A Review on Isotopic Traceability of Renewable Oils in Co-Processed Fuels: Exploring the Analytical Potential of IRMS

Abstract

Reducing dependence on fossil fuels through the integration of renewable oils into the refinery infrastructure requires an accurate determination of the renewable fraction in the final products, which remains challenging in complex matrices where fossil and biogenic feedstocks exhibit similar isotopic signatures. Accelerator mass spectrometry (AMS) is the current reference method, but its high cost, limited accessibility, and long analysis time motivate the search for alternatives. This review examines the application of isotope ratio mass spectrometry (IRMS) for tracing renewable content in coprocessed systems, discussing its capabilities and limitations based on studies that demonstrate its feasibility at low blend ratios with characterized end-members, system-specific calibration, and validation against AMS, which may support refineries in optimizing biogenic carbon introduction through accessible, fast, and low-cost equipment. Remaining challenges include the limited number of investigations available, the isotopic contrast between renewable and fossil end-members, the lack of standardized methodologies and validation protocols for routine analysis, and the predominant reliance on a stable carbon isotope signature. Other approaches for renewable fraction determination, including energy and mass balance methods, were also discussed together with current challenges and future perspectives for IRMS development. Whereas previous reviews broadly compare renewable carbon tracking methods for coprocessed fuels, this review focuses specifically on the analytical potential, current evidence base, and unresolved limitations of IRMS for renewable carbon traceability.