Pavegen To Tap Pedestrians For Power In the UK 197
An anonymous reader writes "Several years ago Laurence Kembell-Cook unveiled Pavegen floor tiles, which capture kinetic energy from footsteps and convert it to electricity. Now after two years of product testing and picking up a slew of awards across the U.K., Pavegen has received its first commercial order — to light up the new Westfield Stratford City Shopping Centre."
entrepreneurialism in the UK dead since '80s (Score:2, Insightful)
There have been very few interesting inventions in the UK since the '80s, and when they are the authorities / marketroids / everyone are so keen to say "LOOK BRITAIN ISN'T DEAD YET!" that every so often there's a hilarious amount of hubbub surrounding nothing.
Thatcher taught the current 30-somethings that there is no personal gain in actually producing anything (and it's still communist to do anything other than for personal gain): if you want to get rich, become a middleman. So that's where most of the intelligence has gone.
Upscaling, this is the real reason why we have the financial crisis[tm] in much of Europe: we have neither the production nor sufficient means of production any more. Germany was careful to maintain its own, thus retaining a now dominant economy - they've taken over Europe in a far more rational and subtle way than earlier last century. The rest of us, taught by the worst, have been spending the last couple of decades moving numbers around, signifying nothing.
Waste of energy in manufacture (Score:5, Insightful)
Some quick back of the envelope calculations: FTFA, each tile generates "2.1 W" per step. If we assume a typical step time of 500ms based a pace of 120 steps per minute this could be interpreted as about 1.05J captured per step.
The casing is made from stainless steel which required about 53 MJ/kg [bssa.org.uk] for production in 2004. If we assume a tile casing mass of 2kg that is 106 MJ required for the steel production alone.
The shopping centre may be open around 10 hours a day with perhaps 20 seconds between each step averaged over a typical day. This is 1800 steps per day at 1.05J per step giving a total of 1890 J captured per day. Assuming 100% efficiency and a never-closing shopping centre, this gives an energy breakeven for the steel alone of around 56000 days or 153 years.
I know that other factors are in play such as the potential to raise awareness of environmental issues but this is ridiculous. I noticed that the award that the guy is in the running for is sponsored by Shell and part of me suspects that they know that these things are crap but want to be seen to promote something like this which appeals to the public and appears "green".
Re:Errors in article (Score:5, Insightful)
It produces 2.1 watts for how long? 1 second? 100ms?
For as long as you keep walking, I guess. As long as you produce a Joule each second, you're producing 1 Watt.
The potential energy in a gravitational field is m * g * h, so if you sink 5 mm with every step, you're producing 9.81 * 0.005 = 0.04905 Joule for every kg of body weight at each step. If you take p(ace) steps per second while walking, you're producing p * m * 0.04905 Joules per second, i.e. Watts, as long as you keep walking. So an 80 kg (~160 lbs) person who walks at 2 steps per second could theoretically (i.e. at 100% efficiency) produce 2 * 80 * 0.04905 = 7.8 Watts. So 2.1 Watts means a 30% efficiency. Doesn't seem unbelievable to me.