Biochar Carbon Removal (BCR)
How biochar removes carbon dioxide from the atmosphere and stores it for the long term.
How biochar carbon removal works
Plants naturally remove carbon dioxide from the atmosphere through photosynthesis, storing carbon in their biomass. When that biomass dies, decomposes or is burned, much of the carbon is eventually returned to the atmosphere.
Biochar carbon removal (BCR) changes this cycle by using pyrolysis to convert biomass into a stable, carbon-rich material. Pyrolysis heats biomass under oxygen-limited conditions, converting part of the biomass carbon into biochar rather than allowing it to return rapidly to the atmosphere.
When the biochar is used or stored appropriately, this stable carbon can remain out of the atmosphere for long periods. The pyrolysis process also produces gases and thermal energy that can potentially be recovered and put to useful purposes such as drying biomass or providing heat.
For BCR to represent a genuine net carbon removal, the whole process needs to be considered, including the source of the biomass, processing and transport emissions, pyrolysis emissions, the properties of the biochar and what ultimately happens to it.
Biochar carbon removal is available today
Biochar carbon removal can be deployed using biomass resources and pyrolysis technologies that are already available today.
Unlike some carbon removal pathways that depend on large new infrastructure, BCR can operate at different scales and in distributed locations close to sources of biomass.
This creates opportunities to combine carbon removal with practical benefits such as managing biomass residues, producing useful heat and creating biochar for appropriate applications.
The scale and quality of carbon removal, however, depend on how the biomass is sourced, how the pyrolysis process is operated and how the resulting biochar is used and accounted for.
How BCR compares with other carbon removal methods
Biochar carbon removal is one of a number of approaches being developed and deployed to remove carbon dioxide from the atmosphere.
Other pathways include afforestation and reforestation, bioenergy with carbon capture and storage (BECCS), direct air capture with carbon storage (DACCS), and enhanced weathering.
These approaches differ considerably in their cost, scalability, energy requirements, land requirements, permanence and wider environmental impacts. BCR is distinctive because it uses biological carbon capture through plant growth, followed by pyrolysis to convert part of that carbon into a more persistent solid form.
It can also produce useful thermal energy and a physical biochar product, although the benefits and net carbon removal achieved depend on the particular project.
How is biochar carbon removal measured?
Producing biochar does not automatically mean that the same quantity of carbon can be claimed as carbon dioxide removal. The net removal depends on the carbon stored in the biochar and the emissions associated with producing, transporting and using it.
Biochar carbon removal projects therefore need to measure and document important information about the feedstock, production process, biochar and its final use or storage.
This can include the source and quantity of biomass, production conditions, the carbon content and stability of the biochar, energy use, transport and other project emissions, and evidence of where the biochar ultimately goes.
These measurements can be used to calculate the net quantity of atmospheric CO₂ stored by the project and provide the evidence required for monitoring, reporting and verification (MRV).
How long does biochar store carbon?
Pyrolysis transforms part of the carbon in biomass into forms that are much more resistant to biological decomposition than the original material.
The persistence of biochar is not identical for every biochar. It depends on factors including the feedstock, pyrolysis conditions and properties of the resulting material. This is why biochar characterisation and appropriate carbon accounting are important when estimating long-term carbon removal.
Can biochar generate carbon removal credits?
Biochar carbon removal can form the basis of verified carbon removal credits where a project meets the requirements of an appropriate carbon removal methodology or standard.
This typically requires evidence covering biomass sourcing, production, biochar quality, lifecycle emissions and the final storage or use of the biochar. The resulting carbon removal is therefore based on the net climate benefit of the project, rather than simply the quantity of biochar produced.
Biochar, soil carbon and carbon removal
Biochar is often applied to soils, where it can provide a long-term store for carbon while potentially contributing to soil management objectives. However, soil carbon sequestration and biochar carbon removal are not exactly the same thing.
Our guide to soil carbon sequestration explains the wider role of soils in storing carbon and where biochar fits within that system.