Eligibility and scope

Eligible Project Developers

Distributed biochar projects uniquely operate with a network of many actors. All recognized actors and their roles are outlined below. Upon validation, Project Developers shall provide a detailed description of all actors in the project and their responsibilities.

See the Appendix for the Operating Procedure and responsibilities for Kiln Operators, Kiln Supervisors and Project Developers.

Type of actor	Operational role	Carbon project role
Kiln operator	The individual performing pyrolysis and producing biochar. This includes preparing biomass, loading it into the kiln, surveilling pyrolysis, storing biochar, taking biochar samples, and ensuring durable biochar end use.	Executes the carbon removal activity and records raw data and proof. Receives carbon finance from credit sales, distributed by the kiln supervisor or Project Developer.
Kiln supervisor	Hired by the Project Developer to be the party responsible for ensuring quality of the operations by on-the-ground presence and random visits to kiln operators.	Visits each kiln operator at least once per year, and coordinates biochar bulk density measurements onsite. May provide trainings to kiln operators. The kiln supervisor shall not receive payments or other incentives related to number of carbon credits issued.
Project Developer	Coordinates with kiln supervisors to ensure high quality biochar production, sampling and measurements; manage data and proof for submission to Rainbow and VVB (i.e. check anomalies). May also train, provide dMRV, provide kilns, and operate kilns.	An intermediary between Rainbow and on-the-ground operations, including kiln operators and supervisors. Responsible for centralized project data management, registration, VVB interactions, and distributing carbon finance to kiln operators.
dMRV provider	Provides dMRV platform (digital monitoring, reporting and verification), in the form of an application or website, to allow kiln operators to record operations.	The dMRV tool must have all features needed to for kiln operators to prove compliance with methodology requirements. Full requirements here. Can also be a Project Developer.
Technology provider	Provides the physical kiln used to perform pyrolysis and produce biochar.	Must provide kilns that meet methodology requirements, and help defining which kilns are the same type, for defining the production batch. Full requirements here. Can also be a Project Developer.

Eligible technologies

Project design

The distributed network of actors results in several project scopes and designs. A typology is provided below, and all designs are eligible under this methodology.

	Collective	Self-sufficient
Mobile	Portable Community Kilns Kiln is moved from site to site, Central operator provides pyrolysis as a service to multiple farmers. Kiln travels to centralized biomass sources, and biochar is left with farmers or distributed locally.	Portable Farmer Units Kiln is moved from site to site, Kiln Operator moves the kiln to pyrolyze farmers' biomass on-site or nearby, and use biochar on the same farm not a common model
Stationary	Shared Pyrolysis Hubs Kiln at a fixed and shared location Central operator manages the kiln Biomass comes from several sources, biochar distributed to users who may not have provided the biomass	On-Farm Producers Kiln at a fixed location, at an individual's farm Farmers pyrolyze their own biomass and use the biochar on their own land.

Eligible kilns

Only open kilns are eligible under this methodology. Eligible kilns must:

• maintain pyrolysis temperatures of at least 350°C, for the entire pyrolysis duration (excluding ramp up period)

• be equipped with integrated temperature sensors, placed in the same spot on all kilns. See the temperature curve requirements for further instructions

• demonstrate a kiln design that is cone-shaped, with at least 2 m diameter at the top and 1.5 m high

• no individual kiln may produce more than 500 m³ of biochar annually

• come with safety protocols and instructions for operators

After a kiln design is validated and approved as eligible by Rainbow and a VVB, the design will be added to Rainbow’s published list of eligible kilns. For any future projects using the same kiln design, the kiln shall be considered automatically eligible. Project Developers only need demonstrate that their kiln matches a design already listed.

Eligible biomass feedstock

Eligible biomasses are those that:

• could not have been used valuable products (e.g. low quality wood),

• were not grown for the purpose of CDR or bioenergy production.

For simplification, all feedstocks that meet the above requirements will be referred to hereafter as waste. Biomass feedstocks are categorized accordingly:

Biomass type	Description	Source
Forest waste from secondary forest	Natural but not primary old-growth forest, may still be managed for timber	Default if no other forest type can be proven
Forest waste from managed forest	Managed mixed-use forests that may include agroforestry, plantations or rotational logging	Must provide proof
Necessary tree removal from any forest	Damaged trees, or trees removed for planned forest management such as preventing disease spread or fires	Must provide proof
Agricultural residues with value	Residues left on soil or reapplied to soils for nutrient recycling (e.g. mulching, composting, spreading fast-decaying cellulose-based residues with decay within 5 years)	Default if prior use could not be determined
Agricultural residues with no value	Plowed into soil, burnt in the field, no substantial return of nutrients to soil	Must provide proof
Other waste or residue	To be evaluated on a case by case basis according to criteria outlined in the present document	Must provide proof
Invasive species	Plants that are not native to the local area and are disruptive or harmful to ecosystems	Must provide proof

Only one singular biomass may be used for a given production batch. One project may use multiple types of biomass feedstock, but must meet the following requirements:

• Only one type of biomass shall be used for each kiln run (see definition of biomass type in the Production batch section).

