That’s right, if the airflow at your air outlet has been used up, then theoretically speaking, it can be used to generate electricity. If you use a fan to blow air for generating electricity, that won’t work, because With every transformation of energy there is a loss.
Furthermore, since the density of air is very small, the energy carried by the wind per unit volume is very small. Therefore, to obtain relatively large power, a wind wheel with a large diameter must be used. Only Only in this way can benefits be produced, and the energy conversion limit of wind turbines is only 0.59, less than 0.6. Generally, large wind turbines are actually 0.5, so wind power generation must be scaled up to achieve benefits.