Posts tagged ‘conservation of energy’

Vampiric Regeneration

How can you get free power?  Well, one way is to steal it from other people.  And if you steal it in small enough bites from a lot of people, they may never notice.

This seems to be the basic idea in this article in the Guardian, whose author clearly attended lots of journalism classes while studiously avoiding any class that might have made mention of the first law of thermodynamics.

"Green" speed bumps that will generate electricity as cars drive over them are to be introduced on Britain's roads. The hi-tech "sleeping policemen" will power street lights, traffic lights and road signs in a pilot scheme in London that could be rolled out nationwide.

Speed bumps have long been the bane of motorists' lives, but these will capture the kinetic energy of vehicles.

Peter Hughes, the designer behind the idea, said: "They are speed bumps, but they are not like conventional speed bumps. They don't damage your car or waste petrol when you drive over them - and they have the added advantage that they produce energy free of charge." An engineer who formerly advised the United Nations on renewable energy sources, Hughes added: "If it [the energy] wasn't harnessed by the speed bumps, it would go to waste."

The ramps - which cost between £20,000 and £55,000, depending on size - consist of a series of panels set in a pad virtually flush to the road. As the traffic passes over it, the panels go up and down, setting a cog in motion under the road. This then turns a motor, which produces mechanical energy. A steady stream of traffic passing over the bump can generate 10-36kW of power.

OK, I am willing to believe that you might be able to recover some net energy from a system with this kind of dynamic speed bump replacing an existing static bump  (but I am skeptical, and would want to see the math).  Of course, if you really have a road with a speed bump and so much traffic that it will generate this much power and repay a large investment, then you probably have a road/traffic design issue.

But the article seems to be positing that towns could install these as flat devices --"virtually flush to the road" --  that drivers would hardly notice.  Power from these devices would help the town power its lights and other devices.  But unless these guys have invented the perpetual motion machine, there is no free energy to be had here.  In fact, due to that nasty old spoil-sport, the second law of thermodynamics, there has to be a total system loss.  The device might only steal the equivalent energy of a thousandth of a gallon of gas from each driver, so the driver of each car won't really notice, but the total system expenditure of the thousands of drivers who power the device will still be there, just hidden.  This is a new stealth tax on drivers, dressed up in green clothing.

Next up:  Britain proposes to put windmills on the roofs of electric cars as a power source.  After all, when you are driving at 60 miles per hour, all that wind energy coming past your car is just lost, right?  Once you got the car up to speed, it would just generate its own electricity.  LOL.  I shouldn't laugh, there is probably a billion or so for this in Obama's stimulus bill.

via Tom Nelson.