Publications

Zero-Emission Bus Evaluation Results: County Connection Battery Electric Buses

12/10/2018

The U.S. Department of Transportation's (DOT's) Federal Transit Administration (FTA) supports the research, development, and demonstration of low- and zero-emission technology for transit buses. FTA funds research projects with a goal of facilitating commercialization of advanced technologies for transit buses that will increase efficiency and improve transit operations. DOT's Research, Development, and Technology Office (OST-R) also has an interest in zero-emission bus (ZEB) technology deployment and commercialization. OST-R is coordinating and collaborating with FTA on the evaluation process and results by providing funding to cover additional evaluations. FTA and OST-R are collaborating with the U.S. Department of Energy (DOE) and DOE's National Renewable Energy Laboratory (NREL) to conduct in-service evaluations of advanced technology buses developed under its programs. NREL uses a standard evaluation protocol for evaluating the advanced technologies deployed under the FTA programs. FTA seeks to provide results from new technologies being adopted by transit agencies. The eight evaluations selected to date include battery electric buses (BEBs) and fuel cell electric buses (FCEBs) from different manufacturers operating in fleets located in both cold and hot climates. The purpose of this report is to present the results from Central Contra Costa Transit Authority (County Connection) deployment of four BEBs in Concord, California. NREL's evaluation of the BEBs at County Connection was funded by OST-R.

Authors: Eudy, L.; Jeffers, M.

The Plug-In Electric Vehicle Tax Credit

11/7/2018

Buyers of qualifying plug-in electric vehicles (PEVs) may be able to claim a federal income tax credit of up to $7,500. This fact sheet provides an overview of the PEV tax credit and briefly discusses relevant economic policy considerations.

Authors: Sherlock, M.F.

Clean Cities Coalitions 2016 Activity Report

10/10/2018

The U.S. Department of Energy's (DOE's) national network of Clean Cities Coalitions advance the nation's economic, environmental, and energy security by supporting local actions to promote the use of domestic fuels within transportation. The nearly 100 Clean Cities coalitions, whose territory covers 80% of the U.S. population, bring together stakeholders in the public and private sectors to use alternative and renewable fuels, idle-reduction (IR) measures, fuel economy improvements, and new transportation technologies as they emerge. To ensure success, coalitions leverage a robust set of expert resources and tools provided by national laboratories and DOE. Each year, Clean Cities coordinators submit annual reports of their activities and accomplishments for the previous calendar year. Data and information are submitted via an online tool that is maintained as part of the Alternative Fuels Data Center (AFDC) at the National Renewable Energy Laboratory (NREL). Coordinators submit a range of data that characterize the membership, funding, projects, and activities of their coalitions. They also submit data about sales of alternative fuels; use of alternative fuel vehicles (AFVs), plug-in electric vehicles (PEVs), and hybrid electric vehicles (HEVs); IR initiatives; fuel economy improvement activities; and programs to reduce vehicle miles traveled (VMT). NREL analyzes the submitted data to determine how broadly energy use in the U.S. has shifted due to coalition activities, which are summarized in this report.

Authors: Johnson, C.; Singer, M.

Foothill Transit Agency Battery Electric Bus Progress Report, Data Period Focus: Jan. 2018 through Jun. 2018

10/8/2018

This report summarizes results of a battery electric bus (BEB) evaluation at Foothill Transit, located in the San Gabriel Valley area of Los Angeles. Foothill Transit is collaborating with the California Air Resources Board and the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) to evaluate the buses in revenue service. The focus of this evaluation is to compare the performance and the operating costs of the BEBs to that of conventional technology buses and to track progress over time. Previous reports documented results from April 2014 through December 2017. This report extends the data analysis through June 2018. NREL plans to publish progress reports on the Foothill Transit fleet every six months through 2020. performance and the operating costs of the BEBs to that of conventional technology buses and to track progress over time. Previous reports documented results from April 2014 through December 2017. This report extends the data analysis through June 2018. NREL plans to publish progress reports on the Foothill Transit fleet every six months through 2020.

Authors: Eudy, L.; Jeffers, M.

Value to the Grid from Managed Charging Based on California's High Renewables Study

10/1/2018

Managed charging of plug-in electric vehicle (PEV) loads has the potential to use renewable energy more effectively, shave peak demand, and fill demand valleys while serving transportation needs. However, to date the potential value to the grid from managed charging has not been fully quantified. This paper quantifies value to the grid from managed charging by using three levels of managed loads for 13 terawatt-hours of annual load from three million PEVs in a 2030 California grid scenario.

