Application of landfill gas as a liquefied natural gas fuel for refuse trucks in Texas

Abstract

The energy consumption throughout the world has increased substantially over the past few years and the trend is projected to continue indefinitely. The primary sources of energy are conventional fuels such as oil, natural gas and coal. The most apparent negative impacts of these conventional fuels are global warming, poor air-quality, and adverse health effects. Considering these negative impacts, it is necessary to develop and use non-conventional sources of energy. Landfill gas (LFG) generated at landfills can serve as a source of cleaner energy. LFG has substantial energy generation potential and, if cleaned of certain impurities, can be used for several applications such as electricity generation and conversion to high Btu gas. This thesis considers another application of LFG, which consists of using it as a vehicular fuel for refuse trucks. Currently, limited research has been performed on the development of such a methodology to evaluate the application of LFG as a vehicular fuel for refuse truck operations. The purpose of this thesis is to develop a methodology that can be used to evaluate the use of LFG generated at landfills as a Liquefied Natural Gas (LNG) fuel source for refuse trucks in Texas. The methodology simulates the gas generation process at a landfill by using standard models developed by the Environmental Protection Agency. The operations of a refuse truck fleet are replicated by using generic drive cycles developed as part of this research. The economic feasibility is evaluated by estimating the costs required for cleaning the LFG and converting the truck fleet from diesel to LNG as well as quantifying the benefits obtained due to change in fuel consumption and emission generation by the refuse trucks. The methodology was applied to a potential landfill in Texas. The results show that the methodology offers an innovative tool that allows the stakeholders to evaluate the economic feasibility of using LFG for refuse truck operations. The methodology also provides a flexible framework wherein each component can be changed or tailored to meet the specific needs of the stakeholders.