Puro.earth Launches Public Consultation for Carbonated Materials Methodology Update

We are pleased to announce the launch of a public consultation for the update to the Puro.earth Carbonated Materials methodology for permanent Carbon Dioxide Removal (CDR) under the Puro Standard.

This update comes at a time of promising developments in this CDR pathway and reflects new technical and scientific advancements as well as increasing variety in approaches within the scope of Carbonated Materials . Additionally, the updated methodology aligns with the latest Puro General Rules and the ICVCM CCP.

The carbonated materials methodology covers CDR pathways that store atmospheric CO₂ permanently in the form of durable carbonate minerals. Alkaline industrial byproducts like steel slag, mine tailings, or end-of-life concrete, are typical feedstocks that react with CO₂ upon direct contact with the atmosphere or with CO₂ that was previously captured from biomass treatment or by direct air capture (DAC). Such reactions form rock-like carbonate minerals like calcium carbonate (CaCO₃), which are durable for more than 1000 years (IPCC, 2005)[1].

For this update, we collaborated with a working group of experts from academia, industry, and the non-profit sector, held four workshops, and interviewed other relevant stakeholders. We thank all of them for their invaluable contribution to the methodology development process.

Highlighted Changes in this Update

• Scientific sampling and quantification requirements to promote robustness: Following the best available scientific principles and approaches in sampling and quantitative analysis is crucial for accurate monitoring and robust carbon accounting. This update sets clear requirements for sampling and identifies eligible quantification approaches grounded in science.  
• Increased detail and specificity to promote transparency: In line with the evolution of Puro Standard methodologies more generally, the detailed rules in this update allow CORC buyers and the wider public to understand in detail the rigorous process and multitude of requirements project developers adhere to for the purpose of CORC accreditation.
• Updated life cycle emissions accounting to promote rigor: Precise and transparent life cycle accounting is essential to make sure that CORCs reflect net carbon removal. This update sets a cradle-to-gate system boundary and requires operational and embodied emissions to be reported separately, with detailed rules on which emission sources to include at each life cycle stage. It also sets clear rules for allocating emissions to co-products and for accounting for waste and recycled feedstocks, together with guidance on emission factors, level of detail and supporting evidence. As a result, life cycle assessments remain realistic and based on actual project operations, while being verifiable and comparable across projects.
• Improved baseline accounting to promote credibility: Counterfactual carbonation, the carbonation of the feedstock that would have occurred in the absence of the carbonated materials activity, is a crucial correction required for most projects. This update sets clear and conservative guidelines for baseline estimation based on modeling and/or measurements that ensure that 1 CORC equals 1 ton of CO₂ removed in addition to the counterfactual scenario.   
• Eligibility of emerging pathways to promote technological diversity: This update expands the scope of the Carbonated-Materials methodology to promising varieties of carbonated materials such as carbonated concrete and open-air carbonation of industrial residues in large, exposed settings like mine tailings facilities. For eligible carbonated concrete projects, the proposed rules introduce a targeted approach to emissions accounting that distinguishes the additional carbon removal by carbonisation from the product of the concrete material, which must be pre-existing independently of the carbon removal activity. This is subject to specific safeguards, including a verified Environmental Product Declaration (EPD) and production under an emissions compliance regime, while ensuring that all emissions associated with the carbon removal activity and counterfactual natural carbonation are accounted for.
• Uncertainty management to promote reliability: In line with general trends in the voluntary carbon market and engineered CO₂ removals, this update requires robust quantification of uncertainty by frequentist or Bayesian approaches for the different components of the carbon removal calculation (“CORC equation”) and introduces an uncertainty discount.
  

Public Consultation Period, and How to Participate

We invite all stakeholders, scientists, project developers, and other interested parties to review the draft methodology and provide feedback. Your insights during the public consultation period are invaluable to ensure the robustness and applicability of this methodology in supporting high-integrity carbon removals.

To participate, download the methodology draft and the feedback form . Please submit your insights and comments using the feedback form and email the completed form to contact@puro.earth by December 2^nd, 2026.

To submit feedback, please ensure to use the feedback form and use the following format for the email subject line: Public Consultation for Carbonated Materials Methodology Update 2026 – Submission – (Company name/Participant name).

Webinar

A webinar to present the methodology and answer stakeholder questions will be held on November 19^th at 10:00 a.m. EST / 4:00 p.m . CET.

Key Areas for Feedback

As part of this public consultation, we invite stakeholders to provide input on specific aspects of the draft methodology. In particular, we seek feedback on:

• Baseline estimation – Are the modeling and measurement options to quantify counterfactual carbonation appropriate and clear?
• Environmental risk requirements – Are the requirements comprehensive and proportionate to the potential risks of the different varieties of carbonated materials projects?
• Monitoring, quantification, and sampling – Are the requirements (e.g., sampling density and frequency) clear and feasible for ensuring representative measurements? Are the eligible quantification approaches appropriate and sufficiently exhaustive?
• System boundaries and life cycle analysis – Is the proposed scheme for emissions accounting and allocation fair and appropriate?
• Quantifying and discounting uncertainty – Are the proposed approaches robust, practical, and transparent?

Your feedback on these topics will help strengthen the methodology and ensure it is scientifically rigorous, practical to implement, and aligned with best practices.

Public Consultation Information

Consultation dates: November 11^th – December 2^nd, 2026 (3 weeks)

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[1] Mazzotti, M., Abanaes, J. C., Allam, R., Lackner, K. S., Meunier, F., Rubin, E., Sanchez, J. C., Yogo, K., & Zevenhoven, R. (2005). Mineral carbonation and industrial uses of carbon dioxide. In B. Eliasson & R. T. M. Sutamihardja (Eds.), IPCC special report on carbon dioxide capture and storage (1. publ). Cambridge Univ. Press.