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Viewing 1 to 30 of 162
2015-04-14
Technical Paper
2015-01-1687
Eric Wood, Jeremy S. Neubauer, Evan Burton
The disparate characteristics between conventional (CVs) and electric vehicles (EVs) in terms of driving range, refill/recharge time, and availability of refuel/recharge infrastructure inherently limits the relative utility of EVs when benchmarked against traditional driver travel patterns. However, given a high penetration of high power public charging availability combined with driver tolerance for rerouting travel to facilitate charging on long distance trips, the difference in utility between CVs and EVs could be marginalized. Herein we quantify the relationships between EV utility, the deployment of fast chargers, and driver tolerance for rerouting travel and extending travel durations by simulating EVs operated to real-world travel patterns using the National Renewable Energy Laboratory’s (NREL) Battery Lifetime Analysis and Simulation Tool for Vehicles (BLAST-V). Under support from the U.S.
2015-04-14
Technical Paper
2015-01-1688
Eric Wood, Jeremy S. Neubauer, Evan Burton
With support from the Vehicle Technologies Office in the U.S. Department of Energy, the National Renewable Energy Laboratory (NREL) has developed BLAST-V—the Battery Lifetime Analysis and Simulation Tool for Vehicles. The addition of high resolution spatial-temporal travel histories has enabled BLAST-V to investigate user-defined infrastructure rollouts of publically accessible charging infrastructure, as well as quantify impacts on vehicle and station owners in terms of improved vehicle utility and station throughput. This paper will present simulation outputs from BLAST-V quantifying the utility improvements of multiple distinct rollouts of publically available level 2 electric vehicle service equipment (EVSE) in the Seattle metropolitan area. Publically available data on existing level 2 EVSE will also be used as an input to BLAST-V with resulting vehicle utility compared to a number of mock rollout scenarios.
2015-04-14
Technical Paper
2015-01-1709
Daniel Leighton
Electric drive vehicles (EDVs) have complex thermal management requirements not present in traditional internal combustion engine vehicles. In addition to cabin conditioning, the battery, power electronics, and electric motor drivetrain sub-systems also require thermal management. Many current generation EDVs utilize separate cooling systems for each of these sub-systems, which adds both weight and cost. Another issue for EDVs is the lack of abundant waste heat from the engine for cabin heating. In many cases EDVs use battery energy to heat the cabin via an electrical resistance heater, which results in vehicle range reductions of nearly 50% under cold ambient conditions. These EDV thermal challenges present an opportunity for integrated vehicle thermal management technologies which can reduce cost and weight, and enable efficient heating methods that increase vehicle range.
2015-04-14
Technical Paper
2015-01-0974
Aaron Brooker, Jeffrey Gonder, Sean Lopp, Jacob Ward
The ADOPT model is a light duty vehicle consumer choice and stock model supported by the U.S. Department of Energy Vehicle Technologies Office. It estimates technology improvement impacts on U.S. light duty vehicles sales, petroleum use, and greenhouse gas (GHG) emission. The ADOPT model uses a logit function to estimate sales. The majority of existing vehicle makes, models, and trims are included to fully represent the market. The logit function estimates their sales based on key attributes including vehicle price, fuel cost, acceleration, range and usable volume. The average importance of several attributes changes nonlinearly across its range, and changes with income. For several attributes, a distribution of importance around the average value is used to represent consumer heterogeneity. Engine downsizing and balancing net incentives/penalties are used to ensure that the Corporate Average Fuel Economy (CAFE) is met.
2015-04-14
Technical Paper
2015-01-0351
Jason Aaron Lustbader, Cory Kreutzer
Annual fuel use for sleeper cab truck rest period idling is estimated at 667 million gallons in the United States. Idling of the truck during a rest period represents a zero freight efficiency condition and is partially done to supply accessory power for climate conditioning of the cab. The U.S. Department of Energy’s (DOE) National Renewable Energy Laboratory’s (NREL) CoolCab project aims to reduce HVAC loads and resulting fuel use from rest period idling by working closely with industry to design efficient long-haul truck thermal management systems while maintaining occupant comfort. Enhancing the thermal performance of cab/sleepers will enable smaller, lighter, and more cost-effective idle reduction solutions. In addition, if the fuel savings from new technologies provide a one- to three-year payback period, fleet owners will be economically motivated to incorporate them.
