Feedstock emissions
The feedstock biomass consists of crop waste from the farmer's harvest, for example corn cobs and stalks. In the base case scenario the biomass is burned or left to decompose naturally, significant emissions are generated. No emissions are produced during the preparation or storage of the feedstock biomass. The farmers are trained to ensure proper drying and storage of the biomass before pyrolysis. There are no emissions associated with the transportation of the feedstock since it remains on the farmers' land.
Emissions from conversion
The farmers use the flame curtain, kon-tiki method of pyrolysis for biochar production. This pyrolysis technology does not consume any electricity or fuel. For every 1,000 kg of biochar produced, 30 kg of CH4 emissions are accounted for. The global warming potential over a 20-year period (GWP20) for this emission is 2.6 t CO2eq.
CH4 Compensation
The project leverages the avoidance of greenhouse gas (GHG) emissions from burning crop residues or biomass decomposition to compensate for the emissions generated during pyrolysis. If necessary, the semi-persistent carbon of biochar can be considered for methane compensation, as outlined in the Artisan Guideline.
Emissions from Application
There are no emissions associated with the preparation of the biochar-based fertilizer. Farmers are trained to use locally available inputs like compost or manure to charge the biochar before applying it to their soil.
Security Margin
A security margin of 3% of biochar carbon is considered to address any minor emissions generated, as stated in the Artisan Guideline.
Carbon Persistence
The project aims to deliver highly durable carbon sinks that last for over 1,000 years. The polyaromatic fraction (PAC) of the biochar will be used for carbon sinks and the credits which are ultimately retired. Additional details regarding persistence, PAC vs. SPC, and carbon sink calculations can be found in Chapter 14 of the Artisan Guideline.
Carbon Content and Sampling
Random samples are taken to ensure the H/C ratio is below 0.4 and to determine the C-content. Biochar Life has conducted multiple samples of different feedstocks such as corn cob and stalk feedstocks, resulting in C-contents of 63.8% and 80%, respectively. The C-content is approved by CSI.
