Electrification
continued
The electrified accessories include the propulsion system; the radiator fans; and the heating, ventilation and air conditioning system. Electric power steering will be added when the manufacturer makes it available. Miami-Dade Transit initiated the electrification process on a trial bus in early 2010. When the pilot proved successful the agency electrified eight buses and put its last five into service in April 2011. Based on the anticipated savings, the county says it expects to recoup its investment by 2015. As part of its effort to implement environmentally conscious initiatives, MDT has committed to purchasing only hybrid buses. Over the next five years the agency says it plans to electrify other bus components such as power steering, doors, air compressors and wheelchair ramps. Oahu Transit, Honolulu, HI, has taken delivery of 10 buses with all-electric HVAV with 48 more buses currently being delivered. Culver City, CA, is running 22 buses, and Antelope Valley, CA, is running 13 units with 17 more on order.
Gardena Municipal Bus Lines
The new Gardena Municipal Bus Lines (GMBL), Gardena, CA, is one of the nation’s only transit systems to feature 100 percent electric heating, ventilation and air conditioning systems on its hybrid buses. However, it relies on the allelectric HVAC technology Thermo King developed in 1994.
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July 2012
Gardena Municipal Bus Lines (GMBL), Gardena, CA, features all-electric HVAC systems on its 53 hybrid buses.
This technology has increased fuel efficiency on its 53 hybrid buses by an estimated 8 percent and lowered operating costs while providing 13,500 consistently comfortable rides on an average weekday. The City of Gardena selected and installed the all-electric HVAC systems in 2010 to reflect a city-wide commitment to increased sustainability, greater reliability and reduced energy and repair costs, and to adhere to forthcoming California Air Resource Board regulations. “Beyond the cost savings and the sustainability benefits, the consistent reliability of the electrified HVAC systems has been a huge benefit for the agency,” said Tony Cohen, equipment maintenance superintendent for GMBL. “The hybrid buses are so dependable that we’ve seen most repair costs and passenger complaints become a thing of the past.” Because energy needs to come from somewhere to power an all-electric HVAC system, Thermo King has applied this technology first to electric rail cars, trolley buses and most recently to hybrid-electric transit buses. Other municipal transit fleets to utilize this HVAC technology include Hamilton, ON, Canada; Victoria, BC, Canada; Chicago Transit Authority, Chicago, IL, and Long Beach, CA. Typically, the HVAC on a 40-foot bus is capable of putting out 110,000 BTUs at high engine speeds, even though the capacity required to cool and maintain a passenger filled bus is actually somewhere between 60,000 – 70,000 BTUs. The tendency has been to design oversized HVAC systems to compensate for performance specifications and variable capacity due to variable engine speeds. All-electric HVAC with its constant output is not affected by varying engine speed. All this leads bus operators to reconsider ways the industry measures performance of buses in terms of pull-down requirements. With new technology the standards will evolve accordingly. BR
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