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Which is Greener: Idle, or Stop and Restart? Comparing Fuel Use and Emissions for Short Passenger-Car Stops (PDF)
2/11/2013
The argument against parking and going into a business, rather than using a drive-through window, has been that the emissions and fuel use associated with restarting your car are greater than those incurred by idling for that time. Argonne National Laboratory undertook a series of measurements to determine whether this was true, by comparing actual idling fuel use and emissions with those for restarting. This work seeks to answer the question: Considering both fuel use and emissions, how long can you idle in a queue before impacts from idling are greater than they are for restarting? Fuel use and carbon dioxide emissions are always greater for idling over 10 seconds; the crossover times are found to vary by pollutant.
Authors: Gaines, L., Rask, E., Keller, G.
Transportation Energy Futures Series: Potential for Energy Efficiency Improvement Beyond the Light-Duty-Vehicle Sector (PDF)
2/1/2013
Considerable research has focused on energy efficiency and fuel substitution options for light-duty vehicles, while much less attention has been given to medium- and heavy-duty trucks, buses, aircraft, marine vessels, trains, pipeline, and off-road equipment. This report brings together the salient findings from an extensive review of literature on future energy efficiency options for these non-light-duty modes. Projected activity increases to 2050 are combined with forecasts of overall fuel efficiency improvement potential to estimate the future total petroleum and greenhouse gas (GHG) emissions relative to current levels. This is one of a series of reports produced as a result of the Transportation Energy Futures (TEF) project, a Department of Energy-sponsored multi-agency project initiated to pinpoint underexplored strategies for abating GHGs and reducing petroleum dependence related to transportation.
Authors: Vyas, A. D.; Patel, D. M.; Bertram, K. M.
Clean Cities 2011 Annual Metrics Report (PDF)
12/1/2012
This annual report details the petroleum savings and vehicle emissions reductions achieved by the U.S. Department of Energy's Clean Cities program in 2011. The report also details other performance metrics, including the number of stakeholders in Clean Cities coalitions, outreach activities by coalitions and national laboratories, and alternative fuel vehicles deployed.
Authors: Johnson, C.
Clean Cities 2010 Annual Metrics Report (PDF)
10/1/2012
Each year, the U.S. Department of Energy (DOE) asks Clean Cities coordinators to submit an annual report of their activities and accomplishments for the previous calendar year. Data and information are submitted to an online database that is maintained as part of the Alternative Fuels and Advanced Vehicles Data Center (AFDC) at the National Renewable Energy Laboratory (NREL). Coordinators submit a range of data that characterizes the membership, funding, projects, and activities of their coalitions. They also submit data about sales of alternative fuels, deployment of alternative fuel vehicles (AFVs) and hybrid electric vehicles (HEVs), idle reduction initiatives, fuel economy activities, and programs to reduce vehicle miles traveled (VMT). NREL analyzes the data and translates them into gasoline use reduction impacts, which are summarized in this report.
Authors: Johnson, C.
Eighteen-Month Final Evaluation of UPS Second Generation Diesel Hybrid-Electric Delivery Vans (PDF)
9/1/2012
A parallel hybrid-electric diesel delivery van propulsion system was evaluated at a UPS facility in Minneapolis using on-vehicle data logging, fueling, and maintenance records. Route and drive cycle analysis showed different duty cycles for hybrid vs. conventional delivery vans; routes were switched between the study groups to provide a valid comparison. The hybrids demonstrated greater advantage on the more urban routes; the initial conventional vans' routes had less dense delivery zones. The fuel economy of the hybrids on the original conventional group's routes was 10.4 mpg vs. 9.2 mpg for the conventional group on those routes a year earlier. The hybrid group's fuel economy on the original hybrid route assignments was 9.4 mpg vs. 7.9 mpg for the conventional group on those routes a year later. There was no statistically significant difference in total maintenance cost per mile or for the vehicle total cost of operation per mile. Propulsion-related maintenance cost per mile was 77% higher for the hybrids, but only 52% more on a cost-per-delivery-day basis. Laboratory dynamometer testing demonstrated 13%-36% hybrid fuel economy improvement, depending on duty cycle, and up to a 45% improvement in ton-mi/gal. NOx emissions increased 21%-49% for the hybrids in laboratory testing.
Authors: Lammert, M. and Walkowiczm K.
Plug-In Electric Vehicle Deployment in the Northeast; A Market Overview and Literature Review (PDF)
9/1/2012
Electric vehicles have the potential to decrease our nation's dependence on oil and drastically reduce greenhouse gas emissions from the transportation sector. In an effort to stimulate economic growth, decrease the United States' dependence on oil, and lessen the operating cost of personal transportation, the federal government issued a final rule in 2012 requiring new cars to average 54.5 miles per gallon by 2025. This goal is ambitious and will be difficult to accomplish without significant numbers of alternative fuel vehicles. Several alternative fuels are currently available, but electric vehicles (EVs) are emerging as the predominant alternative for passenger vehicles. While EVs are hitting the market and offer numerous advantages, such as zero tailpipe emissions, lower fuel costs, and the convenience of filling up at home, a number of barriers stand in the way of wide-scale EV deployment.
This literature review, prepared by the Center for Climate and Energy Solutions, provides an overview of plug-in electric vehicle (PEV) deployment in the Northeast and Mid-Atlantic states. The report assesses current electric vehicle and electric vehicle charging station technology, looks at the state of PEV markets, reviews the benefits of PEV deployment, and identifies the barriers and challenges to PEVs in gaining market acceptance. The literature review is intended to serve as a resource for consumers and policy makers who seek to better understand the nature of electric vehicle deployment in this region and related challenges.
Authors: Zhu, C.; Nigro, N.
