The conversion conditions that determine product grade, the quality controls that govern every batch, and why the output specification is decided before production begins — not after.
Most agricultural residue has a roughly predictable elemental composition — a known carbon-to-hydrogen ratio, a known ash content, a moisture range. What determines whether the output is biochar, activated carbon feedstock, or carbon fuel is not a single technical variable. It is a set of controlled conditions — temperature, atmosphere, residence time, and subsequent treatment — that are deliberately configured before each production run depending on the grade target for that batch.
Conversion temperature has the strongest influence on H/Corg ratio. Higher temperatures drive off more hydrogen and oxygen, producing a more aromatic, more stable carbon structure. The tradeoff is yield: higher temperature means less total mass output per unit of feedstock. A biochar run optimised for permanence (H/Corg < 0.35) will produce less mass per tonne of feedstock than a carbon fuel run where energy density matters more than structural stability.
Activated carbon requires an additional step after initial conversion: activation. This opens the micropore structure — creates the surface area where adsorption happens. The activation conditions determine pore size distribution, which in turn determines which contaminants the carbon will be effective against. A micropore-dominant material is better for small molecules (chlorine, VOCs, pharmaceuticals). A more mesopore-rich material handles larger molecules (humic acids, dyes, some PFAS compounds). We target a micropore-dominant distribution optimised for the most common water treatment applications.
Incoming agricultural residue is weighed, moisture-tested, and assessed for consistency before entering the production system. Moisture above 30% is managed by pre-conditioning before conversion — high-moisture feedstock lowers conversion efficiency and makes product quality control harder. Batch number is assigned at intake. All downstream records trace back to this point.
The production run is configured for a target grade before it begins. Temperature profile, atmosphere, and residence time are set to deliver the intended output specification. Continuous process monitoring logs these parameters throughout the run. Deviation outside defined control limits triggers a hold and review before product is released for the next stage.
Carbon destined for the activated carbon product line undergoes a controlled activation step that develops the internal pore structure. The activation conditions — agent, temperature, and duration — are calibrated to the target iodine number and BET surface area for that production batch. Activation yield is lower than conversion yield; this is factored into grade pricing.
Output is sized to specification: biochar is screened to particle size range; activated carbon is milled to GAC mesh size or PAC fineness; carbon fuel is densified into briquette or pellet form to a specified bulk density. Form factor affects handling, storage, and application logistics as much as it affects the product's end-use performance.
Every batch is sampled before release. Samples go to an accredited third-party laboratory. Results are reviewed against grade specification. Product is not released until laboratory results are confirmed. For biochar batches, H/Corg and heavy metal results must both clear before the batch is eligible for CDR credit documentation. For activated carbon, iodine number and surface area are the release gates.
Quality control in specialty carbon materials is not an end-of-line check. It is a chain of documented decisions — at intake, during conversion, at output, and at application — with a third-party laboratory as the final word before product is released.
Before conversion begins, feedstock is assessed for moisture, apparent density, and visual consistency. Batches outside moisture tolerance are pre-conditioned.
Conversion parameters are logged continuously. Temperature profile, atmosphere readings, and residence time are recorded and compared to grade targets in real time.
Every batch is sampled and sent to an accredited external laboratory before release. Lab results must meet grade specification. The batch certificate is issued only after confirmation.
For soil application and CDR credit generation, GPS coordinates, application rate, date, and operator are recorded. These records form the final link in the MRV chain and are required for credit issuance.
A batch certificate from Bombay Bioworks includes: feedstock origin and intake date, production batch number, conversion run parameters, third-party laboratory results (with accreditation number), and product grade against specification. For biochar batches going to soil application, the application record is appended when available.
This documentation set is what CDR buyers, carbon registries, and regulatory agencies require. It is not produced retroactively — it is generated sequentially as part of normal production practice. The records exist because the process requires them, not because a buyer asked for them after the fact.
We don't generate documentation to support a carbon claim. We generate carbon that supports a documentation claim.
The distinction matters in audits. A documentation system that works backwards from a desired credit outcome will eventually fail under third-party scrutiny. A production system that generates records as a byproduct of controlled manufacturing practice will not.
Buyers who need to understand the provenance record in detail — for registry submission, for ESG reporting, or for due diligence purposes — can request a sample documentation package before placing an order. We don't require a purchase commitment to share how the records are structured.
Contact us for documentation samples →