razing skyscrapers from the inside

Generating energy when skyscrapers are being demolished, using a method environmentally safer and more energy-efficient. Much like how hybrid cars generate energy when their brakes are applied, the cranes can do the same when lowering debris inside the building. The power they make can be used to run lights and other equipment:

http://www.japantimes.co.jp/news/2013/01/08/national/razing-skyscrapers-from-the-inside/