LANDFILL DATA FROM CHINA: ADDRESSING INFORMATION NEEDS FOR METHANE RECOVERY

Urban populations and their waste generation are increasing worldwide, and the majority of the waste is disposed of in landfills. Over 80 percent of waste generated in China is landfilled, in a variety of ways. Over 5 percent of the landfills are sanitary landfills conforming to U.S. standards, nearly 40 percent are landfills that do not conform to such standards, and over 50 percent are open dumps. Landfills are a major source of emissions of methane, a potent greenhouse gas. Increasing the percentage of waste put into sanitary landfills would result in greater methane emissions because of increased anaerobic reactions. However, China’s National Action Plan on Urban Solid Waste Landfill Gas Collection and Utilization emphasizes sanitary landfills with methane recovery, and this could have benefits such as greater sustainability, improved public health, increased energy efficiency, and reduced global warming. A lack of reliable data on solid waste generation and management is a fundamental problem in estimating landfill contributions to methane emissions inventories, determining the potential for methane recovery, and identifying best candidate sites for methane recovery projects in developing countries. The U.S. Environmental Protection Agency (EPA) is developing an international database on solid waste generation and management in major urban areas, focusing initially on China, India, Brazil, Mexico, South Korea, and select sub-Saharan countries. This paper provides preliminary findings from China on the amount and characteristics of urban waste generated, the characteristics of urban waste, landfills, and current management of methane emissions at landfills. Specific information on landfills in five major urban areas, including Beijing, Tianjin, Shanghai, Nanjing, and Harbin, is also discussed. 1.0 INTRODUCTION Methane, a potent greenhouse gas, is the second largest contributor to global warming among anthropogenic greenhouse gases after carbon dioxide (CO2). Although it comprises a relatively small percentage of the atmosphere, it is 21 times more effective at trapping heat in the atmosphere than carbon dioxide over a 100-year time period, and currently accounts for over 15 percent of expected future warming from climate change (Metz et al., 2001). Although methane is emitted from both natural and anthropogenic sources, anthropogenic sources account for more than half of current global methane emissions (Watson et al., 2001). Waste management (landfills and wastewater treatment) accounts for over 18 percent of these anthropogenic sources (U.S. EPA, 1994). Landfills worldwide produce an estimated 20 to 60 teragrams (Tg) of methane per year through the production of landfill gas (LFG). LFG, which comprises approximately 50-60 percent methane, 40-45 percent CO2, and trace amounts of other volatile organics and halogenated organics, is generated when organic material decomposes anaerobically. Recovering LFG and the methane it contains can make significant strides toward mitigating climate change. Although a more potent greenhouse gas than CO2, methane remains in the atmosphere for a much shorter period: only 8 to 12 years compared to 50 to 200 years for CO2 (IPCC, 1996). In addition, LFG recovery projects can have other major economic and environmental benefits. LFG can be used as a medium quality fuel in electricity generation and co-generation, industrial uses, and residential and commercial cooking and heating. Local economies can benefit from the sale or use of this electricity, and from increased local employment for drilling, piping, construction, and operations. Methane recovery can also reduce the dependence on nonrenewable resources such as coal and oil, reducing emissions of air pollutants such as SO2, NOx, and particulate matter (PM) that contribute to local smog and acid rain. With population growth, economic development, and increased urbanization, methane emissions from landfills in developing countries now account for nearly 40 percent of annual global landfill methane emissions (U.S. EPA, 2001), and are expected to increase in the future (IEA, 1996). Important factors in this increase are the continuing priority of many developing countries to reduce unmanaged dumping and develop larger, solid waste disposal sites, which typically have higher methane emissions (Metz et al., 2000). Although almost 80 percent of waste generated in developing countries is landfilled, much of it is deposited in open dumps. As these dumps are replaced with covered landfills, methane emissions will increase substantially. However, there are also substantial opportunities for capturing methane emissions in these countries. If 70 percent of the estimated 290 million tons of municipal solid waste that China is expected to produce in 2010 is deposited in landfills with methane collection systems, the landfill gas recovered could be equivalent to 40 to 280 billion m of natural gas (Li, 1999).