Tought Leader Meet the All-Electric School Bus


Everything student transporters generally need to know about electric vehicles versus diesel and diesel engine variants WRITTEN BY ROBERT T. PUDLEWSKI


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ver the past couple of years, we have seen numerous releases on new alternative power systems


for school buses, and a lot of new things that are being done. Te general feeling toward electric


power has been that there is a real need for a breakthrough in battery technology for the hybrid or electric drive to become mainstream or to even significantly penetrate the market. Most school bus operators believe, and I think this is very sound, that diesel is going to be a primary fuel for a long time to come. As a result of GHG Phase II, (the fully phased-in “Phase II GHG” standards by 2027 is anticipated to achieve up to 24-percent improve- ment in vehicle fuel consumption and subsequent reduction in CO2 relative to Phase I, 2017), we can expect to see some breakthroughs in diesel/ electric hybrid, plug-in hybrid electric, electric ve- hicle (EV) and diesel power plant variants (CNG, LPG). In the short term, we will see changes to diesel engine applications, such as sizing, as we’re seeing in a couple of product announcements this year with smaller engines coming from Cummins, and some other things going on with CNG and propane and other technologies at other diesel engine manufacturers. Any growth in school bus market share by EVs will depend on either new regulations, such as in California, or educated consumers fulfilling a need to achieve “zero” tailpipe emissions within their operating environment. However, the cost differential of EV over fossil fuel variants will remain challenging, possibly somewhat relieved through federal and regional energy grants tar- geting bus replacement and via the potential for increased manufacturing in the EV segment to help lower cost. Following are some key aspects of what school bus operators should know about electric powered school buses, what is relevant when comparing fuels and what could impact a buying decision:


50School Transportation News • NOVEMBER 2016 Electric vehicles convert about 59


percent to 62 percent of the electrical energy from the grid to power at the wheels—conventional diesel vehicles convert about 30 percent to 40 percemt of the energy stored in diesel fuel to power at the wheels, while gasoline converts even less at approximately 20


percent. EVs can reduce fuel costs dramatically over the useful life of a school bus because of the low cost of electricity relative to conventional fuel. Because they rely in whole on electric power, their fuel economy is measured differently than in conventional vehicles. Miles per gallon of gasoline equivalent (mpge) and kilowatt-hours (kWh) per 100 miles are common metrics. Depending on how they’re driven, it is said that today’s conven- tional school bus EVs can drive approximately 75 miles consuming only 100 kWh. According to the U.S. Energy Information Administration, the cost of 1 kilowatt hour is approximately $0.014, which varies slightly based on regional production because electricity is a secondary energy source. Let’s use the assumption that the average duty


cycle of a typical diesel school bus is five hours a day, 180 days a year and 75 miles per day.


Pudlewski is STN’s tech- nical editor and a 40-plus year veteran of the school bus industry. He is the retired vice president of fleet operations, procure- ment and maintenance for Laidlaw and is a member of the National School Transportation Association Hall of Fame.


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