Predictive Models of Li-ion Battery Lifetime
9/12/2014
Predictive models of Li-ion battery reliability must consider a multiplicity of electrochemical, thermal and mechanical degradation modes experienced by batteries in application environments. Complicating matters, Li-ion batteries can experience several path dependent degradation trajectories dependent on storage and cycling history of the application environment. Rates of degradation are controlled by factors such as temperature history, electrochemical operating window, and charge/discharge rate. Lacking accurate models and tests, lifetime uncertainty must be absorbed by overdesign and warranty costs. Degradation models are needed that predict lifetime more accurately and with less test data. Models should also provide engineering feedback for next generation battery designs. This presentation reviews both multi-dimensional physical models and simpler, lumped surrogate models of battery electrochemical and mechanical degradation. Models are compared with cell- and pack-level aging data from commercial Li-ion chemistries. The analysis elucidates the relative importance of electrochemical and mechanical stress-induced degradation mechanisms in real-world operating environments. Opportunities for extending the lifetime of commercial battery systems are explored.
Authors: Smith,K.; Wood, E.; Santhanagopalan, S. Kim, G.; Shi, Y.; Pesaran, A.
Costs Associated with Compressed Natural Gas Vehicle Fueling Infrastructure
9/9/2014
This document is designed to help fleets understand the cost factors associated with fueling infrastructure for compressed natural gas (CNG) vehicles. It provides estimated cost ranges for various sizes and types of CNG fueling stations and an overview of factors that contribute to the total cost of an installed station. The information presented is based on input from professionals in the natural gas industry who design, sell equipment for, and/or own and operate CNG stations.
Authors: Smith, M.; Gonzales, J.
Transitioning the Transportation Sector: Exploring the Intersection of Hydrogen Fuel Cell and Natural Gas Vehicles
9/9/2014
On September 9, 2014, Sandia National Laboratories, American Gas Association, and Toyota, in support of the U.S. Department of Energy's Fuel Cell Technologies and Vehicle Technologies Offices, convened stakeholders across the hydrogen and natural gas communities to consider opportunities and challenges at the intersection of their development as alternative transportation fuels. Although natural gas and hydrogen have an obvious intersection - natural gas is the feedstock for 95% of the hydrogen produced in the U.S. - little attention has been given to how these fuels can evolve in the context of each other. This workshop explored infrastructure requirements, regional trends, and market opportunities at the intersection of hydrogen fuel cell and natural gas use for on road transportation. The goal of the workshop was to provide background and context for thinking through the dynamic evolution of these two transportation options in tandem, and to identify opportunities that can support the synergistic development of both fuels.
Hydrogen and Fuel Cell Technologies Office: Hydrogen Production
9/1/2014
This 2-page fact sheet provides a brief introduction to hydrogen production technologies. Intended for a non-technical audience, it explains how different resources and processes can be used to produce hydrogen. It includes an overview of research goals as well as "quick facts" about hydrogen energy resources and production technologies.
Distributed Solar Photovoltaics for Electric Vehicle Charging: Regulatory and Policy Considerations
9/1/2014
Increasing demand for EV charging provides an opportunity for market expansion of distributed solar technology. A major barrier to the current deployment of solar technology for EV charging is a lack of clear information for policymakers, utilities, and potential adopters. This paper introduces regulatory and policy options available to policymakers and regulators wanting to incentivize solar EV charging. Additionally, it summarizes considerations regarding EV charging during the day versus at night and benefits and grid implications of combining solar and EV charging technologies.
Authors: McLaren, J.
BC Transit Fuel Cell Bus Project Evaluation Results: Second Report
9/1/2014
This is the second report evaluating a fuel cell electric bus (FCEB) demonstration led by British Columbia Transit (BC Transit) in Whistler, Canada. The FCEB fleet was introduced during the 2010 Winter Olympic Games and operated through March 2014. BC Transit collaborated with the California Air Resources Board and the U.S. Department of Energy's National Renewable Energy Laboratory to evaluate the buses in revenue service. NREL published its first report on the demonstration in February 2014. This report is an update to the previous report; it covers 3 full years of revenue service data on the buses from April 2011 through March 2014 and focuses on the final experiences and lessons learned.
Authors: Eudy, L.; Post, M.
Reliable Temperature Compensation is Critical to CNG Vehicle Safety
8/18/2014
This Technical Bulletin addresses the potential hazards created by failure of compressed natural gas (CNG) dispensers that do not accurately compensate for the temperature of the natural gas in vehicle storage containers as they are filled and the history of serious incidents as a result. Fueling requirements are included.
Costs Associated with Propane Vehicle Fueling Infrastructure
8/5/2014
This document is designed to help fleets understand the cost factors associated with propane vehicle fueling infrastructure. It provides an overview of the equipment and processes necessary to develop a propane fueling station and offers estimated cost ranges.
Authors: Smith, M.; Gonzales, J.
Biogas Opportunities Roadmap
8/1/2014
Biogas is a proven source of energy used in the United States and around the world for decades. As such, biogas systems can and should be an integral part of America's energy strategy moving forward. The Biogas Opportunities Roadmap builds on progress made to date to identify voluntary actions that can be taken to reduce methane emissions through the use of biogas systems and outlines strategies to overcome barriers limiting further expansion and development of a robust biogas industry in the United States.
Clean Cities Alternative Fuel Price Report, July 2014
7/31/2014
The Clean Cities Alternative Fuel Price Report for July 2014 is a quarterly report on the prices of alternative fuels in the U.S. and their relation to gasoline and diesel prices. This issue describes prices that were gathered from Clean Cities coordinators and stakeholders between July 1, 2014 and July 15, 2014, and then averaged in order to determine regional price trends by fuel and variability in fuel price within regions and among regions. The prices collected for this report represent retail, at-the-pump sales prices for each fuel, including Federal and state motor fuel taxes.
Table 1 reports that the nationwide average price (all amounts are per gallon) for regular gasoline has increased 5 cents from $3.65 to $3.70; diesel decreased 6 cents from $3.97 to $3.91; CNG price increased 2 cents from $2.15 to $2.17; ethanol (E85) decreased 18 cents from $3.41 to $3.23; propane decreased 24 cents from $3.31 to $3.07; and biodiesel (B20) has decreased 3 cents from $4.01 to 3.98.
According to Table 2, CNG is $1.53 less than gasoline on an energy-equivalent basis, while E85 is $0.86 more than gasoline on an energy-equivalent basis.
Authors: Bourbon, E.
Planning and Installation Guide: North Carolina Compressed Natural Gas Fueling Stations
7/25/2014
This is a guide to planning and installing a compressed natural gas (CNG) fueling station for fleets. It includes contact information for resources in North Carolina and a checklist of important items to consider when planning for a CNG station. This Guide is part of the North Carolina State University Clean Energy Technology Center's Alternative Fuel Implementation Toolkit, an on-line resource for fleet vehicle and fuel purchasers, program managers, and organization leaders who are interested in using alternative fuel vehicles.