Bumpy road to ‘free’ energy

This was originally published here on Matters Scientific, the Cherwell science ’blog.

Magical speed bumps which will generate ‘free’ energy are being trialled in London.

The ‘electro-kinetic road ramp’, a name which sounds like it should be preceded by ‘come and behold the amazing’ at a Victorian street fair, was developed by British inventor Peter Hughes. The weight of passing cars moves plates embedded in the road, and a series of Wallace-and-Gromit–esque levers, cams and axles spins a dynamo which creates electricity—for free!!

Now, as any self-respecting Key Stage 2 student knows, energy cannot be created or destroyed: someone must be paying for this lunch. Indeed, the first question of the Hughes Research FAQ asks ‘Doesn’t the ramp just steal pennies from our petrol tanks?’ Well, hopefully not, because the intended use of the device is in areas where cars should already by trying to slow down, like roundabout approaches, and thus the tiny theft is from wear on your brake pads. In this situation, the panels lie almost flat, and it’s apparently near-impossible to notice that you’re passing over one. An alternative configuration leaves a lump in the road, which would allow traffic calming and ‘free’ energy-grabbing simultaneously. The energy created can then be used to power local road signs, traffic lights or street lamps, or fed into the national grid if there is an excess.

Accordingly, the inventor has seemingly had plenty of interest from local councils. However, press coverage seems a little worryingly uncritical and, by extension, I am concerned that councils’ appraisals will be too. Am I being too cynical? As long as some critical thinking is employed when deciding where to site these generators, it can be no bad thing, right?

What is not obvious is how the true costs of these devices could be estimated. They are not cheap to buy, costing £20–50,000 depending on size—but Hughes claims that an electro-kinetic ramp in a busy spot will pay for itself in a few years, and presumably this trial will provide the definitive shoot-out between usable electricity generated and installation and maintenance costs.

The quantity which worries me more is the cost in wear on passing motor vehicles’ suspension, tyres and so on. These tiny quantities are difficult to measure, but the carbon cost of building and replacing new car parts is sufficiently vast that we should be worrying about it. I have not seen any research which addresses this, let alone demonstrates it one way or the other. It might even be that those used in the speed bump configuration would be less damaging than current solid concrete humps—but until someone works this out, it is irresponsible to proceed.

My supplementary, and more general, concern is the intrinsic appeal of this device, and others like it as reported in the media—there is an elegant rhetorical symmetry in cars’ wasted energy powering roadside paraphernalia. It adds to the sensation that we’re already doing enough for the environment—even better, we’re actually helping by driving cars, which are meant to be bad, right?!

What journalists, councillors and happy drivers forget is that this device is just a new and bizarre way of generating electricity. There is loads of ‘wasted’ energy waiting to be harnessed in nature, like sunlight or flowing water, which may be cheaper or easier to transform into electrical power.

That said, if the electro-kinetic road ramp genuinely does pay for itself and its upkeep in carbon as well as cash, we should get them out there as soon as possible. I just hope that someone is doing the sums, and that the media will provide us with a less simpering appraisal when they have.

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