Grain Ecosystem

Before you read this article, you might also want to read 

In biochar production, feedstock is more than just a raw material: it’s the foundation of your carbon removal claim. The type of biomass you use, where it comes from, and what happens to it when it’s not turned into biochar all play a central role in whether your project qualifies for carbon credits under today’s most trusted standards. 

But different registries have different rules, and proving your feedstock is sustainable means more than saying it’s a “residue”: it means providing evidence that it meets environmental safeguards, avoids displacing beneficial uses, and is traceable from source to site as needed. 

This article breaks down what it takes to prove feedstock sustainability for biochar production across some key feedstock categories, and how the four major carbon Standards (Puro.Earth, Verra VCS, Climate Action Reserve, and Isometric) define and assess that proof. 

While each standard has its own definitions and documentation requirements, there are a few things they all care about when it comes to feedstock sustainability. Across Puro.Earth, Verra VCS, CAR, and Isometric, you’ll be expected to: 

What counts as valid evidence varies, but generally includes contracts, management plans, certifications, receipts, public records, and signed declarations. 

While all standards require projects to prove that their feedstock is sustainable, each one defines that sustainability a bit differently. Some prioritize traceability and legality, others focus on counterfactual carbon storage, baseline scenarios, or leakage risks. In the next section, we break down how the four main carbon standards —Puro.Earth, Verra VCS, Climate Action Reserve, and Isometric— approach feedstock sustainability and what kind of evidence they require, regardless of the biomass type you’re working with. 

Accepted Proof by Standard – All Feedstock Types 

To determine which feedstocks are eligible under each methodology, refer to 

Before diving into each category, there are some requirements that apply to all feedstocks. After reviewing these general requirements, consult the specific criteria for your feedstock type. Each standard outlines the type of documentation accepted to demonstrate compliance. Gathering and submitting the right records is essential. 

Puro.Earth requires that biomass sourcing must not harm natural ecosystems or result in unmitigated indirect effects. Any potential impurities, micropollutants, toxic elements (PTEs), or biological hazards in the feedstock must be properly managed during biochar production. To ensure this, CO₂ Removal Suppliers must have ongoing monitoring procedures in place to assess both the sustainability and eligibility of all biomass used. 

Verra Verified Carbon Standard (Verra VCS) 

To qualify under Verra VCS, feedstocks must: 

Projects must conduct a five-year retrospective assessment to demonstrate the feedstock is waste biomass, following 

For all projects, biomass sources must be confirmed as included on the 

 and must comply with Environmental Safeguards. Project developers must also identify the baseline fate of each type of feedstock —such as combustion, decomposition, or another disposal method— and provide evidence supporting that baseline scenario.  

In cases where biomass is diverted from a power plant, the project must demonstrate that the facility was not supply-limited, meaning the amount of energy the power plant is providing is not reduced due to a lack of feedstock. Additionally, the project must provide chain-of-custody documentation proving its origin and traceability. 

Isometric assesses three core factors for all feedstocks: 

Isometric requires projects to assess what would have happened to the biomass in the absence of the project. This includes the baseline fate (e.g., decomposition, burning) and the counterfactual storage (the portion of carbon that would have remained stored in long-lived wood products or undisturbed ecosystems). 

Isometric also evaluates two types of market leakage: 

Market Leakage documentation may include: 

Because this is a broad topic, we’ve broken it down into separate articles by feedstock type. Click below to explore the one most relevant to you: 

This is a summary table to help you compare key requirements across standards, but it's just a snapshot. Please make sure to read the full article for all the details. 

Securing Your Feedstock How to Prove it’s Sustainable Summary 2

*Table S10. You can also download the full PDF 

Table S10

A practical guide to proving feedstock sustainability for biochar projects under Puro.Earth, Verra VCS, CAR, and Isometric.

