Method for In-Use Measurement and Evaluation of the Activity, Fuel Use, Electricity Use, and Emissions of a Plug-In Hybrid Diesel-Electric School Bus

Choi, Hyung-Wook; Frey, H. Christopher

doi:10.1021/es903330k

Cited by 18 publications

(14 citation statements)

References 22 publications

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“…The slopes of the parity plots for CO, CO 2 , and NO ranged from 0.92 to 1.05, indicating good accuracy (17). More information on PEMS precision, accuracy, and calibration are detailed elsewhere (9)(10)(11)(17)(18)(19).…”

Section: Portable Emissions Measurement Systemmentioning

confidence: 99%

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Comparison of Locomotive Emissions Measured during Dynamometer versus Rail Yard Engine Load Tests

Graver

Frey

2013

Transportation Research Record: Journal of the Transportation R

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For environmental emissions certification, locomotive prime mover engines undergo rigorous measurements with the use of federal reference methods (FRMs). However, there are nonregulatory reasons for engine emissions measurement, such as to compare relative differences in fuel use and emissions as a result of engine rebuild or between engines in a fleet. Portable emissions measurement systems (PEMSs) are widely used for highway vehicle and nonroad construction equipment but have had limited locomotive applications. The objectives are to (a) demonstrate an approach for quantifying locomotive emission rates with a PEMS during dynamometer and rail yard engine load tests, (b) compare the emissions measured in dynamometer versus rail yard load tests, and (c) assess the relative change in fuel use and emissions from engine rebuild. Measurements were conducted on 3,000-hp prime movers, including an EMD 16-645 for a GP40 and two EMD 12-710s for F59PHs. Fuel use and PEMS-based emission rates for nitric oxide, carbon monoxide, hydrocarbons, and particulate matter were compared between dynamometer and rail yard load tests and with data from previous literature. Fuel use and oxides of nitrogen (NOx) emission rates after engine rebuild were lower for the GP40 prime mover, and the fuel use and NOx emission rates for the F59PH rebuilt engines were lower than those of the rebuilt GP40 engine. PEMS is not a substitute for locomotive FRMs if compliance certification is needed but provides useful data for comparative assessment.

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Section: Portable Emissions Measurement Systemmentioning

confidence: 99%

“…Additional details on data processing and quality assurance procedures are given elsewhere (9)(10)(11)19).…”

Section: Data Collectionmentioning

confidence: 99%

Comparison of Locomotive Emissions Measured during Dynamometer versus Rail Yard Engine Load Tests

Graver

Frey

2013

Transportation Research Record: Journal of the Transportation R

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“…Choi and Frey et al [5] conducted a study which compared energy use for a plug-in parallel-hybrid dieselelectric school bus (PHSB) to a conventional school bus using five real-world driving cycles. They found that the direct diesel fuel economy was 3.2% to 9.5% better for the PHSB compared to the conventional bus.…”

Section: Performance Of Hybrid School Busesmentioning

confidence: 99%

Comparison of In-Use Operating Costs of Hybrid-Electric and Conventional School Buses

Hallmark¹,

Sperry²

2012

JTTs

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Hybrid-electric school buses became available in the US through a national consortium designed to bring hybrid-electric school buses to market by creating enough demand among school districts to encourage manufacturers to invest in development of the technology. A number of school districts in the US joined the HESB project to purchase plug-in hybrid-electric school buses. Sixteen hybrid-electric school buses were purchased and piloted in 11 states. Two of the hybrid-electric school buses were purchased by the Nevada and Sigourney school districts in the state of Iowa, US. In-use fuel economy and electricity operating costs were monitored for the two Iowa hybrid school buses and two control buses (one in each district). Fuel consumption and other operational metrics were calculated and compared for each school district. The hybrid buses were deployed in January 2008 and data were recorded through May 2010. Valuation of the data indicated that the Nevada HESB had 29.6% better fuel economy than the control bus and the Sigourney HESB had 39.2% better fuel economy than the control bus. Electrical costs per mile were also calculated for the two hybrid-electric school buses. Total operating costs per mile were calculated based on fuel use per mile for all buses and electrical costs for the hybrid-electric school buses. The cost to operate the hybrid bus in Nevada was 37 cents/mile while the control bus cost 42 cents/mile, making the hybrid bus 13% less expensive to operate. The hybrid bus in Sigourney was 27 cents/mile while the control bus was 34 cents/mile, making the hybrid bus 21% less expensive to operate. All values are in US dollars

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“…However, the hybrid had higher emission rates on two routes with steep uphill grades, and PN emissions were 51% higher on one route and 24% higher on the other. Choi and Frey (2010) evaluated emissions for a plug-in hybrid (PHSB) and conventional school bus (CDSB) using a portable emissions monitor. Results were presented by type of route.…”

Section: Introductionmentioning

confidence: 99%

Comparison of on-road emissions for hybrid and regular transit buses

Hallmark

Wang

Sperry

2013

Journal of the Air & Waste Management Association

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Hybrid technology offers an attractive option for transit buses, since it has the potential to significantly reduce operating costs for transit agencies. The main impetus behind use of hybrid transit vehicles is fuel savings and reduced emissions. Laboratory tests have indicated that hybrid transit buses can have significantly lower emissions compared with conventional transit buses. However, the number of studies is limited and laboratory tests may not represent actual driving conditions, since in-use vehicle operation differs from laboratory test cycles. This paper describes an on-road evaluation of in-use emission differences between hybrid-electric and conventional transit buses for the Ames, Iowa transit authority, CyRide. Emissions were collected on-road using a portable emissions monitoring system (PEMS) for three hybrid and two control buses. Emissions were collected for at least one operating bus day. Each bus was evaluated over the same route pattern, which utilizes the same driver. The number of passengers embarking or disembarking at each stop was collected by an on-board data collector so that passenger load could be included. Vehicle emissions are correlated to engine load demand, which is a function of factors such as vehicle load, speed, and acceleration. PEMS data are provided second by second and vehicle-specific power (VSP) was calculated for each row of data. Instantaneous data were stratified into the defined VSP bins and then average modal emission rates and standard errors were calculated for each bus for each pollutant. Pollutants were then compared by bus type. Carbon dioxide, carbon monoxide, and hydrocarbon emissions were higher for the regular buses across most VSP bins than for the hybrid buses. Nitrogen oxide emissions were unexpectedly higher for the hybrid buses than for the control buses.Implications: The main reason agencies consider hybrid transit vehicles is fuel savings and reduced emissions. Hybrid electric buses offer an attractive option and have the potential to significantly reduce operating costs and emissions for transit agencies. However, purchase of hybrid buses cost 50-70% more than regular buses. As a result, agencies require more quantitative information about the on-road costs and benefits of hybrid buses. This study assessed on-road emissions for in-use transit buses. The resulting information can be used by transit agencies in assessing the likely emission reduction benefits for hybrid buses.

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Method for In-Use Measurement and Evaluation of the Activity, Fuel Use, Electricity Use, and Emissions of a Plug-In Hybrid Diesel-Electric School Bus

Cited by 18 publications

References 22 publications

Comparison of Locomotive Emissions Measured during Dynamometer versus Rail Yard Engine Load Tests

Comparison of Locomotive Emissions Measured during Dynamometer versus Rail Yard Engine Load Tests

Comparison of In-Use Operating Costs of Hybrid-Electric and Conventional School Buses

Comparison of on-road emissions for hybrid and regular transit buses

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