Authors: Zhang, J.; Jorgenson, J.; Markel. T.; Walkowicz, K.

Notes: This IEEE Transactions on Power Systems article (Vol. 34, Issue 2, (March 2019): pp. 831-840) is copyrighted by IEEE and can be accessed through IEEE Xplore.

Transitioning to zero-emission heavy-duty freight vehicles

9/26/2018

This report compares the evolution of heavy-duty diesel, diesel hybrid, natural gas, fuel cell, and battery electric technologies in the 2025-2030 timeframe. It synthesizes data from the research literature, demonstrations, and low-volume commercial trucks regarding their potential to deliver freight with zero tailpipe emissions. Additionally, it analyzes the emerging technologies by their cost of ownership and life-cycle greenhouse gas emissions for the three vehicle markets of China, Europe, and the United States.

Authors: Moultak, M.; Lutsey, N.; Hall, D.

Notes:

This copyrighted publication can be accessed on The International Council on Clean Transportation's website.

Policies that Impact the Acceleration of Electric Vehicle Adoption

9/26/2018

To better understand the influence of policy initiatives that relate to electric vehicles (EVs) have on accelerated deployment, this project focused on a number of successful public and private initiatives and policies designed to encourage the adoption of EVs and related infrastructure. This report highlights programs that have influenced adoption, provides a critique of best practices, and includes references to databases EV policy initiatives.

Authors: Kettles, C.

The Zero Emission Vehicle Regulation

8/24/2018

This fact sheet provides an overview of California’s zero-emission vehicle (ZEV) regulation, which is designed to achieve the state’s long-term emission reduction goals by requiring manufacturers to offer for sale specific numbers of the very cleanest cars available. The ZEV regulation has been adopted by other states.

Electrification Futures Study: Scenarios of Electric Technology Adoption and Power Consumption for the United States

8/8/2018

This report is the second publication in a series of Electrification Futures Study publications. The report presents scenarios of electric end-use technology adoption and resulting electricity consumption in the United States. The scenarios reflect a wide range of electricity demand growth through 2050 that result from various electric technology adoption and efficiency projections in the transportation, residential and commercial buildings, and industrial sectors.

Authors: Mai, T.; Jadun, P.; Logan, J.; McMillan, C.; Muratori, M.; Steinberg, D.; Vimmerstedt, L.; Jones, R.; Haley, B.; Nelson, B.

Model Year 2018: Alternative Fuel and Advanced Technology Vehicles

8/7/2018

The fact sheet details the model, vehicle type, emission class, transmission type/speeds, engine size, and fuel economy of a variety of flexible fuel vehicles, hybrid electric vehicles, all-electric, and extended range electric vehicles, as well as CNG and propane vehicles.

Workplace Charge Management with Aggregated Building Loads

8/1/2018

This paper was presented at the 2018 IEEE Transportation Electrification Conference and Expo (ITEC), 13-15 June 2018, Long Beach, California. It describes a workplace charge management system developed to control plug-in electric vehicle charging stations based on aggregated building loads. A system to collect information from drivers was also developed for better charge management performance since the present AC charging station standard does not provide battery state of charge information. First, simulations with uncontrolled charging data were conducted to investigate several scenarios and control methods, and then one method with the most power curtailment during peak load was selected for verification tests. This paper illustrates load reduction test results for 36 charging stations and real-time campus net load data.

Authors: Jun, M.; Meintz, A.

Notes:

This copyrighted publication can be viewed and purchased on the Institute of Electrical and Electronics Engineers's website.

Future Automotive Systems Technology Simulator (FASTSim) Validation Report

7/27/2018

The National Renewable Energy Laboratory's Future Automotive Systems Technology Simulator (FASTSim) captures the most important factors influencing vehicle power demands and performs large-scale fuel efficiency calculations very quickly. These features make FASTSim well suited to evaluate a representative distribution of real-world fuel efficiency over a large quantity of in-use driving profiles, which have become increasingly available in recent years owing to incorporation of global positioning system data collection into various travel surveys and studies. In addition, by being open source, computationally lightweight, freely available, and free from expensive third-party software requirements, analyses conducted using FASTSim may be easily replicated and critiqued in an open forum. This is highly desirable for situations in which technical experts seek to reach consensus over questions about what vehicle development plans or public interest strategies could maximize fuel savings and minimize adverse environmental impacts with an evolving vehicle fleet. While FASTSim continues to be refined and improved on an on-going basis, this report compiles available runs using versions of the tool from the past few years to provide illustrative comparison of the model results against measured data.

