This would depend on the total surface area of roofs in a city.

VOA: special.2010.03.02

the total amount of the work that we can get out is just given by the area inside this curve.

能够输出的功就是,我们可以得出来,曲线所包围的面积。

麻省理工公开课 - 热力学与动力学课程节选