Puro.earth Biochar Methodology Update: Offstream’s Key Insights for Navigating the Preliminary Changes

Written by Grant Faber. Grant is Head of Carbon Compliance at Offstream, where he ensures internal and customer compliance across numerous monitoring, reporting, and verification (MRV) methodologies. Working in carbon tech since 2018, he has assisted countless startups and other organizations across the space with MRV, life cycle assessment, and strategy development.

The biochar industry is constantly evolving, and with it, the methodologies that govern carbon credit certification and project validation. For biochar project developers, staying on top of these changes is crucial to ensuring long-term success and compliance. The release of a proposed Puro.earth biochar methodology, set to take effect by the end of 2025, will introduce notable changes to how biochar projects are certified.

With these updates on the horizon, our Head of Carbon Compliance, Grant Faber, has been closely monitoring these developments to ensure our clients are well prepared for the transition. Here’s what Grant has to say about the new rules and what biochar project developers need to know.

New Methodology Timeline

Certification and carbon removal credit generation through Puro currently involves both Facility Audits, which allow biochar production sites to be listed on the Puro registry, and Output Audits, which allow carbon removal credits to be generated on an ongoing basis. Each type of audit has specific rules, documentation requirements, and auditor expectations.

Once adopted, the updated methodology is expected to be published by the end of June 2025 and take full effect by December 1st, 2025, with optional implementation for Facility Audits starting as early as August. If Puro certifies a facility under the existing 2022 methodology before December, it can continue conducting Output Audits under the current guidelines until the end of its five-year crediting period.

What this means for you: 

Projects certified under the current Puro biochar methodology will remain valid throughout their crediting period but will need to align with the new framework upon renewal. The updated methodology is expected to govern both new project submissions and recertification efforts after the transition date, offering a clearer and more consistent structure moving forward.

Methodology Expansion and Increased Effort

The new methodology is far more comprehensive; it is nearly 10 times as long as its predecessor. It introduces new categories of emissions to account for and provides more detailed guidelines on biochar production as well as carbon storage monitoring over longer periods.

What this means for you: 

You’ll need to update your life cycle assessments (LCAs) and monitoring, reporting, and verification (MRV) approaches. This means updated and more detailed calculations of LCA categories such as expected biochar decay, baseline removals, and indirect emissions arising from factors such as market leakage and land-use change.

Costs and effort requirements for certification and monitoring will increase but so too will the credibility of generated credits. To align with strict and dynamic market expectations, developers will need to be meticulous in documenting and communicating every step from feedstock harvesting to long-term carbon storage.

New Coverage and Audit Category

The new methodology has expanded coverage to mobile biochar projects. They specifically allow a fleet of biochar reactors operating in a defined geographical space as an alternative to stationary biochar production facilities. 

Additionally, in addition to the familiar Facility Audits and Output Audits, there will now be a new category: Capacity Expansion Audits. These will enable certification of an increased capacity of credits generated via the addition of new reactors at existing sites or within the spatial extent of a mobile biochar production project.

What this means for you: 

Mobile units are now explicitly a viable option for CORC generation. 

Separately, if you plan on expanding your stationary or mobile facility during the course of its crediting period, you’ll need to conduct an additional audit to demonstrate that your increased capacity still meets all methodology requirements. This could entail additional site visits, more complex reports, and higher costs and effort levels for verification. As your operations grow, so will your documentation and reporting requirements. Stay ahead of the game by ensuring your facility has the proper plans in place to accommodate these changes.

Clarifications on Biomass Sourcing

The 2025 methodology no longer relies on the EBC Positive List for eligible feedstocks and instead defines its own allowed and disallowed categories. Puro is updating its biomass sourcing criteria to offer clearer guidance on allowable feedstocks, required evidence, and how to demonstrate sustainability. The updated guidance also clarifies requirements related to sources, batches, and categories of biomass feedstocks, as well as blending, stockpiling, and impurities.

What this means for you: 

You’ll need to ensure that your biomass is compliant with the updated sourcing criteria. It will remain important to keep detailed records of biomass acquisition covering items like sourcing information, quality, and batch categorization. If your biomass comes from different suppliers or types, you’ll have more administrative work to ensure compliance.

You will also need to mitigate risks of stockpiling such as degradation of biomass quality, contamination, and loss of traceability over time. Implementing clear inventory controls, labeling systems, and storage protocols to prevent mixing of batches and exposure to contaminants will help on this front. Additional procedures may also be required to monitor and manage impurities like plastics, metals, glass, minerals, and micropollutants.

Biochar Quality and Carbon Storage Durability 

The expected duration of carbon storage has been extended to 200 years, aligning with the new European Union rules on carbon storage. This creates a more standardized approach across different carbon market standards but means biochar projects must provide stronger evidence and use slightly different calculation methods for carbon storage. Puro also provides some guidance on optional random reflectance testing that may indicate  longer-term storage if project developers want to demonstrate say 500 - 1000 year permanence.

