Subsurface Biomass Carbon Removal and Storage

1.0 Summary

This Protocol provides the requirements and procedures for the calculation of net CO₂e removal (The term used to represent the CO₂ taken out of the atmosphere as a result of a CDR process.) from the atmosphere via the processing of biomass and storage in the shallow subsurface for long term sequestration of atmospheric CO₂. Storage of biomass in the shallow subsurface 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”.) is considered a subsector of Biomass Carbon Removal and Storage (BiCRS) (A range of processes that use biogenic material to remove carbon dioxide (CO₂) from the atmosphere and store that CO₂ underground or in long-lived products (LLNL BiCRS Roadmap, 2020).). The shallow subsurface shall include biomass placed at depths of not more than 100 meters below the ground surface. This Protocol applies to biomass storage technologies or Projects (An activity or process or group of activities or processes that alter the condition of a Baseline and leads to Removals or Reductions.), which typically consist of activities associated with the following sub-processes: biomass growth, processing of biomass prior to storage, emplacement in the shallow subsurface and storage.

The Protocol accounts for quantification of the gross amount of CO₂ removed via storage in the shallow subsurface, as well as the accounting for all net greenhouse gas (GHG) emissions associated with the process, including emissions associated with the biomass feedstock (Raw material which is used for CO₂ Removal or GHG Reduction.), biomass storage processes, all transportation and embodied emissions (Life cycle GHG emissions associated with production of materials, transportation, and construction or other processes for goods or buildings.) emissions associated with the process, and emissions associated with leakage (The increase in GHG emissions outside the geographic or temporal boundary of a project that results from that project's activities.). The GHG Statement (The process by which all emissions associated with a Project's Removal or Reduction process, including leakages, are accounted for.) is considered as a 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.) analysis.

This Protocol is developed to adhere to the requirements of ISO (A worldwide federation (NGO) of national standards bodies from more than 160 countries, one from each member country.) 14064-2: 2019 – Greenhouse Gases – Part 2: Specification with guidance at the project level for quantification, monitoring, and reporting of greenhouse gas emission reductions or removal enhancements. The Protocol ensures:

• consistent, accurate procedures are used to measure and monitor all aspects of the process required to enable accurate accounting of 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
• consistent system boundaries and calculations are utilized to quantify net CO₂e removal for biomass storage in the shallow subsurface
• requirements are met to ensure the CO₂ removals are additional (An evaluation of the likelihood that an intervention—for example, a CDR Project—causes a climate benefit above and beyond what would have happened in a no-intervention Baseline scenario.)
• evidence is provided and verified (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).) by Validation and Verification Bodies (VVBs) (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.) to support all net CO₂e removal claims

2.0 Sources and Reference Standards & Methodologies

Specific Standards (Standard physical constants as well as standard values set forth by bodies such as the National Institute of Standards and Technology (NIST) or others.) and Protocols which are utilized as the foundation of this Protocol and for which this Protocol is intended to be fully compliant with are the following:

• Isometric Standard
• ISO 14064-2: 2019 – Greenhouse Gases – Part 2: Specification with guidance at the project level for quantification, monitoring, and reporting of greenhouse gas emission reductions or removal enhancements

Additional reference standards that inform the requirements and overall practices incorporated in this Protocol include:

• ISO 14064-3: 2019 – Greenhouse Gases – Part 3: Specification with Guidance for the verification and validation of greenhouse gas statements
• ISO 14040: 2006 - Environmental Management - life cycle Assessment - Principles & Framework
• ISO 14044: 2006 - Environmental Management - life cycle Assessment - Requirements & Guidelines

3.0 Future Versions

This Protocol was developed based on the current state of the art and current publicly available science regarding biomass processing and biomass storage. Because biomass storage is a novel 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.) approach, with limited published literature, the Protocol incorporates requirements that may be more stringent than some current relevant regulations for underground storage or other Protocols related to biomass utilization for CDR.

This approach, notably when specifying requirements for demonstrating biomass subsurface storage 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.), will likely be altered in future versions of the Protocol as the stability of biomass in the subsurface becomes well demonstrated and documented, reversal (The escape of CO₂ to the atmosphere after it has been stored, and after a Credit 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.) risks are proven to be limited or non-existent, and the overall body of knowledge and data regarding all processes, from feedstock supply, to processing, and to durable storage is significantly increased.

4.0 Applicability

This Protocol applies to projects or processes which:

• utilize agricultural or forestry residues as eligible feedstocks in accordance with the framework set out in the Biomass Feedstock Accounting Module 1v1.23.
• emplace the biomass into engineered subsurface storage for long duration storage purposes

This Protocol applies to projects and associated operations that meet all of the following project conditions:

• The Project provides a net-negative CO₂e impact (net CO₂e removal), as calculated in the GHG Statement, in compliance with Section 78
• The biomass feedstock utilized is sustainably sourced
• The Project does no net harm to the environment and society
• The Project is considered additional (An evaluation of the likelihood that an intervention—for example, a CDR Project—causes a climate benefit above and beyond what would have happened in a no-intervention Baseline scenario.), in accordance with the requirements of Section 6.4
• The storage site is located in an area governed by the US, Canada, United Kingdom or the European Union
• The storage site is properly permitted in accordance with all applicable regulations

Projects that are explicitly NOT eligible include the following:

• Projects that do not use sustainably sourced biomass feedstocks as detailed in Section 7.2.

