NREL Report on CT Transit Fuel Cell Bus

A report on the results of a preliminary evaluation of a prototype plug-in fuel-cell hybrid bus at Connecticut Transit (CTTRANSIT) in Hartford by the National Renewable Energy Laboratory (NREL) found that while the experience for operators and riders with the fuel cell bus has been positive, there have been a number of specific problems and limitations that resulted in bus availability consistently below the 85% target.

These problems include initial quality assurance of the bus manufacturing/integration, the traction batteries, heating and air conditioning, operating in slippery conditions, maximum bus operating speed, and degradation of the fuel cell power system.

The NREL researchers emphasize that there is no intent to consider this implementation of fuel cell buses as commercial (or full revenue transit service). Their evaluation focused on documenting progress and opportunities for improving the vehicles, infrastructure, and procedures.

CTTRANSIT introduced its fuel cell bus into service in April 2007. The prototype bus uses a series configuration hybrid-electric drive system from ISE Corporation, with a 120 kW fuel cell from UTC Corporation and a 53 kWh Zebra sodium nickel chloride energy storage system. The fuel cell power system and battery pack work together to provide power to two electric drive motors (170 kW continuous total), which are coupled to the driveline through a combining gearbox.

The NREL evaluation covers the period from April 2007 through June 2008 and includes results from diesel baseline buses.

During this period, the fuel cell bus accumulated 12,115 miles, and the fuel cell systems accumulated 2,049 hours. These numbers indicate an overall average speed of 5.9 mph, which is significantly slower than the average CTTRANSIT speed of 12 mph. The bus fell significantly short of its target availability (85%), due in large part to the problems noted above. Primary reasons for unavailability were the UTC fuel cell (38%), problems with the batteries (32%), and ISE hybrid propulsion system and fuel system (23%).

For the complete article, go to:  http://www.greencarcongress.com/2008/10/nrel-report-fin.html#more

Source: Green Car Congress