Inertinite Permanence Benchmark
Citation: Sanei H, Rudra A, Przyswitt ZMM, Kousted S, Sindlev MB, Zheng X, Nielsen SB, Petersen HI (2024). Assessing biochar’s permanence: An inertinite benchmark. International Journal of Coal Geology 281: 104409. https://doi.org/10.1016/j.coal.2023.104409 (open access)
What it is: The petrography paper behind the “inertinite / random reflectance” camp in the permanence debate. It proposes a reflectance threshold for classing biochar carbon as inertinite-like, and therefore effectively permanent.
Key figures
| Figure | Value | Where | Check |
|---|---|---|---|
| Proposed benchmark | Random reflectance Ro = 2% (“IBRo2%“) | Abstract | ✓ abstract |
| Commercial samples meeting it | 76% of studied commercial biochars had their entire Ro distribution above 2% | Abstract | ✓ abstract |
| Modelled persistence | ~100 million years for a typical inertinite biochar to lose half its carbon, assuming a highly oxidizing environment at a constant 30 °C | Abstract | ✓ abstract |
| Other carbon pools | Incompletely carbonized biochar may hold up to three less-stable pools, measurable with geochemical pyrolysis plus Ro | Abstract | ✓ abstract |
| Carbonization temperature | Ro can be used to back-calculate the peak temperature biochar particles reached | Abstract | ✓ abstract |
Use with care
- The half-life comes from a kinetic model for inertinite under stated conditions. It isn’t a field measurement of biochar decay.
- Crediting reflectance is a standards decision; see Permanence Science for Credits and Puro vs Other Standards. Critiques of the approach: Risks and Controversies.
Related: Permanence · Reflectance Ro and HyPy · Permanence Debates · models soil GHG from biochar · Key Sources