Environmental attributes refer to the quantified sustainability characteristics or qualities of energy sources and other activities. These may include emissions reductions, carbon intensity, etc.
In the case of SAF, environmental attributes refer to the quantified emission reductions associated with the use of SAF as compared to the use of traditional jet fuel. Environmental attributes are tracked, purchased, and claimed separately from the physical SAF they are associated with.
This process of tracking, purchasing, and claiming environmental attributes separately is part of a “chain of custody” model called “book and claim.” Book and claim enables entities or individuals to support SAF by purchasing environmental attributes, and to make an associated claim to the environmental benefit the attributes represent – without being connected to the physical fuel supply chain (i.e., without being able to decide whether or not SAF is physically loaded into an exact flight that one is flying on).
What is chain of custody model
As defined by the ISO standard 22095:2020, a chain of custody model is a process by which inputs, outputs, and associated information are transferred, monitored, and controlled as they move through each step in the relevant supply chain. In regard to book and claim, ISO defines a book and claim chain of custody model as one in which the administrative record flow is not necessarily connected to the physical flow of material or product throughout the supply chain.
This model enables the environmental benefits of SAF to be tracked, purchased, and claimed separately from the physical fuel – which in turn enables individuals and entities that do not have control over the physical fuel supply chain to still support SAF and leverage associated emission reduction claims.