Assessment of carbon dioxide quality from industrial point sources for carbon utilization

Carbon dioxide (CO2) is increasingly viewed not only as a climate liability but also as a potential feedstock in circular carbon strategies. However, its practical utilization critically depends on both its chemical composition – including application-specific impurity tolerances – and its origin, whether fossil-based or biogenic. This study presents a comprehensive compositional assessment of CO2-rich streams from twelve industrial point sources in Finland, with a special focus on biogas upgrading facilities employing diverse purification technologies (membrane separation, water/amine scrubbing, pressure swing absorption (PSA)). Using Fourier Transform Infrared (FTIR), gas chromatograph (GC), adsorption tubes and biogenicity analysis, key impurities affecting downstream suitability for five major applications –food, medical, fuel synthesis, greenhouse use, and permanent storage – were identified, along with the assessment of biogenicity of streams.
The results indicate that measured membrane-based upgrading plants provided the most suitable CO2 quality (95.9–97.3 vol-%) for high-purity applications, including the food and beverage industry, medicinal use, and chemical production. This stream requires only limited removal of residual moisture, nitrogen, and oxygen, although elevated concentrations of methane and hydrogen remain a challenge. In contrast, amine scrubbing and PSA processes exhibited higher impurity levels, particularly hydrogen sulfide and volatile organic compounds. Nevertheless, CO2-rich off-gas streams from biogas upgrading plants can be directly applied to greenhouse enrichment and concrete curing when appropriate dilutions are performed. Biogenicity values of almost 100 % modern 14C for biogas plants confirm that these CO2 streams originate fully from renewable sources, which is critical for regulatory compliance and carbon accounting.