Connecticut Transit (CTTRANSIT) began to operate a prototype plug-in hybrid bus in April 2007 with the hopes that additional vehicles could be purchased in the near future. The National Renewable Energy Laboratory (NREL) has issued a report that may put these plans on hold for awhile. NREL conducted a 14 month-long test of CTTRANSIT’s prototype to determine if the current infrastructure and maintenance facilities were sufficient for ongoing use. The report showed that the prototype bus was struggling to meet performance benchmarks set by the Hartford-based transit authority.
The CTTRANSIT prototype uses a hybrid drive system produced by ISE Corporation. This system is powered at 120 kWh by a hydrogen fuel cell system and a sodium nickel chloride battery from UTC Corporation and Zebra respectively. At the time of the report’s publication, CTTRANSIT had run the prototype for a total of 12, 115 miles to adequately test hybrid capabilities.
NREL documented several major problems with the prototype that drove it below an availability level of 85%. The most significant problem was a premature loss of power due to repeated charging and high-speed operation. CTTRANSIT was unable to use the prototype for highway routes because the bus maxed out at 48 miles per hour. CTTRANSIT drivers found that the special propulsion system aboard the bus had difficulties operating in Hartford’s winter weather. NREL researchers also found that climate controls were insufficient for public transit with weak heating and excessive air conditioner noise.
NREL researchers Kevin Chandler and Leslie Eudy noted that the major reasons for the prototype’s downtime included fuel cell issues (38%) and battery problems (32%). The report’s conclusion notes that CTTRANSIT received funding from the Federal Transit Administration (FTA) for an additional prototype along with replacement parts for the current prototype. NREL is conducting research through the end of 2008 to assess potential improvements in the CTTRANSIT prototype.
The story of CTTRANSIT’s plug-in prototype bus shows that America is still in the early stages of sustainable transportation. We will need to see dozens of similar stories from New England to California before large steps are taken forward. NREL’s report should be seen as the next step in fuel-efficient public transit rather than a source of scorn for hybrid critics. CTTRANSIT and other transit authorities need to take expert advice and adjust their plans accordingly to ensure clean, sustainable and affordable transportation throughout the United States in the 21st century.
