# Principles & requirements

Project Developers shall demonstrate that they comply with all principles and requirements outlined in the applicable version of the [Rainbow Standard Rules](https://docs.rainbowstandard.io/rainbow-standard-documents/rainbow-standard-rules/principles-and-requirements), and described below with a specific focus on mineralization.

## Additionality

To demonstrate additionality, Project Developers shall perform **regulatory surplus analysis, plus either investment or barrier analysis**, using the [Rainbow Additionality Template](https://docs.rainbowstandard.io/rainbow-standard-documents/procedural-templates/additionality-evaluation-template).

{% tabs %}
{% tab title="Regulatory surplus analysis" %}
**Regulatory surplus analysis** shall demonstrate that there are no regulations that require or mandate project activities.

Project Developers must demonstrate that CO<sub>2</sub> capture was not mandated under an Emissions Trading System (ETS). A site may be eligible if the site had already met its ETS obligations, and the captured CO<sub>2</sub> exceeded those required reductions, and the site complies with the [No double counting ](#n1iy4xaxuthk-1)criteria.

At the European Union level, projects automatically pass the regulatory surplus analysis, which has been conducted by the Rainbow Climate Team. Project Developers are only required to provide a country-level regulatory surplus analysis.
{% endtab %}

{% tab title="Investment analysis" %}
**Investment analysis** may be used to prove that revenue from carbon finance is necessary to make the project investment a financially viable and interesting option. The investment may cover:

* The creation and launching of new sites
* Expansion of capacity of existing activities
* Expansion by installing new processes

Business plans shall be provided as initial proof for investment analysis. During verification, audited financial statements shall be used to demonstrate that the initial estimates from the business plan were reasonable, and that carbon finance was used as initially described for the expected investment.

For launching brand new sites, additionality can be simply demonstrated if the business plan shows that carbon finance is expected to make up at least 80% of the company’s revenue, as detailed in the [Rainbow Additionality Template](https://docs.rainbowstandard.io/rainbow-standard-documents/procedural-templates/additionality-evaluation-template).

Note that for investments in expansion, **only the additional carbon removals and avoidance enabled by the expansion shall be eligible for Rainbow Carbon Credits.**
{% endtab %}

{% tab title="Barrier analysis" %}
**Barrier analysis** may be used to prove that the project faces financial, institutional, or technological barriers to ongoing operations that can only be overcome using carbon finance. Examples include but are not limited to:

* Financial barrier: financial analysis demonstrating that the project is not financially viable, evidenced by net cash being lower than the working capital requirements, or proof that the project is not meeting the projected financial targets in the business plans and loan documents, and that carbon finance would make it financially viable.
* Institutional barrier: description of new regulation that the project must make costly changes to comply with, with financial analysis showing that the project cannot fund the changes on their own, and carbon finance is necessary to make it viable.
* Technological barrier:
  * proof that the project's carbonated product struggles to be cost-competitive with baseline products. Carbon finance may be used to lower the selling price of the project’s product, making it more competitive.
  * proof that the large amount and cost of R\&D required for an innovative technology makes the technology unfeasible to scale without carbon finance.&#x20;

For any type of barrier analysis, **audited financial statements must be provided** as proof. These documents should either demonstrate the financial status to prove financial barriers, or show that the project could not independently fund solutions to overcome institutional or technological barriers.
{% endtab %}
{% endtabs %}

## Durability <a href="#n1iy4xaxuthk" id="n1iy4xaxuthk"></a>

#### **Durability threshold**

All projects certified under this methodology shall prove **durable carbon removals for at least 1000 years**. The chemically-bound removed carbon is considered [**permanently stored**](#user-content-fn-1)[^1] **upon mineralization**/material production.&#x20;

The final end use of the material affects its risk of reversal. This risk is mitigated by the project design requirements regarding [eligible uses of carbonated materials](https://docs.rainbowstandard.io/methodologies/eligibility-and-scope#eligible-technologies), which allow only materials that won't be incinerated (i.e. concrete, asphalt, and landfill).

