@article{frey_kuo_villa_2009, title={Effects of Idle Reduction Technologies on Real World Fuel Use and Exhaust Emissions of Idling Long-Haul Trucks}, volume={43}, ISSN={["1520-5851"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-69549124649&partnerID=MN8TOARS}, DOI={10.1021/es900186e}, abstractNote={Idling long-haul freight tucks may consume nearly one billion gallons of diesel fuel per year in the U.S. There is a need for real-world data by which to quantify avoided fuel use and emissions attributable to idle reduction techniques of auxiliary power units (APUs) and shore-power (SP). Field data were obtained from 20 APU-equipped and SP-compatible trucks observed during 2.8 million miles of travel in 42 states. Base engine fuel use and emission rates varied depending on ambient temperature. APU and SP energy use and emission rates varied depending on electrical load. APUs reduced idling fuel use and CO2 emissions for single and team drivers by 22 and 5% annually, respectively. SP offers greater reductions in energy use of 48% for single drivers, as well as in emissions, except for SO2. APUs were cost-effective for single drivers with a large number of APU usage hours per year, but not for team drivers or for single drivers with low APU utilization rates. The findings support more accurate assessments of avoided fuel use and emissions, and recommendations to encourage greater APU utilization by single drivers and to further develop infrastructure for SP.}, number={17}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Frey, H. Christopher and Kuo, Po-Yao and Villa, Charles}, year={2009}, month={Sep}, pages={6875–6881} }
 @article{frey_kuo_2009, title={Real-World Energy Use and Emission Rates for Idling Long-Haul Trucks and Selected Idle Reduction Technologies}, volume={59}, ISSN={["2162-2906"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-68649109612&partnerID=MN8TOARS}, DOI={10.3155/1047-3289.59.7.857}, abstractNote={Abstract Long-haul freight trucks typically idle for 2000 or more hours per year, motivating interest in reducing idle fuel use and emissions using auxiliary power units (APUs) and shore-power (SP). Fuel-use rates are estimated based on electronic control unit (ECU) data for truck engines and measurements for APU engines. Engine emission factors were measured using a portable emission measurement system. Indirect emissions from SP were based on average utility grid emission factors. Base engine fuel use and APU and SP electrical load were analyzed for 20 trucks monitored for more than 1 yr during 2.76 million mi of activity within 42 U.S. states. The average base engine fuel use varied from 0.46 to 0.65 gal/hr. The average APU fuel use varied from 0.24 to 0.41 gal/hr. Fuel-use rates are typically lowest in mild weather, highest in hot or cold weather, and depend on engine speed (revolutions per minute [RPM]). Compared with the base engine, APU fuel use and emissions of carbon dioxide (CO2) and sulfur dioxide (SO2) are lower by 36–47%. Oxides of nitrogen (NOx) emissions are lower by 80–90%. Reductions in particulate matter (PM), carbon monoxide (CO), and hydrocarbon emissions vary from approximately 10 to over 50%. SP leads to more substantial reductions, except for SO2. The actual achievable reductions will be lower because only a fraction of base engine usage will be replaced by APUs, SP, or both. Recommendations are made for reducing base engine fuel use and emissions, accounting for variability in fuel use and emissions reductions, and further work to quantify real-world avoided fuel use and emissions.}, number={7}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Frey, H. Christopher and Kuo, Po-Yao}, year={2009}, month={Jul}, pages={857–864} }