Examining Hydrogen Transitions
2/1/2007
This report describes the results of efforts to identify key analytic issues associated with modeling a transition to hydrogen as a fuel for light-duty vehicles.
Authors: Plotkin, S.
SunLine Transit Agency Hydrogen-Powered Transit Buses: Preliminary Evaluation Results
2/1/2007
This preliminary report covers NREL's evaluation of hydrogen and fuel cell buses in service at SunLine Transit Agency in Thousand Palms, California. The report includes 11 months of performance data on two hydrogen-fueled buses: one fuel cell bus and one hybrid hydrogen-fueled internal combustion engine bus. The report also outlines the overall experience of the transit agency and its project partners in demonstrating these buses.
Authors: Chandler, K.; Eudy, L.
Performance of Automotive Fuel Cell Systems with Nanostructured Thin Film Catalysts
1/1/2007
Cost and durability are generally regarded as the major challenges to commercialization of fuel cells. Size, weight, and system complexity are also important barriers to adoption of fuel cells in light duty vehicles. In addition, thermal and water management for fuel cells are outstanding issues. Fuel cell operation at lower temperatures creates a small difference between the operating and ambient temperatures, necessitating large heat exchangers. Fuel and air feed streams need to be humidified for proper operation of fuel cells. In this paper, we evaluate the prospects of overcoming the barriers of cost, durability, weight, volume, thermal management, and water management by using nanostructured thin film catalysts (NTFCs) in membrane electrode assemblies (MEAs) In laboratory tests, the NSTF catalysts have shown significantly enhanced stability against surface area loss from Pt dissolution when compared to conventional Pt/C dispersed catalysts under both accelerated voltage cycling from 0.6 to 1.2 V and real-time start stop cycles. Also NSTF catalyst support-whiskers have shown total resistance to corrosion when held at potentials up to 1.5 V for 3 hours.
Authors: Ahluwalia, R.; Wang, X.; Lasher, S.; Sinha, J.; Yang, Y.; Sriramulu, S.
Santa Clara Valley Transportation Authority and San Mateo County Transit District Fuel Cell Transit Buses: Evaluation Results
11/1/2006
This report provides evaluation results of prototype fuel cell transit buses operating at Santa Clara Valley Transportation Authority (VTA) in San Jose, California. VTA has been operating three fuel cell transit buses in extra revenue service since February 28, 2005. The report includes 17 months of performance data on three 40-ft. Gillig buses with a fuel cell system by Ballard Power Systems. The report also outlines the overall experience for the transit agency and its project partners in demonstrating these zero-emission buses. The analysis in this report reflects the prototype status of these vehicles. There is no intent to consider the implementation of these fuel cell buses as commercial (or full revenue transit service. The evaluation focuses on documenting progress and opportunities for improving the vehicles, infrastructure, and procedures.
Authors: Chandler, K.; Eudy, L.
Geographically Based Hydrogen Consumer Demand and Infrastructure Analysis Final Report
10/1/2006
In fiscal 2004 and 2005, the National Renewable Energy Lab developed a proposed minimal infrastructure to support nationwide deployment of hydrogen vehicles by offering infrastructure scenarios that facilitated interstate travel. The current (FY06) project aims to identify key metropolitan areas and regions on which to focus infrastruce efforts during the early hydrogen transition. The objectives of this analysis are to (1) quantify projected hydrogen vehicle demand across the U.S. and in targeted metropolitan areas; and, (2) quantify the projected hydrogen fuel demands corresponding with different levels of hydrogen vehicle demand to inform infrastructure analyses such as siting hydrogen fueling stations and selecting between centralized and distributed hydrogen production.
Authors: Melendez, M.; Milbrandt, A.
Designing New Transit Bus Garages to be Fuel Flexible
5/12/2006
The basic differences between the properties of gaseous and liquid fuels influence building design requirements for transit bus garages. Leaks, flammability range, and ignition temperatures must be considered when designing the structure, utilities, ventilation, and safety equipment.
Authors: Adams, R.
AC Transit Demos Three Prototype Fuel Cell Buses
5/1/2006
The Alameda-Contra Costa (AC) Transit District is currently collaborating with the U.S. Department of Energy's Hydrogen, Fuel Cells & Infrastructure Technologies Program on the evaluation of the three fuel cell buses. The hybrid system used is a series configuration, meaning the powerplant is not mechanically coupled to the drive axle.
