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Methodology · 01

The five-party CSI structure.

The Global Artisan C-Sink standard is built around five parties that have to be in their right roles for any credit to be issued. Knowing who does what is the fastest way to understand whether a biochar project is real or marketing.

The five parties

Climate B2C is the C-Sink Manager (party #3) for our coffee projects. We arrange the equipment (party #4 producer infrastructure), select and contract a CSI-endorsed certifier (#2), and feed data to the Registry (#5). The standard owner (#1) audits the standard itself, not us.

  1. 1

    Endorsing Agent

    Carbon Standards International (CSI)

    Owns and maintains the Global Artisan C-Sink standard, endorses certifiers, technologies, and dMRV apps. Operates the public Global C-Sink Registry where every issued credit lives.

  2. 2

    Certifier (VVB)

    Independent third-party body, ISO 17065:2012 accredited

    Conducts the validation and verification audits. Visits each Artisan Pro site and the C-Sink Manager onsite at least once a year. The certifier, not the project, is who decides whether biochar becomes a registered credit.

  3. 3

    C-Sink Manager

    In-country organization (a co-op federation, exporter, or nonprofit)

    Trains producers, runs the dMRV, manages the Internal Control System, transfers data to the Registry, and is the entity actually certified for each country of operation. The Manager is who gets audited annually.

  4. 4

    Artisan Biochar Producers

    C-Sink Farmers · Artisan Pro · C-Sink Cooks

    The people running the kilns. Three categories defined by annual volume, see below. Each producer must be trained, examined, and registered through their Manager.

  5. 5

    Global C-Sink Registry

    Public registry of issued credits

    Where C-Sink Units are listed, transferred, and retired. Buyers can be shown the registry entries directly. Sales can be bilateral or via marketplaces (Supercritical, Patch, Cloverly), but transfers and retirements always pass through the registry.

Three producer categories

The category determines monitoring intensity, audit frequency, and how a biochar production is grouped into a C-Sink Unit. The thresholds are by annual volume per registered producer/site, not number of kilns.

< 100 m³ biochar / yr

C-Sink Farmer

Individual farmer producing biochar from feedstock on his/her own farm and applying it back on that same farm. Up to 1,000 farmers can be grouped into a single C-Sink Network within a 50 km radius, sharing the certification overhead.

Monitoring
Simpler. The Manager visits each farmer at least once a year. Moisture spot-checks rather than per-load logging. Field GPS data captured at registration.

Best fit
Smallholder co-ops with many small kilns. Pruning residue, used on-farm.

100 – 1,500 m³ biochar / yr

Artisan Pro

Registered company or co-op site producing biochar at a defined location with registered equipment. Feedstock can come from a 30 km sourcing radius. Biochar is generally sold to other farmers or industries, not used on-site.

Monitoring
Full per-load records: feedstock type, mix ratios, moisture per load, two georeferenced photos per kiln run, bulk-density measurement every 500 m³, annual lab analysis per feedstock blend.

Best fit
Mill-based projects (wet/dry mills with husk and pulp). Most Climate B2C Tier-3 projects sit here.

Per-household via TLUD stove

C-Sink Cook

Households using TLUD stoves (top-lit updraft micro-gasifiers) for cooking that produce biochar as a co-product. Grouped into C-Sink Villages of up to 50+ families within a 10 km radius. Biochar is collected by a certified Biochar Processor.

Monitoring
No per-run record. Total volume measured when the Processor picks up. Pro-rata methane accounting (only emissions attributable to the biochar fraction count).

Best fit
Rural households where cooking is the primary purpose; biochar is incidental.

Above 1,500 m³/yr

The Artisan ceiling. A producer above 1,500 m³/yr has to either split into genuinely separate sites/teams (rare and risky in audit) or transition to the World Biochar Certification (WBC) industrial pathway. For most coffee mills this is two or more years out. Artisan Pro is the right starting point.

Eligible technology

The certified entity is the combination of technology and trained operator, not the kiln alone. A perfectly designed kiln run badly produces uncertified char. Equipment requirements are practical, not exotic.

  • Earthen kiln (flame-curtain pyrolysis)

    A small-scale on-farm kiln where pyrolysis gases pass through a fire front before atmospheric release. Designs are simple: a lined pit or a conical metal vessel. Suits single-farm operation with crop residue. Costs range from very low (a soil pit) up to a few thousand dollars for an engineered metal kiln.

  • Mid-size mobile reactor

    Engineered batch reactor with built-in emissions controls. Towable, so the same unit can serve a single farm or rotate among member farms in a co-op. Throughput is a few hundred kilos of biochar per run with sensor-based monitoring that plugs into the standard MRV workflow.

  • Continuous reactor at the mill

    Continuously fed system designed for processing centers with year-round residue. Higher throughput and more automation than the batch alternatives. The right fit when one location aggregates enough biomass to keep it running.

  • Top-lit updraft cooking stoves

    Household-scale micro-gasifiers used for cooking that produce biochar as a co-product. Each stove model must be individually endorsed under the standard. Pro-rata methane accounting applies, only emissions attributable to the biochar fraction count toward the credit.

  • What is NOT eligible

    Traditional charcoal piles or retorts where pyrolysis gases escape without passing through a combustion zone. Any technology that fails to oxidize pyrolysis gases. Forest wood as feedstock. Cutting trees for biomass.

Continue → MRV workflowOr jump to persistence & methane →

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