origination

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<p></p><p><em>Before you read this article, you might also want to read </em><a href="https://grainecosystem.com/knowledge-hub/articles/67362abaea63cff8e65976e2" target="_blank" rel="noopener noreferrer"><em>Biochar: Feedstock Sourcing & Eligibility for every Standard</em></a><em> </em></p><p>In biochar production, feedstock is more than just a raw material: it’s the foundation of your carbon removal claim. The type of biomass you use, where it comes from, and what happens to it when it’s not turned into biochar all play a central role in whether your project qualifies for carbon credits under today’s most trusted standards. </p><p>But different registries have different rules, and proving your feedstock is sustainable means more than saying it’s a “residue”: it means providing evidence that it meets environmental safeguards, avoids displacing beneficial uses, and is traceable from source to site as needed. </p><p>This article breaks down what it takes to prove feedstock sustainability for biochar production across some key feedstock categories, and how the four major carbon Standards (Puro.Earth, Verra VCS, Climate Action Reserve, and Isometric) define and assess that proof. </p><h2>Core Requirements Across All Standards </h2><p>While each standard has its own definitions and documentation requirements, there are a few things they all care about when it comes to feedstock sustainability. Across Puro.Earth, Verra VCS, CAR, and Isometric, you’ll be expected to: </p><ul class="bullet"><li value=1>Prove the biomass is waste — not purpose-grown, not marketable, and not competing with other beneficial uses. </li></ul><ul class="bullet"><li value=1>Demonstrate environmental safeguards — including protection of soil health, biodiversity, water resources, and carbon stocks. </li></ul><ul class="bullet"><li value=1>Provide traceability — documenting the origin, type, quantity, and transport of every biomass delivery. </li></ul><ul class="bullet"><li value=1>Show the baseline fate — explaining what would have happened to the feedstock in the absence of the project (e.g., decomposition, open burning, left unused). </li></ul><ul class="bullet"><li value=1>Account for leakage risks — in some cases, showing that your feedstock sourcing doesn’t cause unintended emissions or market distortions. </li></ul><p>What counts as valid evidence varies, but generally includes contracts, management plans, certifications, receipts, public records, and signed declarations. </p><p>While all standards require projects to prove that their feedstock is sustainable, each one defines that sustainability a bit differently. Some prioritize traceability and legality, others focus on counterfactual carbon storage, baseline scenarios, or leakage risks. In the next section, we break down how the four main carbon standards —Puro.Earth, Verra VCS, Climate Action Reserve, and Isometric— approach feedstock sustainability and what kind of evidence they require, regardless of the biomass type you’re working with. </p><h2>Accepted Proof by Standard – All Feedstock Types </h2><p>To determine which feedstocks are eligible under each methodology, refer to <a href="https://grainecosystem.com/knowledge-hub/articles/67362abaea63cff8e65976e2" target="_blank" rel="noopener noreferrer">this article</a>. </p><p>Before diving into each category, there are some requirements that apply to all feedstocks. After reviewing these general requirements, consult the specific criteria for your feedstock type. Each standard outlines the type of documentation accepted to demonstrate compliance. Gathering and submitting the right records is essential. </p><h3>Puro.Earth</h3><p>Puro.Earth requires that biomass sourcing must not harm natural ecosystems or result in unmitigated indirect effects. Any potential impurities, micropollutants, toxic elements (PTEs), or biological hazards in the feedstock must be properly managed during biochar production. To ensure this, CO₂ Removal Suppliers must have ongoing monitoring procedures in place to assess both the sustainability and eligibility of all biomass used. </p><p>Suppliers must:  </p><ul class="bullet"><li value=1>Declare all biomass sources that are or will be supplied to the Production Facility and keep this list continuously updated throughout the crediting period. </li></ul><ul class="bullet"><li value=1>Maintain detailed records for every biomass batch (also referred to as lots, deliveries, or consignments). These records must allow for verification of volume, category, origin, and sustainability status, and be supported by evidence when