In recent years, the book and claim concept has gained significant attention in the aviation industry. The reason is simple: it directly relates to how Sustainable Aviation Fuels (SAF) are distributed and accounted for, a key contributor towards aviation’s efforts to decarbonize by 2050.
Book and claim is part of a family of “chain-of-custody” models with common characteristics which can vary in their design and application. Book and claim differentiates from other chain-of-custody models, such as physical segregation and mass balance. Robust chain-of-custody models are essential to ensure that the environmental benefits of SAF are transparently and credibly accounted for under greenhouse gas reduction schemes (GHG) such as ICAO’s Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA). Figure 1 illustrates how the three main chain-of-custody models affect the supply chain of SAF. The case shown for book and claim is just one example, additional examples are provided in Figure 2.
The three main chain-of-custody models
- Physical segregation directly ties the sustainability attributes (or environmental benefits) of SAF to its physical molecules. This approach ensures maximum traceability of the fuel, since only SAF physically delivered to an aircraft can be claimed by its operator for a specific flight. However, considering that many airports rely on interconnected infrastructure (e.g. pipelines, tanks, hydrant systems, etc.), physical segregation often faces scalability constraints and may lead to higher logistics costs.
- Mass balance allows the sustainability attributes of SAF to be allocated to end-users (e.g. aeroplane operators) in proportion to the volume of SAF delivered into the interconnected system. This approach provides more flexibility than physical segregation by reducing the constraints linked to the fuel distribution infrastructure while maintaining a physical link between SAF production and use.
- Book and claim allow the sustainability attributes of SAF to be fully decoupled from its physical molecules. It allows producers to “book” SAF volumes somewhere into the system, and end-users (e.g. aeroplane operators) to “claim” the associated sustainability attributes somewhere else, even if there are no physical connections along the supply chain. This approach provides the greatest flexibility out of the three chain-of-custody models described, allowing SAF to be virtually used in those regions lacking production, blending and/or distribution infrastructure. Book and claim models rely heavily on robust traceability and transparency to preserve the integrity of the system (e.g. prevent double counting of SAF environmental benefits).
How book and claim works
As explained above, book and claim models can be designed in different ways, which can depend on the objectives of the policy framework implemented. These design choices directly affect how SAF is distributed across markets, and how its sustainability attributes are allocated and accounted for. Establishing clear rules and governance mechanisms is essential to maintain transparency, avoid double counting and build trust in the model.
Figure 2 illustrates different possible scenarios of SAF distribution and accounting under book and claim models.
- Case 1, which is also allowed under the mass balance approach, shows that SAF distributed to the fuel tank of airport X, and therefore to be physically distributed to all aeroplane operators A, B and C refuelling at that airport, can be claimed by a single aeroplane operator A. While all aeroplane operators will be refuelled with physical molecules of SAF, the sustainability attributes of that SAF can be freely allocated among those aeroplane operators refuelling at airport X.
- In Case 2, the book and claim model allows aeroplane operator A, operating from airport X, to buy SAF distributed to airport X and claim its sustainability attributes in airport Y. By decoupling the sustainability attributes of SAF from its physical molecules, it allows aeroplane operator A to freely allocate the SAF purchased to any part of its operations.
- Case 3 goes even further and allows aeroplane operator D, who is not operating from airport X, to claim the sustainability attributes of the SAF delivered to airport X, in airport Y (or any other airport). This scenario provides the most flexibility regarding SAF distribution and accounting.
In all of these scenarios, SAF can be sold and bought by any economic operator along the supply chain (e.g. fuel producers, aeroplane operators, etc.). The system must be implemented so that traceability and transparency is maintained at every step of the process in order to preserve the integrity of the policy framework.
What chain-of-custody model is used under CORSIA?
CORSIA is the first global market-based scheme that applies to a sector, and it aims at keeping international aviation emissions below baseline established in October 2022, during our 41st ICAO Assembly: 85% of 2019 emissions from 2024 until 2035, which is when the scheme is scheduled to end. CORSIA allows aeroplane operators to reduce their offsetting requirements using CORSIA Eligible Fuels (CEF), which in the context of ICAO are SAF or Lower Carbon Aviation Fuels (LCAF) that have been certified to meet the CORSIA Sustainability Criteria.
