Entscheidungsprotokolle · ADR-014
ADR-014: Carbon as a registry-immobilised wrapper plus attestations; no primary issuance
Carbon credits are never created on-chain: the reference records credits immobilised in their registry, links tonnes to lots, mirrors retirement and publishes an attestation.
- Dokument-ID
- ADR-014
- Datum
- 2026-09-21
- Quelle
- docs/adr/ADR-014.md
| Field | Value |
|---|---|
| ID | ADR-014 |
| Subject area | Sustainability |
| Status | Accepted |
| Date | 2026-09-21 |
| Owners | A-REX Contributors |
| Related requirements | FR-12 (SDD §3) |
| Supersedes / superseded by | — |
Context
The earlier carbon module generated its own serial numbers and issued credits on-chain. Verra prohibits tokens representing retired credits and accepts tokenization only of credits immobilised in its registry; Gold Standard has a similar policy. The EU Directive 2024/825 treats unsubstantiated environmental claims as unfair commercial practices.
Issue
How can a lot carry a carbon claim without issuing credits outside their registry?
Assumptions
- Registries are the source of truth for credits.
- Claims attached to a lot must be verifiable against the registry.
Constraints
- Registry tokenization policies; EU Directive 2024/825.
Alternatives considered
| Alternative | For | Against | Outcome |
|---|---|---|---|
| On-chain issuance of credits | Self-contained | Violates registry policy; double-counting risk; legal exposure | Rejected |
| A wrapper of immobilisations linked to lots, with mirrored retirement and an attestation | Registry remains authoritative; claim verifiable | Needs a trusted registrar with registry access | Accepted |
Decision
CarbonImmobilizationWrapper records immobilisations (registry, serial range, vintage, tonnes, proof hash), links tonnes to lots without exceeding the immobilised amount, mirrors retirement and release, and writes the attestation AREX:CARBON:IMMOBILIZED. It never mints credits.
Argument
The registry already solves issuance and double counting; the token's job is to make the link between a lot and immobilised credits visible and verifiable.
Consequences
Positive
- Compatible with registry policies.
- A carbon claim on a lot is an attestation anyone can check.
Negative
- The registrar role is the trust anchor and must be accountable.
Obligations it creates
- The registrar mirrors registry retirements promptly.
Implementation and evidence
| What | Where |
|---|---|
| Contract | contracts/reference/extensions/CarbonImmobilizationWrapper.sol |
| Test | test/standard/Extensions.test.js: records registry immobilisations, links them to batches, mirrors retirement and release, attests |