5.0 Environmental and Social Safeguarding

The Project must consider environmental and social impacts at all Project locations, including the biomass sourcing, processing and burial sites as well as during biomass transportation.

Appropriate measures must be implemented to identify and eliminate potential risks to terrestrial and aquatic ecosystems and biodiversity.

Where risks cannot be eliminated, the Project Design Document (PDD) must identify measures to monitor ecosystem health and mitigate adverse effects through a project-specific mitigation plan. Mitigation plans must be carried out by subject matter experts, in consultation with Isometric. Refer to Sectionthe 3.7relevant section of the Isometric Standard for further guidelines on environmental and social impacts.

5.1 Overarching Principles

Following the Isometric Standard, Credits issued under this Protocol are contingent on the implementation, transparent reporting and independent verification of comprehensive safeguards. These safeguards encompass a wide range of considerations, including environmental protection, social equity, community engagement and respect for cultural values. The process mandates that safeguard plans be incorporated into all major project phases, with detailed reports made accessible to stakeholders. Adherence to and verification of environmental and social safeguards is a condition for all Crediting Projects.

5.1.1 Governance and Legal Framework

5.2 Risk Mitigation Strategies

Environmental and social risk assessment in adherence with Sectionthe 3.7relevant section of the Isometric Standard must be completed to identify potential risks, followed by the development of tailored mitigation plans. These plans must encompass specific actions to avoid, minimize or rectify identified impacts. Effective implementation of these measures must also be accompanied by a robust monitoring plan to detect negative impacts and stop projects when necessary.

The Project Proponent must conduct an environmental risk assessment which adheres to Sectionthe 3.7.1relevant section of the Isometric Standard. Potential additional environmental risks associated with biomass storage in the shallow subsurface are listed below. The severity of these risks vary based on site specifics and the intensity and duration of activities. Environmental and social risk identification, assessment, avoidance, and mitigation planning will be unique to each Project’s technical, environmental, and social contexts. This list contains minimum considerations; Isometric and the Project Proponent may add risks on a case by case basis in the PDD.

5.2.1 Environmental Safeguards

5.2.1.1 Pollution Prevention and Co-Products

Projects may utilize synthetic material, such as storage liners or biomass wrappers, to increase the durability of biomass stored in the shallow subsurface. These synthetic materials may be required by Isometric in relevant storage Modules and/or utilized under the discretion of the Project Proponent.

5.2.2 Socio-economic Safeguards

The Project Proponent must conduct a social risk assessment which adheres to Sectionthe 3.7.2relevant section of the Isometric Standard on Social Impacts.

5.2.2.1 Stakeholder Engagement

Per Section 3.5 of the Isometric Standard, Project Proponents must demonstrate active stakeholder engagement throughout Project planning and operation, ensuring that all risk mitigation strategies contribute to sustainable project outcomes. Local stakeholders situated in the vicinity of the project site may contribute an in-depth understanding of the local system and provide invaluable insights and recommendations on the potential risks, necessary safeguards and specific monitoring needs. The Stakeholder input process must adhere to requirements outlined in Sectionthe 3.5relevant section of the Isometric Standard, and evidence of these meetings must be submitted in the PDD.

5.2.3 Adaptive Management

6.0 Relation to the Isometric Standard

The following topics are covered briefly in this Protocol due to their inclusion in the Isometric Standard, which governs all Isometric Protocols. See in-text references to the Isometric Standard for further guidance.

6.1 Project Design Document

For each specific Project to be evaluated under this Protocol, the Project Proponent must document Project characteristics in a Project Design Document (The document that clearly outlines how a Project will generate rigorously quantifiable Additional high-quality Removals or Reductions.) (PDD) as outlined in Sectionthe 3.2relevant section of the Isometric Standard. The PDD will form the basis for Project 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).) and evaluation in accordance with this Protocol, and must include consideration of processes unique to biomass such as:

• location information for biomass production and the storage location and area
• conditions of biomass use prior to project initiation
• details on technologies, products, and services relevant to biomass processing, including production rates and volumes

6.2 Validation and Verification

Projects must be validated and project net CO₂e removals verified by an independent third party, consistent with the requirements described in this Protocol, as well as in Section 4 of the Isometric Standard.

The Validation and Verification Body (VVB) (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.) must consider following requisite components:

1. Validate that feedstock adheres to the requirements listed in the Biomass Feedstock Accounting Module 1v1.23.
2. Verify that storage sites adhere to the requirements listed in the relevant storage Module.
3. Verify that the quantification approach and monitoring plan adheres to requirements of Section 78, including demonstration of required records.
4. Verify that the Environmental & Social Safeguards are met.
5. Verify that the Project is compliant with requirements outlined in the Isometric Standard.

6.2.1 Verification Materiality

The threshold for Materiality (An acceptable difference between reported Removals/emissions or Reductions/emissions and what an auditor determines is the actual Removal/emissions or Reduction/emissions.), considering the totality of all omissions, errors and mis-statements, is 5%, in accordance with Section 4.3 of the Isometric Standard.

