Analysis of the Fuel Economy Benefit of Drivetrain Hybridization

Parallel- and series-configured hybrid vehicles likely feasible in next decade arc defined and evaluated using NREL's flexible ADvanced VehIcle SimulatOR ADVISOR. Fuel economics of these two diesel-powered hybrid vehicles are compared to a comparable-technology diesel- powered internal-combustion-engine vehicle. Sensitivities of these fuel economies to various vehicle and component parameters are determined and differences among them are explained. The fuel economy of the parallel hybrid defined here is 24% better than the internal- combustion-engine vehicle and 4% better than the series hybrid

Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project Initial Fuel Cell Efficiency and Durability Results

The objective of the U.S. Department of Energy’s “Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project” is to conduct an integrated field validation that simultaneously examines the performance of fuel cell vehicles and the supporting hydrogen infrastructure. This paper provides initial results in the form of composite data products, which aggregate individual performance into a range that protects the intellectual property and the identity of each industry team, while showing overall industry progress toward technology readiness. Technical insights from the project are fed back into DOE’s research and development program, making this project a “learning demonstration.” Key results to-date include fuel economy, driving range, fuel cell efficiency, and initial fuel cell durability projections based on voltage degradation

U.S. Fuel Cell Vehicle Learning Demonstration: Status Update and Early Second-Generation Vehicle Results

The National Learning Demonstration is conducting an integrated field validation to examine the performance of fuel cell vehicles and their supporting hydrogen infrastructure. NREL has now analyzed data from over four years of the six-year project, including 140 vehicles and 20 refueling stations, resulting in over 346,000 vehicle trips across 1,900,000 miles and over 90,000 kg of hydrogen produced or dispensed. Public analytical results from this project are presented in the form of composite data products (CDPs), which aggregate individual performance to protect the intellectual property and the identity of each company, while still publishing overall status and progress. In the spring of 2009, the National Renewable Energy Laboratory (NREL) published the latest set of CDPs, making a total of 60 individual results and many new analyses publicly available. Highlights from the vehicle results include meeting the 250-mile driving range program milestone with 700-bar hydrogen storage tanks, stacks that have demonstrated almost 2,000 hours without repair, maintenance categorization from the powertrain and fuel cell system, and fuel cell stack usage data on trips/hour and time at various voltage levels. Infrastructure results include well-to-wheel greenhouse gas emissions calculated using actual fuel economy and production efficiency and a deep-dive into refueling rates. The project is continuing into 2010, with a significant number of vehicles planned for daily use through the end of the project. Results will continue to be published by NREL every six months and a final report is planned at the end of the project

Final Results from U.S. FCEV Learning Demonstration

The “Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project,” also known as the National Fuel Cell Electric Vehicle Learning Demonstration, is a U.S. Department of Energy (DOE) project started in 2004 and concluded in late 2011. The purpose of this project was to conduct an integrated field validation that simultaneously examined the performance of fuel cell vehicles and the supporting hydrogen fueling infrastructure. The DOE’s National Renewable Energy Laboratory (NREL) received and analyzed all of the raw technical data collected by the industry partners through their participation in the project over its seven-year duration. This paper reviews highlights from the project and draws conclusions about the demonstrated status of the fuel cell vehicle and hydrogen fueling infrastructure technology. Through September 2011, 183 fuel cell electric vehicles were deployed, 25 project fueling stations were placed in use, and no fundamental safety issues were identified. We have analyzed data from more than 500,000 individual vehicle trips covering 3.5 million miles traveled and more than 150,000 kg hydrogen produced or dispensed. Public analytical results from this project are in the form of composite data products (CDPs), which aggregate individual performance to protect the intellectual property and the identity of each company while still publishing overall status and progress. Ninety-nine of these CDPs have been generated for public use and posted on NREL’s technology validation website. The results indicate that fuel cell vehicle technology continues to make rapid progress toward commercial readiness and that the fueling infrastructure technology is ready to provide a consumer-friendly fast fill and long range experience consistent with expectations of gasoline vehicle customers

FCV Learning Demonstration: Project Midpoint Status and First-Generation Vehicle Results

