this post was submitted on 02 Jul 2025
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[–] [email protected] 3 points 2 days ago (2 children)

You're eating the air resistance anyway so probably not the worst idea if it generates a more than negligible amount.

[–] [email protected] 26 points 2 days ago* (last edited 2 days ago) (1 children)

It will increase air resistance, so you don't gain anything (a turbine will need more power to spin when there is an electric load).

[–] [email protected] 3 points 2 days ago (2 children)

It will increase air resistance,

Not if you position it, say, in front of the car so that you're getting energy without getting hit without much additional force. If you somehow don't need to see, the whole front of the car can be turned into a turbine. Now obviously we're not making a perpetual motion machine here, but this could theoretically be the air resistance equivalent of regenerative braking.

[–] [email protected] 1 points 23 hours ago

Still increases air resistance. It gets hit by air, and that pushes it back into the fuselage.

Larger aircraft commonly have a ram air turbine (RAT) or Air Driven Generator (ADG) to provide some electrical power and hydraulics in certain emergency situations.

On CRJs, it's right up the front: https://www.youtube.com/watch?v=MxgPrpjByTE

Still delivers a percent or two penalty to fuel burn, and the tiny little generator doesn't even come remotely close to making up for that.

[–] [email protected] 10 points 1 day ago (1 children)

It doesn’t work because the car’s front is shaped to minimize drag, and a turbine would add drag — forcing the motor to work harder to maintain speed. Turbines generate energy by resisting airflow, not letting it slide past. So you’re not harvesting free energy; you’re paying for it with more fuel or battery.

[–] [email protected] 1 points 23 hours ago

So you’re not harvesting free energy; you’re paying for it with more fuel or battery.

Of course it's not free energy, but strictly theoretically if the turbine, say, doubles the air resistance in the area where it's installed and works at 80% efficiency, then instead of losing A amount of power you're losing 2A and getting 1.6A, for a total of 0.4A net loss. Now I have no idea if these numbers are even remotely realistic, but that's kind of beside the point. Of course the turbine would simply be turning battery into less battery, but that's better than the car's front turning battery into no battery.

[–] [email protected] 4 points 2 days ago

You have just invented a perpetuum mobile machine. The turbine will power the car which, whilst moving, will in turn power the turbine. Pure genious.