Robert M. Moore

Life cycle assessment of fuel cell vehicles a methodology example of input data treatment for future technologies

Life cycle assessment (LCA) will always involve some subjectivity and uncertainty. This reality is especially true when the analysis concerns new technologies. Dealing with uncertainty can generate richer information and minimize some of the result mismatches currently encountered in the literature. As a way of analyzing future fuel cell vehicles and their potential new fuels, the Fuel Upstream Energy and Emission Model (FUEEM) developed at the University of California—Davis, pioneered two different ways to incorporate uncertainty into the analysis. First, the model works with probabilistic curves as inputs and with Monte Carlo simulation techniques to propagate the uncertainties. Second, the project involved the interested parties in the entire process, not only in the critical review phase. The objective of this paper is to present, as a case study, the tools and the methodologies developed to acquire most of the knowledge held by interested parties and to deal with their — eventually conflicted—interests. The analysis calculation methodology, the scenarios, and all assumed probabilistic curves were derived from a consensus of an international expert network discussion, using existing data in the literature along with new information collected from companies. The main part of the expert discussion process uses a variant of the Delphi technique, focusing on the group learning process through the information feedback feature. A qualitative analysis indicates that a higher level of credibility and a higher quality of information can be achieved through a more participatory process. The FUEEM method works well within technical information and also in establishing a reasonable set of simple scenarios. However, for a complex combination of scenarios, it will require some improvement. The time spent in the process was the major drawback of the method and some alternatives to share this time cost are suggested.

Life-Cycle Emissions of Alternative Fuels for Transportation: Dealing with Uncertanties

A principal motivation for introducing alternative fuels is to reduce air pollution and greenhouse gas emissions. A comprehensive evaluation of the reductions must include all Life Cycle activities from the vehicle operation to the feedstock extraction. This paper focuses on the fuel upstream activities only. We compare the results and methods of the three most comprehensive existing fuel upstream models in the U.S.A. and we explore the differences and uncertainties of these types of analyses. To explicitly include the impact of uncertainties, we create a new model using the following approaches: - Instead of using a single value as input, the new model deals with ranges around the most probable value - Ranges are discussed and calibrated by an expert network, in terms of their relative probability. - Probabilistic function techniques are applied to study the impact of the uncertainties on the model output. The paper also presents the rationale and benefits of using each of the alternative approaches that are discussed and reviewed.

Catalytic burner for an indirect methanol fuel cell vehicle fuel processor

Abstract Major impediments to the wide-scale implementation of hydrogen/air fuel cell vehicles are the lack of hydrogen infrastructure and on-board hydrogen storage. One proposed source of hydrogen exists in the development of on-board methanol (and other hydrocarbon) fuel processors. Packaging limitations and fuel processor performance constraints on efficiency and transient response play key roles in vehicular applications. These constraints may be addressed by considering proper thermal integration between two major components of the fuel processor: the reformer and catalytic burner. The focus of this research is on the effects of the catalytic burner on reformer performance in a thermally well-integrated configuration. Specifically, the work has focused on the generation of a detailed numerical model incorporating kinetics and mass and heat transfer to accurately characterize the burner. Unlike a simple, thermodynamic model, the detailed model provides a level of complexity necessary to understand the impact of thermal integration on reformer transient response, reformate composition, and emissions.

A Comparison of Energy Use for a Direct-Hydrogen Hybrid Versus a Direct-Hydrogen Load-Following Fuel Cell Vehicle

Hybridizing a fuel cell vehicle has the potential to improve the vehicle efficiency largely due to the ability to recover braking energy. However, tradeoffs do exist, and the advantages (in terms of potential fuel savings) are largely dependent on the drive cycle. The tradeoffs include added energy losses associated with the DC/DC converter and the battery pack itself. Additional tradeoffs not explicitly addressed in this study include added overall complexity, additional packaging constraints, and potentially higher overall cost. This report will focus on a quantitative analysis of the performance of the direct-hydrogen (DH) hybrid and load-following fuel cell vehicles (FCVs) from the viewpoint of the energy use throughout the system. Specifically, the vehicle energy use and efficiency will be compared between the load following and hybrid vehicle platforms. Several hybrid component configurations were studied. When the DC/DC converter is placed in the path of the fuel cell stack current, there does not appear to be much benefit, in terms of energy usage, in hybridizing the DH fuel cell vehicle. Specifically, on the US EPA cycles, the load following vehicle outperformed the hybrid on the HIWAY sequence, but the hybrid had slightly better results on the FUDS cycle. However, if the DC/DC converter is placed in the battery current path only, with the fuel cell stack directly connected to the electric drive train, the benefits in terms of improved fuel economy are larger than in the first configuration. This later configuration will be the design used for this study. Overall, three main factors affect these vehicle results, all of which will be explicitly examined in this study. These factors are: vehicle weight, fuel cell system efficiency (including the battery), and regenerative braking capabilities. Specifically, the hybrid vehicle fuel economy was reduced due to a ∼10% heavier vehicle, and a lower overall system efficiency (when including the battery and DC/DC converter losses). The important factor, therefore, is the regenerative braking capability and whether this gain outweighs the added losses.

