Determining the biomass fraction of mixed waste fuels: A comparison of existing industry and 14C-based methodologies

•Compares industry standard and 14C methods for determining bioenergy content of MSW.•Differences quantified through study at an operational energy from waste plant.•Manual sort and selective dissolution are unreliable measures of feedstock bioenergy.•14C methods (esp. AMS) improve precision and reliability of bioenergy determination.•Implications for electricity generators and regulators for award of bio-incentives.

14C analysis of flue gas by accelerator mass spectrometry (AMS) and liquid scintillation counting (LSC) were used to determine the biomass fraction of mixed waste at an operational energy-from-waste (EfW) plant. Results were converted to bioenergy (% total) using mathematical algorithms and assessed against existing industry methodologies which involve manual sorting and selective dissolution (SD) of feedstock. Simultaneous determinations using flue gas showed excellent agreement: 44.8 ± 2.7% for AMS and 44.6 ± 12.3% for LSC. Comparable bioenergy results were obtained using a feedstock manual sort procedure (41.4%), whilst a procedure based on selective dissolution of representative waste material is reported as 75.5% (no errors quoted). 14C techniques present significant advantages in data acquisition, precision and reliability for both electricity generator and industry regulator.