Petrobras, Brazil's state-controlled energy company, is testing Cardano to track the environmental attributes of sustainable aviation fuel (SAF) and prevent double-counting of carbon claims, the Cardano Foundation announced on Sept. 30.

The research and development collaboration has already delivered working applications for both SAF and Diesel R, Petrobras' renewable diesel brand, according to the Foundation's published case study.

The SAF project targets a structural flaw in environmental-attribute markets: the buyer of a fuel's green benefit is often not the party that physically purchases or burns the fuel. The pilot implements a Book-and-Claim model, allowing an airline, corporate buyer, or individual passenger to receive an environmental benefit even when the SAF itself is produced or consumed elsewhere in the supply chain.

Petrobras developed the platform alongside PUC-Rio University's Ledger Labs and the Cardano Foundation. The system represents SAF environmental attributes as standardized CS-SAF tokens issued on the Cardano blockchain.

Each token can be created, transferred, verified, and retired. Retirement is the critical mechanism: once an attribute is retired, it cannot be claimed again. The digital record also traces every allocation back to the original fuel certificate, creating an auditable chain of custody for the environmental claim.

The design mirrors the double-spending problem in cryptocurrency. Just as a blockchain prevents the same digital asset from being spent twice, the tokenized system prevents the same carbon benefit from being claimed twice by different parties.

The pilot includes a consumer-facing component. Travelers can enter their departure and destination airports, calculate a CS-SAF allocation, and receive a certificate showing their route, distance, and allocated benefit, according to the Foundation. That claim remains cryptographically linked to the original SAF certificate throughout its lifecycle.

The token metadata aligns with CORSIA, the Carbon Offsetting and Reduction Scheme for International Aviation, the United Nations-backed framework that requires airlines to offset emissions growth on international routes.

The Book-and-Claim approach has drawn independent accounting scrutiny. In guidance published June 16, the Roundtable on Sustainable Biomaterials (RSB) stated that Book-and-Claim changes neither the physical fuel a buyer uses nor its associated emissions. Airlines should disclose supported reductions separately from their operational emissions figures, the guidance says. Different participants across the value chain can make distinct claims on the same underlying fuel, provided their disclosures do not misrepresent the aggregate reduction achieved.

Beyond aviation: Diesel R lifecycle tracking

The second track of the collaboration, the Diesel R project developed with PUC-Rio, proposes blockchain checkpoints across production, transportation, and fuel use. The goal is a continuous lifecycle record for renewable diesel that could support Scope 3 emissions reporting, the category covering indirect emissions across a company's extended value chain.

That architecture would connect data held separately by suppliers and logistics providers, giving corporate emissions reporting a traceable supply-chain history it currently lacks. The Foundation characterizes this system as a proposed model within the R&D phase rather than a deployed commercial product.

The commercial footprint of the work remains unquantified. The Foundation's disclosures provide no transaction volumes, participant counts, or revenue figures, and neither Petrobras nor the Foundation has committed to a production timeline.

Operational stakes

For Petrobras, the pilots address a compliance problem rather than a speculative one. CORSIA obligations phase in progressively for international aviation, and corporate Scope 3 disclosure requirements are tightening across major jurisdictions. Double-counted claims have repeatedly undermined voluntary carbon markets, and tokenized retirement offers one auditable answer to that credibility gap.

For Cardano, the deployment demonstrates enterprise use of its native token infrastructure in a regulatory-adjacent context, where traceability and verifiability matter more than throughput. The pilot does not yet translate into measurable network activity.

The next milestone to watch is whether either application moves from R&D status into production use. The Foundation's case study framework suggests further enterprise disclosures will follow as CORSIA's compliance phases expand and corporate emissions reporting mandates tighten through the decade.