Comparison of alternative methods for managing the residual of material recovery facilities using life cycle assessment

Excessive waste generation caused by exponential growth in resource use for the production of consumer goods, electronics and packaging has placed a growing burden on waste management globally. In Australia, waste is currently generated at a rate of 43 million tonne per annum and has a projected growth rate of 4.5% per annum. Diminishing landfill capacity adds to the pressure faced by governments to consider alternative waste technologies put forward by industry. In Australia, residual waste from material recovery facilities is under consideration by energy and waste companies for alternative management by waste-to-energy. This waste is not feasible to be efficiently separated for further processing. In this study, the environmental performance of the material recovery facilities' residual waste based in Sydney, Australia, is assessed using a life cycle assessment that estimates the potential impacts of acidification, climate change, eutrophication and photochemical oxidation. A sensitivity analysis tests different waste fractions of MRF residual waste composition. The study found that landfill had the lowest greenhouse gas emissions regardless of whether credits offset electricity, and of the carbon accounting methods used to measure biogenic carbon dioxide. The results also found landfill to have the lowest acidifying emissions but found the waste-to-energy technologies performed better in minimizing euthrophying and photochemical oxidation emissions. Aggregated by normalization and weightings, landfilling was found to have the lowest single score. The study reported electricity generation potentials through thermal turbine, synthetic gas engine and landfill gas combustion, and found incineration to have highest electricity generation potential, followed by gasification-pyrolysis.