Checando los blogs que acostumbro leer encontre esto... una forma de ahorar un poco de energia que hoy en dia es muy necesario....
When it comes to new ways of generating energy, it doesn't get any greener than the contraption recently installed in Tokyo's Shibuya train station. Developed by Japan's Sound Power, the FB-0001 platform generates electric power when the hundreds of thousands of station visitors step on its surface.
With the massive crowds that fill Shibuya daily, this brief experiment scheduled to last until Christmas may actually generate so much power that it wouldn't be surprising to see the rail company consider making the platforms permanent. If you think you know an energy efficient location to place the platforms you can rent your own starting at 50,000 yen ($550) here.