๐Ÿฅ‡Carbon Sequestration through Accelerated Carbonation of Concrete Aggregate

Table of Contents


Scope, Applicability, and Entry into Force

Significance and Environmental Impact

Baseline Methodology

Demo Video

Policy Workflow

Policy Guide

Available Roles

Important Documents & Schemas

Token (Verified Emission Reduction)

Step By Step


This methodology focuses on sequestering CO2 in demolished concrete (concrete aggregate) through the processes of carbonation. The concrete aggregate is exposed to increased CO2 concentration, reacting with the cement phase to form stable carbonate minerals, permanently storing CO2. Two processes, direct and indirect mineral carbonation, achieve CO2 sequestration, generate negative greenhouse gas emissions, and produce raw materials for the construction industry.

Scope, Applicability, and Entry into Force


  • Applicable to technology-based CO2 sequestration through mineralization in recycled concrete aggregate (Carbonated Concrete Aggregate).


  • Applicable for projects using direct or indirect mineral carbonation of demolished concrete.

  • Uses concrete aggregate to sequester CO2 before downstream processes or landfilling.

  • Specific conditions for project implementation outlined, including source of CO2, facility requirements, and adherence to quality standards.

  • Guidelines for using CaCO3 from indirect mineral carbonation in various applications.


  • Ensures compliance with national, sub-national, and local regulations.

  • Measures to prevent double counting and clear communication of emission sequestration claims.

Significance and Environmental Impact

Carbon sequestration projects play a crucial role in addressing global climate change. The accelerated carbonation of concrete aggregate is particularly significant in today's world for several reasons:

  • Climate Mitigation: By permanently storing CO2 in stable carbonate minerals, this methodology contributes to mitigating climate change by reducing the overall concentration of greenhouse gases in the atmosphere.

  • Circular Economy: The process involves recycling demolished concrete, promoting a circular economy by reusing materials and reducing the need for new resource extraction.

  • Construction Industry Sustainability: The generated raw materials from carbonated concrete aggregate are essential in the construction industry, providing a sustainable alternative to traditional materials.

  • Urban Development: As urbanization continues, the demand for construction materials rises. Carbon sequestration in concrete aligns with sustainable urban development practices, reducing the environmental impact of infrastructure projects.

Baseline Methodology

Project Boundary

  • Defines the spatial extent of the project boundary, including concrete recycling facility, carbonation plant, CO2 source, and end product usage sites.

Emissions Sources Included

  • Outlines GHGs emissions sources included in the project boundary, considering power consumption, processing, and transportation.

  • Accounts for emissions associated with solvent supply in the indirect mineral carbonation process.

Demonstration of Additionality

  • Uses the "Combined tool to identify the baseline scenario and demonstrate additionality" to assess and demonstrate additionality.

  • Transparent documentation to support the additionality demonstration.

Baseline Scenario Determination

  • Identifies plausible baseline scenarios considering realistic and credible alternatives.

  • Utilizes the latest approved version of the CDM Tool 02 for baseline scenario determination.

  • Lists baseline alternatives, considering different scenarios for demolition concrete treatment and CO2 sources.

Demo Video


Policy Workflow

Policy Guide

This policy is published to Hedera network and can either be imported via Github (.policy file) or IPFS timestamp.

Available Roles

Project Proponent - The project proponent is responsible for executing the emission reduction project. The project proponent must adhere to the requirements outlined by Gold Standardโ€™s methodology and provide evidence of the emission reductions achieved. Upon successful verification, the project proponent receives Verified Emission Reductions (VER) as an incentive for their emission reductions.

Verification and Validation Body (VVB) - The VVB plays a critical role in independently verifying and validating the project data submitted by the project proponent. They thoroughly assess the project's emission reduction potential, methodologies, and adherence to the policy guidelines. Based on their evaluation, the VVB either approves or rejects the project for registration.

Registry (Gold Standard) โ€“ With Gold Standard as the registry they take on responsibilities that encompass project intake, pipeline management, and final review of project descriptions and monitoring reports. This process ensures that emission reduction projects meet the highest standards before tokens are issued.

Important Documents & Schemas

  1. Project Details โ€“ Project Participant information, standard project information, methodology information like baseline emissions, project emissions, etc.

  2. Project Sinks โ€“ Project Sinks are equivalent to the amount of CO2 sequestered in carbonated concrete aggregate by applying direct or indirect mineral carbonation with biogenic CO2 in the project activity. The ex-ante and ex-post values will be calculated by filling out the project form.

  3. Project Emissions โ€“ Project emissions are associated with activities related to the operation of carbonation plants for CO2 treatment. These emissions will be calculated once the project form is filled.

  4. Leakage Emissions โ€“ Leakage emissions can be calculated once the project form is filled, and they consist of:

    1. Emissions due to the energy consumption associated with the additional crushing effort to reach higher CO2 uptake efficiencies of the concrete aggregate.

    2. Emissions due to electricity and heat demand associated with the capture, separation, and collection of the CO2.

    3. Emissions due to the energy consumption of the CO2 tank associated with refrigerating the CO2.

    4. Emissions due to electricity consumption associated with the liquefaction of CO2.

    5. Emissions associated with the transportation of liquefied CO2 to the carbonation plant.

    6. Emissions associated with the transportation of concrete aggregate and regenerated sand.

  5. Emissions Reduction โ€“ Schema included within the project information form; this is filled out by the project participant to calculate annual emission reductions.

  6. Monitoring Report โ€“ The monitoring report is to be filled out based on the monitoring plan mentioned within the methodology.

Token (Verified Emission Reduction)

Verified Emission Reduction (VER) credits, each equivalent to one tonne of CO2.

Step by Step

Note: If you would like to organize your data before adding it to the project form refer the GS Carbon Sequestration through Accelerated Carbonation Excel workbook. You can find this file in the GitHub methodology library. Make sure macros are enabled before using.

  1. Create a new user and assign role as Project Proponent.

  1. Create a New project by clicking on "New Project" button and enter all the required details.

  1. Once project details are submitted, the Registry adds the project to the project pipeline.

  1. Now, we create a new user and assign its role as VVB.

  1. We need to set the VVBโ€™s name.

  1. Now we login as SR and approve VVB.

  1. Now we login as the Project Proponent and assign project to VVB.

  1. Now we login as VVB and validate the project by viewing project document details. Once validated, VVB clicks on Validate button.

  1. Login as the SR and add the project to the project registry.

  1. At this point the Technical Advisory Committee and the NGO Supporters have a commenting feature available. An account can be created and assigned to each role. This can be used to review the project data and leave a comment. It is optional.

  1. Once validated, we login as Project Proponent and Add Monitoring Report.

  1. Once the report is submitted, we now login as VVB and validate the monitoring report by clicking on Verify button.

  1. Once the monitoring report is validated, we login as SR and click on Approve then the Mint button should appear which can then be used to mint the tokens.

  1. Once minting is completed, we can view tokens in Token History tab

  1. Trustchain can also be viewed by clicking on View TrustChain button:

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