Release note: Publication of the Puro Biomass Sourcing Criteria, Version 1.3 

Puro.earth has published version 1.3 of the Biomass Sourcing Criteria, approved by Puro’s Scientific Advisory Board on 3 September 2026. The main update is the introduction of a new Section 3 – Biomass Counterfactual Storage, together with several clarifications and editorial improvements to the existing criteria.  

New requirements for biomass counterfactual storage 

Version 1.3 introduces an additional safeguard to ensure that biomass-based CORCs also represent a near-term climate benefit relative to what would most plausibly have happened to the biomass without the CDR activity.  

For biomass associated with CORC issuance, Suppliers must either demonstrate that the counterfactual scenario results in negligible carbon storage, or quantify the carbon that would have remained stored and deduct it from the amount eligible for CORC issuance.  

To support this assessment, the criteria provide a table of counterfactual situations that are deemed to result in negligible storage, together with the types of evidence that can be used to substantiate each case. These counterfactual situations are intended to provide a practical framework for assessing different biomass sources. 

Implications for Suppliers and Auditors 

The new requirements apply to all Production Facilities subject to a Methodology that references the Puro Biomass Sourcing Criteria, with transition provisions based on the Crediting Period Start Date.  

• Facilities with a start date on or after 1 January 2029 must comply from their first Production Facility Audit.  

• Facilities with an earlier start date must comply no later than their Crediting Period Renewal, with voluntary early adoption permitted.  

For Suppliers, this means documenting the applicable counterfactual scenario for relevant biomass sources and maintaining sufficient supporting evidence. Where required, Suppliers must also quantify counterfactual carbon storage and update the assessment when sourcing conditions or underlying assumptions materially change.  

For Auditors, the Supplier’s counterfactual assessment and supporting evidence become part of demonstrating compliance with the applicable Biomass Sourcing Criteria. 

Version 1.3 also includes correction of typographical errors, clarification of Category C description, and formatting improvements which enable easier referencing of criteria and evidence options.