Verifiers should also verify the documentation of uncertainty (A lack of knowledge of the exact amount of CO₂ removed by a particular process, Uncertainty may be quantified using probability distributions, confidence intervals, or variance estimates.) 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.) as required by Section 2.5.7 of the Isometric Standard. Qualitative Materiality issues may also be identified and documented, such as ¹:

• control issues that erode the verifier’s confidence in the reported data;
• poorly managed documented information;
• difficulty in locating requested information;
• noncompliance with regulations indirectly related to GHG emissions, removals or storage

6.2.2 Site Visits

Project validation and verification must incorporate site visits to project facilities in accordance with the requirements of ISO 14064-3, 6.1.4.2, including, at a minimum, site visits during validation and initial verification to the biomass processing site and the biomass storage site. Validators should, whenever possible, observe operation of the biomass processing and burial to ensure full documentation of process inputs and outputs through visual observation.

A site visit must occur at least once every 2 years at each location.

6.2.3 Verifier Qualifications & Requirements

Verifiers and validators must comply with the requirements defined in Section 4 of the Isometric Standard. In addition, teams must maintain and demonstrate expertise associated with the specific technologies of interest, including biomass growth or production, biomass processing, biomass production and terrestrial storage.

Competency must be demonstrated in accordance with Isometric's VVB policy, for example based on the relevant sectoral scope accreditations in IAF MD 14, or another demonstration of relevant expertise for this protocol and the selected storage module(s).

6.3 Ownership

CDR via biomass storage is often a result of a multi-step process (such as biomass growth, harvesting, transport, processing, burial, and storage), with activities in each step managed and operated by a different operator, company, or owner. When there are multiple parties involved in the process (e.g., forestry owner or burial site operator), and to avoid double counting (Improperly allocating the same Removal or Reduction from a Project Proponent more than once to multiple Buyers.) of net CO₂e removals, a single Project Proponent must be specified contractually as the sole owner of the Credits in order to avoid double counting of net CO₂e removals. Contracts must comply with all requirements defined in Sectionthe 3.1relevant section of the Isometric Standard.

6.4 Additionality

The Project Proponent must be able to demonstrate additionality through compliance with Section 2.5.3 of the Isometric Standard. The baseline (A set of data describing pre-intervention or control conditions to be used as a reference scenario for comparison.) scenario and counterfactual (An assessment of what would have happened in the absence of a particular intervention – i.e., assuming the Baseline scenario.) utilized to assess additionality must be project-specific, and are described in Section 7.2 of this Protocol.

Additionality determinations should be reviewed and completed every two years, at a minimum, or whenever project operating conditions change significantly, such as the following:

• regulatory requirements or other legal obligations for project implementation change or new requirements are implemented;
• project financials indicate carbon finance (Resources provided to projects that are generating, or are expected to generate, greenhouse gas (GHG) Emission Reductions or Removals.) is no longer required, potentially due to, for example:
  • increased tipping fees for waste feedstocks;
  • sale of co-products that make the business viable without carbon finance;
  • reduced rates for capital access.

Any review and change in the determination of additionality shall not affect the availability of carbon finance and carbon 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.) for the current or past Crediting Periods (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.), but, if the review indicates the Project has become non-additional, this shall make the Project ineligible for future Credits².

6.5 Uncertainty

The uncertainty in the overall estimate of the net CO₂e removal as a result of the Project must be accounted for. The total net CO₂e removed, ([math: CO_2e_{Removal}]), for a specific batch ([math: n]) must be conservatively (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.) determined based on the requirements outlined in Section 2.5.7 of the Isometric Standard.

6.5.1 Reporting of Uncertainty

Projects must report a list of all input variables used in the net CO₂e removal calculation and their uncertainties,including:

• emission factors utilized, as published in public and other databases used;
• values of measured parameters from process instrumentation, such as truck weights from weigh scales, flow rates from flow meters, electricity usage from utility power meters, and other similar equipment;
• laboratory analyses, including analysis of carbon content of biomass.

The uncertainty information should at least include the minimum and maximum values of a variable. More detailed uncertainty information should be provided if available, as outlined in Section 2.5.7 of the Isometric Standard.

In addition, a sensitivity analysis (An analysis of how much different components in a Model contribute to the overall Uncertainty.) that demonstrates the impact of each input parameter’s uncertainty on the final net CO₂e uncertainty must be provided. Details of the sensitivity analysis method must be provided such that a third party can reproduce the results. Input variables may be omitted from an uncertanty analysis if they contribute to a < 1% change in the net CO₂e removal. For all other parameters, information about uncertainty must be specified.

