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Sarasota
County Area Transit (SCAT) introduced its fi rst diesel-electric
hybrid bus to the fleet on Aug. 7, 2006. Th ere are now 10
hybrid buses in the SCAT fleet. The new hybrid buses are part of
Sarasota County’s commitment to reducing fossil fuel use through
an initiative called the 2030 Challenge, which was adopted by
the Board of County Commissioners on July 11.
How It Works
When the bus accelerates from a stop, the battery-powered
electric motors assist the diesel engine for powerful
acceleration. Once under way, the engine-driven generator
charges the batteries. The vehicle’s regenerative braking
captures energy normally lost as brake heat, and returns it the
vehicle’s energy storage.
Fuel Economy and Cost
Savings
- 25-30 percent reduction in diesel fuel
consumption.
- Average annual reduction of 7,000 gallons
of diesel fuel each year.
- Savings of about $21,000 in diesel fuel
costs per year, with an average cost of $3 per gallon.
Emissions
- Emissions will be reduced by more than 90
percent on some items as compared to conventional
diesel-fuel engines.
- 97 percent lower carbon monoxide
emissions
- 95 percent lower particulate matter
emissions
- 50 percent lower environmental noise
pollution
- 50 percent lower nitrogen oxide emissions
- 33 percent lower greenhouse gas emissions
Noise
The noise level for the new hybrid is roughly half of what
someone can expect from a standard diesel bus, or equivalent to
that of a passenger car, about 79 decibels.
Energy Storage
The energy storage units supply electrical energy to the motors.
Energy storage lessens the demands of the clean diesel engine,
reducing emission, fuel consumption and noise.
Regenerative Braking
Up to 40 percent of the energy to accelerate the bus is energy
saved during regenerative braking. When stopping or
decelerating, vehicle energy is converted to electrical energy
and stored.
Battery
Advanced nickel metal hydride (NiMH) 600-volt battery pack has a
six-year life with no requirement for maintenance.
Engine Features
- Two-mode hybrid system
- 8.9-liter diesel (replaces 11.0-liter
diesel)
- Two 100-kilowatt motors
- 50 percent faster acceleration
Manufacturers
Allison-General Motors of Detroit, Mich., developed the
transmission. Gillig Corp. of Hayward, Calif., designed and
built the bus.
Cost
The BRT hybrid bus costs approximately $500,000. A standard
diesel bus costs about $300,000. The
hybrids are purchased through Federal Transit Administration
grants.
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Citizens Advisory
