By Nickolas J. Themelis, Maria Elena Diaz Barriga, Paula Estevez, and Maria Gaviota Velasco

Disposal of municipal solid waste in sanitary landfills is still the main waste management method in the Attica region, as in most regions of Greece. Nevertheless, diversion from landfilling is being promoted by regional plans, in which the perspectives of new waste treatment technologies are being evaluated. The present study aimed to assess the greenhouse gas (GHG) emissions impact of different municipal solid waste treatment technologies currently under assessment in the new regional plan for Attica.

According to the State of Garbage, in 2006, forty-six of the fifty states reported tonnage data for “recycled” (composted or mulched) organics, including yard trimmings and food residuals, and/or wood (non-C&D). The total tonnage of organics composted or mulched was 20,368,139 tons in 2006 [1]. This amount represented 5% of estimated Municipal Solid Waste (MSW) generated in the U.S. (387 million tons).

The statistical entropy (SE) function has been applied to waste treatment systems to account for dilution or concentration effects on metals. We later extended it to account for carbon flows, especially in waste management systems involving thermal treatment. Now, a simple lifecycle “net energy” metric – encompassing the “lost energy” that would have been gained when high-calorific materials are landfilled rather than combusted with energy recovery – is introduced to account for additional influxes of carbon when using landfilling as the primary disposal method. When combining net energy calculations and long terms effects of landfilling, waste to energy (WTE) becomes a more attractive option for dealing with non-recycled municipal solid waste (MSW). A greenhouse gasforcing factor is also introduced to account for the entropy generating effects of methane. When incorporating forcing and lost energy, WTE performs notably better than landfills with respect to entropy generation and carbon.