If a wall of "sound-a-volt" generator cells 200 feet long x 15 feet high were installed along side of an airport runway or along the sides of a subway tunnel, it could produce an output of current of 120 amps x 20 volts or 2400 watts of power. Here are some numbers, 200ft, x 15ft.= 3000 x 144 sq. inches x 2 = 864,000 sq. inches. Each "sound-a-volt" generator cell (which is a 5-cell unit) requires an installation area of 36 sq. inches. which when divided into the number as noted above =24,000 cells in all. Each 5-cell unit will generate a current of approximately .005ma x 24,000 cells =120 amps. x 20 volts or 2400 watts of power. If the output voltage of 5-cell unit could be increased to 110 volts, the output would be 13,200 watts of power (120 x 110 = 13,200 ). This is just an estimate of the possible power that this "sound-a-volt" generator system could produce and more. Not bad for something that produces such a low current per cell unit, but when multiplied look what happens...Never overlook the small....Epower