• Biochar produced from different feedstocks must be kept physically separate during production, storage, and sampling.

• Biochar produced from different feedstocks must be reported separately for all measurements and end-use applications.

Eligible biochar product and end use

Credits shall be issued based on the end use of biochar (as opposed to production of biochar), specifically when it is mixed into a permanent matrix. A permanent matrix is defined as a medium that ensures the biochar cannot be physically separated or used for energy (e.g., as fuel).

Eligible end uses include:

• Direct application to soil

• Mixing into soil-related products, such as compost, manure, or fertilizer mixes. To be considered sufficiently mixed, biochar must make up less than 50% by volume of the total mixture.

• Addition to concrete mixtures

All biochar must have a molar $H/C_{org}$​ below 0.7.

Certification requirements

Crediting period duration: the maximum duration of the crediting period for projects certified under this methodology is 5 years. Upon reaching the maximum duration, a project's crediting period may be renewed, according to the Crediting Period Renewal procedure.

Monitoring period duration: The default monitoring period duration is one year, but may be shorter at the Project Developer's request. Project Developers shall submit a Monitoring Report at least once per 24 months. Failure to do so shall result in the project being deregistered.

Site audits: validation site audits for projects under this methodology must be done in-person and must be conducted at least once per year (not only once during validation). The Validation and Verification Body (VVB, the auditor) shall visit:

• if there are more than 10 sites, at least 10% of the operating sites, or

• if there are fewer than 10 sites, visit those that make up the top 60% of annual biochar production by mass.

If a project has 51 operating sites, the VVB shall visit 6 sites (10% of 51, rounded up).

If a project has 4 operating sites, and Site #1 produces 70% of the biochar mass, and Sites #2-4 each produce 10%, the VVB is only required to visit Site #1, as it accounts for ≥60% of annual biochar production on its own.

If a project has 4 operating sites, and Site #1 produces 40% of the biochar mass, Site #2 produces 30%, and Sites #3 and 4 each produce 15%, the VVB shall visit Sites #1 and #2, as their combined production (70%) meets the 60% threshold.

The site audit must include the direct observation of one kiln run at each site and a series of bulk density measurements, in addition to the general site audit requirements in the Rainbow Procedures Manual.

Versioning and project compliance: When this methodology is revised, projects are required to comply with the latest version for subsequent verifications of RCCs.

Project scope

One project is defined as:

• the operation of one or more kilns, across one or more sites,

• within a single country,

• using the same kiln technology,

• using the same dMRV approach, and

• operated at sites that are under the oversight or data access of a single Project Developer.

The project scope is cradle-to-grave and includes all processes that result from biochar production and application. This includes but is not limited to the following:

• carbon removals from biochar production

• induced emissions from

  • biomass sourcing

  • leakage

  • upstream and downstream transport

  • embodied emissions from infrastructure and machinery

  • onsite process emissions from biomass and biochar processing and energy use.

Any processes that would have occurred regardless of the biochar production and application activities may be excluded from the project scope.

Baseline scope

The baseline shall include any permanent carbon removal that would have occurred in the absence of the project. For biomass use, this includes permanent carbon storage from the alternate fate of the biomass feedstock used for pyrolysis.

Project Developers shall justify the alternate fate of business-as-usual biomass feedstock use.

• If biomass would have been left on agricultural fields, or otherwise applied to soil to decompose, a default 0.5% of the carbon in the biomass feedstock is assumed to be permanently stored.

• For any other alternate fate of biomass, it is assumed that no carbon is permanently stored, and no baseline is considered for this module.

It shall be assumed by default that no biomass feedstock would have been used for dedicated carbon removal projects in the absence of the project (i.e. there is no share of the project activity in the baseline scenario).

More conservative baseline scenarios may be applied on a case-by-base basis. They must be representative and transparently justified.

See the GHG quantification section for more details on how baseline removals are calculated.