Puro CORC200+
What this note is: the durable-credit concept note — what CORC200+ means as a permanence claim and labelling transition, and how it sits in the Puro product family.
What this note is not: a full reprint of Edition 2025 rules. For exhaustive eligibility, feedstock, end uses, LCA, and equations, open Puro Biochar Methodology Edition 2025. For audits and US producer ops, open Puro Project Cycle and MRV.
| Operator | Puro.earth (Puro Standard + Registry) |
| Unit | CO₂ Removal Certificate labelled CORC200+ = 1 tCO₂e net removal |
| Current biochar method | Puro Biochar Methodology Edition 2025 — V1 12 Jun 2025; v2 (retail R3) 27 Nov 2025 |
| Prior biochar label | CORC100+ under Edition 2022 |
| Index | CORCCHAR |
| Compare | Puro vs Other Standards |
Science: Permanence · Permanence Science for Credits · Biochar as Durable CDR · Properties
One-sentence definition
CORC200+ is Puro’s Edition 2025 biochar credit label asserting net durable CDR with a permanence framing of several centuries (≥200 years), quantified with a revised power-law decay model (H/C_org + soil temperature, 80% CI lower bound), and issued ex-post only after biochar reaches a durable eligible use.
Snapshot table
| Item | Value |
|---|---|
| What it credits | Net CDR across biomass → thermochemical conversion → eligible use |
| Durability label | Several centuries (≥200 years); EU “permanent removal” alignment cited by Puro |
| Prior label | CORC100+ (Edition 2022; models soil GHG from biochar multi-pool) |
| H/C_org gate | < 0.70 |
| Crediting period (Ed. 2025) | 10 years, renewable twice |
| Issuance | Ex-post after durable eligible use + Output Audit |
| Ro / reflectance | Reporting encouraged; does not affect quantification yet |
| Buffer | No default reversal buffer |
| Index (Aug 2026) | CORCCHAR €135.35 |
| ICVCM | Program CCP-Eligible (General Rules v4.2+, Dec 2025); biochar methodology not yet CCP-Approved |
| Biochar projects since 2019 | 70+ (Puro permanence post) |
Label history: from Spokas / 100+ to 200+
| Label | Biochar methodology | Permanence framing | Decay basis |
|---|---|---|---|
| Early (Edition 2019) | Spokas 2010 O:C framing | 100-year style | Spokas |
| CORC100+ | Edition 2022 | ~100 years | Woolf et al. 2021 multi-pool exponential; H/C_org + soil T |
| CORC200+ | Edition 2025 (v1 Jun 2025; v2 Nov 2025) | Several centuries (≥200 years) | Revised power-law decay; H/C_org + soil T; 80% CI lower bound; open-source notebook |
Source: Puro permanence explainer, 2025-07-03; Edition 2025 v2 §1.1, §6.2.
Why the rename matters commercially
- Buyers and offtake term sheets increasingly distinguish 100-year, 200-year / centuries, and 1000-year / millennial claims (Puro vs Other Standards · Buyers and Offtakes).
- Marketing baseline CORCs still often say “100+ year durability” across pathways; biochar Edition 2025 specifically issues CORC200+ — do not conflate pathway-generic CORC marketing with the biochar label.
- CCP methodology labels are a separate integrity layer: Puro program eligible ≠ biochar method CCP-Approved (Puro.earth Overview).
Permanence claim — what is asserted, what is not
Asserted
- Quantification horizon of 200 years under a power-law persistence model.
- After 200 years, deeper-soil protection is assumed for further centuries → marketing/label claim of several centuries / CORC200+.
- Conservatism via the lower bound of an 80% confidence interval.
- Soil temperature from Puro dataset with a 7 °C floor; H/C_org domain 0–0.7.
Not asserted (yet)
- Millennial / 1000+ year inertinite-equivalent permanence as a quantified CORC factor.
- That Ro (random reflectance) changes the number of CORCs — it is encouraged reporting only.
- That program CCP-Eligibility equals a CCP credit label on biochar CORCs.
