Any meters used must be calibrated for the fuel being used both initially and at regular intervals in accordance with manufacturer specifications.
Recommendations for additional considerations for four common modes of transportation (road, rail, ship, and pipeline) are included below.
Road:
Rail:
Ship:
Pipeline:
Aircraft:
A Project Proponent for a Biomass Geological Storage Project collects data based on the system boundary defined in the Protocol. To estimate staff travel emissions, the Proponent gathers high-level information via email, learning that five local staff members commute approximately 5–10 km each way to the Project site daily.
Meanwhile, the Proponent identifies biomass transport (>100 km daily) as a major emission source, and suspects staff travel emissions are negligible. Rather than obtaining detailed travel data, the Proponent conservatively assumes:
An average car emission factor from the GLEC Framework is applied to calculate [math: CO_2e_{SSR \;Estimated,\;RP}].
Using estimated staff travel emissions and the total estimated net CO2e removals for the Reporting Period ([math: CO_2e_{Removal\;Estimated,\;RP}]), the Proponent calculates the materiality of the emission source ([math: M_{SSR}]). The result shows staff travel emissions are < 1% of net removals.
Because the staff travel emissions, and all other excluded SSRs, remain collectively < 1%, staff travel is excluded from the system boundary.
The Proponent documents:
Projects credited under Isometric must use project-level consequential analysis to determine net CO2e removals associated with project activities. Project emissions and removals must be assessed against a baseline scenario of The Project not taking place. When submitting Claimed Removals, The Project's emissions ([math: CO_2e_{Emissions}]), removals ([math: CO_2e_{Stored}]) and counterfactual ([math: CO_2e_{Counterfactual}]) must be presented together in net metric tonnes of CO2e as part of a GHG Statement. Isometric follows the terminology outlined in ISO 14064-2 to describe GHG Sources, Sinks and Reservoirs that are relevant to The Project including those that are Controlled, Related and Affected.
The distinctions between attributional and consequential analysis are often unclear1920. Some elements of Isometric’s approach are not wholly aligned with consequential analysis principles. This is as a result of conservatism and the way in which carbon markets operate, and is described in more detail below:
Currently a standard for applying project-level consequential analysis for CDR Projects does not exist. Isometric will continue to revise the approach outlined for project-level consequential analysis in line with literature and best practice.
The following examples illustrate how the co-product allocation rules can be applied. All processes and values are purely illustrative and are not intended to reflect real-world data or to enable direct comparison between procedures
Scenario: A Project Proponent operates a direct air capture (DAC) facility where the CDR activity is the capture of CO₂ from ambient air and its durable storage via ex-situ mineralization. The process generates a marketable co-product (heat), which is sold to a nearby greenhouse for space heating.
GHG Statement: The DAC facility consumes 500,000 kWh of electricity per year, resulting in 200 tCO₂e. The Project Proponent has elected to follow the emissions allocation method outlined in Procedure 1. Under this procedure, all Project emissions are allocated to the CDR activity.
Result: The total value for [math: CO_{2e,Emissions}] is 200 tCO₂e. The co-product (heat) is treated as having a zero-emissions burden within the GHG Statement. This approach is the most conservative as it ensures emissions associated with the CDR activity are not underestimated.
Note: The greenhouse must still comply with its own emissions accounting requirements where they apply, which may result in the double counting of these emissions in its own reporting.
Scenario: A Project Proponent retrofits a bioenergy facility, which has been operational since 2017, with a CO₂ capture and storage unit in 2025. The CDR activity is the capture and subsequent storage of CO₂, while the co-product is electricity.
GHG Statement: The Project Proponent has elected to follow the emissions allocation method outlined in Procedure 2. This procedure is applicable as the CDR process is a retrofit to an existing, operational facility, satisfying Eligibility Criteria 1 (EC1). The GHG Statement boundary for the CDR activity is limited to the materials and processes necessary for the retrofit. In this case, the electricity consumption of the CO₂ capture unit is physically separable and separately metered at 100,000 kWh/year, which corresponds to 40 tCO₂e. Emissions associated with the pre-existing combustion and power generation processes are excluded from the GHG Statement boundary.
Result: The total value for [math: CO_{2e,Emissions}] allocated to the CDR activity is 40 tCO₂e. The electricity co-product is subject to its own life cycle GHG accounting, separate from the CDR Project.
Scenario: A Project Proponent operates a biochar facility that produces a CDR product (biochar) and a co-product (electricity), which is sold to the grid. The Project is demonstrably net-negative before the application of substitution.
GHG Statement: The Project Proponent has elected to follow Procedure 3: "Substitution method". The total facility emissions are 200 tCO₂e. In line with the implementation criteria, the Proponent submits a Decarbonisation Statement, justifying the split of these emissions into:
Downstream emissions of the co-product ([math: CO_{2e,CoProduct}]): 0 (The Proponent has demonstrated that use-phase emissions are equal to or lower than the substituted product)
Applying Equation 5: The total emissions are calculated by subtracting the discounted substituted emissions from the residual emissions only, and then adding back the non-residual emissions.
[math: CO_{2e,Emissions} = \max\Bigg(0,\;\Big[CO_2e_{Residual}\Big] -\Big[Q_{CoProduct} * EF_{Substituted} * SR *U-CO_2e_{CoProduct}\big]\Bigg)+\Big[CO_{2eNon-residual}\Big]]
[math: CO_{2e,Emissions} = max(0, [150 − (500 × 0.3 × 1 × 0.5 − 0)]) + 50 = max(0, [150 − 75]) + 50 = 75 + 50 = 125 tCO₂e]
Result: After applying the substitution method, the net facility emissions allocated to the CDR activity ([math: CO_{2e,Emissions}]) are reduced from 200 tCO₂e to 125 tCO₂e. The avoided emissions from the electricity co-product are used exclusively to offset the facility's residual emissions, and a conservative 50% uncertainty discount is applied. Non-residual emissions remain fully accounted for, ensuring the method does not disincentivise decarbonisation efforts.
