You can see a little fan in the cover image of this post. It is a brush less DC Fan. You can see such type of fans inside your CPUs and U.P.S systems.
It consumes just 2.2 watts of electricity and is very economical in this regard. The power consumption is low but the air is cool. It may work well at the times of electricity breakdown.
You can use it as an exhaust fan in your kitchen or washroom. It is not meant for this purpose but its performance is awesome.
You can ask a mechanic to join some 3 to 4 fans as per your requirement.
Image source : Image is my own