翻译：这句话主要想表达的意思是吹气会造成能量消耗但同时也减少了列车阻力减阻相当于节约能量二者之差即为吹气所需要的额外能耗。

The main idea behind this sentence is that blowing air causes energy consumption, but at the same time it reduces the train's resistance, which is equivalent to saving energy. The difference between the two is the additional energy consumption required for blowing air.