6.6 Data sharing

In accordance with the Isometric Standard, all evidence and data related to the underlying quantification of CO₂e removal will be available to the public through Isometric's platform (A community resource where Project Proponents publish and visualize their early processes, Removal and Reduction data and Protocols – enabling the scientific community to share feedback and advice.). That includes:

• Project Design Document
• 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.)
• Measurements taken
• Emission factors used
• Scientific literature used

The Project Proponent can request certain information to be restricted (only available to authorized buyers (An entity that purchases Removals or Reductions, often with the purpose of Retiring Credits to make a Removal or Reduction claim.), the Registry (A database that holds information on Verified Removals and Reductions based on Protocols. Registries Issue Credits, and track their ownership and Retirement.) and VVB) where it is subject to confidentiality. This includes emissions factors from licensed databases. However, all other numerical data produced or used as part of the quantification of net CO₂e removal will be made available.

7.0 Quantification of net CO₂e removal

7.1 System Boundary & GHG Emissions Scope

The scope of this Protocol includes 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 (SSRs) associated with a biomass burial CDR project. 

A cradle-to-grave GHG Statement must be prepared encompassing the GHG emissions relating to the activities outlined within the system boundary (Figure 1).

GHG emissions and removals associated with The Project may be direct emissions from a process, or indirect emissions from combustion of fuels, electricity generation, or other sources. Emissions for processes within the system boundary must include all GHG SSRs within the system boundary, from the construction or manufacturing of each physical site and associated equipment, closure and disposal of each site and associated equipment, and operation of each process (biomass production, biomass storage), to includeincluding embodied emissions of equipment and consumables used in the processproject. The Project Proponent is responsible for identifying all sources of emissions directly or indirectly related to project activities.

Any emissions from sub-processes or process changes that would not have taken place without the involvement of the CDR process, such as subsequent transportation and refining,Project must be fully considered in the system boundary. PairedAny withactivity exclusionthat ultimately leads to the issuance of wasteCredits inputshould emissionsbe whenincluded in the criteriasystem are met (see Section 7.1.1), this allows for accurate consideration of additional, incremental emissions induced by the CDR processboundary.

The system boundary must include all relevant GHG SSRs controlled by and related to theThe Project, including but not limited to the SSRs set out in FigureTable 1 and TableFigure 1. If any GHG SSRs within Table 1 are deemed not appropriate to include in the system boundary, they may be excluded provided that robust justification and appropriate evidence is provided in the PDD.

Figure 1. Process flow diagram showing system boundary for biomass burial projects

Figure[Image: 1System boundary diagrams (20)]

Table 1 GHG SSRs for Biomass Carbon Removal and Storage

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-yr 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).

Miscellaneous GHG emissions are those that cannot be categorized by the GHG SSR categories provided in Table 1. The Project Proponent is responsible for identifying all sources of emissions directly or indirectly related to project activities and must report any outside of the SSR categories identified as miscellaneous emissions.

Emissions associated with aThe projectProject's impact on activities that fall outside of the system boundary of aThe projectProject must also be considered. This is covered under Leakage (The increase in GHG emissions outside the geographic or temporal boundary of a project that results from that project's activities.) in Section 7.38.5.54.

In line with the GHG Accounting Module v1.1, the Project 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 (N20) 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;
• Quantify emissions in tonnes CO₂ equivalent (t CO₂e) using the 100-year Global Warming Potential (GWP) for the GHG of interest, based on the most recent volume of the IPCC Assessment Report (currently the Sixth Assessment Report); and
• Consider materiality of SSRs in line with Isometric requirements.

7.1.1 Exclusions from system boundary

The following are excluded from system boundaries.

7.1.1.1 Ancillary activities

Ancillary activities (such as supplementary research and development activities and corporate administrative activities) that are associated with a project but are not directly or indirectly related to the issuance of Credits can be excluded from the system boundary.

7.1.1.2 Secondary Impacts on GHG emissions

Emissions reductions associated with other processes that could arise as a result of the Project should not be credited toward the Project.

7.1.1.3 Considerations for Waste Input Emissions

Embodied emissions associated with system inputs considered as waste products can be excluded from the accounting of the GHG Statement system boundary of the CDR process if all of the below criteria are met:

• The waste product is fundamentally tied to or is the result of a separate process.
• The separate process was already operating or was likely to continue operating in absence of the CDR process.
• The amount of the waste product used by the CDR project was not already being utilized as a valuable by-product or co-product by another party for non-CDR uses.
• Market leakage emissions are fully considered.
• The separate process has a pathway toward compliance with net-zero emissions.

An example to illustrate this would be biomass residues generated by forest maintenance. If the residues would likely be generated without a biomass burial project as a baseline scenario, and the rest of the criteria above are met, they can be used in the GHG accounting without an emissions burden. However, emissions relating to the processing of these residues, such as drying and transport, should be included in the GHG Statement. The Project Proponent must provide documentation that the above criteria are met in order to omit such emissions from the GHG Statement.

In the case that a relevant separate process would not continue operating or would not begin operating without revenue from waste product valorization, emissions should be allocated to the waste product used in the system boundary. In the case that a waste product from a separate process was already being used as a by-product to serve some other process, emissions generated from the displacement of the supply of the by-product must be considered as part of the Leakage assessment.

7.1.1.4 Considerations for Project Activities Integratedintegrated into Existingexisting Practices

In some instances, thebiomass Projectburial CDR project activities may be integrated into existing activities, such as rock spreading whilst seeding. Activities or portions of activities that were already occurring in the baseline and would continuehave continued to occur without the biomass burial CDR project may be omitted from the system boundary, subject to the conditions set below.

