Squeezing The Most From Technology
Innovation isn’t all about coming up with entirely new technology. Applying existing technology to new situations can have a similarly important impact and be equally innovative. That’s what first struck me when I heard about plans to use the energy generated from pedestrian footfall to power supermarkets, railway stations, nightclubs and tourist attractions. Richard Scott questions whether piezoelectric devices could pave the way to another useful source of renewable energy...
The technology was developed in the mid-18th century but only relatively recently have piezoelectric devices been used in attempts to produce energy from footfall. The essential idea is that there is a lot of wasted energy out there, and not just that which is produced by the wind, the sun or the oceans. By ‘harvesting’ small amounts of energy from the pressure of a footstep it is hoped that when expanded to a large scale, each footstep will contribute to a useful overall energy supply.
Past attempts to harvest energy in this manner have included trying to generate and store electricity from soldiers’ boots. They managed to produce 3-6 watts of power output, but the technology was deemed impractical and subsequently dropped. This has proved a major stumbling block for piezoelectric, and indeed other microgeneration sources. They do produce electricity, but in very small increments, so are you going to have a useful amount of energy when you need it? And is the process of producing it more hassle than its worth? The soldiers also found that the devices fitted to their boots required additional energy expenditure when walking with them, which is clearly a problem in a combat situation.
So what’s new here? Well, the technology has been moved from the shoe-wearer to the floor itself, which seems entirely logical, and allows the floor of any building to become a giant generator. Due to the high level of footfall in areas such as railway stations it is hoped that, for example, the 34,000 passing through Victoria Station per hour could power 6,500 lightbulbs. But as piezoelectric devices require mechanical stress in order to produce electricity, the floor must have to give way a little on each step, thereby subjecting the crystals to the necessary pressure. The idea of walking across a slightly spongy or springy floor doesn’t sound horrific, but there might be practical problems with dragging heavy trollies over it (quite likely in a railway station) and it would make life much more difficult for people in wheelchairs. Another projected site for piezoelectric flooring is the Spinnaker Tower in Portsmouth, whose 560 steps could incorporate piezoelectric technology to help power lighting. Now, I’m not advocating laziness, but I imagine the 560 steps are already tiring enough!
That said, there are also plans to use the natural sway of the tower to produce electricity using the same principle. This seems a potentially more valuable and more practical use of the technology as it doesn’t impinge in any way on how visitors move through the structure but can still produce large amounts of energy, if maybe on a less consistent basis than footfall.
My view is that this way of using piezoelectric devices could be a very useful addition to other renewable energy sources, but only in a relatively narrow range of applications. Despite the obvious attraction of charging electrical devices or systems while you walk, it would be best to remove humans out of the equation altogether and develop more products that can be charged via other forms of motion. Over the past few years, wireless industrial sensors have been designed which charge through vibration and even from the impact of raindrops. This is an ideal application as the piezoelectric technology perfectly replaces the need for a battery, and improves upon it.
Expanding from these ideas, there should be countless opportunities for new products that harvest kinetic energy. Along with sensors, wireless sounders or beacons that warn of excessive vibration on machines, or harvesting the energy from traffic passing over bridges to help power lighting. Just a few ideas, and I'll probably think of more as soon as I've finished writing this piece, but it would also be interesting to hear of other possible ideas from EPA readers. Send them through to richard.scott@imlgroup.co.uk and I'll put a selection up on this page.
Enjoy the newsletter,
Richard Scott
Editor
Your Comments:
I agree entirely, 560 steps up the Spinnaker Tower is enough without having to extract more energy for the lights... however if you had one side of the steps for going up, without piezo-energy-sapping flooring, and the other side for going down with the micro generators, that wouldn't be so bad. Perhaps the piezo flooring would soften the footfall on the way down, helping people with dodgy knees (ok, so they're taking the lift anyway, but you know what I mean!) The masochists could then choose to walk on the "down" side while going up, just for a more extreme experience if they so desired!
However I reckon you could probably generate much more energy if you gave every one a rope to pull on on the way down, it could again help take weight off your legs but also generate power. Or what about a sort of power generating belt that you stood on at the top of each flight of steps, likeone of those torturous stairmasters in gyms, only in reverse?
Even more fun would have been to fit the tower with a helter skelter with power generating mats, rather than wasting all that energy to friction! However it might be easier to make an even better visitor attraction out of it if by making a "quick way down" option.... just step out of the door at the top, connected to a long fall-arrest device (I think they're called "fall limiters" or "self retracting lifelines") that generates power at it pays line out (slowly), delivering you safely to the ground... people would pay for that!!!! .... hmmm ...that would cost a bit to run because I suppose you would need to have a person watching over it in case some adrenaline junkies got hooked on it and didn't let the elderly and infirm have a go.
Think I'd better go and do some work now!
Regards,
Dr. Richard Stewart
Portadown
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