Biochar is readily available biomass (wood, stalks from grain crops, vine cutting etc.) reduced to carbon in a low oxygen atmosphere through a process called pyrolysis. Anybody that has ever made a fire in the garden to burn garden waste will have noticed that a fire that smoulders slowly tends to produce carbon plus ash. The carbon is the result of a low oxygen atmosphere during the process (plenty of heat but not enough oxygen to make the carbon burn).
Biochar is important in two ways:
- it offers the only currently realisable way to remove CO2 from the atmosphere,
- it can act as a soil conditioner, improving soils that have lost their fertility and which rely on fertilisers to produce adequate crops.
CO2 Sequestration
Although pyrolysis could be considered as the “burning” of biomass, the absence of oxygen means that most of the carbon in the biomass is retained, as carbon. This carbon was extracted from the atmosphere (as CO2) as the plant grew. Thus biochar is atmospheric CO2 “made solid”.
Biochar In the Soil
Scientific consensus is that bio-char will remain stable in soils for up to 2000 years. During the first year that biochar is incorporated in to soil there is some initial carbon loss. However, most of the biochar will remain in the soil for up to 2000 years. The on-going, long-term large-scale "Brazilian experiment is a further validation of this.
Biochar as a soil conditioner
Biochar can improve soils and allow soils to remain fertile even under difficult conditions. This assertion is validated by the "Brazilian experiment" as well as on-going work in Europe and elsewhere. There are large areas of the planet which could benefit from soil conditioners.
Biochar and Climate Change
Humanity faces two issues with respect to climate change: reduce current and future GHG emissions and address the current high levels of CO2 in the atmosphere. At the moment, it has three tools with which to address current and future emissions:
- Renewables
- Energy efficiency
- Carbon capture and storage (CCS)
Biochar is the fourth tool and sits in its own category in that it is the ONLY currently available system able to safely sequester existing atmospheric CO2.