Sanei et al. (2025): Quantifying inertinite carbon in biochar

Hamed Sanei, Małgorzata Wojtaszek-Kalaitzidi, Niels Hemmingsen Schovsbo, Rasmus Stenshøj, Zhiheng Zhou, Hans-Peter Schmidt, Nikolas Hagemann, David Chiaramonti, Tryfonas Kiaitsis, Arka Rudra, Anna J. Lehner, Robert W. Brown, Sophie Gill, Erica Dorr, Stavros Kalaitzidis, Fariborz Goodarzi and Henrik Ingermann Petersen, IN: International Journal of Coal Geology, https://doi.org/10.1016/j.coal.2025.104886

The carbon dioxide removal (CDR) potential of biochar is determined by the long-term stability of its biogenic carbon, derived from atmospheric CO₂ fixed by photosynthesis and stabilized in solid form. This stability (carbon permanence) is commonly assessed using decay models to evaluate resistance to re-emission as greenhouse gases. However, these models are limited, as they focus primarily on short-term degradation of labile carbon fractions and are not suited to project the behavior of the highly recalcitrant component of biochar over extended timescales. Inertinite represents highly aromatized and condensed carbon structures that are geochemically stable over millennia. This paper builds upon the Inertinite Benchmarking (IBRo₂) methodology, directly quantifying the stable carbon fraction in biochar rather than relying on modeling. The method combines thermochemical analysis and incident-light microscopy to measure the reactive (labile) component and solid carbonized macerals, respectively.

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