Air hybrid system will allow buses to recharge by braking

A regenerative braking concept that uses the energy created when a vehicle decelerates to compress air is being developed for a new breed of lower-cost, fuel-efficient buses and delivery vans.    

Engineering researchers from Brunel and Loughborough universities are developing the ‘air hybrid’ concept through a three-year £477,067 EPSRC-funded project. The effort has received industrial support from engine manufacturer Guangxi Yuchai Machinery, which recently signed a technology development and licensing deal with Brunel for its air hybrid technology.

Project investigator Prof Rui Chen, of Loughborough University, explained that the concept effectively runs a four-stroke engine in reverse when a vehicle brakes.

A four-stroke engine intakes fuel and air into a chamber, compresses it and then combusts the mixture to create the motion that propels a vehicle.

Chen said the air hybrid concept uses the force of the vehicle braking to power the engine’s pistons, which compress air. This air would then be stored in a compressed air storage tank already available on buses and delivery vehicles.