What biochar actually is
Biochar is the solid carbon-rich product of pyrolysing biomass (typically agricultural residues or forestry waste) in low-oxygen conditions. The pyrolysis process locks the carbon into a stable molecular structure that resists decomposition for hundreds to thousands of years when stored properly in soil or other long-term sinks. From a carbon accounting perspective, biochar is one of the few durable carbon removal pathways currently scalable at commercially relevant volumes.
Why the Puro.earth methodology dominates
The Puro.earth registry, established in 2019 and majority-owned by Nasdaq since 2021, has become the de facto standard for engineered carbon removal credits — including biochar, direct air capture, enhanced rock weathering and bio-oil sequestration. The Puro Biochar methodology was the first internationally recognised standard specifically for biochar carbon credits.
What the methodology requires
- Feedstock traceability — the biomass used must come from documented sustainable sources, not deforestation or land-use change
- Pyrolysis process monitoring — temperature, residence time, and oxygen levels must be logged and verified
- H/Corg ratio threshold — the molecular hydrogen-to-organic-carbon ratio must be below 0.4 (the recognised threshold for centuries-scale stability)
- Permanence accounting — credits are issued with a 100-year permanence assumption, with verification that the biochar is stored in conditions that preserve durability
- Life-cycle assessment of net carbon — emissions from feedstock collection, pyrolysis energy, and transport must be subtracted from gross removal
Why biochar credits often score Diamond
On the ClimSen Premium Score, biochar projects under the Puro methodology often achieve Diamond tier (90+ points). This is driven by three factors: (1) the methodology integrity itself is exceptionally rigorous, (2) the permanence is centuries-scale versus decades for forest carbon, and (3) the engineering pathway means additionality is straightforward to verify — the facility either pyrolyses biomass or it does not.
What satellite monitoring cannot do for biochar
Unlike forest projects, biochar facilities cannot be verified by NDVI satellite imagery. There is no vegetation canopy to measure. ClimSen verifies biochar projects through registry serial issuance cadence cross-referenced against the operator's audited facility output. This is documented as the verification method on each biochar project page.