Travellers' tales for power providers

9 November 2009

These are not like conventional speed bumps. They do not damage your car or waste petrol when you drive over them

An article featured in an old-established British newspaper, The Observer, has brought me news of a pilot installation in London: traffic-driven generators are to supply street lamps, road signs, traffic signals and other electrically operated evidences of highway life. The installations may be at times reminiscent of the inert bumps (known as speed bumps) that have been placed at intervals along some motor-roads to enforce speed limits. The bumps’ jolting presence compels drivers to slow down, and elicits their sardonic comments when described by officialdom as ‘traffic calming’ – more popular epithets include ‘frustrating’, ‘annoying’ and ‘maddening’.

Inevitably the Observer reporter calls the new installations ‘speed bumps’ although they are not always as obtrusive. They are designed to act as such if required, but they can be made to lie flush with the road surface, so that drivers do not notice them.

The idea of putting roadwheel-actuated generators in the path of vehicles has been mooted before now but I have not heard of it being taken so seriously. According to the article the London borough of Ealing has budgeted a large sum of money for the trial installation, and many other British local authorities (not to mention supermarkets etc) are showing interest.

The devices apparently employ adjustable

panels or ramps that can be forced by passing vehicles’ wheels into a reciprocating motion that is converted into rotation which is transmitted to a generator drive shaft. According to the Observer writer the designer ‘behind’ these ‘hi-tech ramps’, a former UN adviser on renewable energy, is an engineer who has said that ‘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’. He does admit that the equipment entails a capital cost but he insists that the energy it generates is not only ‘free’ thereafter but also ‘green’.*

Spoilsports will point out that, because the vehicles that actuate the sub-surface mechanisms must consume a little (paid-for) fuel for the purpose, the power output of the generators can be no more greenly obtained than any of the other power required of the prime movers in the traffic stream.

Sadly I have to add that there is no suggestion in the article of reimbursement (perhaps on turnpikes) of the extra costs that would have to be met by motorists travelling along highways calmed, illuminated and otherwise improved by such methods. I have little doubt that the drivers’ sardonic remarks would be embellished.

Could the answer be a lemon?

Beloved of many a science schoolmaster are the quaint or homely means whereby the principles of electrochemical cells can be demonstrated to juveniles. A barely adolescent scholar of my acquaintance has reminded me of the tradition by telling me, excitedly, about an experiment he has watched. I think he wanted me to know that he, too, now knew something about making electricity. His class had been shown it being done with the aid of two half-lemons mounted, respectively, on copper and zinc spikes. Appropriately coupled they made a ‘citrus cell’, the lad rather grandly informed me, and this generated enough power to drive an electric clock. He was already ambitious himself to drive an electric car.

Today’s electric automobiles, alas, still lack adequate batteries. Hopes rest on the development of lithium-ion cells but there are sceptics who believe that only hybrid or hydrogen-fuelled vehicles are worth thinking about.

Maybe my young friend will grow up to be the scientist who proves the pessimists wrong, or the engineer who himself develops the winning cell and the at-last triumphant electric car. I cherish the thought: that way, he could, despite everything, make it all happen in my lifetime.†

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