Lessons Learned from Alternative Transportation Fuels: Modeling Transition Dynamics
2/1/2006
Much attention has been given to the use of hydrogen as an alternative transportation fuel, but hydrogen was certainly not the first fuel considered as an alternative to gasoline for transportation applications. Options ranging from all-electric vehicles to those running on natural gas, propane, ethanol, and biodiesel have also received both industry and government attention. Unfortunately, previous government efforts to encourage widespread adoption of alternative fuel vehicles have been largely unsuccessful. The National Academy of Engineering suggested that 'DOE might have its greatest impact by leading the private economy toward transition strategies rather than to ultimate visions of an energy infrastructure markedly different from the one now in place.'
This report focuses on understanding how analytical system modeling coupled with actual data from previous alternative-fuel experiences could improve our understanding of the dynamic forces governing the transition to an alternative-fueled vehicle system.
Authors: Welch, Cory
Transitioning to a Hydrogen Future: Learning from the Alternative Fuels Experience
2/1/2006
A wealth of practical knowledge concerning alternative fuel technologies, products, national policies, and market introduction exists within industry, regulated fleets, and voluntary programs. Issues relating to consumer choice, capital investment, business decision making, manufacturing, and infrastructure construction will need to be understood in the alternative fuels context if the hydrogen transition is to occur efficiently. The overall objective of this project is to assess relevant knowledge within the alternative fuels community and recommend transitional strategies and tactics that will further the hydrogen transition in the transportation sector and help avoid stranded assets in the alternative fuels industry.
Authors: Melendez, M.
Hydrogen Infrastructure Transition Analysis
1/1/2006
The analysis done in fiscal year (FY) 2005 built upon the FY 2004 work described in the March 2005 report, Analysis of the Hydrogen Infrastructure Needed to Enable Commercial Introduction of Hydrogen-Fueled Vehicles1. The FY 2005 project: Identified existing hydrogen production facilities and alternative fuel stations; Identified highway traffic volumes throughout the U.S. interstate system; Selected specific north/south and east/west routes as a focus for the project; Incorporated existing hydrogen production facilities, hydrogen and natural gas fueling stations, railroads, traffic volume, and county population data; Placed stations on the U.S. interstate network according to population density and station distances; and identified a significant potential to co-locate refueling with federal government partners. In FY 2005, analysis focused on using the basic refueling station network proposed in FY 2004 to evaluate various scenarios for transition. These strategies and analyses are described in this report.
Authors: Melendez, M.; Milbrandt, A.
Steam Reforming of Ethanol at Elevated Pressures for Distributed Hydrogen Production
1/1/2006
Ethanol is an attractive renewable fuel because, as a liquid fuel, it has a high energy density, it is easy to transport, and it is environmentally more benign than petroleum-derived fuels. The hydrogen produced by reforming needs to be purified and compressed to the appropriate storage and dispensing pressures. Compressing hydrogen is energy intensive and can consume a significant fraction of the fuel's heating value. A promising option for producing hydrogen from ethanol is by conducting the ethanol steam reforming reaction at an elevated pressure, since injecting liquid feeds (ethanol and water) into a pressurized reactor requires very little energy.
Authors: Lee, S.; Papadias, D.; Ahluwalia, R.; Ahmed, S.
Development and Demonstration of Hydrogen and Compressed Natural Gas (H/CNG) Blend Transit Buses
11/1/2005
One approach being put forth for the advancement of hydrogen fueled vehicles is to blend hydrogen with compressed natural gas (H/CNG) for use in state-of-the-art internal combustion engine vehicles. Current natural gas engines and vehicles can be modified to operate on H/CNG with available technology. This report reviews a small-scale study of this concept. The project demonstrated that with minor engine and vehicle modifications, the 20/80 hydrogen/CNG blend can be used in revenue service fleets with similar operational performance as CNG. However, additional optimization of the H/CNG engine calibration is necessary to attain equivalent fuel economy, or alternatively increased fuel economy at equivalent NOx emissions.
Authors: Del Toro, A.; Frailey, M.; Lynch, F.; Munshi, S.; Wayne, S.
VTA, SamTrans Look into Future with Bus Demo
9/1/2005
This fact sheet provides information about the Santa Clara Valley Transportation Authority (VTA) Zero-Emission Bus Program. VTA is currently collaborating with the U.S. Department of Energy's (DOE) Hydrogen, Fuel Cells, & Infrastructure Technologies Program to evaluate the performance of three fuel cell transit buses developed by Ballard Power Systems and Gillig Corporation.