Incinerating Old Waste from Landfills? An Assessment of Dynamic Climate Change Impacts

Chinese waste incinerators have substantial excess capacity, and it has been suggested that waste from landfills be excavated to increase the energy recovery by using vacant incineration capacity. By means of life cycle assessment (LCA), we assess this suggestion in terms of its climate change impacts. Given the temporal properties of the issue, we used a dynamic LCA approach by specifying emissions and energy recovery for each year over a 100-year period. We then quantified climate change in terms of radiative forcing (W/m²) for each year, in contrast to a traditional LCA approach summarizing emissions and energy recovery over a 100-year period in terms of kg CO₂-equivalents. We considered several waste compositions and a range of ages of landfilled waste. The results of dynamic LCA revealed that for a time horizon of 10-50 years, excavation and incineration of landfilled waste is beneficial only for reducing the cumulative radiative forcing if the waste is only 2-3 years old. Waste older than 4 years old should, in all cases, remain in the landfill from a climate change point of view. The traditional LCA approach revealed its shortcomings compared with the dynamic LCA approach. Considering technologies with time-distributed emissions and energy recoveries, we warn against indiscriminate use of the traditional approach when decisions are supposed to contribute to reducing climate change impacts to meet political targets set for the next few decades.