Comparative assessment of radiocarbon and balance method for determining biogenic and fossil CO2 emissions from waste-to-energy plants in Austria and China

Abstract

Accurate quantification of biogenic and fossil CO<inf>2</inf> emissions from waste-to-energy (WtE) plants is essential for greenhouse gas (GHG) reporting and emissions trading. This study compares two standardized methods − the Radiocarbon Method (ISO 13833) and the Balance Method (ISO 18466) − based on extensive sampling campaigns at three Austrian and one Chinese WtE facility. The Radiocarbon Method determines the biogenic CO<inf>2</inf> share via ¹⁴C analysis of flue gas, while the Balance Method derives biogenic and fossil fractions through coupled mass- and energy-balance modeling. Across all facilities, both methods yielded highly consistent results for biogenic CO<inf>2</inf> shares, ranging from 55 to 64% for the Austrian plants and 53–63% for the Chinese plant. Fossil CO<inf>2</inf> emission factors ranged from 320–470 kg CO<inf>2</inf> t⁻¹ waste in Austria and 340–370 kg CO<inf>2</inf> t⁻¹ waste in China, closely matching literature data. However, deviations in absolute fossil CO<inf>2</inf> masses of up to several thousand tonnes per year were observed, mainly due to uncertainties in flue gas volume measurement. Energy-balance-based reconciliation in the Balance Method significantly reduced such discrepancies. Extrapolated over annual operation, measurement inconsistencies could affect reported annual fossil CO<inf>2</inf> emissions by several thousand tonnes, corresponding to economic deviations of several hundred thousand euros or yuan in CO<inf>2</inf> certificates. The study confirms the applicability of both approaches under different waste and plant conditions and emphasizes the Balance Method's potential as a reliable, continuous monitoring tool for integrating WtE into carbon accounting frameworks.