- Fuel cell electric buses are hybrid electric buses using fuel cells to power the electric motor(s).
- The fuel cell uses hydrogen and oxygen to generate electricity by an electro-chemical process producing only heat and water as a by-product (no harmful emissions). The heat can be used again to warm the passenger compartment, such that as little energy as possible is lost in the process.
- The hydrogen is safely stored on-board in gaseous storage tanks on the roof.
- The energy storage devices (such as a battery or ultra-capacitor) are included to improve performance and fuel efficiency.
- The bus structure and other non-electric components are the same as the ones of conventional buses.
- Hydrogen offers much higher energy density compared to electrical storage systems (e.g. batteries, super-capacitors), this leads to a substantial driving range for the buses (more than sufficient for a day’s operation). FCEB’s can be operated up to 16 hours a day, in all climate conditions.
- In the fuel cell hybrid bus, the fuel cell produces directly the electric power for the electric motor and/or to recharge the batteries. In addition, both types allow, through a process called regenerative braking, to recover energy lost due to braking to be utilized to charge the battery. Also called brake energy recuperation.
In a regenerative braking system, the objective is to recapture the energy byproduct that results when the brakes are applied. In electric or hybrid vehicles, the electric motor that drives the car's wheels plays a major part during braking. When the brake pedal is pressed, the regenerative braking circuit switches the motor so that it now operates in reverse to counter the direction of the wheels. This reversal actually makes it perform like a power generator or dynamo that produces electrical energy. The electricity developed is routed towards the vehicle's storage batteries to recharge them.
- Schematic Principle of Fuel Cell Electric bus: