Energy from car brakes could cut fuel consumption

LONDON - Every time the brake is applied in a car, energy is generated. Though the energy is not used, new research shows that it is perfectly possible to save it for later use in the form of compressed air.

It can then provide extra power to the engine when the car is started and save fuel by avoiding idle operation when the car is at a standstill.

Air hybrids or pneumatic hybrids as they are also known, are not yet in production. Nonetheless, electric cars and electric hybrid cars already make use of the brake energy to power a generator that charges the batteries, according to a Lund University statement in Sweden.

However, according to Per Tunestl, researcher at Lund University, air hybrids would be much cheaper to manufacture. The step to commercialisation does not have to be a large one.

The technology is fully realistic. I was recently contacted by a vehicle manufacturer in India which wanted to start making air hybrids, he says.

The technology is particularly attractive for jerky and slow driving, like for buses in urban traffic.

My simulations show that buses in cities could reduce their fuel consumption by 60 percent, says doctoral student at Lund University Sasa Trajkovic who recently defended a thesis on the subject.

Sasa Trajkovic also calculated that 48 percent of the brake energy, which is compressed and saved in a small air tank connected to the engine, could be reused later.

This means that the degree of reuse for air hybrids could match that of todays electric hybrids. The engine does not require any expensive materials and is therefore cheap to manufacture.