Hybrid buses with ultra-capacitors roll out in California
Maxwell is already pushing out its newly-released Heavy Duty Transportation module (HTM) 390-volt Boostcap ultracapacitor to industrial and transportation markets including for use in a number of hybrid city buses being rolled out in California. The HTM 390 has been designed to provide scalable, easy-to-integrate, energy storage and power delivery solutions of up to 1,170 volts for heavy duty electrical systems and hybrids. Margery Conner over at EDN had a test drive on one the new buses and was impressed with the smooth acceleration of the new hybrid powertrain.
Petrol-electric hybrid buses are being road tested in parts of California as a direct alternative to traditional diesel engines. While oil burners are far more fuel efficient than petrol vehicles, they have a bad reputation on the emissions front, especially with NOx emissions - a real concern in many large, Californian cities. The petrol-electric hybrid powertrain returns only slightly better fuel efficiency than a diesel engine - 5 mpg versus 3 to 5 mpg - but harmful emissions are hugely reduced. This has led ISE, the bus hybrid electro-mechanical subsystem contractor, towards utilising a series hybrid model where the engine drives a generator that produces electricity to run the electric motors driving the wheels. For Grover City, the flat terrain suits the petrol-electric hybrid, whereas in hilly Oakland, the hybrid buses will use fuel-cells instead of an electric motor.
Analysis: Using a series hybrid configuration is a good idea to allow the engine to be swapped out for different models or fuel-cells or the like. I think they should be giving a modern clean diesel configuration a go, though, to get the best of both worlds. Especially if they could run it on biodiesel.
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[Source: EDN.com]
Reader Comments (Page 1 of 1)
Chris M 6:40PM (4/09/2007)
Quote: "in hilly Oakland, the hybrid buses will use fuel-cells instead of an electric motor"
Fuel cells produce electricity, thus the busses would STILL use electric motors. I think you meant to say "in hilly Oakland, the hybrid buses will use fuel-cells instead of a petrol engine"
I cannot think of any practical reason why fuel cells would be preferred in hilly country. What is needed there is light high performance Lithium batteries, to make maximum use of downhill regeneration.
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