Digital fuel passports

What should a digital fuel passport do?

A digital fuel passport should make a fuel claim traceable: which delivery it concerns, which evidence supports it, which calculation rules apply and who must correct the record when that evidence changes.

In the Carbon Basel Accord, the passport is part of a proposed architecture for maritime carbon governance. This guide develops that proposal into practical evidence questions. It does not describe the CBA passport as an adopted IMO instrument or a universally required statutory document.

The starting point is a connected record. A reviewer should be able to move from a supplier's claim to the underlying delivery, the relevant sustainability evidence, the emissions methodology and the scope of verification. A digital format is useful when it preserves those relationships and their revision history.

Different records establish different facts.

Commission guidance distinguishes the delivery record from the sustainability evidence supporting relevant fuel claims. Evidence can arrive at different times; the review should record what is still outstanding and when it must be available. Do not assume a universal “30-day” Proof of Sustainability deadline. [1]

Four questions the record should answer

1. Which fuel and delivery?

Identify the ship, port, date, supplier, delivery reference and batch or consignment. Reconcile quantity and units. For a blend, state the fractions and whether they are expressed on a mass or energy basis.

2. Which characteristics and evidence?

Record the feedstock, production pathway and relevant chain-of-custody method. Link any sustainability claim to its supporting evidence and covered quantity. Check the certification scheme's recognised scope and the operator certificate's validity. Recognition for one pathway or activity does not automatically cover every other one. [2]

3. Which calculation?

State the GHG value, unit, lifecycle boundary and energy basis. Identify the method and version, and distinguish default factors from actual or certified values. Record relevant engine or converter assumptions and methane-slip treatment. IMO's Fuel Lifecycle Label provides a useful reference for organising lifecycle information. [3]

4. Who may rely on it, and who corrects it?

Identify the intended reporting or commercial use, verification scope and unresolved limitations. Preserve the issuer, review date and document version. Give every material discrepancy an owner, a due date and a closure record.

These are recommended companion controls. Their applicability depends on the fuel, claim and governing framework; they are not a statement that every field is legally compulsory for every delivery.

Traceability must follow the applicable rules.

A chain-of-custody method explains how fuel characteristics are assigned through a supply chain. Commission FuelEU guidance recognises the role of RED-compliant mass balance in certification; unrestricted book-and-claim is not an interchangeable substitute. Record the applicable method instead of describing every transfer as physical segregation. [4]

The same guidance also distinguishes fossil fuels from fuels requiring sustainability certification. Do not request a sustainability certificate merely because a passport template contains that field. Equally, a supplier-specific value cannot automatically replace a default factor where the rules prescribe that default. [4]

A digital signature can support issuer identification and detection of later alteration. It does not independently establish that the original quantity, feedstock or emissions claim was correct. The review must still reach the evidence behind the record.

When the delivery and the claim disagree

Suppose the delivered quantity on a bunker delivery note does not reconcile with the quantity allocated by the accompanying sustainability evidence. This is a hypothetical documentation discrepancy, not an allegation of fraud.

1. Record the mismatch. Link both documents and specify the quantities and units that disagree.
2. Control reliance. Mark the affected claim as awaiting clarification and identify reports or commercial statements that may depend on it.
3. Assign the response. Request the supplier's explanation and identify the internal owner and relevant verifier interface.
4. Preserve the correction. Retain the original, the revised evidence, the reason for change and the review decision.
5. Close the downstream action. Record which affected users or reports received the correction and who accepted closure.

Use the fuel-evidence checklist to capture these questions. For a numerical discrepancy, see the worked example.

A shared record needs shared accountability.

The proposed passport connects the book's three pillars. Global Measurement establishes the meaning of a claim. Interoperable Carbon Pricing examines the conditions for using it across systems. Coordinated Supervision assigns responsibility for discrepancies and their resolution.

The test is practical: can an independent reviewer reconstruct the claim, identify its limits and follow a correction to closure? Read the executive brief for the wider proposed framework.