In-Use Performance Results of Medium Duty Electric Vehicles

This presentation describes a DOE program to monitor and report on vehicle performance and energy utilization of medium-duty and heavy-duty electric vehicles

Coca-Cola Refreshments Class 8 Diesel Electric Hybrid Tractor Evaluation: 13-Month Final Report

This 13-month evaluation used five Kenworth T370 hybrid tractors and five Freightliner M2106 standard diesel tractors at a Coca Cola Refreshments facility in Miami, Florida. The primary objective was to evaluate the fuel economy, emissions, and operational field performance of hybrid electric vehicles when compared to similar-use conventional diesel vehicles. A random dispatch system ensures the vehicles are used in a similar manner. GPS logging, fueling, and maintenance records and laboratory dynamometer testing are used to evaluate the performance of these hybrid tractors. Both groups drive similar duty cycles with similar kinetic intensity (0.95 vs. 0.69), average speed (20.6 vs. 24.3 mph), and stops per mile (1.9 vs. 1.5). The study demonstrated the hybrid group had a 13.7% fuel economy improvement over the diesel group. Laboratory fuel economy and field fuel economy study showed similar trends along the range of KI and stops per mile. Hybrid maintenance costs were 51% lower per mile; hybrid fuel costs per mile were 12% less than for the diesels; and hybrid vehicle total cost of operation per mile was 24% less than the cost of operation for the diesel group

King County Metro Transit Hybrid Articulated Buses: Final Evaluation Results

Final technical report compares and evaluates new diesel and diesel hybrid-electric articulated buses operated as part of the King County Metro Transit (KC Metro) fleet in Seattle, Washington. The evaluation lasted 12 months

Measured Laboratory and In-Use Fuel Economy Observed over Targeted Drive Cycles for Comparable Hybrid and Conventional Package Delivery Vehicles

In-use and laboratory-derived fuel economies were analyzed for a medium-duty hybrid electric drivetrain with 'engine off at idle' capability and a conventional drivetrain in a typical commercial package delivery application. Vehicles studied included eleven 2010 Freightliner P100H hybrids in service at a United Parcel Service facility in Minneapolis during the first half of 2010. The hybrids were evaluated for 18 months against eleven 2010 Freightliner P100D diesels at the same facility. Both vehicle groups use the same 2009 Cummins ISB 200-HP engine. In-use fuel economy was evaluated using UPS's fueling and mileage records, periodic ECM image downloads, and J1939 CAN bus recordings during the periods of duty cycle study. Analysis of the in-use fuel economy showed 13%-29% hybrid advantage depending on measurement method, and a delivery route assignment analysis showed 13%-26% hybrid advantage on the less kinetically intense original diesel route assignments and 20%-33% hybrid advantage on the more kinetically intense original hybrid route assignments. Three standardized laboratory drive cycles were selected that encompassed the range of real-world in-use data. The hybrid vehicle demonstrated improvements in ton-mi./gal fuel economy of 39%, 45%, and 21% on the NYC Comp, HTUF Class 4, and CARB HHDDT test cycles, respectively

Thirty-Six Month Evaluation of UPS Diesel Hybrid-Electric Delivery Vans

This evaluation compared six hybrids and six standard diesels in UPS facilities in Phoenix, Arizona. Dispatch and maintenance practices are the same at both facilities. GPS logging, fueling, and maintenance records are used to evaluate the performance of these step delivery vans. The hybrids' average monthly mileage rate was 18% less than the diesel vans. The hybrids consistently were driven a fewer number of miles throughout the evaluation period. The hybrids idled more and operating at slower speeds than the diesels, and the diesels spent slightly more time operating at greater speeds, accounting for much of the hybrids fewer monthly miles. The average fuel economy for the hybrid vans is 13.0 mpg, 23% greater than the diesel vans 10.6 mpg. Total hybrid maintenance cost/mile of $0.141 was 9$0.130 for the diesel vans. Propulsion-related maintenance cost/mile of $0.037 for the hybrid vans was 25$0.029 for the diesel vans. Neither difference was found to be statistically significant. The hybrid group had a cumulative average of 96.3% uptime, less than the diesel group's 99.0% uptime. The hybrids experienced troubleshooting and recalibration issues related to prototype components that were primarily responsible for the lower uptime figures

