Re: bild it your self (D.I.Y enegy)

[j_pigden]

Energy can be neither created nor destroyed, only transformed.

Having quoted that, let me ask where the energy to turn the fans comes from? A windmill uses solar energy third-hand. The sun heats the earth; earth heats the air; air moves windmill. Fan attached to front of car decreases fuel economy; entropy says energy gained is lower than the energy value of the fuel because of inefficiency of internal combustion engine, and energy losses in the re-conversion and storage processes.