‘Biochar’ is currently the focus of extraordinary levels of both technological optimism and debate. As a substance, biochar refers quite simply to the carbon-rich product that results when biomass – from wood or leaves to manure or crop residues – is burned under oxygen-deprived conditions. But around the idea of biochar and the processes of generating and then burying it are emerging claims and hopes with far-reaching implications. The promise of biochar is generating a mass of research, imagination, and investment that for the moment far outpace actual practices, implementation and systems on the ground. Critique and counter-arguments are swirling too, in a mass of sometimes heated and polarized debate.

This paper tracks key narratives and positions in this emerging ‘politics of technological promise’ around biochar, and thus reflects on the prospects of biochar becoming part of pathways to sustainability that also meet the livelihood priorities of small farmers in rural African settings and beyond.