Yeah, it could make power, but fans tend to draw a lot of amperage. Your alternator would be putting out much more amperage than normal. This higher amperage draw from the alternator makes it harder for the engine to turn it.
Thus, the power that is gained from an electric turbocharger would most likely not be seen due to the added rotational resistance from the alternator.
It's kinda like when you put your AC on, and you notice a loss of power. The AC compressor adds rotational resistance just like an alternator would if more current was being drawn from it.
You could probably power the electric turbocharger with an additional car battery in the trunk. Power gains would be noticed then. The turbo charger motor would definetly need to be mated to a gear box in order to get sufficient boost. The only down side is, you'll only get boost when the battery is charged. It would be like having NOS, when the battery is outta juice you have to recharge it. Actually its probably better than NOS because you won't have to pay to recharge it.
I might have to try this myself!!
hope this helps.