For the purpose of this provision, an "activity" may refer to an operational sub-unit, such as an individual trip leg, a single pass of field equipment, or a discrete processing step, where such sub-units can be cleanly delineated by equipment, timing, and physical scope. Where a pre-existing activity is partially modified by the project (for example, a transport trip whose route is extended to include project-specific stops, or a field operation whose pass is lengthened to include project inputs), the activity must be partitioned into:

• portions that are materially unchanged by the project, which may be excluded from the system boundary under this provision; and
• portions that are new, extended, or altered as a result of the GHG accountingproject, ifwhich evidencemust thatremain within the system boundary and be quantified in the relevant sub-section of Section 8.5.

An activity, or portion of an activity, may only be excluded where the Project Proponent can demonstrate all of the following:

• it was already occurring andas part of routine operations prior to project activities;
• it would have continued to occur in the absence of the biomass burial CDR project; and
• its scope, frequency, equipment, route, payload, and intensity are not materially altered as a result of project canactivities.

Evidence supporting these conditions must be provided in the PDD. This must include either:

• Historic records documenting the activity prior to project start. Acceptable records include management logs, operational records, applicator invoices, or equivalent documentation; or
• A signed affidavit from the relevant operator (e.g., farmer, land manager, applicator, or equivalent party) confirming the activity was part of routine operations prior to the project.

And the following:

• A signed affidavit from the relevant operator (e.g., farmer, land manager, applicator, or equivalent party) confirming:
  • the equipment, route, timing, cadence, and intensity of the activity are not materially changed as a result of the biomass burial CDR project; and
  • the activity would have continued at a comparable level absent the project.

Where these conditions are met, only the emissions associated with the activity as it would have occurred in the baseline may be excluded. Any incremental emissions attributable to the project must remain within the system boundary and be accounted for in the relevant emissions sub-section.

7.2 Baseline

The baseline scenario for biomass storage projects assumes the activities associated with the Project do not take place and any associated infrastructure is not built.

The counterfactual is the CO₂ stored in the biomass feedstock that would have remained durably stored in the biomass in the absence of the Project. This is known as ineligible biomass, given that the CO₂ stored would have remained stored in the biomass in the absence of the CDR project and is therefore not eligible to count towards Crediting. The Biomass Feedstock Accounting Module 1v1.23 sets out requirements for establishing ineligible biomass as part of the Counterfactual Storage Eligibility criteria. The Biomass Feedstock Accounting Module 1v1.23 includes details for quantification of [math: CO_2e_{Counterfactual}].

7

8.30 Net CO2eCDR Removal Calculation

7.3

8.1 Calculation Approach

The biomass storage process typically involves a processing step followed by a burial step. The processing step may operate on a continual or batch basis and may involve single or mixed forms of biomass. Irrespective of whether the processing step is operated continually or batch wise or whether it involves single or mixed forms of biomass, the processing step yields a known amount of biomass containing a known amount of carbon. A 'Production Batch', [math: p], is then a an amount of processed biomass, produced over a specific time period to be mutually agreed between Isometric and Project Proponent (e.g., a day, week, or month).

An ‘Burial Batch’, [math: n], is a single burial activity where a quantity of biomass is buried at an approved storage site. The Burial Batch consists of the biomass from the processing step which is buried for durable storage.

The approach for emissions calculations here is based on Burial Batches and the specific calculation of net CO₂e removal for each Burial Batch. The following sections outline the process for calculating the net CO₂e removed for each specific Burial Batch of biomass processed and associated biomass burial, defined as a Removal.

The Reporting Period for shallow subsurface biomass storage projects represents an interval of time over which removals are calculated and reported for verification. When total net CO₂e removals must be calculated for a Reporting Period, for example during submission of Claimed Removals in a GHG statement, it is calculated as the sum of removals during the Reporting Period:

[math: CO_2e_{Removal,\ RP} = \sum_{n=1}^{k} CO_2e_{Removal,\ n}]

(Equation 1)

Where

• [math: k] = number of Burial Batches [math: n]
• [math: CO_2e_{Removal,\ RP}] = the total net CO₂e removal for Reporting Period [math: RP], in tonnes of CO₂e
• [math: CO_2e_{Removal,\ n}] = the total net CO₂e removal for Burial Batch [math: n] occurring in Reporting Period [math: RP], in tonnes of CO₂e, see Section 7.38.2, Equation 2

Note: Reversals occur after Credits have been issued so are not included in this equation. See Sectionthe 5.6relevant section of the Isometric Standard for further information.

7.3

8.2 Calculation of CO₂eRemoval, n

Net CO₂e removal for a process biomass storage Project can be calculated as follows. Note that the calculation is completed for a discrete batch, [math: n], of biomass that is buried (‘Burial Batch’). The final net CO₂e quantification must be conservatively determined, giving high confidence that at least the estimated amount of carbon dioxide was removed.

