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Open Access Publications from the University of California

Scholarly Works (2 results)

  • Thesis
  • Peer Reviewed
UC Irvine Electronic Theses and Dissertations (2016)

Initiatives to improve air quality in urban areas and to mitigate climate change through the reduction of greenhouse gas emissions have resulted in new mandates and legislation to implement zero emissions vehicles (ZEV). While several studies have focused on fueling infrastructure for light-duty fuel cell electric vehicles, there is a lack of knowledge regarding the nature of hydrogen supply chains for fuel cell electric buses. This thesis presents an analysis of hydrogen infrastructures to guide policymakers and transit agencies in the identification of preferable scenarios for the deployment of hydrogen fuel cell electric buses.

Based on research for light-duty vehicles conducted at the Advanced Power and Energy Program in the University of California, Irvine, two novel computer-based tools were developed to design and analyze environmentally sensitive hydrogen fueling infrastructure that addresses the wide range of requirements faced by transit agencies in the deployment of fuel cell buses. The first tool provides spatially-resolved allocation of hydrogen demand and identifies feedstocks for hydrogen production. The second tool provides a systematic evaluation of hydrogen supply chain scenarios through the analysis of well-to-wheel energy and water demand, and the emission of greenhouse gases and criteria pollutants. In addition, this evaluation includes a detailed analysis of the space requirements and operations modifications for the placement of hydrogen fueling infrastructure at transit agencies.

The tools were used to establish hydrogen fueling infrastructures scenarios at three levels of deployment: national, state and county. At the national level, the spatial allocation of hydrogen demand and potential environmental benefits of different hydrogen scenarios were developed for transit agencies in the U.S. At the state level, the hydrogen demand allocation and spatial rollout of possible feedstock sources were established for the state of California. At the local level, preferable hydrogen scenarios were developed for a large transit agency (the Orange County Transportation Authority) along with the quantification of emissions and resources and cost projections of hydrogen distribution pathways.

    Cover page: Deployment of Fuel Cell Electric Buses in Transit Agencies: Allocation of Hydrogen Demand and Rollout of Preferable Infrastructure ScenariosCreative Commons 'BY-NC-ND' version 4.0 license
    • Article
    ITS reports (2019)
    To aid in addressing issues of air quality and greenhouse gas (GHG) emissions in the South Coast Air Basin, local transit agencies are considering a shift to battery electric buses (BEBs) and hydrogen fuel cell electric buses (FCEBs). Each of these options vary in their overall effectiveness in reducing different emission types over their life cycle, associated life cycle costs, ability to meet operational needs of transit agencies, and life cycle environmental footprint. This project carried out a life cycle-based analysis and comparison of the GHG emissions, criteria pollutant emissions, and other environmental externalities associated with BEBs and FCEBs, taking into account their ability to meet operational constraints of the Orange County Transportation Authority. From an environmental footprint perspective, this study found the following. First, both FCEBs and long-range BEBs have comparable impacts for global warming potential and particulate matter formation but when the FCEBs were fueled using renewable hydrogen. Second, using electricity from the current California grid mix to drive electrolysis to produce hydrogen for FCEBs produced only marginal benefits compared to current natural-gas fueled vehicles due to the low supply chain efficiency of this pathway. Third, the mining of precious metals is a major contributor to environmental footprint categories for both BEBs and FCEBs. Fourth, both FCEVs and long-range BEBs provide significant reductions in environmental footprint compared to conventional diesel and natural gas buses. From a cost perspective, this study found the following. First, with current-day cost inputs, FCEBs and BEBs have comparable total cost of ownership, but both have slightly higher costs than diesel and natural gas buses. Second, FCEBs have an equivalent total cost of ownership to BEBs when the electricity rate for charging is $0.24/kWh. Higher values render FCEBs as the cheaper option and lower values render BEBs as the cheaper option. Second, the total cost of ownership of these technologies is highly sensitive to electricity costs, and the rapid evolution of the electricity system has strong implications for the economic comparison between BEBs and FCEBs. Overall, this study finds that while both FCEBs and BEBs provide life-cycle environmental benefits, further cost reductions in electricity rates and initial purchase costs are needed to achieve total cost of ownership parity with conventional bus powertrains. With the rapid evolution of the electricity system and falling costs for renewable electricity resources, these cost reductions may occur in the near future.
      Cover page: Life Cycle Assessment of Environmental and Economic Impacts of Deploying Alternative Urban Bus Powertrain Technologies in the South Coast Air Basin
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