2015-04-14
Technical Paper
2015-01-0342
Forrest Jehlik, Eric Wood, Jeffrey Gonder, Sean Lopp
It is widely understood that cold-temperature powertrain operation negatively impacts vehicle fuel use due to heat transfer losses, increased friction (high viscosity engine oil), and enrichment strategies (accelerated catalyst heating). In addition, various drive cycle characteristics significantly impact overall consumption. However, relatively little effort has been dedicated to thoroughly quantifying these impacts across a large number of driving cycles and ambient conditions. This work leverages experimental vehicle data collected at various ambient conditions to develop a simplified modeling framework for quantifying thermal effects on energy consumption over a wide array of real-world usage profiles. Additionally, mitigation strategies including energy retention and exhaust heat recovery are explored with benefits quantified for each approach.
2015-04-14
Technical Paper
2015-01-1196
Jeremy S. Neubauer, Eric Wood
Fast charging is attractive to electric vehicle (EV) drivers for its ability to enable long-distance travel and quickly recharge depleted batteries on short notice. However, such aggressive charging and the sustained vehicle operation that results could lead to excessive battery temperatures and degradation. Properly assessing the consequences of fast charging requires accounting for disparate cycling, heating, and aging of individual cells in large EV packs when subjected to realistic travel patterns, usage of fast chargers, and climates over long durations (i.e. years). The U.S. Department of Energy’s Vehicle Technologies Office has supported NREL’s development of BLAST-V—the Battery Lifetime Analysis and Simulation Tool for Vehicles – to create a tool capable of accounting for all of these factors. Herein the authors shall present on the findings of applying this tool to realistic fast charge scenarios.
2015-04-14
Technical Paper
2015-01-1708
Tibor Kiss, Jason Lustbader
For electric vehicles (EVs), there is a great need for highly optimized thermal management systems. Due to the relative shortage of waste heat, heating the passenger cabin in electric vehicles is difficult. Cooling the cabin can take a high portion of the energy available in the battery, significantly reducing vehicle efficiency and range. The range reduction can be as much as 50% by at least one report. Therefore, compared to IC engine driven vehicles, different heating methods and more efficient cooling methods are needed, which can make the electric vehicle’s thermal management system more complex. The more complex systems typically allow various alternative modes of operation which can be selected based on driving and ambient conditions. Investigating a number of system alternatives and determining the best ranges for the various operating modes with experimental methods can be very time consuming.
2015-04-14
Technical Paper
2015-01-0355
Matthew A. Jeffers, Larry Chaney, John Rugh
When operated, the climate control system is the largest auxiliary load on a vehicle. This load has significant impact on fuel economy, and more importantly, it drastically reduces the driving range of electric-drive vehicles (EVs). Heating is even more detrimental to EV range than cooling, since no engine waste heat is available. Reducing the thermal loads on the HVAC system will extend driving range and increase the market penetration of EVs. Researchers at the National Renewable Energy Laboratory are evaluating strategies for vehicle climate control load reduction, with special attention toward GCEDVs. The goal is to increase EV range by 10% during operation of the climate control system. Outdoor vehicle thermal testing and computational modeling are jointly used to explore possibilities for improved thermal management and to evaluate the effectiveness of load-reduction technologies. A thermal comfort model is also being used to evaluate zonal climate control concepts.
2015-04-14
Technical Paper
2015-01-0973
Aaron Brooker, Jeffrey Gonder, Lijuan Wang, Eric Wood, Sean Lopp, Laurie Ramroth
The Future Automotive Systems Technology Simulator (FASTSim) is a high level advanced vehicle powertrain analysis tool supported by the U.S. Department of Energy Vehicle Technologies Office. FASTSim provides a quick and easy way to estimate and compare the impact of technology improvements on light or heavy duty vehicle efficiency, performance, cost, and battery life. It automatically imports the required inputs for almost any existing light duty vehicle. Those inputs can be modified to represent variations of the vehicle or powertrain. The vehicle and its components are then simulated through a speed versus time drive cycle. At each time step FASTSim accounts for drag, acceleration, ascent, rolling resistance, each powertrain components’ efficiency and power limits, and regenerative braking.
