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# Is it possible to use the fan in a laptop or computer to produce kinetic energy that will produce extra energy for power Answered

its not like powering a windturbine with lots of desk fans because obviously thats pointless but we need the fan in the computer and we could also use the thermal energy that usually escapes the computer as extra energy. what do you think? im guessing this is gonna have a simple answer why not because someonme should have allready thought of this, a car powered by kinetic energy from the wheels and or wind power outside the car. the ultimate green peace kinda car should be powered by wind rotation, wheel rotation, solar power on the bonnet or roof. iv heard some electric cars do use the motor spin to produce extra energy, when i said the spin of the wheels i also ment the spin of the motor, would using the wheels produce more power than juist the motor, thanks for any help instructables-ers ?

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bwrussell (author)2012-06-11

When you extract energy from something you generally make it less efficient. Take the idea of capturing energy from the air moving past a car. Since the air isn't really moving past the car, the car is moving through the air, you are creating significant drag on the car which means you need more energy to move the car forward. Due to losses (friction, heat, etc,) you won't be able to make up this extra energy with the system so you will be operating at a net loss. What you are describing is, or is very close to, a perpetual motion machine, which is impossible.

In regards to the computer, yes you could capture the thermal energy put off by the computer without causing losses put it would be bulky and would make the portability of the laptop moot, also the cooling issues mentioned already. You could also capture a very small amount of energy from the air that the fans move but be careful. If you ask the fans to run longer or faster than they need to to cool the computer then you will be operating at a loss.

Putting electricity into a fan to push air to turn a turbine to generate electricity is either a perpetual motion machine or operating at a loss and therefore useless. Of more use would be a more efficient fan, processes for cooling CPU's, or more efficient CPU's.

The Skinnerz (author)2012-06-10

While the processor of a computer is dissipating a significant amount of energy (hence the large heatsink), it is not usually worth trying to extract. Trying to extract this energy impedes cooling and adds to cost, so is not used. There are a few sterling engine driven CPU fans, but these are mainly for novelty than an efficient cooling solution.

As for cars, you will always get less energy out than you put in, like with any system. In theory, you could use wind power to provide energy to a car, but this would be highly impractical, and the added weight and drag would probably reduce the overall efficiency.

As you suggest, solar panels are a viable way of supplying additional energy to an electric car, and the kinetic energy of the car can be recycled when slowing down by regenerative braking which uses the motor as a generator.

Kiteman (author)2012-06-10

Desk fans already generate kinetic energy - they move air.

You can use a sterling cycle engine to extract useful energy from a source of heat.

Electric cars don't produce *extra* energy from the spin of the wheels, they regain energy when braking (google for regenerative braking - it is a basic law of the Universe that you cannot extract more power from a system than you put in.