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Carbon Removal Technology

Biochar Carbon
Removal

Durable carbon, measured and traced from residue to soil.

Close-up of charcoal-black biochar fragments layered over dark soil
Biomass feedstock moving along conveyors inside a biochar production facility
Exomad Green's biochar facility in Bolivia (photo: Exomad Green)
Overview

Biochar Carbon Removal (BCR) is among the most immediately scalable and cost-competitive durable carbon dioxide removal pathways available today. In 2024, 86% of all durable CDR deliveries came from biochar, making it the leading durable method actually in the ground rather than on a roadmap. For India, sitting on hundreds of millions of tonnes of annual crop residue, the constraint has never been feedstock. It has been verifiable evidence.

How It Works

86%

of 2024 durable CDR deliveries

0.5–2 Gt

CO₂ / year potential by 2050

500–700°C

pyrolysis conversion window

100+ yrs

carbon permanence horizon

Market position

The pathway that actually delivers

Biochar accounted for the overwhelming majority of durable carbon removal delivered in 2024. While other engineered pathways are still commissioning first plants, BCR is shipping tonnes today, which is why it dominates buyer procurement.

Removal potential

0.5–2 gigatonnes a year

Current assessments of globally available sustainable residue feedstock put biochar's annual removal ceiling in the gigatonne range by 2050, without competing for land that food or forests need.

End uses

Soil, feed, and the built environment

Credited biochar is worked into agricultural soil, blended into animal feed and bedding, or bound into concrete and asphalt. Each route keeps the carbon out of the atmosphere on a different timescale.

What has to be evidenced

Four checkpoints turn that process into a creditable tonne

01

At the feedstock

Prove the biomass is genuinely residue. Satellite land-cover history over the sourcing area shows no standing forest was cleared to feed the kiln.

02

At the reactor

Log every run: input mass and moisture, peak temperature, residence time, output yield. A single spot reading will not satisfy a verifier.

03

At the laboratory

Tie each batch to its certificate (carbon content and H:Corg molar ratio) so the durable fraction is measured rather than assumed.

04

At the field

Record where the material actually went, with coordinates and quantities. Credits attach to durable end use, not to production alone.

The science

Why the carbon stays put.

Durability is the whole argument for biochar. Everything a buyer pays a premium for (and everything a verifier will interrogate) comes back to whether the carbon in a given batch is genuinely resistant to decay.

The mechanism

What pyrolysis actually changes

Left alone, crop residue rots or burns, and within a season or two the carbon it holds is back in the atmosphere. Pyrolysis interrupts that cycle at exactly the point of release. Heating biomass to 500–700°C in a low-oxygen environment drives off water and volatile compounds without letting the carbon combust.

What remains is not simply burnt plant matter. The carbon reorganises into sheets of fused aromatic rings, a dense, highly ordered structure that offers very few of the chemical footholds soil microbes rely on to break organic matter down. That structural change is the removal. Everything afterwards is a question of proving it happened and keeping the material somewhere it will stay.

The practice itself is not new. The terra preta soils of the Amazon basin, deliberately enriched with charred biomass over 2,000 years ago, remain measurably carbon-rich and fertile today. What is new is the ability to prove it, batch by batch, at commercial scale.

Quality

What decides whether biochar actually lasts

Not every tonne of biochar is equivalent. The feedstock it came from, how wet that feedstock was, and how hot and how long the reactor ran all shape the final product, and therefore how much of it counts as durable carbon.

  • H:Corg molar ratio: the primary proxy for how thoroughly biomass has carbonised. Below 0.7 is the threshold most standards require; below 0.4 indicates highly recalcitrant carbon.
  • Random reflectance (Ro%): a petrographic measurement borrowed from coal science. Carbon above the inertinite threshold is treated as geologically stable, not merely slow to decay.
  • Feedstock character: woody and hardwood inputs carbonise to higher fixed-carbon fractions. Agricultural residues are more nutrient-rich but yield lower structural stability at the same temperature.
  • Process temperature: a higher peak drives a greater recalcitrant fraction, which is why continuous kiln telemetry, rather than a single spot reading, is what a verifier needs to see.

Which of these a standard treats as decisive varies. That is why Sylithe records all of them against every batch rather than optimising for one registry's current preference.

Evidence

Three independent lines of evidence

The permanence case does not rest on a single study. Three separate strands of published work converge on the same conclusion, each closing a different gap an auditor might otherwise push on.

