Retire credits

Retire credits onchain from Carbon Wallet (NFT burn plus certificate), or use the optional off-chain depository.

"Retiring" permanently takes a credit out of circulation so it can be claimed against emissions. Carbonized has two separate mechanisms. Pick deliberately; they do not update each other.

	Onchain retire (in the app)	Depository retire (optional)
Where	Carbon Wallet → NFT Credits → Retire	Carbon Wallet → Depository tab
What changes	NFT is burned, a `RetirementCertificate` is stored, `CreditRetired` is emitted	Backend ledger marks the credit `Retired` (with reason)
Needs	NFT in your wallet (not wrapped), not already retired	A backend you operate at `NEXT_PUBLIC_BACKEND_URL`; credit listed as Active in the depository
Verifiable onchain	Yes: Certificates	No

What a retirement proves

An onchain retirement proves that a token was burned by your wallet, with the reason you typed. It does not prove that the underlying project is real. The reason is a self-declared, unverified beneficiary statement and is public and permanent, so do not put personal data in it.

Path A — Retire onchain in the app

Open Carbon Wallet

Go to /app/carbon-wallet and connect your wallet; there is no password. Open the NFT Credits tab. Wrapped credits are held by the CCT contract and are not listed: unwrap them first on Tokenize (Unwrap tab).

Retire

Click Retire on a card (or tick several cards and click Retire selected), type a reason (for example Scope 1 offset 2026), tick the confirmation and click Retire permanently. The app calls retireCredit (one credit) or batchRetire (up to 50) and waits for the receipt.

Open the certificate

The success dialog links to View certificate (/app/certificates/<txHash>). The page is green only when the NFT contract's stored record matches the event and the credit is issuer-backed; a read error shows an amber "Could not verify" state and demo credits show a "Registration / demo credit" notice.

Path B — Retire with the contracts directly

If you prefer not to use the app, interact with the contracts directly. The examples use Foundry's cast; any wallet-capable tool works.

Unwrap if needed

A wrapped NFT is owned by the CarbonCreditToken contract and cannot be retired. Unwrapping burns the matching CCT, so you must hold at least the NFT's tonnes in CCT:

cast send <CCT_ADDRESS> "unwrapCredit(uint256)" <tokenId> \
  --rpc-url <RPC> --private-key <key>

Reverts: NFT not wrapped, Insufficient CCT balance.

Retire

batchRetire accepts 1–50 token IDs and one shared reason; each token must be owned by the sender and not yet retired.

cast send <NFT_ADDRESS> "batchRetire(uint256[],string)" "[12,13]" "Q1 2026 corporate offset" \
  --rpc-url <RPC> --private-key <key>

For a single token use retireCredit(uint256,string), which additionally requires a non-empty reason (Reason required). Other reverts: Not owner / Not credit owner, Already retired, Invalid batch size.

Read the certificate

cast call <NFT_ADDRESS> \
  "getRetirementCertificate(uint256)((uint256,address,uint256,string,uint256))" 12 \
  --rpc-url <RPC>

Returns originalTokenId, retiredBy, retirementDate, retirementReason, co2Tonnes (tonnes in 18-decimal units). The CreditRetired(tokenId, retiredBy, timestamp, co2Tonnes, reason) event carries the same data; tokenId and retiredBy are indexed.

Retired NFTs are burned, so they disappear from balanceOf and from the app's NFT lists. Global counters (totalRetiredTonnes, userRetiredTonnes) increase.

Optional: depository retire

Only if you run a depository backend and set NEXT_PUBLIC_BACKEND_URL: open Carbon Wallet → Depository, click Retire on an Active row, optionally type a reason and confirm. The app sends POST /depository/credits/:creditId/retire. This only changes the backend ledger: no blockchain transaction occurs, the NFT is not burned and no onchain certificate exists. Do not treat it as proof of retirement.

Reference: CarbonCreditNFT · Carbon Wallet page

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