Availability and spatial distribution of crop and forest biomass residues for biochar production in Kenya

Uptake of biochar for fuel briquetting and soil amendment is constrained in sub-Saharan Africa by inadequate knowledge of the quantity and distribution of feedstocks. This study assessed the quantities and spatial distribution of crop and forest residues available for biochar production in Kenya based on productivity data from 2021 and 2022. The residues were quantified using residue product ratios, surplus available factors and economically viable factors. Kenya produces (0.5-2.4) × 10⁷ Mg y^-1 of crop residues and (1.48-1.8) × 10⁵ Mg y^-1 of forest residues that are potentially available for biochar production. While crop and forest production are the core drivers of the availability of economically viable residues, residue to product ratios and surplus available factors are the primary drivers of residue densities. Crop residues were concentrated in counties located in western, central and southern Kenya. While all counties possess diverse types of residues, maize stalks were prevalent in all 47 counties. No county satisfied the combined requirements of high amounts of residues, high residue density and low supply uncertainties. Therefore, although Kenya has abundant and diverse residues that could produce economically viable biochar, locating production facilities will require a trade-off between counties with high residue densities, or those with supply uncertainty.