Quote from someone on Reddit more knowledgeable than myself:
"The turbine is taking energy directly from each vehicle passing by. Yes, its a tiny amount, but it is not zero.
There was a fast food place about ten years ago that installed a system to generate "free" electricity from the cars going through it's parking lot. There was a speed bump that was pushed down by the cars driving over it. To overcome the tiny bit of resistance of pushing down the bump, the cars had to burn a tiny bit more fuel. Sure, it was a tiny bit from each individual car, but it was directly sapping the energy from each car that went over it and was not "green" like the company selling it claimed it was." ~ u/nemom
Basically, these things are not free energy; they're windmills powered by petroleum.
If you're wondering about the cost to the car, the quote continues:
"Granted, the turbine is better than that, but it is still sucking a tiny bit of energy from each passing vehicle. For a vehicle to move, it has to push the air in front of it out of its way. If there are obstructions to the air moving out of the way, the resistance to the vehicle is higher and it needs to expend more energy to move. Again, it is a tiny amount per obstruction, but it is not zero."
"The turbine is taking energy directly from each vehicle passing by. Yes, its a tiny amount, but it is not zero.
There was a fast food place about ten years ago that installed a system to generate "free" electricity from the cars going through it's parking lot. There was a speed bump that was pushed down by the cars driving over it. To overcome the tiny bit of resistance of pushing down the bump, the cars had to burn a tiny bit more fuel. Sure, it was a tiny bit from each individual car, but it was directly sapping the energy from each car that went over it and was not "green" like the company selling it claimed it was." ~ u/nemom
Basically, these things are not free energy; they're windmills powered by petroleum.
"Granted, the turbine is better than that, but it is still sucking a tiny bit of energy from each passing vehicle. For a vehicle to move, it has to push the air in front of it out of its way. If there are obstructions to the air moving out of the way, the resistance to the vehicle is higher and it needs to expend more energy to move. Again, it is a tiny amount per obstruction, but it is not zero."