Scenario-based case study: low-carbon fuels

This case study uses a hypothetical chemical manufacturing scenario to explore how market instruments can account for biomethane used in hydrogen peroxide production, comparing mass balance with product-level book-and-claim. Developed by WBCSD in collaboration with Carbon Trust, with input from participating member companies, it reflects the practical sourcing decisions companies face today. All figures are illustrative.

The worked example shows how the same underlying biomethane purchase can support a buyer’s claim through either route, even from different physical starting points. It explains why, what remains unresolved on attribution and reporting under current standards, and how companies can make credible claims as standards evolve.

Through this case study, readers can:

• Understand how mass balance allocation could apply when a low-carbon input, like biomethane, is physically blended into a shared system and cannot be traced molecule by molecule
• Compare mass balance allocation with book-and-claim for the same underlying production, and see how each changes what gets reported
• Follow how the GHG Protocol’s emerging multi-statement reporting framework applies to inventory reporting and claims in this example