2015-04-14
Technical Paper
2015-01-0763
Gina M. Chupka, Earl Christensen, Lisa Fouts, Teresa L. Alleman, Matthew A. Ratcliff, Robert L. McCormick
The objective of this work was to measure knock resistance metrics for ethanol-hydrocarbon blends with a primary focus on development of methods to measure the heat of vaporization (HOV). Blends of ethanol at 10 to 50 volume percent were prepared with three gasoline blendstocks and a natural gasoline. Performance properties and composition of the blendstocks and blends were measured, including research octane number (RON), motor octane number (MON), net heating value, density, distillation curve, and vapor pressure. RON increases upon blending ethanol but with diminishing returns above about 30 vol%. Above 30% to 40% ethanol the curves flatten and converge at a RON of about 103 to 105, even for the much lower RON NG blendstock. Octane sensitivity (S = RON – MON) also increases upon ethanol blending. Gasoline blendstocks with nearly identical S can show significantly different sensitivities when blended with ethanol.
2015-04-14
Technical Paper
2015-01-1306
Jeremy S. Neubauer
Battery second use – putting used plug-in electric vehicle (PEV) batteries into a secondary service following their automotive tenure – has been proposed as a means to decrease the cost of PEVs while providing low cost energy storage to other fields (e.g. electric utility markets). Under the support of the U.S. Department of Energy’s Vehicle Technologies Office, the National Renewable Energy Laboratory (NREL) has conducted a comprehensive study of this topic. This presentation will focus on a subset of that study focusing on battery degradation and value, specifically addressing the following key questions: How long will PEV batteries last in automotive service? How healthy will PEV batteries be when they leave automotive service? How long will retired PEV batteries last in second-use service? How can we best predict the second-use lifetime of a used automotive battery? What’s the value of a second-use battery?
2015-04-14
Technical Paper
2015-01-0329
Mark Hepokoski, Allen Curran, Richard Burke, John Rugh, Larry Chaney, Clay Maranville
Reliable assessment of occupant thermal comfort can be difficult to obtain within automotive environments, especially under transient and asymmetric heating and cooling scenarios. Evaluation of HVAC system performance in terms of comfort commonly requires human subject testing, which may involve multiple repetitions, as well as multiple test subjects. Instrumentation (typically comprising of an array of temperature sensors) is usually only sparsely applied across the human body, significantly reducing the spatial resolution of available test data. Further, since comfort is highly subjective in nature, a single test protocol can yield a wide variation in results which can only be overcome by increasing the number of test replications and subjects. In light of these difficulties, various types of manikins are finding use in automotive testing scenarios.
2014-09-30
Journal Article
2014-01-2438
Michael P. Lammert, Adam Duran, Jeremy Diez, Kevin Burton, Alex Nicholson
Abstract This research project evaluates fuel consumption results of two Class 8 tractor-trailer combinations platooned together compared to their standalone fuel consumption. A series of ten modified SAE Type II J1321 fuel consumption track tests were performed to document fuel consumption of two platooned vehicles and a control vehicle at varying steady-state speeds, following distances, and gross vehicle weights (GVWs). The steady-state speeds ranged from 55 mph to 70 mph, the following distances ranged from a 20-ft following distance to a 75-ft following distance, and the GVWs were 65K lbs and 80K lbs. All tractors involved had U.S. Environmental Protection Agency (EPA) SmartWay-compliant aerodynamics packages installed, and the trailers were equipped with side skirts. Effects of vehicle speed, following distance, and GVW on fuel consumption were observed and analyzed.
