Mass Balance Chain of Custody

An alternative chain of custody model that decouples physical product flow from the sustainability certificate. A producer of sustainable input (e.g., renewable electricity) registers their output, receives a certificate, and sells it to a buyer who claims the environmental benefit, regardless of physical connectivity.

• Key Distinction: Unlike mass balance, the physical product and its certificate are traded independently.
• Common Use: Renewable energy markets (RECs) and sustainable aviation fuel (SAFc).
• Risk: Requires rigorous registry oversight to prevent double counting of attributes.

The most stringent chain of custody model where a specific, identifiable batch of sustainable material is physically segregated from conventional material throughout the entire supply chain. The exact source is traceable to the final product.

• Key Distinction: No mixing with non-certified material is permitted.
• Common Use: Premium organic foods, Fairtrade coffee, and conflict-free minerals.
• Trade-off: Highest level of claim integrity but incurs significant logistical cost and complexity.

A model where certified sustainable material is kept physically separate from non-certified material, but different batches of certified material from various sources are allowed to mix. The final product is guaranteed to be 100% certified.

• Key Distinction: Mixing is allowed only within the certified pool, not with conventional stock.
• Common Use: Forest Stewardship Council (FSC) 100% labels and Roundtable on Sustainable Palm Oil (RSPO) Segregated supply chains.
• Advantage: Provides a high-integrity claim while allowing for some logistical aggregation of certified volumes.

A specific form of mass balance where the ratio of sustainable to conventional input is strictly controlled at a defined percentage at the point of mixing. The output claim is directly proportional to the certified input volume.

• Key Distinction: The blend ratio is fixed and audited, unlike general mass balance which may allow flexible attribution over a time period.
• Common Use: RSPO Mass Balance supply chain model for palm oil derivatives.
• Mechanism: Requires precise inventory tracking to ensure the physical blend matches the claimed percentage at all times.

A system where the sustainable attribute is converted into a tradable digital certificate representing a fixed quantity (e.g., 1 MWh or 1 ton CO2e). Credits are issued, traded, and retired independently of the physical material.

• Key Distinction: The environmental attribute is a financialized instrument, not a physical trace.
• Common Use: Carbon credits (Verra, Gold Standard) and Energy Attribute Certificates (EACs).
• Relevance: Often used in conjunction with mass balance for Scope 3 emission reporting when physical segregation is impractical.

The unbroken digital or paper record that documents the sequence of custody, control, transfer, and transformation of materials and their associated sustainability claims. It is the foundational evidence for any certification scheme.

• Components: Purchase orders, delivery notes, weighbridge tickets, production logs, and inventory records.
• Requirement: Must demonstrate that the volume of sustainable output sold never exceeds the volume of certified input received, adjusted for conversion factors.
• Technology: Increasingly managed via blockchain or distributed ledger technology to provide immutable, real-time verification of mass balance calculations.