#### **Reversal risk assessment**

The carbon reversal risks from mineralization of alkaline materials are:

* **Exposure to high temperatures** via combustion, where carbonated material is incinerated or subjected to extreme heat, causing thermal decomposition of carbonate minerals and re-emission of CO<sub>2</sub>.
* **Exposure to strong acids**, where carbonated material comes into contact with acidic environments (e.g. acid rain, acidic groundwater infiltration, or industrial acid exposure), causing dissolution of carbonate minerals and re-emission of CO<sub>2</sub>.

This methodology establishes the following mandatory project requirements to mitigate these risks, detailed in the following sections:

* verification of carbonation extent and mineralogical stability
* evaluation of carbonated material end use

Upon meeting these requirements at project validation, the risk of reversal is considered **negligible** for mineralization of alkaline materials. There are no further project requirements to assess reversal risks or conduct post-crediting monitoring for reversals.

All projects certified under this methodology shall contribute the default minimum 2% of their verified removal RCCs to the Rainbow Buffer Pool, as defined in the Rainbow Standard Rules.

#### Risk mitigation: verification of mineralogical stability

Project Developers shall describe **the type of carbonate minerals produced** and their specific risk of reversal under relevant heat and pH conditions. This assessment shall&#x20;

* be based on project-specific primary data (e.g. laboratory measurements such as XRD analysis) or secondary data that are highly representative of the project conditions, and
* address the carbonate type produced (e.g. anhydrous vs hydrated), and the resulting implications for resistance to thermal decomposition and acid dissolution.

#### Risk mitigation: evaluation of carbonated material end use

Project Developers shall demonstrate that the **intended end use of carbonated material mitigates reversal risk**. Eligible end uses include but are not limited to incorporation into concrete, construction aggregates, or other non-combustible permanent materials.&#x20;

Project Developers shall describe the expected end use, including building or structure type and geographic location, and, in relation to the mineralogical stability assessment above, demonstrate minimized risk of exposure to thermal decomposition and acid dissolution.

## No double counting <a href="#n1iy4xaxuthk" id="n1iy4xaxuthk"></a>

Project Developers shall sign the [Rainbow MRV & Registry Terms & Conditions](https://docs.rainbowstandard.io/other/terms-and-contracts/terms-and-conditions-for-project-developers-mrv-+-registry), committing to follow the requirements outlined in the [Rainbow Standard Rules](https://docs.rainbowstandard.io/rainbow-standard-documents/rainbow-standard-rules), including not double using or double issuing carbon credits.

The following double counting risks have been identified for alkaline material mineralization projects. Project Developers shall follow the outlined requirements for each risk.&#x20;

<table data-full-width="true"><thead><tr><th width="170">Double counting risk</th><th width="250">Explanation</th><th>Requirement</th></tr></thead><tbody><tr><td>Double issuance of carbon credits with downstream material users</td><td>Users of low-carbon concrete may seek to issue carbon credits in building methodologies in regulated or voluntary carbon markets</td><td><ul><li>Identify all direct downstream users/buyers/actors in their supply chain.</li><li>Provide the company/organization name, name of an individual contact person at the company/organization, and their contact information (email address at minimum).</li><li>Provide signed agreements and/or sales contract clauses stating carbon credits have already been issued, and users will not claim benefits or issue carbon credits for the product.</li></ul></td></tr><tr><td>Double claiming of removals or reductions with EPDs</td><td>If there is an EPD for the carbonated product, then  carbon removals and/or avoidance may be claimed by downstream users throughout the supply chain, who may issue credits or claim other environmental labels for the carbon benefit already counted and sold elsewhere</td><td><ul><li><p>Provide the product’s EPD, including:</p><ul><li>actual GWP values with carbon benefits, as required by norms/standard, and</li><li>a clause specifying when users must exclude carbon benefits in calculations using values from the EPD.</li></ul></li></ul></td></tr><tr><td>Double issuance of carbon credits with upstream CO<sub>2</sub> capture (e.g. DACCS projects)</td><td>Carbon capture projects are well incorporated in carbon markets (e.g. BECCS, DACCS), and Project Developers must agree on which entity is issued credits/how to repartition credits or carbon finance</td><td><ul><li>Identify all CO<sub>2</sub> suppliers in their supply chain.</li><li>Provide the company/ organization name, name of an individual contact person at the company/organization, and their contact information (email address at minimum).</li><li>Provide signed agreements and/or sales contract clauses stating carbon credits have been issued by the CO<sub>2</sub> user, and CO<sub>2</sub> suppliers will not claim/issue the same carbon benefits in the carbonated material.</li></ul></td></tr><tr><td>Double claiming of removals or reductions with ETS</td><td>CO<sub>2</sub> used for mineralization may be captured from heavy emitting industry sites that are covered by an ETS. When the site captures CO<sub>2</sub> emissions, they can claim the benefit in the ETS, or participate in the carbon credit issuing project, but not both.</td><td><ul><li>Demonstrate that the CO<sub>2</sub> supplier is not covered by an ETS.</li><li>If the CO<sub>2</sub> supplier is covered by an ETS, provide their official ETS reporting documents, showing that reductions that were issued carbon credits under the present methodology are not included in ETS reporting.</li></ul></td></tr></tbody></table>