2014-09-30
Journal Article
2014-01-2375
Michael P. Lammert, Jonathan Burton, Petr Sindler, Adam Duran
Abstract This research project compares laboratory-measured fuel economy of a medium-duty diesel powered hydraulic hybrid vehicle drivetrain to both a conventional diesel drivetrain and a conventional gasoline drivetrain in a typical commercial parcel delivery application. Vehicles in this study included a model year 2012 Freightliner P10HH hybrid compared to a 2012 conventional gasoline P100 and a 2012 conventional diesel parcel delivery van of similar specifications. Drive cycle analysis of 484 days of hybrid parcel delivery van commercial operation from multiple vehicles was used to select three standard laboratory drive cycles as well as to create a custom representative cycle. These four cycles encompass and bracket the range of real world in-use data observed in Baltimore United Parcel Service operations.
2014-04-01
Technical Paper
2014-01-1789
Eric Wood, Evan Burton, Adam Duran, Jeffrey Gonder
Abstract Understanding the real-world power demand of modern automobiles is of critical importance to engineers using modeling and simulation in the design of increasingly efficient powertrains. Increased use of global positioning system (GPS) devices has made large-scale data collection of vehicle speed (and associated power demand) a reality. While the availability of real-world GPS data has improved the industry's understanding of in-use vehicle power demand, relatively little attention has been paid to the incremental power requirements imposed by road grade. This analysis quantifies the incremental efficiency impacts of real-world road grade by appending high-fidelity elevation profiles to GPS speed traces and performing a large simulation study. Employing a large, real-world dataset from the National Renewable Energy Laboratory's Transportation Secure Data Center, vehicle powertrain simulations are performed with and without road grade under five vehicle models.
2014-04-01
Technical Paper
2014-01-0680
Jason Aaron Lustbader, Cory Kreutzer, Matthew A. Jeffers, Steven Adelman, Skip Yeakel, Philip Brontz, Kurt Olson, James Ohlinger
Abstract Cab climate conditioning is one of the primary reasons for operating the main engine in a long-haul truck during driver rest periods. In the United States, sleeper cab trucks use approximately 667 million gallons of fuel annually for rest period idling. The U.S. Department of Energy's National Renewable Energy Laboratory's (NREL) CoolCab Project works closely with industry to design efficient thermal management systems for long-haul trucks that minimize engine idling and fuel use while maintaining occupant comfort. Heat transfer to the vehicle interior from opaque exterior surfaces is one of the major heat pathways that contribute to air conditioning loads during long-haul truck daytime rest period idling. To quantify the impact of paint color and the opportunity for advanced paints, NREL collaborated with Volvo Group North America, PPG Industries, and Dometic Environmental Corporation.
2014-04-01
Technical Paper
2014-01-1969
Marc W. Melaina
Abstract Both hydrogen and plug-in electric vehicles offer significant social and environmental benefits to enhance energy security and reduce criteria and greenhouse gas emissions from the transportation sector. However, the rollout of electric vehicle supply equipment (EVSE) and hydrogen retail stations (HRS) requires substantial investments with high risks due to many uncertainties. We compare retail infrastructure costs on a common basis - cost per mile, assuming fueling service to 10% of all light-duty vehicles in a typical 1.5 million person city in 2025. Our analysis considers three HRS sizes, four distinct types of EVSE and two distinct EVSE scenarios. EVSE station costs, including equipment and installation, are assumed to be 15% less than today's costs. We find that levelized retail capital costs per mile are essentially indistinguishable given the uncertainty and variability around input assumptions.
2014-04-01
Journal Article
2014-01-0669
Tibor Kiss, Jason Lustbader
The operation of air conditioning (A/C) systems is a significant contributor to the total amount of fuel used by light-and heavy-duty vehicles. Therefore, continued improvement of the efficiency of these mobile A/C systems is important. Numerical simulation has been used to reduce the system development time and to improve the electronic controls, but numerical models that include highly detailed physics run slower than desired for carrying out vehicle-focused drive cycle-based system optimization. Therefore, faster models are needed even if some accuracy is sacrificed. In this study, a validated model with highly detailed physics, the “Fully-Detailed” model, and two models with different levels of simplification, the “Quasi-Transient” and the “Mapped-Component” models, are compared. The Quasi-Transient model applies some simplifications compared to the Fully-Detailed model to allow faster model execution speeds.
