Biochar

Feedstocks

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Feedstocks

Hub for biomass inputs to biochar: taxonomy, property consequences, logistics, and sustainability screens. Deep contrast chapter: Woody vs Manure Ag Feedstocks. Process coupling: Production · Biochar Quality from Process · Gasification Residues. Report context: 2026-09-16.

Related notes: Contaminants and Quality · MRV Stack · Product Standards EBC IBI · NRCS soil carbon amendment in US ag · Production Hub · Key Sources

1. Why feedstock choice matters

DimensionWhy it mattersWhere detailed
Carbon yield & permanence proxiesSets durable C per tonne feedstock/productWoody vs Manure Ag Feedstocks · Permanence
ContaminantsPAH process risk + metals/PFAS feedstock riskContaminants and Quality
Nutrients / ashFertilizer value vs salinity/metalsProperties · Heavy Metals and Ash
Competing usesFuel, feed, soil OM, materialsThis note §4
LogisticsMoisture, density, seasonality, transportThis note §5
Additionality / baselineWould biomass have decayed, burned, or been landfilled?Methodology notes via MRV Stack

2. Taxonomy (practical classes)

Aligned with Woolf Table 1–2 classes and EBC positive-list culture (Woolf 2021; EBC 10.5E §4):

  1. Woody — forest residues, mill residuals, untreated wood chips (sustainability proof for virgin forest wood: FSC/PEFC/EU-RED etc. per EBC §4.7)
  2. Herbaceous ag residues — straws, stovers, grasses, bagasse
  3. High-silica residues — rice husks/straw (high ash)
  4. Nut shells / pits / stones — high lignin, often high FC
  5. Manures & digestates — high ash/nutrients; EBC H/C_org < 0.4
  6. Biosolids / paper sludge — metals/PFAS scrutiny; often materials-grade only
  7. Dedicated crops — e.g. miscanthus, SRF; EBC requires soil-C and input sustainability (§4.6)
  8. Invasive / landscape biomass — project-specific contamination checks

EBC positive list governs which biomasses enter which certification classes; fossil carbon generally banned (limited EBC-Basic exceptions with tracking) (EBC §4).

3. Property consequences (already quantified in vault)

C_org of finished biochar commonly <20% to ~95% DM depending on feedstock/process (EBC §7.1); wood/nutshell chars often 70–90%, straw often 40–50% (same section).

4. Sustainability screens (research checklist — not invented criteria)

Before claiming climate benefit:

  • No deforestation / clear-cuts for feedstock (EBC §4.7; reviews biochar climate mitigation energy/land framing · DOI)
  • Plastic/rubber contamination limits (EBC: ≤1% for soil classes; up to 10% materials with approval — §4.5)
  • Food vs fuel competition and ILUC — evaluate in LCA; do not invent vault thresholds
  • Baseline fate (decay, open burn, landfill CH₄) dominates system GHG (CDR Potential and IPCC Accounting)

Registry feedstock rules: point to Puro Biochar Methodology Edition 2025, Verra VM0044 Methodology and Eligibility, Isometric Biochar Protocol, CSI Global Biochar C-Sink rather than duplicating.

5. Logistics & preprocessing

  • Moisture: drying is often the largest energy sink before pyrolysis; EBC energy-efficiency calculus includes drying energy (EBC §8.5).
  • Particle size: chipping/grinding for reactor feed; FeedPlus may recommend grinding char <3 mm to reduce stone/glass injury risk (EBC §10.3).
  • Seasonality & density: herbaceous residues bulky/seasonal; woody more storable if dry.
  • US farm context: NRCS soil carbon amendment in US ag · guides farm biochar application.

6. Practice takeaway

  1. Classify feedstock with Woolf/EBC vocabulary before modeling CDR tonnes.
  2. Run contaminant risk by class (metals/PFAS for manures/biosolids; PAH for all via process).
  3. Document sustainability proof at procurement—not only at kiln exit.

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