In-Use and Vehicle Dynamometer Evaluation and Comparison of Class 7 Hybrid Electric and Conventional Diesel Delivery Trucks

This study compared fuel economy and emissions between heavy-duty hybrid electric vehicles (HEVs) and equivalent conventional diesel vehicles. In-use field data were collected from daily fleet operations carried out at a FedEx facility in California on six HEV and six conventional 2010 Freightliner M2-106 straight box trucks. Field data collection primarily focused on route assessment and vehicle fuel consumption over a six-month period. Chassis dynamometer testing was also carried out on one conventional vehicle and one HEV to determine differences in fuel consumption and emissions. Route data from the field study was analyzed to determine the selection of dynamometer test cycles. From this analysis, the New York Composite (NYComp), Hybrid Truck Users Forum Class 6 (HTUF 6), and California Air Resource Board (CARB) Heavy Heavy-Duty Diesel Truck (HHDDT) drive cycles were chosen. The HEV showed 31% better fuel economy on the NYComp cycle, 25% better on the HTUF 6 cycle and 4% worse on the CARB HHDDT cycle when compared to the conventional vehicle. The in-use field data indicates that the HEVs had around 16% better fuel economy than the conventional vehicles. Dynamometer testing also showed that the HEV generally emitted higher levels of nitric oxides than the conventional vehicle over the drive cycles, up to 77% higher on the NYComp cycle (though this may at least in part be attributed to the different engine certification levels in the vehicles tested). The conventional vehicle was found to accelerate up to freeway speeds over ten seconds faster than the HEV

White-light flares on cool stars in the Kepler Quarter 1 Data

We present the results of a search for white light flares on the ~23,000 cool dwarfs in the Kepler Quarter 1 long cadence data. We have identified 373 flaring stars, some of which flare multiple times during the observation period. We calculate relative flare energies, flare rates and durations, and compare these with the quiescent photometric variability of our sample. We find that M dwarfs tend to flare more frequently but for shorter durations than K dwarfs, and that they emit more energy relative to their quiescent luminosity in a given flare than K dwarfs. Stars that are more photometrically variable in quiescence tend to emit relatively more energy during flares, but variability is only weakly correlated with flare frequency. We estimate distances for our sample of flare stars and find that the flaring fraction agrees well with other observations of flare statistics for stars within 300 pc above the Galactic Plane. These observations provide a more rounded view of stellar flares by sampling stars that have not been pre-selected by their activity, and are informative for understanding the influence of these flares on planetary habitability.Comment: 42 pages, 10 figures, 2 tables; Accepted for publication in the Astronomical Journa

Photometric Variability in Kepler Target Stars: The Sun Among Stars -- A First Look

The Kepler mission provides an exciting opportunity to study the lightcurves of stars with unprecedented precision and continuity of coverage. This is the first look at a large sample of stars with photometric data of a quality that has heretofore been only available for our Sun. It provides the first opportunity to compare the irradiance variations of our Sun to a large cohort of stars ranging from vary similar to rather different stellar properties, at a wide variety of ages. Although Kepler data is in an early phase of maturity, and we only analyze the first month of coverage, it is sufficient to garner the first meaningful measurements of our Sun's variability in the context of a large cohort of main sequence stars in the solar neighborhood. We find that nearly half of the full sample is more active than the active Sun, although most of them are not more than twice as active. The active fraction is closer to a third for the stars most similar to the Sun, and rises to well more than half for stars cooler than mid K spectral types.Comment: 13 pages, 4 figures, accepted to ApJ Letter

King County Metro Transit: Allison Hybrid Electric Transit Bus Laboratory Testing

Paper summarizes chassis dynamometer testing of two 60-foot articulated transit buses, one conventional and one hybrid, at NREL's ReFUEL Laboratory. It includes experimental setup, test procedures, and results from vehicle testing performed at the NREL ReFUEL laboratory