EPA Announces Final Rulemaking for Clean Alternative Fuel Vehicle and Engine Conversions
8/1/2012
The U.S. Environmental Protection Agency (EPA) is adopting changes to the regulations found in 40 CFR part 85 subpart F for clean alternative fuel conversion manufacturers. This action affects regulations applicable to manufacturers of light-duty vehicle and heavy-duty highway vehicle and engine clean alternative fuel conversion systems. The revisions will streamline the compliance process while maintaining environmentally protective controls.
Experiences with Compressed Natural Gas in Colorado Vehicle Fleets; Case Study Analysis (PDF)
8/1/2012
This series of case studies is the product of in-person and telephone interviews with three Colorado fleet managers who use compressed natural gas (CNG) as a vehicle fuel and interviews with other CNG stakeholders. The fleets were selected using criteria that are intended to increase the usefulness of the overall product, including geographic diversity, length of CNG experience, diversity of vehicles, and ownership model. The case studies are based on a framework constructed with broad stakeholder input, designed to provide detailed information on fleet manager experiences with CNG vehicles and fueling infrastructure.
Featured fleets include the following: Republic Services (Republic), a private sector waste and environmental management firm with a CNG fleet based in the Denver metro area; Denver International Airport (DIA), an airport with more than 15 years of experience with CNG and proven success as a CNG hub; and City of Grand Junction, a Western Slope municipality with a public/private partnership to provide public CNG fueling.
Coca-Cola Refreshments Class 8 Diesel Electric Hybrid Tractor Evaluation: 13-Month Final Report. (PDF)
8/1/2012
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.
Authors: Walkowicz, K.; Lammert, M.; Curran, P.
Examining the Impacts of Methane Leakage on Life-Cycle Greenhouse Gas Emissions of Shale and Conventional Natural Gas (PDF)
6/1/2012
The development of large-scale shale gas production has been described as a game-changer for the U.S. energy market and has generated interest in expanding the usage of natural gas (NG) in sectors such as electricity generation and transportation. This development has been made possible by improvements in drilling technologies, specifically utilizing hydraulic fracturing in conjunction with horizontal drilling. However, the environmental implications of NG production and its use have been called into question. One of the major concerns is the amount methane (CH4) leakage from production activities and its impact on the life-cycle greenhouse gas (GHG) emissions of NG.
Authors: Burnham, A.; Clark, C.
Notes: This article appears in the June 2012 issue of EM Magazine, a publication of the Air & Waste Management Association (A&WMA; www.awma.org). To obtain copies and reprints, please contact A&WMA directly at 1-412-232-3444.
Annual Energy Outlook 2012; with Projections to 2035 (PDF)
6/1/2012
The projections in the U.S. Energy Information Administration's (EIA's) Annual Energy Outlook 2012 (AEO2012) focus on the factors that shape the U.S. energy system over the long term. Under the assumption that current laws and regulations remain unchanged throughout the projections, the AEO2012 Reference case provides the basis for examination and discussion of energy production, consumption, technology, and market trends and the direction they may take in the future. It also serves as a starting point for analysis of potential changes in energy policies. But AEO2012 is not limited to the Reference case. It also includes 29 alternative cases (see Appendix E, Table E1), which explore important areas of uncertainty for markets, technologies, and policies in the U.S. energy economy. Many of the implications of the alternative cases are discussed in the "Issues in focus" section of this report.
Key results highlighted in AEO2012 include continued modest growth in demand for energy over the next 25 years and increased domestic crude oil and natural gas production, largely driven by rising production from tight oil and shale resources. As a result, U.S. reliance on imported oil is reduced; domestic production of natural gas exceeds consumption, allowing for net exports; a growing share of U.S. electric power generation is met with natural gas and renewables; and energy-related carbon dioxide emissions remain below their 2005 level from 2010 to 2035, even in the absence of new Federal policies designed to mitigate greenhouse gas (GHG) emissions.
Renewable Fuels and Lubricants (ReFUEL) Laboratory (PDF)
3/1/2012
This fact sheet describes the Renewable Fuels and Lubricants (ReFUEL) Laboratory at the U.S. Department of Energy National Renewable Energy Laboratory (NREL) is a state-of-the-art research and testing facility for advanced fuels and vehicles. Research and development aims to improve vehicle efficiency and overcome barriers to the increased use of renewable diesel and other nonpetroleum-based fuels, such as biodiesel and synthetic diesel derived from biomass. The ReFUEL Laboratory features a chassis dynamometer for vehicle performance and emissions research, two engine dynamometer test cells for advanced fuels research, and precise emissions analysis equipment. As a complement to these capabilities, detailed studies of fuel properties, with a focus on ignition quality, are performed at NREL's Fuel Chemistry Laboratory.
Life-Cycle Analysis of Shale Gas and Natural Gas (PDF)
12/1/2011
The technologies and practices that have enabled the recent boom in shale gas production have also brought attention to the environmental impacts of its use. Using the current state of knowledge of the recovery, processing, and distribution of shale gas and conventional natural gas, we have estimated up-to-date, life-cycle greenhouse gas emissions. In addition, we have developed distribution functions for key parameters in each pathway to examine uncertainty and identify data gaps - such as methane emissions from shale gas well completions and conventional natural gas liquid unloadings - that need to be addressed further. Our base case results show that shale gas life-cycle emissions are 6% lower than those of conventional natural gas. However, the range in values for shale and conventional gas overlap, so there is a statistical uncertainty regarding whether shale gas emissions are indeed lower than conventional gas emissions. This life-cycle analysis provides insight into the critical stages in the natural gas industry where emissions occur and where opportunities exist to reduce the greenhouse gas footprint of natural gas.
Authors: Clark, C.E.; Han, J.; Burnham, A.; Dunn, J.B.; Wang, M.
