Comparative analysis of alternative fuels for bus transit
Date
2006
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Publisher
University of Delaware
Abstract
Alternative fuel use is becoming more popular within the United States, especially in transportation applications. In bus transit, conventional diesel is the most heavily used fuel. However, since the Energy Policy Act of 1992, transit agencies have been implementing more alternative fuel buses within their bus operations. The Act listed eight fuels to be designated as alternatives: ethanol, methanol, propane, natural gas, electric, biodiesel, hydrogen, and p-series (added in 1999). The effect of using a particular fuel has not been fully discovered. A comparative analysis is conducted in this thesis to evaluate alternative fuel and conventional diesel buses within a bus transit scenario. ☐ Several parameters are considered when evaluating a certain fuel. The parameters are safety, reliability, serviceability, maintainability, infrastructure, fuel economy, and environmental effects. The alternative fuels are analyzed and compared with No. 2 diesel by examining case studies and traffic simulation software. The fuels that are analyzed are E95 (95% ethanol, 5% Diesel), M100 (100% Methanol), Compressed Natural Gas (CNG), Liquefied Natural Gas (LNG), Hydrogen, B20 (20% Biodiesel, 80% Diesel), and Hybrid-Electric. Given the results of the comparative analysis, data is available to transit agencies, government bodies, and fuel and bus providers on the efficiency of the different fuels to operate along a bus transit network. ☐ Case studies have been conducted by the National Renewable Energy Laboratory (NREL) and Department of Energy (DOE). They have run an alternative fuel bus along the same route as a diesel control bus. The results reflect differences in vehicle failure rates, maintenance and fuel costs, and environmental effects. Once the data is collected, each alternative fuel is compared in terms of bus operations. For example, the high capital costs associated with a hydrogen fuel cell bus are weighed against its efficient fuel economy and zero emissions capabilities. ☐ The data from the case studies can further be analyzed in this thesis by applying it to traffic simulation software. The CORSIM software is utilized to model a bus using a particular fuel. Each fuel is compared on the same network, and changes within the network are made to establish the distinction between the capabilities of each bus. Tests are employed that illustrate changes in volume, number of stops, headway, and city versus highway travel. The results demonstrate how alternative fuel buses compare to diesel buses in terms of travel time, delay, speed, fuel economy, and emission rates. ☐ Transit agencies, government bodies, and fuel and bus providers can use the results of traffic simulation software to determine which type of fuel to develop or implement. The software allows these groups to take information from real-world experiments and apply it to a computer model that replicates any type of network. After weighing each of the parameters, it is clear that the alternative fuels have the capability of outperforming a conventional diesel bus.