Estimates of solid waste disposal rates and reduction targets for landfill gas emissions

Landfill disposal of municipal solidwaste represents one of the largest anthropogenic global methane emission sources(1), and recent policy approaches have targeted significant reductions of these emissions to combat climate change in the US (ref. 2). The efficacy of active gas collection systems in the US was examined by analysing performance data, including fire occurrence, from more than 850 landfills. A generalized linear model showed that the operating status of a landfill-open and actively receiving waste or closed-was the most significant predictor of collection system performance. Gas collection systems at closed landfills were statistically significantly more efficient (p < 0.001) and on average 17 percentage points more efficient than those at open landfills, but open landfills were found to represent 91% of all landfill methane emissions. These results demonstrate the clear need to target open landfills to achieve significant near-term methane emission reductions. This observation is underscored by landfill disposal rates in the US significantly exceeding previously reported national estimates, with this study reporting 262 million tonnes in the year 2012 compared with 122 million tonnes in 2012 as estimated by the US Environmental Protection Agency(3).