[math: CO_2e_{Removal,\ n} = CO_2e_{Stored,\ n}\ –\ CO_2e_{Counterfactual,\ n}\ - \\ CO_2e_{Emissions,\ n}]

(Equation 2)

Where

• [math: CO_2e_{Stored,\ n}] is the total CO₂ removed from the atmosphere and durably stored as organic carbon for batch n, in tonnes of CO₂e, see Section 7.38.3
• [math: CO_2e_{Counterfactual,\ n}] is the total counterfactual CO₂ removed from the atmosphere and durably stored as biogenic carbon in the absence of the Project, for batch n, in tonnes of CO₂e, see Section 7.38.4
• [math: CO_2e_{Emissions,\ n}] is the total GHG emissions for batch [math: n], in tonnes of CO₂e, see Section 7.38.5

7.3

8.3 Calculation of CO₂eStored, n

[math: CO_2e_{Stored}] represents the amount of CO₂ (stored as organic carbon, C) that is buried and stored in the shallow subsurface. This is the gross amount stored for each batch burial and does not account for reversals of storage from the storage formation.

The total amount of CO₂ contained in the buried biomass can be calculated as follows.

Where all biomass production batches are composited prior to burial:

[math: CO_2e_{Stored,\ n} = \frac{C_{Biomass,\ n}\cdot m_{Bur,\ n}}{C_{CO_{2}}}]

(Equation 3)

Where biomass production batches are not blended prior to burial:

[math: CO_2e_{Stored,\ n} = \sum_{p=1}^{j} \bigg(\frac{C_{Biomass,\ p}\cdot m_{Bur,\ p}}{C_{CO_{2}}} \bigg)]

(Equation 4)

Where:

• [math: n] = Burial Batch
• [math: p] = Production Batch
• [math: j] = total number of Production Batches in Burial Batch ([math: n])
• [math: CO_2e_{Stored,\ n}]= the total CO₂ removed for batch [math: n], in tonnes of CO₂e
• [math: C_{Biomass,\ n (p)}] = the concentration as weight percent (%wt) of carbon in the biomass buried for Burial Batch [math: n] OR for each production batch [math: p] included in Burial Batch [math: n]
• [math: m_{Bur,\ n (p)}]= the total mass of biomass emplaced via burial (tonne) for Burial Batch [math: n] OR for each production batch [math: p] included in Burial Batch [math: n]
• [math: C_{CO_{2}}] = the content of C in CO₂ (as a mass percent)

7.3

8.3.1 Measurements - CO₂eStored, n

Calculation of [math: CO_2e_{Stored}] requires two primary measurements:

• [math: C_{Biomass}] - %wt of C in the biomass and
• [math: m_{Bur}] - total mass of the biomass

7.3

8.3.1.1 Biomass Carbon Content Measurement

Method A: Measure every Batch

Using this method, the carbon content of every Burial Batch must be ascertained through direct measurement, either by:

1. Sampling the Burial Batch (which may be blended, or non-blended)
2. Sampling all constituent Production Batches which comprise the Burial Batch, and calculating the carbon content of the Burial Batch through a linear weighted combination of the carbon contents of these Production Batches, as given in Equation 3.

• Note that in the case of an unblended Burial Batch, the Burial Batch originates from only a single Production Batch, by definition, and no calculation is required

For the acceptable minimum number of samples to take per sampled Batch, see Minimum number of samples per Batch below. If multiple samples are taken per Batch, the average carbon content of these samples must be used.

Method B: Sampling a Production Process

For a given Production Process of a feedstock, samples must be taken directly for at least 30 Production Batches, to ensure there is enough data to estimate carbon content for future Production Batches with appropriate statistical significance. Until this threshold is reached, Method A must be used.

Subsequently, samples must be taken at least every 10 Production Batches.

For the acceptable minimum number of samples to take per Batch, see Minimum number of samples per Batch below.

For batches which are not sampled, carbon content must be conservatively estimated, as follows:

[math: C_{Biomass} = \mu_{CC} - \sigma_{\overline{CC}}]

(Equation 5)

[math: \sigma_{\overline{CC}} = \frac{\sigma_{CC}}{\sqrt{n_{samples}}}]

(Equation 6)

where:

• [math: \sigma_{\overline{CC}}] is the standard error of the mean of carbon content, across all eligible samples for this Production Process
• [math: \sigma_{CC}] is the standard deviation of carbon content, across all eligible samples for this Production Process
• [math: n_{samples}] is the number of eligible samples for this Production Process
• [math: \mu_{CC}] is the mean carbon content of all eligible samples for this Production Process

Eligible samples are those taken in the previous 6 months before a specific Production Batch was produced. Older samples may not be used.

Additionally, batches must be subject to random sampling, to alleviate the risk of any given batch containing a substance with a substantially different carbon content.

A random sampling approach must be agreed and documented in the Project Design Document, whereby Isometric will contact the Project Proponent on randomly selected days, at an agreed cadence, which must be no less frequent than once per month, on average. Once contacted, the Project Proponent must sample the carbon content of the subsequent batches processed.

If the Project Proponent is unable to carry this random sampling out on 3 occasions within a 6 month period, or within a 6 month period more than 3 measurements are below 3 SD from the mean, this will trigger a Project review by Isometric.