## Co-benefits

Projects should support at least two **quantifiable and verifiable** environmental or social co-benefits, aligned with the [UN Sustainable Development Goals](https://unstats.un.org/sdgs/indicators/Global-Indicator-Framework-after-2024-refinement-English.pdf) (SDGs) framework. Any co-benefits claimed by the Project Developer shall be quantified, monitored, and audited for each verification and credit issuance.

Common co-benefits under this methodology are detailed in the table below. Project Developers may suggest and prove other co-benefits not mentioned here.

SDG 13 on Climate Action by default is not considered a co-benefit here, since it is implicitly accounted for in the issuance of carbon credits. If the project delivers climate benefits that are not accounted for in the GHG reduction quantifications, then they may be considered as co-benefits.

*Table 1 Common co-benefits that projects under this methodology may provide are detailed, including types of proof that can be used to justify each co-benefit.*

<table><thead><tr><th width="214">UN SDG</th><th width="266">Example</th><th width="113">Proof</th><th>Indicators</th></tr></thead><tbody><tr><td><strong>SDG 12.2</strong> <em>Achieve the sustainable management and efficient use of natural resources</em></td><td>The project’s <a data-footnote-ref href="#user-content-fn-2">circularity </a>will be measured by the <a data-footnote-ref href="#user-content-fn-3">Material Circularity Indicator (MCI)</a>, according to the Ellen MacArthur Foundation's methodology, and compared to the circularity of the baseline product.</td><td>Types of inputs used and waste status</td><td>% circularity, % improvement from baseline</td></tr><tr><td><strong>SDG 9.4</strong> <em>Upgrade infrastructure and retrofit industries to make them sustainable</em></td><td>Increase strength, durability and lifetime of concrete, extending infrastructure lifespan.</td><td>Internal testing, R&#x26;D results</td><td>% extended lifespan</td></tr><tr><td><strong>SDG 8.4</strong> <em>Improve global resource efficiency in consumption and production</em></td><td>Reusing alkaline waste materials in the mineralization process diverts them from other waste treatment methods.</td><td>Invoices and operations records</td><td>tonnes of waste material used</td></tr><tr><td><strong>SDG 6.3</strong> <em>Improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials</em></td><td>Projects that carbonate and reuse cement wastewater contribute to improved and useful wastewater treatment and water quality</td><td>Invoices and operations records</td><td>m<sup>3</sup> of wastewater used</td></tr></tbody></table>

## Environmental and social safeguards

Project Developers shall prove that the **project does not contribute to substantial environmental and social harms.** Projects must follow all national, local and European (if located in Europe) environmental regulations, and prove such compliance using, for example, permits, certifications, or licenses.

In addition to completing the [Rainbow Mineralization risk evaluation](https://docs.rainbowstandard.io/methodologies/mineralization-of-alkaline-materials-ex-situ/risk-assessment-template) below, Project Developers must prove the following elements:

For **fossil CO**<sub>**2**</sub>**&#x20;use**, Project Developers shall prove that the CO<sub>2</sub> was not generated or emitted for the sole purpose of carbon storage, and that it was captured from an existing CO<sub>2</sub> emission source.

