|Proterra battery-electric bus. Click to enlarge.|
An all-electric version of the 35-foot Proterra FCBE 35 transit bus, powered by a UQM PowerPhase 150 electric propulsion system and an Altairnano Li-ion battery pack (earlier post), achieved more than 20 miles per gallon diesel equivalent in fuel economy equivalency testing conducted by the Pennsylvania Transportation Institute at Pennsylvania State University.
Testing of the composite body all-electric version of the FCBE 35 transit bus was conducted using a modified Transit Coach Operating Duty Cycle (ADB) that includes simulated central business district, arterial and commuter operations.
Calculated diesel equivalent fuel economy for each phase was: 21.35 mpg on the central business district phase, 17.55 mpg on the arterial phase and 29.23 mpg on the commuter phase. Each test phase simulated transit-type service at seated load weight and included various passenger pickup stops.
Simulated test phases ranged from 7 stops per mile and a top speed of 20 mph during the central business district phase to 1 stop and a top speed of 40 mph during the commuter phase. The FCBE 35 transit bus was tested at a gross vehicle weight of 36,680 based on a seating capacity of 38 passengers, including the driver and 34 standing passengers.
Fuel economy testing was conducted with the air conditioning system turned off. Air conditioned operations are expected to reduce fuel economy results by approximately 30%. The bus was recharged in less than 20 minutes using the Proterra’s TerraVolt fast charge energy storage system at the end of each completed ADB, replenishing the energy consumed and thereby extending the total daily vehicle range.
The UQM electric propulsion system produces peak torque of 650 N·m and peak power of 150 kW (201 hp). The system has a continuous torque rating of 400 N·m and a continuous power rating of 100 kW (134 hp). The system also features optimized four-quadrant performance, dynamic torque, speed and voltage control, regenerative braking and system energy efficiency of more than 90% across substantially all of its performance regimen.
The test validated that Proterra’s 35-foot transit bus achieves up to 400 percent better performance than today’s conventional diesel or competitor’s hybrid transit buses. These fuel economy improvements together with the ability to extend total daily vehicle range through our TerraVolt rapid charge capability offers a tremendous advantage to transit operators who are looking to reduce both emissions and vehicle operating costs.—Jeff Granato, President of Proterra LLC