If there is a significant change to a Production Process for a feedstock, which is likely to alter the average carbon content of the feedstock, or if significant deviations in carbon content are detected, the feedstock should be considered as a new Production Process. This means that sampling must be restarted, with all prior samples no longer able to be used for estimating carbon content.

Minimum number of samples per Batch

Process for handling carbon content measurement outliers

This process applies only if method B is used to calculate carbon content and should be used whether the a batch was sampled or not. For a given Production Process, an Outlier is defined as any individual sample which lies more than 3 standard deviations, [math: \sigma_{CC}], above or below the mean. To minimize the potential overall impact of outlier measurements, all carbon content measurement outliers must be handled via the applying the technique of "winsorization”, as follows.

For a given measurement, [math: m], the winsorized measurement [math: m_w] is defined as follows:

• For a measurement [math: m] where [math: m > \mu + 3\sigma_{CC}], [math: m_w = \mu + 3\sigma_{CC}]
• For a measurement [math: m] where [math: m < \mu - 3\sigma_{CC}], [math: m_w = \mu - 3\sigma_{CC}]

Where [math: \mu] and [math: \sigma_{CC}] are calculated from all carbon content samples from the same Production Process taken within 6 months of the removal for which we are calculating the carbon content. For estimating the carbon content from sampled batches, only historical samples should be used to calculate [math: \mu] and [math: \sigma_{CC}] and not samples from the batch being calculated. The standard deviation, [math: \sigma_{CC}], should be calculated with the formula for sample standard deviation.

The winsorized measurement, [math: m_w], must be used for the determination of carbon content.

This winsorization process must only be applied once a minimum number of 30 measurements have been taken, to ensure statistical significance.

7

8.3.3.1.2 Measurement of Mass of Biomass Buried

Any scale used must have a current certification in accordance with applicable local, state, or federal regulations for legal-for-trade weights and measures. Testing and calibration of scales must utilize certified weights in accordance with local, state, or other regulations, calibration weights must meet NIST Handbook 44 specifications², and scale testing and calibration must be performed by a state certified entity.

The total mass buried may also be determined by other methods, such as use of a calibrated flow meter and density measurement, or use of calibrated on site weigh scales for smaller containers, where such methods are viable and justified. Note that, due to the typical viscosity of biomass, the use of flow meters is not often viable and can result in poor data quality.

7

8.3.3.2 Required Records & Documentation - CO₂eStored, n

The Project Proponent must maintain the following records as evidence of gross CO₂e stored in buried biomass:

• weigh scale tickets for each delivery of biomass (arrival and departure weights) or other equivalent records
• analytical results for each ASTM D5291, or equivalent, analysis for carbon content of biomass from each batch as required
• Documentation of any biomass losses during burial operations and estimates of quantity lost

Records of all carbon analyses and burial masses (e.g. weigh scale tickets) must be maintained by the burial facility and provided for verification purposes for a period of five years after the end of the monitoring period.

7

8.3.3.34 Other Considerations - CO₂eStoredeStored, n

7.3

8.4 Calculation of CO₂eCounterfactual, n

The calculation of [math: CO_2e_{Counterfactual,\ n}], is determined by the requirements of the Biomass Feedstock Accounting Module 1.23.

7.3

8.5 Calculation of CO₂eEmissions, n

[math: {CO}_{2}^{}e_{Emissions,\ RP}^{}] is the total quantity of GHG emissions associated with a Reporting Period [math: RP]. This can be calculated as:

[math: {CO}_{2}^{}e_{Emissions,\ RP}^{}\ = \ {CO}_{2}^{}e_{Establishment,\ RP}^{}\ + \ {CO}_{2}^{}e_{Operations,\ RP}^{} + \ {CO}_{2}^{}e_{End-of-life,\ RP}^{}+ \ {CO}_{2}^{}e_{Leakage,\ RP}^{}]

(Equation 7)

Where:

• [math: {CO}_{2}^{}e_{Emissions,\ RP}^{}] - the total GHG emissions for a Reporting Period, RP, in tonnes of CO₂e.
• [math: {CO}_{2}^{}e_{Establishment,\ RP}^{}] - the total GHG emissions associated with project establishment for a RP, in tonnes of CO₂e, see Section 8.5.1
• [math: {CO}_{2}^{}e_{Operations,\ RP}^{}] - the total GHG emissions associated with operational processes for a RP, in tonnes of CO₂e, see Section 8.5.2
• [math: {CO}_{2}^{}e_{End-of-life,\ RP}^{}] - the total GHG emissions that occur after the RP and are allocated to the RP, in tonnes of CO₂e, see see Section 7.38.5.43.
• [math: {CO}_{2}^{}e_{Leakage,\ RP}^{}] - represents GHG emissions associated with the Project’s impact on activities that fall outside of the system boundary of a project, over a given Reporting Period, in tonnes of CO₂e, see Section 7.38.5.54.

Note: Reversals occur after Credits have been issued so are not included in this equation. See Section 5.6 of the Isometric Standard for further information. Risk of reversal information is given in Appendix 2: Risk of Reversal Questionnaire, with further information provided within the relevant storage module storage module.

The following sections set out specific quantification requirements for each variable.

