akar.earthBiochar: Definition
What is biochar? How heating biomass without oxygen stores carbon in soil, how biochar carbon removal credits work, and its potential in Indonesia.
Biochar is a charcoal-like material made by heating biomass, such as crop residues, wood waste or husks, in a low-oxygen process called pyrolysis. When added to soil or other long-lived uses, it locks away carbon that would otherwise return to the air as the biomass decays or burns.
Why it matters
Biochar is one of the few carbon removal methods that is already producing credits at scale and is generally treated as a durable removal. Buyers looking for removals beyond forests, especially to neutralise residual emissions under net zero plans, value its long persistence. In agriculture, biochar can also improve soil structure and water holding, though effects vary by soil and application rate.
How it is measured
- Track feedstock type and quantity, and show it is a residue that would otherwise decompose or be burned.
- Monitor pyrolysis conditions and emissions from production.
- Test the biochar for carbon content and stability indicators.
- Record end use (soil, compost, construction materials) and quantity applied.
- Deduct emissions from transport, energy and production.
Methodologies include Verra’s VM0044 and those of Puro.earth and other registries. Check the current version for the stability model used.
Indonesia and Southeast Asia angle
Indonesia generates large volumes of agricultural residues: rice husks, palm empty fruit bunches and shells, coconut shells, cocoa pods and wood waste. Open burning of residues contributes to haze. Turning some of that into biochar for smallholder farms, including coffee and cocoa agroforestry, could combine removals with soil benefits. Feedstock must be truly residual and sustainably sourced, with no clearing for biomass. See soil carbon for smallholders.
Buyers often value biochar for its durability, but they also look closely at feedstock sustainability and production emissions, so transparent data on both supports better prices.
Common mistakes
- Using feedstock that has other productive uses without accounting for it.
- Ignoring methane and soot from simple kilns.
- No proof of where biochar was applied.
More on the agroforestry hub.
Frequently asked questions
How long does biochar carbon last?
Much longer than carbon in plant residues, because pyrolysis turns it into stable aromatic carbon. Methodologies estimate the share that persists over long periods using lab tests of the char, such as its hydrogen to organic carbon ratio.
Can smallholders produce biochar credits?
Some methodologies allow small-scale or artisanal production, but monitoring every kiln is costly. Many credited projects use larger industrial units fed by agricultural or forestry residues.