They were suspended from ropes as they used heavy air-powered hammers to break any loose rock away from the face of the canyon walls.

VOA: special.2009.08.12

The whole thing is being powered by sending heat from the hot to the cold reservoir.

所要做的所有事情,就是把热量从高温热源输送到低温热源。

麻省理工公开课 - 热力学与动力学课程节选