Biochar sequestration is considered carbon negative as it results in a net decrease in atmospheric carbon dioxide over centuries or millennia time scales. Instead of allowing the organic matter to decompose and emit CO2, pyrolysis can be used to sequester the carbon and remove circulating carbon dioxide from the atmosphere and stores it in virtually permanent soil carbon pools, making it a carbon-negative process.
According to Johannes Lehmann of Cornell University, biochar sequestration could make a big difference in the fossil fuel emissions worldwide and act as a major player in the global carbon market with its robust, clean and simple production technology. The use of pyrolysis also provides an opportunity for the processing of agricultural residues, wood wastes and municipal solid waste into useful clean energy. Although some organic matter is necessary for agricultural soil to maintain its productivity, much of the agricultural waste can be turned directly into biochar, bio-oil, and syngas. Pyrolysis transforms organic material such as agricultural residues and wood chips into three main components: syngas, bio-oil and biochar (which contain about 60 per cent of the carbon contained in the biomass.