What is a chain of custody?
A chain of custody is a reliable system that monitors certified biomass flows step-by-step, from cultivation of the crop to the end product. A chain of custody relates to a closed chain, i.e. every link has a Chain of Custody certificate (an annual check is conducted by an independent certification body).
There are various types of chain of custody. Every type sets out whether and how a quantity of renewable raw materials may be mixed:
- with renewable raw materials from another producer
- with fossil raw materials.
There are two chain of custody types for products that are entirely made up of certified biomass:
Identity preserved is the strictest chain of custody type. The certified raw materials may not be mixed with certified raw materials from another producer and neither may they be mixed with other renewable or fossil raw materials. This means that the buyer/consumer knows exactly where (which farm or plantation) the biomass was grown. The disadvantage of this type of chain of custody is that it requires huge efforts from companies in the supply chain. They must strictly separate the certified biomass from other raw materials (also during transport and storage).
Physical segregation enables certified biomass from multiple producers to be combined. The end product must, however, always be made up of 100% certified biomass. Across the whole supply chain, the certified biomass must be physically separated from non-certified biomass.
Multiple raw materials and auxiliary materials are often used for the production of chemical products and plastics. If some of these raw and auxiliary materials are not certified biomass, the end product will only contain a percentage of renewable raw materials. There are two chain of custody types for this type of product:
In the book & claim model, the trade in physical biomass is disconnected from the trade in sustainability certificates. This system can be compared with the trade in renewable energy certificates whereby the ‘renewable claim’ is disconnected from the physical electricity that is supplied at a specific place in the network.
In the mass balance model, batches of biomass with different sustainability characteristics may be physically mixed however the system ensures that they are kept administratively separate. Or:
- The administrative separation ensures that the volume of biomass which is labelled as sustainable at the end of the chain, corresponds with the volume of certified material that was added to the chain, thus taking account of any conversion factors (for processing etc.);
- During transactions between parties, physical biomass and sustainability information are always linked. Trade in sustainability information without simultaneous trade in biomass is not possible.
- Every party in the chain monitors how much biomass, with specific sustainability characteristics, they are buying and selling, so no more certified biomass can be sold than has been bought in (taking account of relevant conversion factors);
- Sustainability characteristics of batches of biomass may not be averaged out, but must remain administratively separate.
The chain of custody type determines which claim is ultimately supplied with the product.