Authors: Gonder, J.; Brooker, A.; Wood, E.; Moniot, M.

The Role of Demand-Side Incentives and Charging Infrastructure on Plug-in Electric Vehicle Adoption: Analysis of US States. Paper No. 074032

7/13/2018

In the U.S., over 400 state and local incentives have been issued to increase the adoption of plug-in electric vehicles (PEVs) since 2008. This article quantifies the influence of key incentives and enabling factors like charging infrastructure and receptive demographics on PEV adoption. The study focuses on three central questions. First, do consumers respond to certain types of state level vehicle purchase incentives? Second, does the density of public charging infrastructure increase PEV purchases? Finally, does the impact of various factors differ for plug-in hybrid electric vehicles (PHEV), battery electric vehicles (BEV) and vehicle attributes within each category? Based on a regression of vehicle purchase data from 2008 to 2016, we found that tax incentives and charging infrastructure significantly influence per capita PEV purchases. Within tax incentives, rebates are generally more effective than tax credits. BEV purchases are more affected by tax incentives than PHEVs. The correlation of public charging and vehicle purchases increases with the battery-only driving range of a PHEV, while decreasing with increasing driving range of BEVs. Results indicate that early investments in charging infrastructure, particularly along highways; tax incentives targeting BEVs at the lower end of the price premium and PHEVs with higher battery only driving range, and better reflection of the environmental cost of owning gasoline vehicles are likely to increase PEV adoption in the U.S.

Authors: Narassimhan, E.; Johnson, C.

Notes:

This journal article (Environmental Research Letters, Volume 13, Number 7) is copyrighted by IOP Publishing and can be downloaded from the IOPScience website.

Total Thermal Management of Battery Electric Vehicles (BEVs). SAE Paper No. 2018-37-0026

5/30/2018

The key hurdles to achieving wide consumer acceptance of battery electric vehicles (BEVs) are weather-dependent drive range, higher cost, and limited battery life. These translate into a strong need to reduce a significant energy drain and resulting drive range loss due to auxiliary electrical loads the predominant of which is the cabin thermal management load. Studies have shown that thermal subsystem loads can reduce the drive range by as much as 45% under ambient temperatures below -10 degrees C. Often, cabin heating relies purely on positive temperature coefficient (PTC) resistive heating, contributing to a significant range loss. Reducing this range loss may improve consumer acceptance of BEVs. The authors present a unified thermal management system (UTEMPRA) that satisfies diverse thermal and design needs of the auxiliary loads in BEVs. Demonstrated on a 2015 Fiat 500e BEV, this system integrates a semi-hermetic refrigeration loop with a coolant network and serves three functions: (1) heating and/or cooling vehicle traction components (battery, power electronics, and motor) (2) heating and cooling of the cabin, and (3) waste energy harvesting and re-use. The modes of operation allow a heat pump and air conditioning system to function without reversing the refrigeration cycle to improve thermal efficiency. The refrigeration loop consists of an electric compressor, a thermal expansion valve, a coolant-cooled condenser, and a chiller, the latter two exchanging heat with hot and cold coolant streams that may be directed to various components of the thermal system. The coolant-based heat distribution is adaptable and saves significant amounts of refrigerant per vehicle. Also, a coolant-based system reduces refrigerant emissions by requiring fewer refrigerant pipe joints. The authors present bench-level test data and simulation analysis and describe a preliminary control scheme for this system.

Authors: Chowdhury, S.; Leitzel, L.; Zima, M.; Santacesaria, M.; Titov, G.; Lustbader, J.; Rugh, J.; Winkler, J.; Khawaja, A.; Govindarajalu, M.

Foothill Transit Agency Battery Electric Bus Progress Report, Data Period Focus: Jan. 2017 through Dec. 2017

5/16/2018

This report summarizes results of a battery electric bus (BEB) evaluation at Foothill Transit, located in the San Gabriel Valley area of Los Angeles. Foothill Transit is collaborating with the California Air Resources Board and the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) to evaluate the buses in revenue service. The focus of this evaluation is to compare the performance and the operating costs of the BEBs to that of conventional technology buses and to track progress over time. Previous reports documented results from April 2014 through December 2016. This report extends the data analysis through December 2017. NREL plans to publish progress reports on the Foothill Transit fleet every six months through 2020.

Authors: Eudy, L.; Jeffers, M.