System dynamics and efficiency of the fuel processor for an indirect methanol fuel cell vehicle

Fuel cell vehicles powered using hydrogen/air fuel cells have received a lot of attention recently as possible alternatives to internal combustion engine. However, the combined problems of on-board hydrogen storage and the lack of hydrogen infrastructure represent major impediments to their wide scale adoption as replacements for IC engine vehicles. On board fuel processors that generate hydrogen from on-board liquid methanol (and other hydrocarbons) have been proposed as possible alternative sources of hydrogen needed by the fuel cell. This paper investigates the dynamic response and efficiency of the on-board fuel processor in an indirect-methanol fuel cell vehicle. This is carried out using a fuel processor model developed in the Matlab/Simulink environment. The fuel processor model includes detailed subsystem models for the steam-reformer, methanol/hydrogen burner, pre-heaters and CO cleanup stages.

A Comparison of Energy Use for a Indirect-Hydrocarbon Hybrid versus an Indirect-Hydrocarbon Load-Following Fuel Cell Vehicle

Hybrid vehicles have been in the news quite a bit of late given the commercial introduction of a number of hybrid vehicles that sport significant improvements in fuel economy. The improved fuel efficiency of these vehicles can be directly attributable to the hybridized power train on board these internal combustion engine vehicles. Similarly, hybridization of fuel cell vehicles not only helps improve fuel economy but can also help overcome other technical barriers (start up delays, transients). For fuel cell vehicles, hybridization of on-board fuel cell systems is expected to have the potential to improve the vehicle efficiency largely due to the ability to recover braking energy and via flexibility in designing the system controls. However, the advantages can be offset by the tradeoffs due to added energy losses associated with the DC/DC converter and the battery pack itself. Additional tradeoffs not explicitly addressed in this study include added overall complexity, additional packaging constraints, and potentially higher overall cost. This report will focus on a quantitative analysis of the performance of the indirect-hydrocarbon (IH, onboard fuel processor using gasoline type fuel), hybrid and load- following fuel cell vehicles (FCVs) from the viewpoint of the energy use throughout the system. Specifically, the vehicle energy use and efficiency will be compared between the load following (non-hybrid) and hybrid vehicle platforms. Several hybrid component configurations were studied and two representative configurations were investigated in depth. The first (Configuration 1), in which the DC/DC converter is placed in the path of the fuel cell stack current, there does appear to be some benefit, in terms of energy usage, in hybridizing the IH fuel cell vehicle. Specifically, on the US EPA cycles, the hybrid vehicle outperformed the load following vehicle on the FUDS sequence but the load following vehicle had slightly better results on the HIWAY cycle. However, if the DC/DC converter is placed in the battery current path only, with the fuel cell stack directly connected to the electric drive train (Configuration 2), the benefits in terms of improved fuel economy are larger than in the first configuration. The results corresponding to both these configurations will be analyzed and discussed in this paper.

A Simulation Model for an Indirect Methanol Fuel Cell Vehicle

Author(s): Hauer, Karl-Heinz; Moore, Robert M; Ramaswamy, Sitaram | Abstract: Presented at the Future Transportation Technology Conference a Exposition, Costa Mesa, CASession: Alternative Fuels a Fuel CellsThis work focuses on the algorithms to simulate and analyze the characteristics of an indirect methanol fuel cell vehicle. The individual components of the electric drive train including transmission, the vehicle properties, such as drag, frontal area, wheel inertia etc., and the fuel cell system are modeled in a dynamic manner. Further the interaction between the individual components and a simple driver model is described. The algorithms are coded using the simulation tool Matlab/Simulink.The simulation tool is strictly set up in a modular form allowing modifications of individual component characteristics or control algorithms without the need to change the remainder of the model. For the benefit of a more in depth discussion of the applied algorithms and the setup of the model this paper focuses solely on the case of an Indirect Methanol Fuel Cell Vehicle (IMFCV) with steam reformer and without any additional energy storage. Other papers expanding this initial work and discussing various cases of hybridization (batteries, ultra capacitors, reformate gas storages or other fuel cell systems) are under preparation.It is important to notice that the focus of the paper is on the explanation of the algorithms and not the calculation of the fuel consumption or emissions associated with one specific vehicle design or technology. Therefore all quoted data are only illustrative but are not intended to serve as evaluations of the potential of a certain technology.

Steam reformer/burner integration and analysis for an indirect methanol fuel cell vehicle

Fuel cell vehicles powered using hydrogen/air fuel cells have received a lot of attention recently as possible alternatives to internal combustion engines. However, the combined problems of on-board hydrogen storage and the lack of hydrogen infrastructure represent major impediments to their wide-scale adoption as replacements for IC engine vehicles. On-board fuel processors that generate hydrogen from on-board liquid methanol (and other hydrocarbons) has been proposed as possible alternative sources of hydrogen needed by the fuel cell. This paper discusses the impact of proper thermal integration between two major components of the fuel processor (reformer and burner) on the dynamic operation of an on-board fuel processor for a fuel cell vehicle. The fuel processor uses the steam reformation of methanol to produce the requisite hydrogen. Since the steam reformation is an endothermic process, the thermal energy required is supplied by a catalytic burner. During dynamic operation of the fuel cell vehicle, the dynamics of the fuel processor become very critical and these dynamics are very strongly influenced by the extent of thermal integration between the reformer and the burner. In order to study these dynamics, the authors developed a fuel processor model in Matlab/Simulink modeling environment.

Indirect-methanol and direct-methanol fuel cell vehicles

Direct fuel oxidization yields major simplifications and potential performance advantages for a fuel cell power system-particularly for a fuel cell vehicle (FCV) application. Following a brief introduction to the unique characteristics of the polymer electrolyte membrane-based direct methanol fuel cell (DMFC) (compared to direct-hydrogen and the indirect-methanol fuel cell), two performance metrics for the DMFC are examined in more detail, and are compared to the same performance metrics for the indirect-methanol fuel cell.