required. </li></ul><h3>Verra Verified Carbon Standard (Verra VCS) </h3><p>To qualify under Verra VCS, feedstocks must: </p><ul class="bullet"><li value=1>Be biogenic waste biomass, not purpose-grown. </li></ul><ul class="bullet"><li value=1>Be material that would have decayed or been combusted without energy recovery. </li></ul><ul class="bullet"><li value=1>Be domestically sourced (no imports). </li></ul><p>Projects must conduct a five-year retrospective assessment to demonstrate the feedstock is waste biomass, following <a href="https://verra.org/wp-content/uploads/2025/06/VM44_v1.2_clean-1.pdf" target="_blank" rel="noopener noreferrer">Appendix 2</a> of the methodology (p. 50): </p><ul class="bullet"><li value=1>If the source is known and the biomass was unused, documentation such as historical management plans or receipts can be provided —or a signed attestation from the supplier— confirming that the biomass was not used for any alternative purpose in the five years prior to the project. </li></ul><ul class="bullet"><li value=1>If the biomass was previously used, the project must demonstrate that the available supply is sufficient to meet both project and non-project demand without disruption. This requires a historical analysis of biomass volumes and future projections, supported by documentation and/or attestations. </li></ul><ul class="bullet"><li value=1>If the biomass source is unknown (e.g. sourced from a residue market), the project must show that there is a regional surplus of at least 25% for that type of biomass. This requires a supply and demand analysis based on the past five years, or at minimum one year of data if it can be shown to be representative. </li></ul><h3>Climate Action Reserve (CAR)<span>unknown node</span> </h3><p>For all projects, biomass sources must be confirmed as included on the <a href="https://www.climateactionreserve.org/wp-content/uploads/2024/03/CAR-Eligible-Biochar-Feedstocks-List-2024-03-19.pdf" target="_blank" rel="noopener noreferrer">applicable Feedstocks List</a> and must comply with Environmental Safeguards. Project developers must also identify the baseline fate of each type of feedstock —such as combustion, decomposition, or another disposal method— and provide evidence supporting that baseline scenario.  </p><p>In cases where biomass is diverted from a power plant, the project must demonstrate that the facility was not supply-limited, meaning the amount of energy the power plant is providing is not reduced due to a lack of feedstock. Additionally, the project must provide chain-of-custody documentation proving its origin and traceability. </p><h3>Isometric </h3><p>Isometric assesses three core factors for all feedstocks: </p><ul class="bullet"><li value=1>Potential for Market Leakage: If feedstock is purchased, provide evidence that payments don’t incentivize overproduction. </li></ul><ul class="bullet"><li value=1>Counterfactual CO₂ Storage Scenario: Show that the biomass would release its carbon within 15 years, or estimate emissions and remaining carbon at year 15. </li></ul><ul class="bullet"><li value=1>Feedstock Purpose: Prove the feedstock is not purpose-grown. </li></ul><p>Isometric requires projects to assess what would have happened to the biomass in the absence of the project. This includes the baseline fate (e.g., decomposition, burning) and the counterfactual storage (the portion of carbon that would have remained stored in long-lived wood products or undisturbed ecosystems). </p><p>Isometric also evaluates two types of market leakage: </p><ul class="bullet"><li value=1>If payment for feedstock may encourage increased production, the project must show that this does not lead to land-use change. </li></ul><ul class="bullet"><li value=1>If the feedstock was previously used in a way that provided environmental services (e.g., manure as fertilizer), the project must account for emissions from the replacement activity. </li></ul><p>Market Leakage documentation may include: </p><ul class="bullet"><li value=1>Feedstock purchase records (price, quantity, date, buyer, seller) </li></ul><ul class="bullet"><li value=1>Cost comparisons proving the feedstock had no viable alternative use </li></ul><ul class="bullet"><li value=1>Signed statements if a third party was paid instead of the supplier </li></ul><p>For counterfactual storage: </p><ul class="bullet"><li value=1>Provide evidence that the biomass would have released its carbon within 15 years </li></ul><ul class="bullet"><li value=1>If this cannot be demonstrated, estimate the emissions that would have occurred by year 15 and the remaining stored carbon by year 50 </li></ul><h2>Feedstock-Specific