Economic Feasibility of Converting Landfill Gas to Natural Gas for Use as a Transportation Fuel in Refuse Trucks
Sprague, Stephen M.
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Approximately 136,000 refuse trucks were in operation in the United States in 2007. These trucks burn approximately 1.2 billion gallons of diesel fuel a year, releasing almost 27 billion pounds of greenhouse gases. In addition to contributing to global climate change, diesel-fueled refuse trucks are one of the most concentrated sources of health-threatening air pollution in most cities. The landfills that they ultimately place their waste in are the second largest source of human-related methane emissions in the United States, accounting for approximately 23 percent of these emissions in 2007. At the same time, methane emissions from landfills represent a lost opportunity to capture and use a significant energy resource. Many landfill-gas-to-energy (LFGTE) projects are underway in an attempt to curb emissions and make better use of this energy. The methane that is extracted from these landfills can be converted into a transportation fuel, sold as a pipeline-quality natural gas, operate turbines for electricity, or be flared. The unique relationship that occurs between refuse trucks' constant visits to the landfill and the ability of the landfill itself to produce a transportation fuel creates an ability to accomplish emissions reduction in two sectors with the implementation of using landfill gas to fuel refuse trucks. Landfill owners and operators are very reluctant to invest in large capital LFGTE projects without knowing their long-term feasibility. The costs and benefits associated with each LFGTE project have been presented in such a way that owners/operators can make informed decisions based on economics while also implementing clean energy technology. Owners/operators benefit from larger economic returns, and the citizens of the surrounding cities benefit from better air quality. This research focused on six scenarios: converting landfill gas (LFG) to liquefied natural gas (LNG) for use as a transportation fuel, converting LFG to compressed natural gas (CNG) for use as a transportation fuel, converting LFG to pipeline-quality natural gas, converting LFG to electricity, flaring LFG, and doing nothing. For the test case of a 280-acre landfill, the option of converting LFG to CNG for use as a transportation fuel provided the best benefit-cost ratio at 5.63. Other significant benefit-cost findings involved the LFG-to-LNG option, providing a 5.51 benefit-cost ratio. Currently, the most commonly used LFGTE option of converting LFG to electricity provides only a 1.35 benefit-cost ratio while flaring which is the most common mitigation strategy provides a 1.21, further providing evidence that converting LFG to LNG/CNG for use as a transportation fuel provides greater economic benefits than the most common LFGTE option or mitigation strategy.