7.3

8.5.1 Emissions allocation

Emissions that occur relating to a batch, [math: n], must be included in the reporting of emissions associated with that batch and may not be allocated across multiple batches. Allocation across multiple batches must be agreed with Isometric on a case by case basis.

Embodied emissions which relate to multiple batches may be allocated in line with the allocation rules set out in the Embodied Emissions Accounting Module v1.0.

When the Project Proponent is planning to cease operations within a given storage site, the monitoring emissions required for post-closure monitoring must be calculated and allocated to the remaining removals taking place at the storage site. If that is not possible, the Project Proponent should allocate those emissions to other projects and/or storage sites they conduct removal operations at, in agreement with Isometric. If for any reason emissions are not appropriately allocated, the Reversal process will be triggered in accordance with Isometric Standard, to account for any remaining monitoring emissions.

In instances where monitoring activities are shared between entities, for example if multiple companies buried biomass into the same storage infrastructure, the emissions associated with these activities must be allocated proportionally between the entities.

7.3.5.2 Calculation of CO₂eEstablishment, RP

GHG emissions associated with [math:project CO_2e_{Establishment, RP}]establishment should include all historic emissions incurred as a result of project establishment, including but not limited to the SSRs set out in Table 1.

Project establishment emissions occur from the point of project inception upto untilthe moment before the first Reportingremoval Periodactivity takes place. EstablishmentGHG emissions associated with project establishment may be accounted for in the following ways, with the allocation method selected and justified by the Project Proponent in the PDD:

• As a one time deduction to the first Reporting Period(s)
• Allocatedamortized over the first half of the anticipated project lifetime, as annual emissions
• Allocatedor per output of product. (i.e.,Requirements perfor tonamortization CO2are removed)outlined basedin onSection estimated total production over the project lifetime

The anticipated lifetime7 of the ProjectGHG shouldAccounting beModule basedv1.1.

7.3

8.5.32 Calculation of CO₂eOperations, RP

GHG emissions associated with [math: CO_2e_{Operations, RP}] should include all emissions associated with operational activities including but not limited to the SSRs set out in Table 1.

[math: CO_2e_{Operations, RP}] emissions occur over the Reporting Period for the period being credited and are applicable to that Reporting Period only. [math: CO_2e_{Operations, RP}] emissions must be attributed to the Reporting Period in which they occur. Allocation may be permitted in certain instances, on a case by case basis in agreement with Isometric.

7.3

8.5.43 Calculation of CO₂eeEnd-of-life

[math: CO_2e_{End-of-lifeLife, RP

CO2eEnd-of-life, RP}] includes all emissions associated with activities that are anticipated to occur after the ReportingCrediting Period, butuntil arethe directlyend orof indirectlythe Project Commitment Period. This includes activities related to the Reporting Period. For example this could include ongoing sampling activitiesmonitoring for MRV for the specific deployment (directly related) if applicable, or end-of-life emissions for project facilities (indirectly related to all deployments)Reversals.

GHG emissions associated with [math: CO_2e_{End-of-Life, RP}] may occur from the end of the Reporting Period onwards, and typically through to completion of project site deconstruction and any other end-of-life activities.

GHG emissions associated with activities that are directly related to each deployment must be quantifiedestimated asupfront part of that Reporting Period. GHG emissions associated with activities that are indirectly related to all deployments may beand allocated in the same waysway as set out infor calculation of [math: CO_2e_{Establishment, RP}].

Given the uncertain nature of [math: CO_2e_{End-of-Life, RP}] emissions, assumptions must be revisited at each CreditingReporting Period and any necessary adjustments made. Furthermore, if there are unexpected [math: CO_2e_{End-of-Life, RP}] emissions associated with a Reporting Period, or the Project as a whole, that occur after the Project has ended, then the Reversal process will be triggered to compensate for any emissions not accounted for.

7.3

8.5.54 Calculation of CO₂eLeakage, RP

[math: CO_2e_{Leakage, RP}] includes emissions associated with a project's impact on activities that fall outside of the system boundary of a project.

It includes increases in GHG emissions as a result of the Project displacing emissions or causing a knock on effect that increases emissions elsewhere. This includes emissions associated with activity-shifting, market leakage and ecological leakage.

It is the Project Proponent's responsibility to identify potential sources of leakage emissions.

[math: CO_2e_{Leakage, RP}] emissions must be attributed to the Reporting Period in which they occur. Allocation may be permitted in certain instances, on a case by case basis in agreement with Isometric.

7.3

8.5.65 Emissions Accounting

GHG emissions accounting must be undertaken in alignment with the GHG Accounting Module v1.1, which ensures a consistently rigorous standard in how GHG emissions are quantified and reported between different CDR Projects and approaches. This sectionincludes:

• Requirements for data quality, including a detailed data quality hierarchy for activity data and emission factors;
• Consideration of themateriality Protocolin outlinesemissions accounting;
• Emissions amortization requirements;
• Co-product forallocation EW emissionsrequirements;
• By-product accounting relating to energyinputs useto the process that are by-products, transportationfor example [list of by-products]; and
• Waste input accounting relating to inputs to the process that are wastes, andfor embodiedexample emissions[list associatedof withwaste ainputs].

7.3.5.6.1