Another people powered energy system!
The actual impact of a human foot step is rather slow and spread out so the transfer of recoverable energy from it is incredibly small! A full day of people walking over a city block of piezo electric transducers would probably not even light up one compact high output LED for more than a hour or two.
Spending tens of thousands of dollars and many hours of human effort to convert one city block worth of sidewalk over to get a hour or two of light in a 100 sq ft area would not be very practical and never cost effective. One roof top solar array with the whole city blocks lighting system set up with LED's would be way cheaper and far more practical and cost effective.
The typical energy the sun puts down on a square foot of earth is around 15 -60 watts per hour over the seasons.
Even capturing 5% of that energy over a 12 hour period is several magnetudes of order or higher than that of the capturable energy that human foot steps can create inthat same area.
I did this writeup a while back but to give you the more realistic numbers to how people equate to usable power I though it would be a worthy repost.
Why Humans are poor sources of energy.
Here is a real life or more toward real life power example. one horsepower = 746 watts. Horsepower in its simpler definition is thats the continuous power a good sized healthy horse can produce. Scale that to good healthy human and you get 1/10 that or about 75 watts continuous. Remember thats continuous rate not peak rate! For a short burst a big healthy athlete can top 1500 watts on one of those generator bikes. I have seen a college football player do it! but for only a few seconds. I could do around 1200 watts at the time but again short burst. One person did 200 watts for about five minutes, A cyclist and great cardio health too.
A person walking without effort is real low, under 10 watts. The only time most people even get close to the 75 watt output is taking the stairs. And how many do that by choice!
Convert Calories to watts. 1 calorie is 1.16 watt hours. So a 2000 calorie a day diet means the average person runs on 2320 watt hours of power. Factor in the estimated calorie drain of just being alive is around half of that or more. You have less than 1 kw of mechanical energy to put to work per day.
So how many people does it take to equal what your average house uses? mine is around 1200 kwh a month. 1200/30/24 = 1.6666 kw continuous load. hmm, I would need about 23 very healthy slaves to keep my house going. give them 8 hour shifts and I would need 69 plus support to feed and keep up everything, now I am up around 80 plus!
Convert that to lazy free will people and its probably ten times that! hmm... hmm... hmm!!! 800 people to run my house! But now who is running their houses while they run mine?
But seriously people power is just not cost effective. There is a reason slaves got replaced by machines as the world industrialized.
Sorry if I just rained all over someones idea. again.