Under CORSIA, aeroplane operators are not per se obligated to purchase and use CEF. They must compensate for their offsetting requirements by either purchasing and using CEF or purchasing and cancelling CORSIA Eligible Emissions Units (CEEUs).
Annex 16, Volume IV containing the Standards and Recommended Practices for CORSIA implementation provides additional details regarding the CEF accounting methodology under CORSIA (see Box 1). It specifies that aeroplane operators must have CEF records of purchasing and blending but that it does not necessarily need to be uplifted to a specific aeroplane on a specific flight to be accounted for. Therefore, an aeroplane operator can claim the use of CEF to reduce its offsetting requirements no matter where it was purchased and used, provided that the aeroplane operator owns the purchasing and blending records.
Under CORSIA, aeroplane operators report their aggregated CO2 emissions data on an annual basis, whereas they are given the option to report their emissions reduction claims from CEF on an annual basis or once for a given three-year compliance period, thus having the flexibility to optimize the allocation of CEF over a CORSIA compliance period.
While the accounting methodology under CORSIA provides for significant flexibility, the sustainability attributes of CEF are not fully decoupled from the fuel itself, since those are directly linked to the purchasing and blending records. However, flexibility on the allocation of the use of CEF does have common elements with some cases of book and claim described earlier.
Scope 3 Emissions and the Greenhouse Gas Protocol
According to the Greenhouse Gas Protocol, emissions from an economic activity can be divided into three scopes. In the case of an aeroplane operator, Scope 1 will be combustion emissions from assets that are owned or controlled by the aeroplane operator and will include emissions from the combustion of fuel in aircraft engines, operations of airline-owned ground support equipment or airline-owned road vehicles, or facilities like boilers, heaters, stoves. Scope 2 emissions would be those associated with electricity, heat and steam purchase. Scope 3 would be indirect emissions not reported under Scope 2, and out of the control of the aeroplane operator, and which are already accounted for under the Scope 1 of another actor, for example, the upstream emissions associated with the refinement and distribution of jet fuel or the emissions from the manufacture of aircraft.
Just like the Scope 3 emissions of aeroplane operators are the Scope 1 of the fuel producers or the aircraft manufacturers, amongst others, for many companies and organizations combustion of jet fuel linked to staff travel will be accounted as part of their Scope 3 emissions. Similarly, the Scope 3 emissions of such companies and organizations are considered Scope 1 emissions for aeroplane operators.
To cover the additional costs of using CEF, aeroplane operators may give the third party entities (i.e., entities other than an aeroplane operator) the opportunity to pay an extra cost (SAF premium) in exchange for documentation verifying the sustainability attributes of the CEF purchased. These documents may be used by those entities to reduce their Scope 3 emissions as long as they are aligned and comply with the Greenhouse Gas Protocol recommendations. It is important to note that these documents cannot be used by those entities to claim the same CEF that is already claimed by an aeroplane operator under CORSIA, under other regulatory GHG schemes, to avoid any risk of fraud and double counting.
Annex 16, Volume IV does not address the methodology for the third-party entities to claim sustainability attributes and eventually reduce their Scope 3 emissions. Such transactions are independent from the chain of custody of the fuel and therefore would not impact on the accounting methodology of CEF under CORSIA. It is simply a way for aeroplane operators to cover the additional costs to their operations incurred by the purchase of CEF. Therefore, third party entities can claim sustainability attributes to reduce their Scope 3 emissions, and aeroplane operators can claim the same sustainability attributes under CORSIA, without characterizing double counting.
Conclusion
Through this article we provided a basic overview of chain-of-custody models including the concept of book and claim, and how it relates to ICAO’s CORSIA Standards and Recommended Practices regarding CEF accounting methodology for aeroplane operators. Many of the aspects mentioned are in active discussion within the ICAO Council’s Committee on Aviation Environmental Protection (CAEP). CAEP continues to work on these items, including studying different SAF accounting methodologies and systems, and their integration and compatibility with CORSIA.
