Estimating emissions from household organic waste collection and transportation: The case of Sydney and surrounding areas, Australia

Abstract

Australian waste related emissions are poorly characterised in National Greenhouse Accounts, with only landfill emissions directly attributed. Direct and indirect emissions however occur at all points along the waste management chain resulting from the consumption of energy and fuel during collection, transportation, and waste recovery activities. Without knowledge of waste-related emissions, it is difficult to evaluate the potential of different management pathways for achieving resource recovery and emission reduction objectives. Previous studies tend to utilise life cycle assessment (LCA) in examining waste transport emissions. Some studies have developed country-specific emissions factors for waste transportation based on LCA, however such factors have high variability owing to these models being dependent on widely varying local conditions. The aim of this study is to estimate emissions associated with kerbside organic waste collection from households and transportation in the Greater Sydney area in 2018–19. High-resolution road network and property-lot waste generation data was utilised in a GIS integrated route optimisation model. Our model considered transport of collection vehicles ‘to’ and ‘from’ transfer stations and kerbside collection areas across the 43 council areas, as well as transport of waste collected to reprocessing and landfill facilities. Greenhouse gas emissions for organic waste transport and collection were estimated at approximately 43,700 t CO 2 -e, equal to approximately 2% of all road transport emissions in the study area. Kerbside collection was the largest contributor to overall transport emissions, accounting for approximately 89%. Average emissions intensity on a tonnes diverted from landfill basis was lowest for councils separating food waste out of the mixed waste stream at 45 kg CO 2 -e/tonne, owing to the greater quantities of waste diverted via food collection and mixed waste recovery pathways. Average emissions intensity across all councils was 96 kg CO 2 -e/tonne. Findings indicate that improved efficiency of bin-lift mechanisms, including increasing the intensity of bin-lifts per stop, as well as collection vehicle fuel efficiency and electrification, would have the greatest impact on reducing tra and collection emissions. • Route optimisation model was applied to estimate emissions from the collection of household organic wastes in Sydney, Aus. • Emissions from waste collection vehicle activities and transfer to recovery and disposal facilities were estimated. • Analysis shows kerbside collection is the most significant contributor to waste transport emissions. • Councils collecting food waste separately had the lowest emissions per-tonne of organic waste diverted from landfill. • Approach has a number of applications in supporting the transition towards low-carbon and cleaner waste systems.