Biochar FAQ
Biochar ˈbī-(ˌ)ōˈ-chär: Biochar is pyrolyzed biomass
How is biochar made? Biochar is made using a process called pyrolysis. During pyrolysis, biomass is heated in the absence of oxygen. Under these conditions, biomass is converted into solid carbon and pyrolysis gas. These pyrolysis gases can be condensed into bio-oil, while solid carbon can be used as a long-term carbon storage method (biochar).
So you’re just burning biomass? Not exactly. When biomass is combusted (burned), it combines with oxygen in the air to generate carbon-dioxide (CO2). When biomass is pyrolyzed, no oxygen is available to generate CO2. Instead, the carbon from the biomass is converted to biochar, an innert and solid form of carbon.
What are suitable feedstocks for making biochar? Biochar can be made from virtually any type of biomass, including wood. Of particular interest to Re-char is the use of agricultural waste feedstocks. These feedstocks include rice hulls, corn stover, wheat straw and nut shells.
Why agricultural waste? Agricultural waste represents a ubiquitous product with few other end-uses. Typically, ag waste is left on fields to decompose, which ultimately results in the release of the greenhouse gases (GHGs) carbon-dioxide (CO2) and methane (CH4). While composting and mulching can generate fertilizers from ag waste, these processes also generate signifcant amounts of greenhouse gases.
How can biochar help to mitigate GHGs? When biomass is pyrolyzed, carbon that would otherwise be released as CO2 and CH4 via decomposition or combustion is locked into an inert form– biochar. Peer-reviewed studies now demonstrate that biochar can remain inert for upwards of 2000 years. By pyrolyzing agricultural wastes that would otherwise genereate GHGs, biochar production can actually help to reduce concentrations of certain greenhouse gases.
How can biochar improve degraded soils? When biomass is pyrolyzed, many of the nutrients (N,P,K) necessary for fertile soils are conserved in the biochar. In addition, solid carbon has an extremely high surface area, making it an ideal habitat for benefiical microorganisms and fungi. By mixing biochar into degraded soils, farmers can help to fight GHGs while reducing their demand on traditional fertilization techniques.
