Abstract
A survey has been conducted across all MSW landfills with gas extraction system in the Lombardia Region (Italy) in order to collect data for an emission inventory assessment of greenhouse gas (GHG) emissions in the timeframe 1975-2008. The survey results identified a large number of landfills opened over the last 35 years and characterized by different kinds and amounts of waste disposed. Using the IPCC methodology, GHG emissions in the year 2008 were quantified to be 1.81 Mt CO2-eq, which corresponds to 1.9% of overall GHG emissions in Lombardia. A dependency between collection efficiency and age of the collecting network has been established and used for the projection of GHG emission in the period 2009-2020, and for two scenarios: a business as usual (BAU) and an alternative one that implies policies to reduce biodegradable carbon content in the residual waste. The latter allows for a 45% reduction of the GHG emissions in 2020 compared to the year 2008, whereas in the BAU scenario the expected reduction is 32%. The sensitivity analysis shows that a variation of parameters that represent the carbon content of the waste category and degradation rate constant, within the range reported in the literature, could affect GHG emission level by about ±18%, whereas the uncertainty due to landfill gas (LFG) composition is less relevant.