Comment It's just about certain, now: Almost everybody in the world has no idea of the most basic facts regarding energy use. Most people don't even know that the words "energy" and "power" have different meanings 1 , and just about everyone is so massively ignorant on the subject that they actually consider that the use of special floor tiles to generate electricity from human footfalls is worth doing.

Don't believe it? Check this out, from that bastion of proper science National Geographic:

Twenty bright green rubber tiles will adorn one of the outdoor walkways at the Westfield Stratford City Mall, which abuts the new Olympic stadium in east London. The squares aren't just ornamental. They are designed to collect the kinetic energy created by the estimated 40 million pedestrians who will use that walkway in a year, generating several hundred kilowatt-hours of electricity from their footsteps. That's enough to power half the mall's outdoor lighting.

It isn't just the French and the Guardian any more. It's us Brits, and supposedly sciencey publications like Nat Geo.

Just for reference, then: even if the vast Stratford City mall uses super-economical LED exterior lighting, just a single light can be expected to require energy supplies of more than 900 kilowatt-hours in a year (Google Doc here). There's no prospect whatsoever that "several hundred kilowatt-hours" could provide half the massive facility's outdoor lighting - this much is obvious straight off the bat.

But it gets worse:

On average, one footstep generates 7 watts of electricity, though the amount varies depending on a person's weight.

Seven watts for how long? This is meaningless twaddle.

And even worse, the headline says:

Tiles May Help Shrink Carbon Footprint by Harnessing Pedestrian Power

Nonsense. The Stratford City mall, we learn from an informative article in the CIBSE journal (pdf), will be supplied by a combination heat/electricity/cooling plant which will be capable of 46.2 Megawatts of heating, 39 Megawatts of cooling and up to 3.34 Megawatts of electrical power. It will not be running at maximum in all three categories at once, but even so we can see that the Stratford City mall's power consumption over time will run in the several tens of megawatts - for annual energy consumption of a few hundred thousand megawatt-hours.

Contrast this with "a few hundred kilowatt-hours" and we can see that the footfall generators will provide roughly one millionth of the energy the mall requires. They will not "reduce its carbon footprint" at all. Even if the whole place was tiled with footfall generators and every person on them generated 7 Watts constantly ... you would have to pack more than half the population of London in there, five million people all walking around without pause, just to keep it powered up. On a really cold or hot day you might need millions more.

It's a big mall, but it's not that big.

This is the same "Crowd Farm" idiocy that came out of the architecture faculty at MIT a few years ago. By this stage, of course, regular Reg readers would expect this sort of technological illiteracy from architects.

However we learn that in fact Laurence Kemball-Cook - the "fresh-faced 26-year-old Londoner" who helms Pavegen, the firm behind the Stratford treadmill generators - is not an architecture graduate. No, he has a degree in industrial design and technology (a course which has no requirement for any proficiency in maths or physics).

In fact of course Pavegen's business model has little to do with actually generating power. It's about marketing and green imagery:

Higher profile gigs loom. Pavegen has partnered with Siemens, the German technology company ... large, sponsored installations are planned for a major London train station and an Athens shopping mall this summer.

Siemens at least has plenty of people who know full well that human beings' muscles cannot supply any significant amount of the power required by a modern civilisation. But nonetheless they intend to sponsor public foot-power installations with their name on them, intended no doubt to suggest to the public that they are a green company making every effort to reduce carbon emissions (and thus that they deserve the large public subsidies and stealth taxes which sustain the green industry).

But if you understand what's Watt you realise just how stupid and pointless a public treadmill installation is ... and you realise that Siemens knows all this ... and your perception of green industry and imagery changes somewhat. You might find that Siemens' assumption that you the pedestrian are so ignorant that them sponsoring public treadmills is a good idea tremendously insulting.

Probably not, of course. As a Reg reader you probably do know a bit about kilowatt-hours - but for the rest of the population, speaking of other publications and their readers, Siemens and Mr Kemball-Cook are probably pretty safe. ®

Bootnote

1 Just in case you've wandered in from somewhere else: Power is the rate at which energy is being transferred or converted. A Watt of power means that one Joule of energy is being transferred or converted per second. As Joules are very small people often use watt-hours (one watt for one hour, ie 3600 Joules) to measure energy, typically in the kilo-, mega- or giga- ranges. A kilowatt-hour (3.6 megajoules) is one "unit" of domestic energy as seen on a British utility bill.