Credit Lifecycle

The MassID → Certificate → Credit lifecycle and relationships in the Carrot Network.

From physical waste to tradeable credits

The Carrot Network transforms verified recycling work into environmental assets through a layered registry structure. Each layer builds on the one before it, creating an unbreakable chain of evidence from physical waste to purchasable credits.

The hierarchy has five layers:

MassID — A verified batch of waste (material type, weight, chain of custody from Waste Generator to Recycler). Implemented as a permanent, non-transferable registry record.
Certificate (GasID or RecycledID) — Represents a verified environmental outcome when MassIDs pass methodology verification at an accredited facility. Implemented as a permanent, non-transferable registry record.
Credit — A tradeable unit of verified environmental impact where 1 credit = 1 metric ton. Issued automatically when certificates are created, in a matching amount. Each methodology issues credits under its own credit symbol (e.g. BOLD Recycling issues C-BIOW, BOLD Carbon (CH₄) issues C-CARB.CH4 for methane). Implemented as a fungible digital unit — issued and transacted in any amount, including fractions.
CreditPurchaseReceipt — A permanent, non-transferable receipt recorded when credits are purchased. Provides immutable proof that the transaction occurred.
CreditRetirementReceipt — A permanent, non-transferable receipt recorded when credits are retired. Provides permanent proof that the environmental offset has been claimed.

How the layers connect

Each layer in the hierarchy references the one below it, creating full traceability:

Layer	Registry object	Public model	Implementation detail	Transferable?	What it proves
Tracking	MassID	Permanent registry record	ERC-721	No	Physical waste was collected, sorted, and transported
Certification	GasID / RecycledID	Permanent registry record	ERC-721	No	Environmental impact was verified by dMRV
Credit issuance	TRC / TCC (e.g. `C-BIOW`, `C-CARB.CH4`)	Fungible credit	ERC-20	Yes	1 credit = 1 metric ton of verified impact
Purchase	`CreditPurchaseReceipt`	Permanent registry record	ERC-721	No	Credits were purchased with USDC payment
Retirement	`CreditRetirementReceipt`	Permanent registry record	ERC-721	No	Credits were permanently destroyed and claimed

All of these records live on the network's public registry.

Why are records non-transferable?

All MassIDs, certificates, and receipts in the Carrot Network's registry are non-transferable — they cannot be moved between accounts. This is a deliberate design choice:

Tamper-proof audit trail — Since tokens cannot be moved, the provenance chain from waste to credit is permanent and verifiable.
No speculative trading — MassIDs and certificates represent verified physical work, not speculative assets. Preventing transfers ensures they remain tied to their original context.
Custody via the Vault — All non-transferable records are held by the Vault, which manages custody on behalf of the network.

Only credits are transferable, because they are the layer designed for market activity — purchasing, holding, and retiring environmental offsets.

Two credit paths

The credit lifecycle produces two independent credit types, each representing a different environmental outcome. Each path is driven by a different methodology framework that processes MassIDs independently:

Recycling path

MassID → RecycledID → Tokenized Recycling Credit (TRC)

Proves that waste material was physically recycled. Tokenized Recycling Credits (TRC) use a unit of 1 metric ton of certified recycled material and are issued proportionally to each certificate's verified quantity. The BOLD Recycling methodology issues TRCs with the credit symbol C-BIOW; other recycling methodologies may use different symbols. TRCs are material-specific — glass TRCs represent recycled glass, plastic TRCs represent recycled plastic.

Carbon path

MassID → GasID → Tokenized Carbon Credit (TCC)

Proves that greenhouse gas emissions were reduced by recycling instead of landfilling. Tokenized Carbon Credits (TCC) use a unit of 1 metric ton of CO₂-equivalent emission reductions and are issued proportionally to each GasID certificate's verified quantity. The BOLD Carbon (CH₄) methodology issues TCCs with the credit symbol C-CARB.CH4 (methane); other carbon methodologies may use different symbols. A carbon methodology calculates the emissions difference between the recycling scenario and the baseline landfill scenario directly from the MassID data.

The same MassID can back both a RecycledID and a GasID, since each certificate is issued by an independent methodology framework — a recycling methodology verifies the physical recycling outcome, while a carbon methodology quantifies the emission reductions.

End-to-end traceability

The credit lifecycle enables full traceability from retired credit back to physical waste:

Credit retirement → CreditRetirementReceipt → Credit (e.g. C-BIOW, C-CARB.CH4) → Certificate (RecycledID or GasID) → MassID → Physical waste batch with chain of custody

This traceability is publicly verifiable through the Carrot Explorer and any blockchain block explorer such as PolygonScan. Any auditor, regulator, or interested party can trace a retired credit back through every layer to the specific waste batches and recycling participants that produced it.

Learn about certificates · Learn about credits · Learn about purchasing · Learn about retirement