2014-04-01
Journal Article
2014-01-1500
Aaron Williams, Robert McCormick, Michael Lance, Chao Xie, Todd Toops, Rasto Brezny
Small impurities in the fuel can have a significant impact on the emissions control system performance over the lifetime of the vehicle. Of particular interest in recent studies has been the impact of sodium, potassium, and calcium that can be introduced either through fuel constituents, such as biodiesel, or as lubricant additives. In a collaboration between the National Renewable Energy Laboratory and the Oak Ridge National Laboratory, a series of accelerated aging studies have been performed to understand the potential impact of these metals on the emissions control system. This paper explores the effect of the rate of accelerated aging on the capture of fuel-borne metal impurities in the emission control devices and the subsequent impact on performance. Aging was accelerated by doping the fuel with high levels of the metals of interest. Three separate evaluations were performed, each with a different rate of accelerated aging.
2013-11-20
Journal Article
2013-01-9071
Teresa L. Alleman
In the last three years, three quality surveys on ethanol-blended fuels intended for use in flex-fuel vehicles have been published. Two of these surveys cover Flex-Fuel quality, and the third encompasses the quality of mid-level ethanol blends (MLEBs) from blender pumps. The purpose of these surveys was to report on the quality of the fuels and provide a snapshot in time of fuel quality. This study examines the larger picture portrayed by these surveys and looks for broader trends in fuel quality. The analysis found that compliance with vapor pressure specification limits for Flex Fuel improved from 40% to 66% in Class 1, from 31% to 43% in Class 2, and from 12% to 30% in Class 3 between 2008 and 2010. Failures on other critical properties, such as acidity, pHe, water, and inorganic chloride were less than 6% in these studies. The 2010 Flex Fuel samples readily met the ethanol content specification, with 88%, 92%, and 95% compliance for Classes 1, 2, and 3, respectively.
2013-09-24
Journal Article
2013-01-2468
Jonathan Burton, Kevin Walkowicz, Petr Sindler, Adam Duran
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.
2013-09-24
Journal Article
2013-01-2471
Eric Wood, Lijuan Wang, Jeffrey Gonder, Michael Ulsh
Battery electric vehicles possess great potential for decreasing lifecycle costs in medium-duty applications, a market segment currently dominated by internal combustion technology. Characterized by frequent repetition of similar routes and daily return to a central depot, medium-duty vocations are well positioned to leverage the low operating costs of battery electric vehicles. Unfortunately, the range limitation of commercially available battery electric vehicles acts as a barrier to widespread adoption. This paper describes the National Renewable Energy Laboratory's collaboration with the U.S. Department of Energy and industry partners to analyze the use of small hydrogen fuel-cell stacks to extend the range of battery electric vehicles as a means of improving utility, and presumably, increasing market adoption.
2013-09-24
Journal Article
2013-01-2400
Adam Duran, Kevin Walkowicz
In an effort to characterize the dynamics typical of school bus operation, National Renewable Energy Laboratory (NREL) researchers set out to gather in-use duty cycle data from school bus fleets operating across the country. Employing a combination of Isaac Instruments GPS/CAN data loggers in conjunction with existing onboard telemetric systems resulted in the capture of operating information for more than 200 individual vehicles in three geographically unique domestic locations. In total, over 1,500 individual operational route shifts from Washington, New York, and Colorado were collected. Upon completing the collection of in-use field data using either NREL-installed data acquisition devices or existing onboard telemetry systems, large-scale duty-cycle statistical analyses were performed to examine underlying vehicle dynamics trends within the data and to explore vehicle operation variations between fleet locations.
2013-05-10
Article
Advanced insulation packages, solar reflective film, and other thermal-management technologies enable heavy vehicles to reduce idle climate control loads, as demonstrated by NREL's CoolCab project in collaboration with industry OEMs and suppliers.