For **biogenic CO**<sub>**2**</sub>**&#x20;use**, Project Developers shall prove that the original biomass used to generate the biogenic CO<sub>2</sub> meets the EU's [RED III](https://eur-lex.europa.eu/eli/dir/2018/2001) Article 29 sustainability criteria for biomass (even if the project is not located in the EU). This includes the following, summarized here for informative purposes only:

* If the biomass is proven to be waste, no further sustainability requirements apply (refer to the positive list in the Rainbow [Biomass feedstock](https://docs.rainbowstandard.io/biomass-carbon-removal-and-storage-bicrs/carbon-capture/biomass-feedstock#waste-status) module).
* If the biomass is not waste, Project Developers shall prove that it did not come from:
  * Primary or old-growth forests
  * Highly biodiverse forests or other wooded land designated as such by competent authorities.
  * Protected areas for rare or endangered ecosystems/species (unless proven that biomass production does not interfere with conservation goals).
  * Highly biodiverse grasslands
  * Heathland, wetlands, or peatlands
  * Recently deforested, converted or degraded ecosystems (within past 20 years)
* Forestry biomass shall follow the requirements listed above, and
  * Respect international, national and regional legal requirements
  * Promote forest regeneration by avoiding large clear-cuts or extraction of stumps/roots
  * Protect biodiversity and soil quality
  * Come from sustainably managed forests

#### Environmental and social risk assessment

Project Developers shall fill in the [Rainbow Mineralization risk evaluation](https://docs.rainbowstandard.io/methodologies/mineralization-of-alkaline-materials-ex-situ/risk-assessment-template), to evaluate the identified environmental and social risks of projects. The identified risks include:

* Heavy metal leaching from stored alkaline feedstock
* Dust and particulate generation from alkaline feedstock storage and handling
* Water use in the mineralization process
* Fugitive CO<sub>2</sub> leaks during the mineralization process
* Hazardous waste generation from the use of chemical additives
* Leaching pollutants from carbonated products during the use phase
* Demand for fossil CO<sub>2</sub> as a valuable product increases fossil fuel output
* Pressure on unsustainable or nonrenewable biomass use for biogenic CO<sub>2</sub> generation
* Environmental impacts from opening a new mine or quarry to obtain alkaline feedstock

Project Developers shall assign a likelihood and severity score of each risk, and provide an explanation of their choices. The VVB and Rainbow’s Certification team shall evaluate the assessment and may recommend changes to the assigned scores.

Any identified material risk (defined as issues with a risk score of moderate or higher) shall be subject to a [Risk Mitigation Plan](https://docs.rainbowstandard.io/rainbow-standard-documents/rainbow-standard-rules/principles-and-requirements#environmental-and-social-risk-assessment), which outlines how Project Developers will mitigate, monitor, report, and if necessary, compensate for any environmental and/or social harms.

Additional proof may be required for certain high risk environmental and social problems.

The Project Developer, the Rainbow Certification Team, or the VVB may suggest additional risks to be considered for a specific project.

{% hint style="info" %}
Note that the **life-cycle GHG reduction calculations account for the climate change impacts of most environmental risks**. Nonetheless, Project Developers shall transparently describe any substantial and sensitive GHG emission risks in the risk evaluation template.
{% endhint %}

{% hint style="info" %}
All risk assessments must also address the [Minimum environmental and social risks ](https://docs.rainbowstandard.io/rainbow-standard-documents/rainbow-standard-rules/principles-and-requirements#environmental-and-social-risk-assessment)defined in the Rainbow Standard Rules.
{% endhint %}

## Leakage <a href="#ekfzu5nkmddm" id="ekfzu5nkmddm"></a>

Mineralization of materials must not contribute to activity shifting leakage. The following leakage risks are covered by other requirements in this methodology:

* **Displacement of baseline mineralization**: any atmospheric carbon removal via mineralization that occurs in the baseline shall be modeled in the [Baseline Scenario](https://docs.rainbowstandard.io/methodologies/ghg-quantification#baseline-co2-stored), and effectively deducted from the project's carbon storage.
* **Increased emissions during use**: leakage emissions from use of carbonated products downstream of the project are mitigated by the [Baseline setting](https://docs.rainbowstandard.io/methodologies/eligibility-and-scope#baseline-scope) requirements, where project materials must have the same performance as baseline/replaced products.

