Hamed Sanei and colleagues, in their study published in BiocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More, critically evaluate the widely used two-pool exponential decay model for estimating biochar permanence. Their findings reveal major flaws in how biochar carbon stability is currently assessed, with significant implications for carbon removal policies and certification frameworks.

The two-pool model divides biochar carbon into a labile fraction (C1), which decomposes quickly, and a recalcitrant fraction (C2), which remains stable over time. However, the study finds that the model is poorly parameterized, effectively treating biochar as if it were composed mostly of the labile fraction. This leads to an overestimation of decay rates, underestimating biochar’s true carbon sequestration potential.

Another key issue is the lack of correlation between C1 and C2 proportions and key biochar properties, such as production temperature and hydrogen-to-carbon (H/C) ratios. Higher pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More temperatures typically increase biochar stability, yet the model fails to reflect this well-established relationship. The study argues that these inconsistencies weaken the model’s ability to predict long-term carbon storage accurately.

The authors propose a multi-pool decay model that better represents biochar’s complex decomposition behavior. They recommend integrating accelerated aging experiments, incubation studies, and molecular modeling to improve parameter accuracy. These refinements would provide a stronger scientific basis for biochar’s role in global carbon management strategies.

This study highlights the need for a more robust modeling framework to ensure that biochar is correctly valued as a durable carbon sink. Future research should focus on refining parameterization methods to align with biochar’s well-documented chemical properties.

Sanei, H., Petersen, H.I., Chiaramonti, D. et al. Evaluating the two-pool decay model for biochar carbon permanence. Biochar 7, 9 (2025). https://doi.org/10.1007/s42773-024-00408-0