Sunday, December 18, 2005

Power from nothing?

From Treehugger I find this "Electro-Kinetic Road Ramp" which promises free power generation due to the action of cars passing over it. The ramp flexes as the vehicle moves over it, and is connected to an electrical generator:



I know I joked previously about the car-mounted wind generators on show in Japan, but in that case at least they were clearly designed as a promotional exercise rather than a serious attempt at power generation. These guys, on the other hand, are for real! Listen to the voice-over on the movie if you don't believe me - this is not being presented as a convenient way of powering off-grid road signs in remote areas, or a way of making speed bumps slightly useful. They actually claim "free electrical energy" and suggest installing them widely in cities:

...designed to generate electricity using kinetic energy from passing traffic. This energy, which is free, would otherwise be lost... The ramp...consumes no aditional fuel, produces no emissions, and is environmentally friendly.


I hope it doesn't really need pointing out to my reader why this is bogus - the ramp steals energy from the passing vehicles, meaning that their fuel consumption is necessarily increased and it's a racing certainty that the overall efficiency of power generation from oil to electricity is way below that of a competently designed power station, for example. I am astonished that anyone with the technical competence to actually design and build such a construction should not be aware of the fundamental physical law that it claims to break.

As an aside, I can't imagine that it would be much fun to cycle over one, still less with a car overtaking simultaneously. But I'm optimistic that no-one will actually get taken in by their claims.

Update 19/12

According to this BBC news article, my assessment of the competence of local authorities was badly misplaced:
More than 200 local authorities had expressed an interest in ordering the £25,000 ramps to power their traffic lights and road signs, Mr Hughes said. Around 300 jobs are due to be created in Somerset for a production run of 2,000 ramps next year.
What a bunch of numpties. I can only hope the manufacturers go bust before too much taxpayers' money gets wasted on these stupid contraptions. Even from the local authorities' narrow viewpoint (ignoring the added cost on the motorist, and the pollution they will generate), the payback time will be decades.

3 comments:

Brian said...

It might work okay in situations where you usually have to brake: highway off-ramps, steep downhills, tight curves (probably a bad idea for curves).

But here's my brilliant idea: put these in car bumpers. Instead of braking to AVOID the front car, you just slow down a little, give their car a light tap, and charge up their battery. I see no complications or problems whatsoever with this idea.

James Annan said...

It might work okay in situations where you usually have to brake: highway off-ramps, steep downhills, tight curves (probably a bad idea for curves).

Sure, there are a few cases where it could be theoretically useful, but I don't see it being a significant breakthrough. It would be hard to make it work safely and usefully for a range of vehicle speeds, weights and suspensions. They've only tried for urban trundling so far.

But here's my brilliant idea: put these in car bumpers. Instead of braking to AVOID the front car, you just slow down a little, give their car a light tap, and charge up their battery. I see no complications or problems whatsoever with this idea.

No, none at all :-) Proper regenerative braking seems like a better (and safer) option.

Carl Colditz said...

Carl Colditz

As far as using more energy to go over the speed bump, be advised that ever time you stop your car and put your foot onthe brake you are wasting energy to just turn the motor over in transmission park mode. That is one reason a stick manual shift car can actually almost compete with a hybid as far as gas mileage if driven conservatively. Additionally you can prove to yourself that if you come to a sped bump and stop and then proceed over the speed bump you will not need to use your accellerator pedal at all. Therefore, since no real extra energy can be shown to needed to be expended, parked mode verses no accellerator need for going over the speed bump, the net use of energy is zero.