Guidance </h2><p>Because this is a broad topic, we’ve broken it down into separate articles by feedstock type. Click below to explore the one most relevant to you: </p><ul class="bullet"><li value=1><a href="https://grainecosystem.com/knowledge-hub/articles/68af4afeb1d72ab2d7467d9e" target="_blank" rel="noopener noreferrer">Forestry Residues & Wood Waste </a></li></ul><ul class="bullet"><li value=1><a href="https://grainecosystem.com/knowledge-hub/articles/68af4c5bb1d72ab2d7467de3" target="_blank" rel="noopener noreferrer">Agricultural Residues</a> </li></ul><ul class="bullet"><li value=1><a href="https://grainecosystem.com/knowledge-hub/articles/68af4f9cb1d72ab2d7467e52" target="_blank" rel="noopener noreferrer">Manure & Animal Waste </a></li></ul><p>This is a summary table to help you compare key requirements across standards, but it's just a snapshot. Please make sure to read the full article for all the details. </p><h3>Summary: </h3><img src="/media/Securing Your Feedstock How to Prove itâs Sustainable Summary 2.jpg" alt="Securing Your Feedstock How to Prove itâs Sustainable Summary 2.jpg" width="744"  height="887"/><p>*Table S10. You can also download the full PDF <a href="https://onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1111%2Fgcbb.13102&file=gcbb13102-sup-0001-Supinfo.pdf" target="_blank" rel="noopener noreferrer">here</a> (p. 10).</p><img src="/media/TableS10.jpg" alt="TableS10.jpg" width="864"  height="1015"/><h2>Sources  </h2><ul class="bullet"><li value=1><a href="https://7518557.fs1.hubspotusercontent-na1.net/hubfs/7518557/Puro%20Biochar%20Methodology%20-%20Edition%202025%20-%20Approved%20Version%20-%20Pending%20Copy%20Edit.pdf" target="_blank" rel="noopener noreferrer">Puro.Earth. (June, 2025). Biochar Methodology, Edition 2025 V1.</a> </li></ul><ul class="bullet"><li value=1><a href="https://7518557.fs1.hubspotusercontent-na1.net/hubfs/7518557/Biochar%20Public%20Consultation%202025/02_Puro%20Biomass%20Sourcing%20Criteria%20v1.1%20-%20Draft%20for%20consultation.pdf" target="_blank" rel="noopener noreferrer">Puro.Earth (2025) Biomass Sourcing Criteria.</a> </li></ul><ul class="bullet"><li value=1><a href="https://verra.org/wp-content/uploads/2025/06/VM44_v1.2_clean-1.pdf" target="_blank" rel="noopener noreferrer">Verra (June, 2025). VM0044 Biochar Utilization in Soil and Non-Soil Applications, v1.2</a> </li></ul><ul class="bullet"><li value=1><a href="https://www.climateactionreserve.org/wp-content/uploads/2024/03/CAR-Eligible-Biochar-Feedstocks-List-2024-03-19.pdf" target="_blank" rel="noopener noreferrer">Climate Action Reserve. (March, 2024). Eligible Biochar Feedstock List.</a> </li></ul><ul class="bullet"><li value=1><a href="https://registry.isometric.com/module/biomass-feedstock-accounting" target="_blank" rel="noopener noreferrer">Isometric (2024). Biomass Feedstock Accounting.</a>  </li><li value=2><a href="https://onlinelibrary.wiley.com/doi/epdf/10.1111/gcbb.13102" target="_blank" rel="noopener noreferrer">Karan, S. K., Woolf, D., Azzi, E. S., Sundberg, C., & Wood, S. A. (2023). Potential for biochar carbon sequestration from crop residues: A global spatially explicit assessment. GCB Bioenergy, 15(12), 1424-1436, DOI: 10.1111/gcbb.13102</a></li><li value=3><a href="https://onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1111%2Fgcbb.13102&file=gcbb13102-sup-0001-Supinfo.pdf" target="_blank" rel="noopener noreferrer">Karan, et. al. (2023). Supplement.</a></li></ul><h2>Related content</h2><ul class="bullet"><li value=1><a href="https://grainecosystem.com/knowledge-hub/articles/67362abaea63cff8e65976e2" target="_blank" rel="noopener noreferrer">Biochar: Feedstock Sourcing & Eligibility for every Standard</a> </li></ul><ul class="bullet"><li value=1><a href="https://grainecosystem.com/knowledge-hub/articles/674763fc0f29280cdf023b34" target="_blank" rel="noopener noreferrer">How to Choose the Best Methodology for your Biochar Project</a> </li></ul><ul class="bullet"><li value=1><a href="https://grainecosystem.com/knowledge-hub/articles/682b51aa3c1b819385ca0d1d" target="_blank" rel="noopener noreferrer">Forestry Mensuration: Calculating Feedstock Volume</a> </li></ul><ul class="bullet"><li value=1><a href="https://grainecosystem.com/knowledge-hub/articles/688a6eb62492b585355e9fd3" target="_blank" rel="noopener noreferrer">The Importance of Laboratory Testing in Biochar Projects</a> </li></ul><ul class="bullet"><li value=1><a href="https://grainecosystem.com/knowledge-hub/articles/6814f3dae44bb4f2fc862292" target="_blank" rel="noopener noreferrer">How to Understand your Biochar Quality</a> </li></ul>

Securing Your Feedstock: How to Prove it’s Sustainable