2013-04-08
Technical Paper
2013-01-0381
Aaron David Brooker, Jacob Ward, Lijuan Wang
In 2011, the United States imported almost half of its petroleum. Lightweighting vehicles reduces that dependency directly by decreasing the engine, braking and rolling resistance losses, and indirectly by enabling a smaller, more efficiently operating engine to provide the same performance. The Future Automotive Systems Technology Simulator (FASTSim) tool was used to quantify these impacts. FASTSim is the U.S. Department of Energy's (DOE's) high-level vehicle powertrain model developed at the National Renewable Energy Laboratory. It steps through a time versus speed drive cycle to estimate the powertrain forces required to meet the cycle. It simulates the major vehicle powertrain components and their losses. It includes a cost model based on component sizing and fuel prices. FASTSim simulated different levels of lightweighting for four different powertrains.
2013-04-08
Technical Paper
2013-01-0500
Jeremy S. Neubauer, Ahmad Pesaran
Battery electric vehicles (BEVs) offer the potential to reduce both oil imports and greenhouse gas emissions, but high upfront costs, battery-limited vehicle range, and concern over high battery replacement costs may discourage potential buyers. A subscription model in which a service provider owns the battery and supplies access to battery swapping infrastructure could reduce upfront and battery replacement costs with a predictable monthly fee, while expanding BEV range. Assessing the costs and benefits of such a proposal are complicated by many factors, including customer drive patterns, the amount of required infrastructure, battery life, etc. The National Renewable Energy Laboratory has applied its Battery Ownership Model to compare the economics and utility of BEV battery swapping service plan options to more traditional direct ownership options.
2013-04-08
Technical Paper
2013-01-1038
Marc W. Melaina, Genevieve Saur
A simple cost analysis framework compares hydrogen and electricity as energy carriers delivering wind energy to light-duty vehicles (LDVs). We compare four wind energy pathways within a 2040-2050 timeframe and at large scale: a dedicated electricity transmission pathway and three distinct wind-hydrogen delivery pathways. Our results suggest that wind-hydrogen pathways will tend to be more costly than pure electricity transmission pathways on a per-mile driven cost basis ($/mile), but to a greater or lesser degree depending upon the pathway. The additional cost could be warranted to the degree that the hydrogen pathway adds value to consumers through full performance fuel cell electric vehicles (FCEV) compared to plug-in electric vehicles (PEVs), or through reduced variability in wind energy supply. If these benefits add value beyond the incremental costs suggested by our simple cost framework, some shift toward co-production or even dedicated hydrogen wind farms may be warranted.
2013-04-08
Technical Paper
2013-01-1453
Jeremy S. Neubauer, Eric Wood
Hybrid electric vehicles, plug-in hybrid electric vehicles, and battery electric vehicles offer the potential to reduce both oil imports and greenhouse gases, as well as to offer a financial benefit to the driver. However, assessing these potential benefits is complicated by several factors, including the driving habits of the operator. We focus on driver aggression, i.e., the level of acceleration and velocity characteristic of travel, to (1) assess its variation within large, real-world drive datasets, (2) quantify its effect on both vehicle efficiency and economics for multiple vehicle types, (3) compare these results to those of standard drive cycles commonly used in the industry, and (4) create a representative drive cycle for future analyses where standard drive cycles are lacking.
2013-04-08
Technical Paper
2013-01-0553
John Rugh, Larry Chaney, Laurie Ramroth, Travis Venson, Matthew Rose
The objective of the study was to assess the impact of a Saflex1 S Series solar control PVB (polyvinyl butyral) windshield on conventional vehicle fuel economy and electric vehicle (EV) range. The approach included outdoor vehicle thermal soak testing, RadTherm cooldown analysis, and vehicle simulations. Thermal soak tests were conducted at the National Renewable Energy Laboratory's Vehicle Testing and Integration Facility in Golden, Colorado. The test results quantified interior temperature reductions and were used to generate initial conditions for the RadTherm cooldown analysis. The RadTherm model determined the potential reduction in air-conditioning (A/C) capacity, which was used to calculate the A/C load for the vehicle simulations. The vehicle simulation tool identified the potential reduction in fuel consumption or improvement in EV range between a baseline and solar control PVB configurations for the city and highway drive cycles.
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