Results of IEA Bioenergy Task 34 Round Robin Study: Analysis of Biomass Liquefaction Oil Composition and Role of Sample Homogeneity on Measurements

Accurate composition analysis of biomass liquefaction oils (BLOs) is essential for evaluating process performance and determining their suitability for end-use applications, further processing or upgrading to fungible fuels. In this study, IEA Bioenergy Task 34 conducted a round robin (RR) or interlaboratory study (ILS) to assess the reliability of analytical methods used for BLO characterization. Building on insights from a previous ILS, this study specifically addressed challenges related to representative sampling and homogeneity while also evaluating the performance of methods not previously included in past ILS comparison. The study focused on widely used composition analyses, including CHN and water content, as well as emerging techniques for measuring trace nitrogen (N), trace sulfur (S), and inorganics via inductively couple plasma (ICP). Homogeneity controls were implemented through blind duplicates and prescribed mixing intensities to assess their impact on analytical consistency. Results showed that global averages aligned with the known origins of the oils, and blind duplicates performed similarly under the applied sampling protocol. Moreover, increased mixing had little effect on global averages but improved within-lab repeatability for specific samples, analyses, and analytes. Nitrogen content determined by traditional CHN analysis were consistently higher than those obtained via chemiluminescence. ICP results exhibited high variability, largely influenced by method selection, the analyte of interest, and detection limits, particularly at concentrations around 100 mg/kg and below. These findings highlight the need for continued refinement of BLO analytical methods, particularly of trace element analysis, to improve reproducibility and support broader adoption of these bio-derived oils in industrial and commercial applications.