Dec 142009

So a while ago I was thinking of a clever noise abatement system for highways.   You could turn all that noise into electrical energy, maybe use it to power street lights.  Then I realized that it’s not completely free, I mean apart from all the hardware and transmission lines etc that you’d need to make it work.  There’s a risk that you’d actually reduce the fuel efficiency of the cars on the road.  I think there’s a risk that all the noise abatement systems in place already do that.   If you hem in a car with walls, then the air around the car is not as free to move, so the pressure must be higher.  And remember you can’t have it both ways:  it can’t be an insignificant loss if there’s a significant gain.

Then I read about somebody trying to harvest energy from crowds.  Now, imagine how tired you’d be when you got home after spending an afternoon in a shopping mall.   The energy would be sucked out of the bounce in your step.   This energy was meant to propel you forward, but a small bit of it got converted into light.  Is that free energy?  Not sure.  In order to produce that little spurt of power, you needed to eat something.  That food likely took an enormous amount of energy to produce.  It may be cheaper to rely on fossil fuel directly, or, heaven forbid, tile the enormous roof of that mall with solar panels interspersed with sky lights.  You could use solar energy to power huge moving walkways that would allow people to rest while shopping, they already have those in airports (although not solar powered that I know of).  Of course, we’re supposed to exercise, and burn off energy, but walking through an airport or a shopping mall is not usually considered an exercise regimen.  Now if they harnessed all the energy put into running tracks and weight lifting that might be a good idea.  But then we might need to subsidize the athletes’ food bills.   At least somebody would get a free lunch!

Now I hear of somebody who wants to use the turbulent wake of your car to charge your cell phone.  I can’t help but think that this is going to introduce drag and be less efficient than just using the power generated by the alternator that’s attached to the engine.  Heck, why not mould a solar panel into the body of your car and use that to charge your cell phone?  That could even charge your phone when you’re not moving, or charge your hybrid’s battery while you work.

Now piezoelectric cells that run off wind power might be a great idea in other places.  Like when I ride my bike to work, burning off all that expensive food.  There are invariably bits of my clothing that flap in the wind, at least they could help keep my mp3 player running, or power my lights.  Or if you happen to live in a windy place, perhaps this could lead to more compact wind power generation, stuff that doesn’t involve erecting a 60 foot mast next to your house.

Of course just because the application that drives somebody to develop a new technology is impractical, this doesn’t mean that the resulting technology is silly.

 Posted by at 11:47 pm

  2 Responses to “Free Energy!”

  1. Interestingly, one of the several energy wasting features of cars is their shock absorbers. The other one that is perhaps more familiar is the brakes.

    I was wondering a while ago how much energy could be generated off the shocks in your average car. It seems that Levant Power ( ) figures they can save 6% for some vehicles. That may be a bit much, but it does sound interesting.

  2. Wow we have yet another crowd of people who seem to have forgotten the laws of physics. In this case, it’s the law of conservation of energy. describes a method for generating power from traffic. The idea is that they’ll drive over tubes full of water, and this will drive turbines.

    Driving over these at any speed other than really slow will bring up another law of physics: conservation of momentum. If you have a tube full of 10kg of water and you drive over that with a car, you’ll be suddenly accelerating a 10kg mass from stationary to something fast. It’ll be like hitting a log.

    C’mon people: go after the waste energy, using a parasitic scheme like this just reduces the energy consumption in one location at the expense of something else.