The idea of mounting a windmill on the roof of a car to generate electricity to recharge the battery is an excellent idea, if only the concept of aerodynamic drag is a myth!
There is no short supply of innovation and ingenuity in our country. For example, our space program is as advanced as it gets and it costs a fraction of what other leading nations spend on their missions out of this world. Popularly called as the Indian jugaad, the innovative spirit of our nation is well known the world over.
We do come up with startlingly simple and efficient solutions to complex problems while simultaneously being penny wise. However, sometimes, we end up stretching the concept of jugaad a bit too much it loses its purpose. Case in point: this Tata Nexon Electric with a humongous windmill on its roof!
Tata Nexon EV with built-in windmill
On first glance one would call the idea of planting a windmill on top of an electric vehicle rather interesting. The set up, which was spotted on a vehicle registered in Rajkot, appears to be used to generate electricity off the wind to replenish the battery pack.
While this endeavor is sure to get brownie points in a high school science exhibition for its out-of-the-box thinking, in real world, it would do more harm than good. Take a look at the innovation at work, in the video below.
Physics of longitudinal performance is simple. A car’s powerplant needs to overcome the resistive force acting on a vehicle in order to move it. The primary components of this resistive force are the vehicle’s own weight and its horizontal component due to road slope, aerodynamic drag, and tyre rolling resistance.
The last two components are functions of velocity and become very significant as speeds build up such as in a highway scenario. In other words, reducing aerodynamic drag is fundamental to reduce the energy consumption of a vehicle.
So, if you think about it, putting a gigantic windmill which dramatically increases the aerodynamic drag and makes the electric traction motor work a lot more than it has to is an anti-thesis of efficiency. In a nutshell, the additional energy consumption due to the drag generated by the roof-mounted windmill would more than off-set the electrical energy it produces and stores in the battery pack.
Plus the whole contraption looks ugly and poses a safety risk to the vehicle itself and fellow road users. At high speeds, say 120 kmph, the forces acting on the mounts would be very significant that it could cause structural failure if not designed properly. And proper design is not the first thing that comes to our mind looking at this contraption.
If you are an electric vehicle owner and if you feel the urge to improve its net energy utilization, a solar panel on the roof would be a better idea than a windmill. After all, ours is a country of bright sunshine throughout the year.