It separates the physical use of greener fuels from the accounting-based attribution of their environmental value.
It accelerates market development and connects limited fuel volumes with customer demand.
Credibility, transparency and chain-of-custody verification.
Neither greenwashing nor a perfect end-state solution. A market-based transitional instrument.
Book-and-claim separates the physical fuel flow from the accounting-based environmental value. A producer generates green methanol in one port — say in Northern Europe — and feeds it into the local bunker system. A vessel in an entirely different location — say in Singapore — bunkers conventional fuel but receives the environmental value of the green methanol through a certificate.
Certification is managed through recognised registry systems. In aviation, the ISCC-CORSIA system has become established; in shipping, systems such as ISCC EU and RSB are increasingly relevant. The certificate contains details on fuel quantity, energy content, greenhouse gas intensity and production location. Traceability is the critical element: each unit produced may be accounted for only once, ensured through chain-of-custody procedures.
For regulatory classification, the central question is whether and how FuelEU Maritime recognises book-and-claim approaches. As of 2026, FuelEU accepts RFNBOs (Renewable Fuels of Non-Biological Origin) and certain biofuels under mass-balance rules, but full book-and-claim decoupling — where physical delivery and accounting-based attribution are entirely separated — has not yet been conclusively clarified from a regulatory standpoint.
Technical implementation also requires a digital infrastructure: blockchain-based or conventional registry databases must ensure that double-counting is excluded. This is no trivial problem — the integrity of the entire system depends on the quality of data processing and the independence of verification.
The greatest challenge of book-and-claim is not the mechanics but the communication. Customers, investors and the public expect clear statements about emission reductions. If a carrier communicates that its transports are “powered by green methanol” whilst the vessel physically uses conventional fuel, insufficient explanation creates a credibility problem.
Best practice involves three-tiered communication: first, disclose the methodology (“on the basis of accounting-based allocation”). Second, limit the scope of the claim (“corresponds to the emission reduction of X tonnes of green methanol”). Third, name the limitations (“conventional fuel was physically used; the environmental contribution occurs elsewhere in the supply chain”).
Contractually, carriers and charterers must clarify who bears the cost of the certificates and who may claim the environmental value. This becomes particularly complex under time charters, where the charterer determines the fuel but the owner may carry compliance responsibility under FuelEU. Without contractual clarity, disputes over the allocation of environmental value are likely.
The aviation industry has already implemented book-and-claim within the framework of Sustainable Aviation Fuel (SAF). Airlines such as Lufthansa and KLM offer customers the option of purchasing the environmental value of SAF through certificates, even when the physical fuel is uplifted at a different airport. Experience shows: the model works, provided communication and verification are robust.
For shipping, transferable lessons emerge. First: the quality of the registry system is decisive. Second: customers accept the model when the explanation is transparent. Third: regulatory recognition takes time, but the market often moves faster than regulation. Operators who understand book-and-claim early and implement it cleanly position themselves as trustworthy partners.
Book-and-claim makes sense when three conditions are met. First: physical availability of the greener fuel is not yet given at the operator's own bunkering ports. Second: customers or regulatory requirements already demand an accounting-based emission reduction. Third: the operator is prepared to communicate transparently about the methodology.
If, however, physical access to greener fuel exists and the price differential is bearable, physical use should be preferred. Book-and-claim is a transitional instrument — not a substitute for genuine fuel switching. Operators who position it as a permanent model put their credibility at stake.
Free initial consultation – we analyze your situation and find the best path forward.
Request Consulting