The Municipal Solid Waste Management (MSWM) sector has developed considerably during the past century, paving the way for maximum resource (materials and energy) recovery and minimising environmental impacts such as global warming associated with it. The current study is assessing the historical development of MSWM in the municipality of Aalborg, Denmark throughout the period of 1970 to 2010, and its implications regarding Global Warming Potential (GWP100), using the Life Cycle Assessment (LCA) approach. Historical data regarding MSW composition, and different treatment technologies such as incineration, recycling and composting has been used in order to perform the analysis. The LCA results show a continuous improvement in environmental performance of MSWM from 1970 to 2010 mainly due to the changes in treatment options, improved efficiency of various treatment technologies and increasing focus on recycling, resulting in a shift from net emission of 618 kg CO2-eq. tonne-1 of MSWM.
Habib, Schmidt and Christensen model five Aalborg scenarios for 1970, 1980, 1990, 2000 and 2010, with treatment of one tonne of municipal solid waste as the functional unit. The scenarios combine changes in waste composition with developments in landfill, incineration, composting and recycling. Using consequential modelling, they include indirect effects: recovered heat and electricity can displace energy production, while recycled materials can displace virgin materials. The system starts with post-consumer waste and applies a zero-burden assumption to upstream impacts.
The results shift from net emissions of 618 kg CO2-equivalent per tonne in 1970 to net savings of 670 kg in 2010. The authors caution that technological improvements in composting and recycling were not modelled, and transport distances were held constant. The estimates also depend on which energy sources are assumed to be displaced. The findings therefore describe historical Aalborg scenarios, rather than a universal result for current waste systems.