Puro explicitly stopped at centuries, not millennia, pending integration (permanence post). Contrast:
| Program | Horizon path |
|---|---|
| Puro CORC200+ | Centuries (200+) |
| Verra VM0044 | 100 years |
| Isometric | 200y or 1000y if Ro≥2% |
| CSI | GPC >1000y / SPC ≤1000y (upper path Ro≥3.8% or HyPy≥90%) |
Science debate map: Permanence Science for Credits · Permanence · Risks and Controversies
Equations and Table 6.1: Puro Biochar Methodology Edition 2025
Quantification sketch (pointer, not full method)
Net CORCs:
[ \mathrm{CORCs} = C_{\mathrm{stored}} - C_{\mathrm{baseline}} - C_{\mathrm{loss}} - E_{\mathrm{project}} - E_{\mathrm{leakage}} ]
- (C_{\mathrm{stored}} = Q_{\mathrm{biochar}} \times C_{\mathrm{org}} \times 44/12)
- Persistence fraction: (PF = M - a \times (H/C_{\mathrm{org}})) with (M,a) from soil-T Table 6.1
- Worked intuition at 20 °C: H/C_org 0.4 → PF ≈ 75.8%; H/C_org 0.2 → ≈ 82.8%
Open-source model: https://github.com/puro-earth/PuroBiocharPersistenceEdition2025
Full eligibility, LCA, baselines, Table 3.2: Puro Biochar Methodology Edition 2025
Lab cadence / CoC: Puro Project Cycle and MRV · MRV Stack
Transition milestones (label + method)
| Milestone | Date |
|---|---|
| Public consultation | 3–28 Apr 2025 |
| Edition 2025 V1 approval | 12 Jun 2025 |
| Publishing | 30 Jun 2025 |
| Launch (Facility Audits under 2025) | 1 Nov 2025 |
| Last 2022 Audit Package (pre-launch regs) | 15 Dec 2025 |
| Edition 2022 termination | 12 Jun 2030 |
| Retail R3 enabled (v2) → still CORC200+ units | 27 Nov 2025 |
Implications for the label:
- New facilities after Launch must issue under Edition 2025 → CORC200+, not CORC100+.
- Legacy Edition 2022 facilities may finish their period as CORC100+ pathway credits, then renew only on latest edition (CORC200+ rules).
- Preliminary Assessments against 2022 do not carry over.
Detail: Puro Biochar Methodology Edition 2025 · ops: Puro Project Cycle and MRV
Where CORC200+ sits in the market
| Signal | Note |
|---|---|
| Public price | CORCCHAR Aug 2026 €135.35; all-CORC CORCX €150.40 |
| Liquidity | Issuance→transfer/retirement 95 → 22 days (2021 → mid-2025, CDR.fyi via Puro) |
| Scale | ~1.88M issued / ~1.08M retired / 119 projects (all methods, registry 2026-09-14); 70+ biochar projects since 2019 |
| Buyers | Early Microsoft CORCs; CDR.fyi BCR leaders include Microsoft, Google, BCG, JPMorgan, Swiss Re, SEB (Puro narrative) — Buyers and Offtakes |
| Integrity gap | Program CCP-Eligible; biochar method pending category CCP approval |
Market volumes: Market Volumes and Pricing · chooser: Puro vs Other Standards
Architecture of the vault’s Puro cluster
| Note | Role |
|---|---|
| This note (Puro CORC200+) | Durable-credit concept — label, claim, transition, pointers |
| Puro.earth Overview | Company, registry, scale, ICVCM, link map |
| Puro Biochar Methodology Edition 2025 | Exhaustive method chapter |
| Puro Project Cycle and MRV | Audits, labs, CoC, US path, pitfalls |
| Puro Pricing and CORC Indexes | CORCCHAR/CORCX, fees, deals |
| Puro vs Other Standards | Comparison + chooser |
Common confusions (quick FAQ)
Is every CORC a CORC200+?
No. CORC200+ is the biochar Edition 2025 label. Other Puro methodologies use other durability labels (100+ / 200+ / 1,000+ depending on pathway).
Is CORC200+ the same as a 1000-year credit?
No. Puro stopped at centuries. Millennial claims live elsewhere (e.g., Isometric Ro path, CSI GPC upper class).
Does Ro unlock more CORCs under Puro?
Not yet. Encouraged reporting only; does not change quantification under Edition 2025.
Does CCP-Eligible program status put a CCP label on my biochar CORCs?
Not by itself. Methodology-category approval is separate; as of 2025-12-11 biochar was not yet CCP-Approved.
When is the credit created?
At first durable eligible use + successful Output Audit — not at the kiln door alone.
Primary links
- Permanence science
- Edition 2025 v2 PDF
- Transition plan PDF
- Retail v2 update
- CORC indexes
- Fees / journey
- CORC page
- Persistence model — https://github.com/puro-earth/PuroBiocharPersistenceEdition2025
- Woolf et al. 2021 — https://doi.org/10.1021/acs.est.1c02425
- inertinite permanence benchmark — https://doi.org/10.1016/j.coal.2023.104409
- Azzi et al. 2024 — https://doi.org/10.1016/j.geoderma.2023.116761
Also: Key Sources
See also
Puro.earth Overview · Puro Biochar Methodology Edition 2025 · Puro Project Cycle and MRV · Puro Pricing and CORC Indexes · Puro vs Other Standards · Biochar as Durable CDR · Permanence Science for Credits · Permanence · MRV Stack · Market Volumes and Pricing · Buyers and Offtakes · Risks and Controversies · Verra VM0044 · Isometric Biochar Protocol · CSI Global Biochar C-Sink · Double Counting and Credit Ownership · Properties · Carbon Markets Hub · Key Sources