Glossary
Biochar carbon removal glossary
Plain-English definitions of the terms that come up in biochar carbon-removal projects — from pyrolysis and the H/Corg ratio to VM0044, CORCs and offtakes. Permanence and price figures are estimates, never guarantees.
Key terms
Biochar
- Biochar is a porous, carbon-rich solid produced when biomass — such as crop residues or woody waste — is heated in a low-oxygen environment (pyrolysis). Around half of the biomass carbon is converted into a stable form that resists decomposition. Applied to soil or locked into durable materials, biochar stores carbon that would otherwise return to the atmosphere, while often improving soil health.
- Related service
Pyrolysis
- Pyrolysis is the thermal decomposition of organic material at high temperature in the near-absence of oxygen. For carbon removal, it converts biomass into biochar (solid), plus syngas and bio-oil that can supply process energy. Production temperature and residence time strongly influence biochar quality and the H/Corg ratio that underpins estimated permanence.
- Related service
Carbon Dioxide Removal (CDR)
- Carbon Dioxide Removal (CDR) means capturing CO₂ that is already in the atmosphere and storing it durably. It is different from emission reductions or avoidance. Biochar is a durable CDR pathway: it removes biogenic carbon and stores it for an estimated centuries-to-millennia timescale, alongside methods like direct air capture and enhanced weathering.
Verra VM0044
- VM0044 is Verra’s methodology, "Methodology for Biochar Utilization in Soil and Non-Soil Applications", under the Verified Carbon Standard. It sets out how to quantify, monitor and verify durable carbon removal from biochar, including permanence based on the H/Corg ratio. It is one of the most widely recognised biochar crediting pathways.
- Related service
CORC (CO₂ Removal Certificate)
- A CORC (CO₂ Removal Certificate) is the credit unit issued by the Puro.earth registry, each representing one tonne of CO₂ removed and durably stored. CORCs are issued for verified durable-removal activities such as biochar, and are widely used by corporate buyers focused specifically on engineered or durable CDR.
- Related service
H/Corg Ratio
- The H/Corg (or H:Corg) ratio is the molar ratio of hydrogen to organic carbon in biochar, measured by accredited lab analysis. A lower ratio indicates more condensed, stable carbon. Methodologies use it to assign estimated permanence: roughly, a ratio below 0.7 is associated with centuries-scale storage and below 0.4 with longer durability. These are scientific estimates, not guarantees.
- Related service
Permanence
- Permanence (or durability) is how long carbon is expected to remain stored before returning to the atmosphere. For biochar, permanence is estimated primarily from the H/Corg ratio and production conditions — commonly hundreds to over a thousand years. All permanence figures are estimates derived from current science and methodology rules, never guarantees.
Additionality
- Additionality is the principle that a project’s carbon removal would not have occurred without the incentive of carbon finance. Demonstrating additionality — financially, regulatorily and against common practice — is central to credit integrity. Removals that would have happened anyway are not genuinely additional and should not be credited.
- Related service
MRV (Measurement, Reporting & Verification)
- MRV — Measurement, Reporting and Verification — is the set of methods and data that substantiate a project’s removals: sampling and lab testing, carbon and H/Corg measurement, production and application records, and conservative treatment of baselines, leakage and uncertainty. Digital MRV (dMRV) captures this data at source for stronger, faster, more auditable verification.
- Related service
Feedstock / Waste-Biomass
- Feedstock is the biomass converted into biochar — for example crop residues, agro-industrial by-products or woody waste. High-integrity projects use sustainable, genuine-waste or surplus biomass that would otherwise be burned or left to decompose, and avoid material that drives land-use change or diverts biomass from existing productive uses.
- Related service
Offtake
- An offtake (or offtake agreement) is a contract under which a buyer commits to purchase a defined volume of carbon credits, frequently before they are issued (a forward offtake). Forward offtakes can help unlock project financing; spot sales capture market pricing at the time of sale. Prices depend on quality, volume and durability and are presented as estimates, not guarantees.
- Related service
Compare
Comparison tables
Quick reference on production models and the leading durable-removal registries.
Artisanal vs industrial production
| Dimension | Artisanal | Industrial |
|---|---|---|
| Typical equipment | Flame-curtain kilns, small batch units | Continuous reactors, often with energy recovery |
| Scale | Farmer / village / FPO level | Mill, aggregator or industrial site |
| Capital intensity | Low | High |
| Best-fit feedstock | Dispersed, seasonal residues | Concentrated, consistent biomass |
| Data capture | Manual; MRV discipline is the challenge | Automated, instrument-grade |
| Buyer appeal | Strong co-benefit / livelihood story | Large, traceable volumes |
Registry comparison: Verra VM0044 vs Puro.earth vs Isometric
| Standard | Credit unit | Durability basis | Often chosen for |
|---|---|---|---|
| Verra VM0044 | VCU (Verified Carbon Unit) | H/Corg ratio; soil & non-soil uses | Broad market familiarity and applications |
| Puro.earth | CORC | H/Corg ratio; durable-removal focus | Established durable-CDR buyer base |
| Isometric | Isometric credit | Science-led protocol; high transparency | Buyers prioritising scientific rigour |