Understanding The Design And Performance Of Distributed Tri-Generation Systems For Home And Neighborhood Refueling

The potential benefits of hydrogen as a transportation fuel, such as zero tailpipe emissions from vehicles and the diversity of energy sources will not be achieved until hydrogen vehicles capture a substantial market share. Although hydrogen fuel cell vehicle (FCV) technology has been making rapid progress, the lack of a hydrogen infrastructure remains a major barrier for FCV adoption and commercialization. The high cost of building an extensive hydrogen station network and low utilization in the near term discourages private and public investment. Innovative, distributed, small-volume hydrogen refueling methods may be required to refuel FCVs in the near term. Among small-volume refueling methods, home and neighborhood tri-generation systems that produce electricity and heat for buildings, as well as hydrogen for vehicles stand out because the technology is available, initial capital investment is modest, and it has potential to alleviate consumer's fuel availability concerns. In addition, it has features attractive to consumers such as convenience and security to refuel at home or in their neighborhood, and thus may prove also to be a desirable long term refueling option for consumers.;The objectives of this dissertation are twofold: to provide analytical tools for stakeholders such as policy makers, manufacturers and consumers to analyze tri-generation and similar energy systems in a systematic way; and to apply these tools to case studies to understand the design and technical, economic, and environmental performances of tri-generation systems for home and neighborhood refueling.;I first present a historical review and comparison of home and neighborhood refueling methods for a wide range of motor vehicles. Analytical tools including an interdisciplinary engineering /economic model are then developed for the detailed assessment of tri-generation systems for home and neighborhood refueling. Consumer's preferences and willingness to pay (WTP) for home and neighborhood refueling systems along with the environmental cost are discussed and incorporated into the model.;I apply these analytical tools to case studies in two categories: home refueling tri-generation systems for a single-family residence; and neighborhood refueling tri-generation systems for multiple nearby households. In each case study, I explore the optimal design of tri-generation systems, which is defined as the determination of system components sizes that allow a tri-generation system to meet the three energy needs with minimal life cycle cost from a consumer's perspective. I also evaluate and compare the technical, economic, and environmental performances of tri-generation systems with two alternatives: the business as usual (BAU) reference system, in which households purchase grid electricity, natural gas (NG) for hot water, and gasoline fuel; and the projected reference system, in which households purchase grid electricity, NG for hot water, and hydrogen fuel from an early public station. A public hydrogen station is different from home and neighborhood refueling because of its scale and location.;I modeled system operation, exploring the optimal size of all components of the system, based on the cost of energy products: electricity, heat and hydrogen. I also compared the cost of energy products and CO2 emissions of a 2 kW (home refueling) and 6.5 kW (neighborhood refueling) tri-generation system with alternatives such as the two reference systems mentioned above. A sensitivity analysis was conducted with respect to uncertainties in energy prices, capital cost reduction (or increase), government incentives and environmental cost.;Overall tri-generation for home and neighborhood refueling has the potential to be included in hydrogen infrastructure plans or portfolio infrastructure solutions in California and other states or countries. It is economically competitive with early public stations for fueling hydrogen cars. The small capacity of the home and neighborhood tri-generation systems (relative to a public hydrogen station) and the valuable co-products helps address the low utilization problem of hydrogen infrastructure while hydrogen vehicle demand is low. In addition, although home tri-generation systems are difficult to compete economically with the BAU reference system unless capital costs are reduced, or energy prices change such as increasing gasoline price, neighborhood tri-generation systems offer better economic performance than the BAU reference system.;Future research might include comparisons of regions with significantly different energy demand profiles to see how the performance of tri-generation systems varies with demand profiles, the use of renewable feedstocks for the tri-generation systems, and viable business models for neighborhood tri-generation systems.