I’m not sure why every NYC high rise doesn’t have one of these, but the Energy Generating Revolving Door is really a no brainer.  A transparent glass ceiling inside the door shows off the door’s inner workings and displays the amount of energy created.  The door will produce up to 4600 kwh of energy each year, but times that by all the revolving doors in one city and we’re talking decent numbers.

[Inhabitat]