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Idea A Day
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Welcome to Day 2601

Create an electricity power generator from peoples' footsteps. The
generator would be installed under the flooring of busy public places,
such as bus or train stations. When people walk, the device will generate
electric power which can be used for lighting.


Is this possible?

It's possible -ish!

Was it this forum where someone brought up the subject of generating electricity with a shoe which harnessed the energy lost when you walk? I seem to remember someone had invented a shoe which recharged a mobile phone. Maybe it was another forum; can't remember.

The back of my favourite envelope showed that in order to do this there has to be some degree of compressibility in the sole of the shoe, and this is what would enable a device to generate electricity.

But the downside of it was that you would, in effect, be forever walking up a never ending series of little steps, as you have to step up onto the uncompressed sole, which then compresses as you add weight to it. This may not be noticeable over short distances, but that extra energy input is real, and has to be accounted for; over a thousand steps you may notice it more. And, just to underline the law in physics that says you cannot create energy from nothing, you would have to consume more calories in order to do all this.

I guess you would be faced with a similar situation if you built some sort of generating device into floors; even a piezoelectric device (which would seem the most obvious way of achieving such a thing) has to be physically stressed to produce its output, so you'd have to build some sort of compressibility or 'flex' into the floor.

Maybe it would be possible to rig up arrays of sound (or vibration) sensors under floors. This may work by absorbing some of the sound energy that is produced as you walk, but it is a very small amount of the energy put into walking. It'd work better on noisy floors, like bare wood, and maybe some fashion designer could make clogs popular again. But then again, if you don't absorb that sound energy with electro-producing devices, it will ultimately be converted into heat anyway (admittedly tiny amounts of it), so in the situation of a building, you would need to factor this heat loss into the equation.

I feel sure that there are other factors involved as well, but theoretically it would be possible to install such a thing under floors, etc., but in some cases they would be noticeably harder work to walk across. Also, it would probably be immensely expensive to produce and install such things, to say nothing of the energy involved in digging up all the bus and train stations to do so.

Muddypause wrote:And, just to underline the law in physics that says you cannot create energy from nothing, you would have to consume more calories in order to do all this.

Nope, I wouldn't!

me neither.

Great way to get fit and lose weight. When can I install such a floor in my house, office, perhaps even the path to the hen house? Then it's just a case of getting the local council to install the system into all the footpaths around here - oh well, I can dream.

Zoe

Might be a go-er - a coupple of MIT students are looking at the same sorta thing - have a look at this link for more info:
http://www.csmonitor.com/2007/0926/p14s02-stgn.html


alright it's the CSM so is probably hoplessly optimistic and cloud cookoo land but is fun to read all the same

Muddypause wrote: I seem to remember someone had invented a shoe which recharged a mobile phone. Maybe it was another forum; can't remember.

Trevor Bayliss (Inventor of the windup radio) proposed this idea a couple of years ago - Article

Muddypause wrote: And, just to underline the law in physics that says you cannot create energy from nothing, you would have to consume more calories in order to do all this.

Using this theory, what about hooking up all those excerise machines/tread mills,bikes in all the gym's to the grid. It'd be harder work so you would loose more weight/buff up better

THe more I think about it the more it appeals, you see all those numpties cycling away, I bet they generate quite a bit of power. You could use it to power the gyms sauner, or hot water.

I don't think the raw energy produced during your average gymmite's workout would power much; it would make sense to draw the power for the exercise machine's onboard computer from it, but it probably wouldn't keep the TV going.

I use my spare energy from my daily exercise routine to propel me to and from work. That works nicely. I'm hoping to use more spare workout energy in the future to keep my allotment cultivated. Fingers crossed.

As for the "moving floor tiles generate enough electricity to light the building" idea: it doesn't take much effort to spot the flaws. Firstly, people move in crowds and, where one person is stepping off a tile, there are probably a couple more stepping back on before it completes the "up-down" cycle which one would asume would be necessary for generation. This "up-down" cycle has to draw energy away from somewhere (no free lunch, according to laws of thermodynamics) and in this case it would come from the legs of the pedestrians. In essence, the floor in question (if it was populated sparsely enough to work) would feel like a cross between a treadmill and a steperciser - each step would be "uphill".

Reminds me of an idea someone had to put windmills along the sides of roads to power cars from their own slipstreams or some such nonsense. At the end of the day, the energy has to come from somewhere. Preferably the sun in one form or another...