  • A measurable threshold: reflectance-based benchmarking separates the genuinely inert fraction from carbon that will eventually cycle, giving verifiers a physical measurement to qualify against instead of a modelled assumption.
  • Fifteen years in the ground: long-term field trials tracking applied biochar found the inertinite and semi-inertinite fractions essentially unchanged over that period, observational support rather than extrapolation from lab conditions.
  • A mechanism, not a correlation: structural studies link degree of aromaticity directly to observed durability, explaining why the lattice resists microbial attack rather than simply reporting that it does.

Scale

One pathway, two very different builds

Biochar is unusual among durable removal pathways in that it works at both ends of the capital spectrum. A farmer cooperative and a commissioned industrial plant are running the same chemistry, but almost nothing else about the two projects looks alike.

Decentralised

Kon-Tiki and artisan kilns

Low-cost, open-flame-curtain kilns that a farmer cooperative can operate at village scale. They put biochar production within reach of the smallholders who generate the residue in the first place, but they make evidence collection the hard part, because there is no plant SCADA to read from.

  • Low capital cost
  • Village-scale deployment
  • Manual batch logging
  • Global Artisan C-Sink route
Industrial

Continuous pyrolysis plants

High-throughput reactors with heat and syngas recovery, running continuously against a steady feedstock supply. Instrumentation is far richer, so the MRV challenge shifts from data capture to reconciling plant telemetry with feedstock provenance and downstream application.

  • High throughput
  • Heat & syngas recovery
  • Continuous telemetry
  • Puro.earth CORC route

The MRV burden inverts between them. Artisan kilns are cheap to run and hard to instrument; industrial plants generate telemetry by default but have to reconcile it against feedstock provenance across a much larger supply catchment. Sylithe adapts to the production model rather than forcing the project to adapt to the software.

End use

Where the carbon ends up decides if it counts

Producing biochar is only half of a carbon removal. The material has to go somewhere it will stay, and standards draw a hard line between end uses that hold the carbon and end uses that eventually release it.

Creditable: durable storage

Worked into agricultural soil, or bound into concrete, asphalt and other building materials. The carbon stays fixed, and the application point can be recorded, sampled and revisited.

Not creditable: transient use

Wastewater filtration, plastics, paper, textiles and metallurgy are genuine industrial markets for biochar, but the carbon can return to the atmosphere at end of life, so standards do not credit them as removals.

This is precisely why chain of custody is not administrative overhead. A tonne that leaves the kiln and cannot be traced to a durable application is a tonne that cannot be credited, however good the laboratory certificate looks.

The Sylithe layer

Biochar credibility is a chain of custody problem.

A forest project can be measured from orbit. A biochar project cannot: its integrity lives in the links between feedstock, kiln, laboratory and field. Break any one link and the credit is unverifiable. Sylithe instruments the whole chain.

Feedstock sourcing & eligibility

Satellite LULC screening proves biomass came from residue streams or sustainably managed land, not from clearing standing forest to feed a kiln.

Production batch records

Every pyrolysis run is logged against mass balance, peak temperature and moisture, then reconciled with lab certificates for H:Corg and carbon content.

Chain of custody to application

Each batch carries a traceable identity from kiln to field. The same QR-linked profile Sylithe uses for tree inventory extends to biochar application plots.

Audit-ready evidence pack

Sampling records, transport logs, application coordinates and lab results assemble into the document set a validation and verification body asks for.

Continuous monitoring

Applied-plot performance and soil condition are tracked over time, so co-benefit claims are backed by measurement rather than a single baseline survey.

Registry-aligned reporting

Outputs are structured for Puro.earth CORC issuance and mapped to Verra and ICM reporting formats, so the same dataset serves multiple pathways.

Standards & methodologies

One evidence set, multiple crediting routes

Sylithe structures BCR project data so the same underlying records can serve whichever pathway your buyers require.

Puro.earth Biochar Methodology logoPURO

Puro.earth Biochar Methodology

The dominant route for durable BCR credits (CORCs). Edition 2025 tightens feedstock sustainability, H:Corg evidence and application tracking.

Rainbow Standard logoRAINBOW

Rainbow Standard

Europe's registry for engineered removals, ICVCM CCP-eligible. Its BiCRS methodology covers pyrolysis and biochar application to agricultural soils.

Verra VM0044 logoVCS

Verra VM0044

Methodology for biochar utilisation in soil and non-soil applications, the VCS pathway for projects already inside a Verra portfolio.

Isometric logoISOMETRIC

Isometric

A science-led registry whose biochar protocol leans hard on laboratory evidence and independent verification before any credit is issued.

Developing a biochar project?