No further methodology requirements apply. Project Developers shall follow the [Leakage](https://docs.rainbowstandard.io/rainbow-standard-documents/rainbow-standard-rules/principles-and-requirements#leakage) requirements in the Rainbow Standard Rules to comply with this requirement.

## Monitoring

Monitoring Plans for this methodology shall include, but are not limited to, tracking of the following information **for each Mineralization Batch.**

#### Eligibility criteria compliance

* Proof of regulatory additionality, that CO<sub>2</sub> didn't have to be captured, wasn't covered by ETS (or mention no change)
* Proof of permanence/low reversal risk, end use of product (or mention no change)
* Proof of no double counting: EPDs, ETS (or mention no change)
* If using biomass feedstock, proof of adherence to Environmental and social safeguards requirements (or mention no change)
* Any co-benefits claimed

#### GHG quantification

* Amount CO<sub>2</sub> leakage during transport
* Repartition of CO<sub>2</sub> types purchased, entering carbonation facility
* Total amount of carbonated material produced per monitoring period, in tonnes of material
* Carbon storage measurements, either:
  * Solid phase:
    * CO<sub>2</sub> measured in solid samples of carbonated material
  * Gas inflow-outflow:
    * Volumetric flow and concentration of CO<sub>2</sub> inflow and outflow
    * Gas void fraction of alkaline feedstock (if carbonating solid materials)
    * Bulk density of the alkaline feedstock (if carbonating solid materials)
    * Amount of carbonated material produced daily, in tonnes of material
    * Ongoing demonstration of equipment calibration and QA/QC procedures
* Transport distance or amount of fuel, and transport mode, for CO<sub>2</sub> delivery, alkaline feedstock delivery, and final product delivery (if >50 km)
* Amount and type of alkaline feedstock used
* Baseline removal calculations from alkaline feedstock carbonation
* Baseline and project removal calculations from concrete use phase carbonation
* Amount cement needed in baseline and project scenario, and chosen cement emission factor (*only for projects issuing avoidance credits from reduced cement use*)
* Energy and/or material use from CO<sub>2</sub> capture, CO<sub>2</sub> purification, alkaline feedstock processing, and carbonation process

The Project Developer is the party responsible for adhering to the Monitoring Plan.

Monitoring Plans shall include the following information for each monitored parameter:

* monitoring frequency
* emission sources and sinks
* data source
* measurement methods/procedures, and their accuracy and calibration
* quality assessment or quality control procedures
* responsible party for collecting and archiving data

[^1]: Baciocchi, R., Costa, G., 2021. CO2 Utilization and Long-Term Storage in Useful Mineral Products by Carbonation of Alkaline Feedstocks. Front. Energy Res. 9. [URL](https://doi.org/10.3389/fenrg.2021.592600).

[^2]: Goddin, J., Marshall, K., Pereira, A., Tuppen, C., Herrmann, S., Jones, S., Krieger, T., Lenges, C., Coleman, B., Pierce, C., Iliefski-Janols, S., Veenendaal, R., Stoltz, P., Ford, L., Goodman, T., Vetere, M., Mistry, M., Graichen, F., Natarajan, A., Sullens, W., 2019. Circularity Indicators: An Approach to Measuring Circularity, Methodology. <https://doi.org/10.13140/RG.2.2.29213.84962>

[^3]: Ellen Macarthur Foundation, ANSYS Granta, 2019. An approach to measuring circularity. Published in 2015, adapted in 2019. [URL](https://emf.thirdlight.com/link/3jtevhlkbukz-9of4s4/@/preview/1?o)