What this means for you: 

The 200-year storage period requirement means you will need to use updated values for expected losses from biochar decay. For a sense of how this might affect credit generation per tonne of biochar, refer to section 6.2 of the proposed methodology and experiment with the regression data provided. We’ve included a simplified example below to help you understand the impact of the updated model. 

Summary of Key Changes

Comparison:

Same Biochar Batch (1,000 t biochar, 80% organic carbon content, H/Cₒᵣ_g = 0.3, 20°C soil, and $200/CORC)

Takeaway: 

The updated 2025 model results in slightly fewer credits for the same batch of biochar due to the extended storage timeframe and confidence interval. While slightly more conservative, the new model better reflects biochar’s durability and recent scientific advances in a way that will help boost confidence.

International Carbon Credit Markets

The updated methodology contains requirements related to (a) assessing whether projects are subject to Paris Agreement Crediting Mechanism (Article 6) requirements; (b) ensuring proper reporting of the trade of covered credits; and (c) proper disclosure to Puro. This will help avoid double counting of credits in national inventories and with international crediting markets such as CORSIA.

What this means for you:

If your project is registered under the new methodology and operates in a country participating in the Paris Agreement (every country except Iran, Libya, Yemen, and the United States), you’ll need to evaluate whether Article 6 applies. For example, if your project generates credits that could be used toward another country’s nationally determined contribution (NDC), you may need to coordinate with the relevant national authority to create a corresponding adjustment. This ensures the credits aren’t double-counted in both your registry and the country’s carbon accounting.

Although Article 6 guidance for durable carbon removals is still emerging, now is the time to:

• Track whether your host country has Article 6 procedures in place or under development
• Begin documenting the intended use of credits whether for voluntary buyers, compliance markets like CORSIA, or potential Article 6 transfers
• Flag potential interactions with national inventories and prepare to disclose relevant information in line with future requirements

Staying ahead of these developments not only supports compliance—it also boosts buyer confidence and positions your project as high integrity in the eyes of international stakeholders.

Expanded End Uses and Clarifications

Table 3.2 in the new methodology explicitly covers a wide range of permissible and impermissible end uses for biochar. While application to agricultural soil is the most common intended use, Puro will now allow for expanded applications across agriculture, animal husbandry, waste management, environmental management, and the built environment. Additional details also clarify what needs to be reported regarding cascading uses and working with intermediary entities.

Referenced Table 3.2 can be found on Page 46 of the new methodology, ending on Page 54.

‍What this means for you: 

With more clarity around allowable end uses, you can better plan for your biochar’s end use and assess trade-offs associated with different options. There are different conditions and evidence requirements among end uses, and it will be important to track those and shape monitoring and data collection plans accordingly to ensure continued compliance.

Detailed Facility Engineering Requests

Significant clarifications and expansions on acceptable biomass conversion processes (e.g., pyrolysis, gasification, etc.) have been made. Puro now outlines additional requirements around carbonization conditions, modes of operation, fossil fuel use, waste management, leaks, safety considerations, methane control, stockpiling, impurity management, and production facility monitoring.

What this means for you:

You’ll need to ensure that your process, and specifically your carbonization reactor, complies or could be made to comply with new production requirements. You will likely need to implement additional process monitoring and reporting. Some of these upgrades will be frontloaded and handled by reactor manufacturers to provide developers with more assurances about eligibility before facility commissioning. Maintain close coordination with your manufacturers to ensure initial and continued eligibility.

Actionable Takeaways for Developers 

Timeline Management: Keep a close eye on the transition timeline. If you’re aiming for approval under the 2022 methodology, make sure your project complies and is certified via a Facility Audit this year. There’s still time to start this process, but moving quickly is key. Contact us if you would like assistance getting started or moving your certification process along.

Updated MRV and LCA: As methodologies evolve, your MRV and LCA approaches will need to reflect new emissions factors, biomass sourcing rules, monitoring processes, and extended carbon storage projections (especially with the new 200-year storage window). Not sure how to update your systems? We can guide you through the necessary changes as your LCA and MRV partner. 

Expanded Audit Preparation: If you’re planning on scaling your facility at any point in its lifetime, you’ll need a plan for the new Capacity Expansion Audits. Keep your facility’s documentation and reporting practices up to date to stay ahead of the game. We can help ensure your project is aligned with the new audit standards and all documentation is in order.

Risk and Leakage Management: The new methodology puts a strong focus on managing emerging and dynamic topics in carbon removal verification such as market leakage and ecological risks. At Offstream, we specialize in helping you assess new trends and mitigate risks, ensuring your project remains in compliance while maximizing its climate impact.

Biochar Methodology Got You Burned Out? Let Offstream Handle the Heat.

By understanding these changes and preparing accordingly, biochar developers can ensure they remain compliant under the new methodology. While navigating these updates can be complex, Offstream is here to guide you. We closely monitor the latest standards and are ready to help you update your MRV and LCA tools, prepare for audits, and ensure your project complies with updated rules as they are published.

Contact us today to make sure you’re ready for what’s next!