What is a Hybrid Bus? | Demonstrations | Emissions | CertificationThe growing need to reduce fuel consumption and lower emissions in the United States transportation sector has spurred urban transit bus operators to pioneer the adoption of alternate fuels and new drive system technologies. One of the most promising technologies to receive attention is hybrid-electric drive, which consists of two or more onboard fuels that supply energy to electric traction motors that in turn drive the wheels. By contrast, conventional drive employs an internal combustion engine to generate rotational force that is then only mechanically transferred to drive the wheels.
A growing number of companies are developing and beginning to supply commercial hybrid-electric drive products to the truck and bus markets. Most of these commercially-available hybrid buses combine an internal combustion engine and traction battery, although there are many possible drive system configurations.
The electric drive improves drive system efficiency, reduces energy consumption, recovers energy, reduces emissions, and improves driveability. Hybrid systems are being used in transit bus applications where pure battery-electric drivetrain is not yet feasible because the power and energy requirements associated with typical urban transit bus drive cycles exceed the performance capabilities -- primarily, range -- of current battery technologies. Transit operators are implementing hybrid buses since the hybrid drive systems can easily meet and exceed the urban transit bus drive cycle requirements while still improving fuel economy and emissions