定义：
是指燃料电池能输出最大的功率除以整个燃料电池系统的重量或体积（或面积），单位是瓦/公斤或瓦/升。

• 对于电池来说，一般是W/Inch3, 即每立方英寸平均输出功率。
• 即比功率(比功率是衡量汽车动力性能的一个综合指标，具体是指汽车发动机最大功率与汽车总质量比)。水电站开发公式：功率密度=总装机容量/该电站满水位时水库淹没的表面积。
• 反应堆功率密度为单位体积核燃料在单位时间内由于核反应释放出的热量。

Definition: intensity or power per unit frequency interval

German: Leistungsdichte

The term power density is sometimes used as a short form of power spectral density in the context of noise specifications. In other cases, it is meant to be an optical power per unit area, but optical intensity or irradiance is then a more appropriate term.

In order to avoid such confusion, it is recommended to avoid the use of this term altogether, unless the context makes clear which meaning is used.