4. Conclusions
The modeling approach used for calculating GHG emissions from both LFE and AIF in this study is explained explicitly in this paper. It provides a framework for policy makers to consider the performance of GHG emissions of different waste disposal scenarios. The aggravation or mitigation of GHGs from the waste sector depends on the technology and the efficiency of waste disposal facilities. Based on the data collected, assumptions made, and system boundary defined in this study, the net GHG emissions from AIF are less than LFE. The findings indicate that the implementation of the proposed waste management policy framework 2005–2014 (Scenario 2) by the HKSAR Government would emit less GHG than the current practice in Hong Kong. Based on this study, some substantive measures to be taken to tackle the GHG emissions in the waste sector include the reduction of landfill CH4 emissions to the atmosphere through a higher CH4 recovery rate and the enhancement of heat and electricity generation through improved performance and efficiency of energy recovery system. Nevertheless, due to heterogeneous characteristics within MSW and complex multi-criteria factors affecting the performance of waste disposal facilities, policy makers should be aware that the variation of some key inputs, as suggested in the sensitivity analyses, might alter the overall impact on net GHG emissions. The relentless growth in the volume of MSW constitutes both a threat and an opportunity to society, depending on how we treat the waste. One opportunity is to convert waste to wealth by enhancing the potential utilization of energy recovery systems. Some results in this study demonstrate that AIF has a great potential for reducing GHG emissions via electricity generated from energy recovery system. Substantial energy and carbon offsets can be achieved by capitalizing on energy conservation through resource recovery of MSW. Economic incentives can be provided to boost energy recovery in the waste sector. In addition, citizen acceptance of proposed waste management policies is critical and should be taken into consideration. Strong local opposition from the public will incur delays for waste disposal facilities to be commissioned. The policy makers have the obligations to pursue a sustainable waste management framework that is environmentally sound, economically feasible and socially acceptable. Supplementary data to this article can be found online at http://dx.doi.org/10.1016/j.scitotenv.2013.04.061.