About the vertical wind turbines installed in the center of highways to use traffic as a source of wind power.

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doesn’t it cause more air drag on the vehicles ? I’m guessing it might be very small but multiplying that by thousands of cars everyday doesn’t it indirectly produce more greenhouse gases than it helps saving ?[highway vertical wind turbine](https://youtu.be/LZrzJXas61E)

In: Engineering
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The drag on the car isn’t going to change a ton, the air on the highway is relatively stationary unless a car is actively traveling through it. The car loses energy to a variety of things from just base fuel consumption to rolling resistance to air resistance, increasing air resistance by 1% doesn’t increase fuel consumption by 1%, but all those wind turbines do cost a lot of money to build and maintain.

The bigger problem is that they produce squat for power. They capture wind in maybe a 2 meter x 0.5 meter area for 1 m^2. A wind turbine with 50 meter long blades (common these days) captures 7800 m^2 There’s a reason we use big spinning discs for power generation rather than the vertical ones

It doesn’t cause more drag on the car. You are merely recovering the energy the car wasted on moving air due to parasitic drag.

In an ideal world, however, we would build cars that are so aerodynamic that drag become negligible, rather than trying to recover energy from the air a car moves. Because there’s a lot of losses and costs involved with recovering energy, so it’s better to not waste it in the first place.

In some cases it’s inevitable to waste energy tho, and a lot easier to recover it. For instance, the waste heat of a power plant. We should focus on this.