Whether you are running a single Kon-Tiki kiln or commissioning an industrial pyrolysis plant, the evidence requirements are the same. Let's build the MRV layer before the first batch, not after the auditor asks.

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FAQs

Common questions from developers and buyers evaluating biochar carbon removal.

What is biochar carbon removal (BCR)?
Biochar carbon removal is a durable carbon dioxide removal method. Waste biomass (crop residue, forestry offcuts, invasive species) is heated to 500–700°C in a low-oxygen environment through a process called pyrolysis. Rather than decomposing or burning and releasing its carbon back to the atmosphere, the biomass is converted into a stable, carbon-rich solid whose aromatic structure resists microbial breakdown for centuries. Applying that biochar to soil or embedding it in construction materials locks the carbon away, creating a measurable, durable removal.
How long does carbon stay locked in biochar?
Durability depends on how completely the biomass was carbonised. Standards use the H:Corg molar ratio as the primary indicator, generally requiring it below 0.7 for credited material. Well-produced biochar is widely credited on a permanence horizon of 100 years or more, and petrographic analysis of the inert fraction supports far longer stability. Long-term field studies tracking applied biochar over fifteen years have found the inertinite and semi-inertinite shares virtually unchanged.
Why is biochar considered a durable removal rather than an avoidance credit?
Avoidance credits stop an emission that would otherwise occur. Biochar physically takes CO₂ out of the atmosphere (through the plant growth that produced the feedstock) and then prevents that carbon from returning by converting it into a form biology cannot easily degrade. Because the removal is completed at the moment of pyrolysis and the resulting carbon has no standing asset that can burn down or be cut, buyers classify it alongside engineered removals such as DACCS and BECCS rather than alongside nature-based avoidance.
Which standards certify biochar carbon credits?
The dominant route is the Puro.earth Biochar Methodology, which issues CO₂ Removal Certificates (CORCs); its 2025 edition tightened requirements on feedstock sustainability, H:Corg evidence and application tracking. Verra's VM0044 covers biochar utilisation under the VCS programme. The European Biochar Certificate (including EBC-Agro and the Global Artisan C-Sink standard) covers both industrial plants and decentralised kilns. Sylithe structures project evidence to serve these pathways from a single dataset.
What does dMRV add to a biochar project?
Biochar credibility rests on a chain of evidence rather than a single satellite measurement: where the feedstock came from, how each batch was produced, what the laboratory found, and where the material was ultimately applied. Digital MRV makes that chain continuous and tamper-evident. Sylithe combines satellite LULC screening of feedstock sourcing, batch-level production records, QR-traceable chain of custody through to the application plot, and an assembled evidence pack ready for a validation and verification body.
Is biochar viable at scale in India?
India is one of the strongest biochar opportunities globally. The country generates several hundred million tonnes of agricultural residue each year, a large share of which is burned in the open, creating both a severe air quality problem and a wasted carbon resource. Converting that residue into biochar addresses residue management, soil degradation and durable carbon removal simultaneously. The constraint is not feedstock availability but verifiable evidence, which is precisely the gap dMRV closes.
How does biochar compare with ARR carbon projects?
They are complementary rather than competing. ARR removes carbon gradually as trees grow across a 20–40 year crediting period, and carries reversal risk from fire, drought and harvest. Biochar completes its removal instantly at pyrolysis and has effectively no reversal exposure once applied. Their measurement stacks differ too: ARR relies on canopy height, above-ground biomass and dynamic baselines, while biochar relies on mass balance, laboratory carbon analysis and chain of custody. Most corporate buyers now hold both: nature-based removals and durable removals sit on separate lines in a credible net-zero portfolio.
What feedstocks can be used for biochar production?
Sustainable biochar uses waste and residue streams: crop residue such as rice husk, straw and bagasse; forestry and sawmill offcuts; prunings from orchards and plantations; and invasive biomass cleared for ecological management. Woody feedstocks generally carbonise to a higher fixed-carbon fraction and greater stability, while agricultural residues are more nutrient-rich but yield lower structural durability at the same temperature. What standards will not accept is biomass sourced by clearing standing forest, which is why satellite verification of feedstock origin matters.
Does biochar have non-durable uses too?
Yes, and the distinction matters for crediting. Biochar used as a soil amendment or bound into construction materials keeps its carbon locked away and can be credited as durable removal. Biochar used in wastewater filtration, plastics, paper, textiles or metallurgy may deliver real industrial value, but the carbon can re-enter the atmosphere at end of life. Standards credit the durable applications, which is why tracking where each batch actually ends up is part of the MRV requirement rather than an optional extra.