Dynamo energy - for better fuel economy?

[samuel23]

When I was young I had a bicycle and it had a dynamo fitted to it so that all the while I was cycling the lights worked. The one problem with this was that when I stopped the lights went out. However I got to thinking ~ why can't we adapt this technology to make cars more fuel efficient? If the cars were fitted with a dynamo on each wheel, all linked to a charger unit, and it charged up a set of batteries whilst the car was being driven along using petrol (or diesel or LPG or bio-fuel). It could then run around town on stored energy, instead of having to plug the electric bit of the hybrid car into the mains thereby saving on the need to be using fossil fuel to recharge the batteries.
Is this feasible?

[kempie]

Cars already do this to a certain degree - the function of the alternator is to power the electrical system and recharge the battery when the engine is running.

Hybrid cars use a more sophisticated generating motor as a replacement to the alternator to achieve the results you describe.

http://en.wikipedia.org/wiki/Alternator

[AussieGeoff]

G'Day

Yes it is very feasible. It was tried many years ago, using electric motors and a heavy flywheel but was not a success - the weight of the flywheel made the system too inefficient.

However with the advent of hybrid vehicles, eg the Toyota Prius, it has become feasible to use Regenerative Braking on cars. It has been used on locomotives etc for decades.

Regenerative braking How it works and a brief history

Geoff

[EDLEE]

The answers above are quite true, but from the tone of your question it sounds, to me, you are picturing free energy. Unfortunatly this is only the case when going down hill. All production of energy requires an input of energy of a different sort (gravity, muscles, heat, etc.) . As I'm sure you have heard before, "There's no such thing as a free lunch".

[samuel23]

Thanks for your answers guys. You're right EDLEE. I was going down the route of perpetual motion / energy created from energy being used. I remember getting a lecture from the proffs at uni telling me that free energy is the impossible dream, but thought that if we could use energy already being generated (e.g the motion of the car) it could create more energy, or even if we stuck a dynamo on the back of a train as the train went along - especially adapted to be propelled by a diesel / electric hybrid motor - it may be that we could create electricity and store it in trackside batteries thereby cutting our energy source useage in half (50% propulsion by diesel/50% by electricity from batteries) Sorry am I rambling now? Late nate / early morning and head is buzzing. lol

[samuel23]

Thanks for the link. That's an interesting site AussieG.