Scenario: A Project Proponent operates a pyrolysis plant that produces two distinct CDR products: biochar and bio-oil. Both products lead to crediting with Isometric.
GHG Statement: The Project Proponent has elected to follow the emissions allocation method outlined in Procedure 4.
The total project emissions are 10,000 tCO₂e. The quantity of CO₂ stored by each CDR product is:
The fraction of emissions assigned to the biochar CDR product ([math: F_{Allocation}]) is calculated using Equation 7:
[math: F_{Allocation}] = [math: CO_{2e,Stored [Biochar], RP}] / [math: CO_{2e,Stored [Total], RP}] = 80,000 tCO₂e / 100,000 tCO₂e = 0.8
The emissions allocated to the biochar project are then calculated using Equation 6:
[math: CO_{2e,Emissions}] (biochar) = [math: F_{Allocation}] × (Total Project Emissions) = 0.8 × 10,000 tCO₂e = 8,000 tCO₂e.
Result: The total value for [math: CO_{2e,Emissions}] allocated to the biochar project is 8,000 tCO₂e, with the remaining 2,000 tCO₂e allocated to the bio-oil project. This method ensures that emissions are distributed proportionally based on the mass of CO₂ stored by each CDR product.
https://ww2.arb.ca.gov/resources/documents/lcfs-life-cycle-analysis-models-and-documentation↩
https://www.gov.uk/government/collections/government-conversion-factors-for-company-reporting↩
Note: The Energy Use Accounting Module is pending ana v1.3 update. For the purposes of the GHG Accounting Module v1.0, the update to Energy Use Accounting Module v1.3 update will cover the inclusion of Book-and-Claim unit requirements, which will be transferred from the Transportation Emissions Accounting Module v1.1. The Transportation Emissions Accounting Module v1.1 and the Embodied Emissions Accounting Module v1.0 willare no longer be maintained for updates following certification of the GHG Accounting Module v1.0, because the relevant content will have beenis transferred to the GHG Accounting Module v1.0 and the Energy Use Accounting Module v1.3. ↩↩2↩3↩4↩5↩6↩7↩8
Adapted from https://ghgprotocol.org/sites/default/files/standards/Product-Life-Cycle-Accounting-Reporting-Standard_041613.pdf↩↩2
[https://www.iso.org/standard/61694.html (https://www.iso.org/standard/61694.html) ↩
Referenced in the Sector Supplement for Measuring and Accounting for Embodied Emissions in the Built Environment A Guide for measuring and reporting embodied emissions using the Greenhouse Gas Protocol version 1.1 - November 2021.↩
Operational energy use (B6) should be accounted for in line with the Energy Use Accounting Module v1.36. ↩
Some Protocol versions may reference the GHG Accounting Module v1.0 alongside a previous version of the Energy Use Accounting Module - v1.2. This is permitted if the Protocol references the GHG Accounting Module v1.0 only for GHG accounting requirements not related to energy use. ↩↩2
https://catalog.data.gov/dataset/supply-chain-greenhouse-gas-emission-factors-v1-3-by-naics-6↩
https://www.tandfonline.com/doi/pdf/10.1080/20430779.2011.637670↩
Buchenau, N. et al. (2023) Allocation of carbon dioxide emissions to the by-products of combined heat and power plants: A methodological guidance. Available at: https://www.sciencedirect.com/science/article/pii/S2667095X23000259↩
A tipping fee refers to an amount paid by the Project Proponent to the producer of the waste to collect the waste. A tipping fee should only cover transportation and collection costs. ↩
The 5% threshold is drawn from the SEC Staff Accounting Bulletin No. 99, an investor-focused standard for significance This is a widely recognized benchmark for assessing materiality in financial reporting and provides a basis for determining when payments are immaterial. https://www.sec.gov/interps/account/sab99.htm↩
For example, the Enhanced Weathering in Agriculture Protocol v1.1 requires that emissions must be amortized over the first half of the anticipated project lifetime (meaning the point at which 50% of the feedstock weathering potential is realized) as annual emissions, or per output of product (i.e., per tonne CO2 removed) so long as establishment emissions are fully accounted by the time 50% of the weathering potential has been realized. ↩
https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2025↩
Brander, M., (2021). The most important GHG accounting concept you have never heard of: the attributional-consequential distinction. Seattle, WA. Greenhouse Gas Management Institute, April 2021. https://ghginstitute.org/wp-content/uploads/2021/04/Consequential-and-AttributionalAccounting-April-2021.pdf↩
Marginal product in consequential analysis refers to the product or service whose production or use changes as a direct consequence of an intervention in a system. For example, if a new project purchases renewable electricity from the grid, but that electricity is already being generated by existing renewable sources, The Project creates additional demand on the system. In many grid systems, this extra demand is initially met by fossil fuel-based power generation, which serves as the marginal supplier. In a true consequential analysis, The Project would only account for the emissions associated with the marginal electricity source in the assessment — in this case, fossil-based generation — because that is the actual system change induced by The Project. The same principle applies to goods like sustainable concrete: even if a project chooses a "green" option, the market response to increased demand may result in production from less sustainable sources. Thus, under consequential analysis, projects would only account for emissions associated with the marginal (often least sustainable) product that fills the new demand. ↩
The default value for the uncertainty factor is 50%. Projects may propose a lower discount, which must be justified with supporting evidence, such as verified product displacement data or binding statements from co-product buyers. ↩