The “Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project,” also known as the Fuel Cell Vehicle and Infrastructure Learning Demonstration, is a 5-year U.S. Department of Energy (DOE) project started in 2004. The purpose of this project is to conduct an integrated field validation that simultaneously examines the performance of fuel cell vehicles and the supporting hydrogen infrastructure. Four industry teams are currently operating more than 77 vehicles and 14 refueling stations, with plans to add over 50 additional vehicles and several additional refueling stations during the remainder of the project duration. This paper covers the progress accomplished by the demonstration and validation project since inception, including results from analysis of six months of new data.With three sets of public results having been presented previously, this paper comes at roughly the midpoint of the project, just as second-generation fuel cell stacks and vehicles are being introduced and some early vehicles are being retired. With many fuel cell stacks having accumulated well over 500 hours of real-world operation, there is now a higher level of confidence in the trends and projections relating to the durability and voltage degradation of these first-generation fuel cell stacks.Public results for this project are in the form of composite data products, which aggregate individual performance into a range that protects the intellectual property and the identity of each company, while still publishing overall status and progress. In addition to generating composite data products, NREL is performing additional analyses to provide detailed recommendations back to the R&D program. This includes analysis to identify sensitivities of fuel cell durability to factors such as vehicle duty cycle, number of on/off cycles, time at idle, and ambient temperature. An overview of this multivariate analysis and preliminary findings will be shared, with future project activities discussed

Entering a New Stage of Learning from the U.S. Fuel Cell Electric Vehicle Demonstration Project

The National Fuel Cell Electric Vehicle Learning Demonstration is a U.S. Department of Energy (DOE) project that started in 2004. The purpose of this project is to conduct an integrated field validation that simultaneously examines the performance of fuel cell vehicles and the supporting hydrogen infrastructure. The DOE’s National Renewable Energy Laboratory (NREL) has now analyzed data from over five years of the seven-year project. During this time, over 144 fuel cell electric vehicles have been deployed, and 23 project refueling stations were placed in use. We have analyzed data from over 430,000 individual vehicle trips covering 2,500,000 miles traveled and over 130,000 kg hydrogen produced or dispensed. During 2010, two of the four project teams will be concluding their involvement in the project, and the other two are continuing. Thus we will be able to focus our analysis efforts on a smaller number of vehicles and stations and enter into a new stage of learning for this project. This will allow us to dig deeper into the data to provide additional technical value to the two remaining teams as they improve their systems’ technical performance in preparation for pre-commercial launch of larger fleets of vehicles in California and New York. It will also give us an opportunity to gather data and analyze performance of improved vehicles compared to those that have been previously demonstrated, since these vehicles are one step closer to commercially available customer vehicles

Optimizing Energy Management Strategy and Degree of Hybridization for a Hydrogen Fuel Cell SUV

Previous work examined degree of hybridization on the fuel economy of a hybrid electric sport utility vehicle. It was observed that not only was the vehicle control strategy important, but that its definition should be coupled with the component sizing process. Both degree of hybridization and the energy management strategy have been optimized simultaneously in this study. Simple mass scaling algorithms were employed to capture the effect of component and vehicle mass variations as a function of degree of hybridization. Additionally, the benefits of regenerative braking and power buffering have been maximized using optimization methods to determine appropriate battery pack sizing. Both local and global optimization routines were applied to improve the confidence in the solution being close to the true optimum. An optimal configuration and energy management strategy that maximizes the benefit of hybridization for a hydrogen fuel cell hybrid SUV was derived. The optimal configuration was explored, and sensitivity to drive cycle in the optimization process was studied

HEV Control Strategy for Real-Time Optimization of Fuel Economy and Emissions

Hybrid electric vehicles (HEV's) offer additional flexibility to enhance the fuel economy and emissions of vehicles. The Real-Time Control Strategy (RTCS) presented here optimizes efficiency and emissions of a parallel configuration HEV. In order to determine the ideal operating point of the vehicle's engine and motor, the control strategy considers all possible engine-motor torque pairs. For a given operating point, the strategy predicts the possible energy consumption and the emissions emitted by the vehicle. The strategy calculates the "replacement energy" that would restore the battery's state of charge (SOC) to its initial level. This replacement energy accounts for inefficiencies in the energy storage system conversion process. Userand standards-based weightings of time-averaged fuel economy and emissions performance determine an overall impact function. The strategy continuously selects the operating point that is the minimum of this cost function. Previous control strategies em..