Project Idea
My project idea is to figure out if it is possible to increase an electric vehicle's(EV) efficiency with added wind power. My project is research based and to see if I can attach 2 wind turbines to an electric vehicle that can also maintain the vehicle's nice aesthetics along with following certain road laws. This project was done to aid EV's greatest cons, long recharge times and shorter ranges. As my research continued, I learned that it is not possible to increase EV efficiency with wind power.
Hypothesis
If wind-turbines are added to an EV, then the battery efficiency and range should increase
Why I thought this would be a good idea
Along with every great thing comes its cons as well, the typical gas-powered car that we have built society standards on, has been eating away at our planet. The air pollution rates lately have been at an all-time high, and so what did we do? We took the gas-powered vehicle and upgraded it into the electric-powered vehicle. Of course, it's not like EV's have no emissions, but the emissions it does have been way fewer than conventional vehicles. As I said above, 'every great thing has an equally great con.' The electric vehicle has its huge recharge time and typically short ranges. This is not the only, but a great factor to why most people don't convert from a gas-powered vehicle. They are just not efficient enough. So, what if we could delay the need of charging. What if we could increase the distance this vehicle could travel.
All I wanted to do was see if I could improve the efficiency by even a little.
Prior to my research, I hadn't a clue why nothing was being done to implement wind-turbines, so I sought to test and research the theories building in my head. The driving factor towards this project was the following sentence that formed in my mind. "Couldn't we just use the wind created by the movement of a vehicle, to repower the car?" That is how I began thinking of ways I could implement a wind-turbine onto an electric vehicle and how my journey began.
Research
How it works
To start, I knew I was going to need to use an electric vehicle. The reasoning behind this is because I needed to be able to recharge the battery. Next, I figured I needed to know everything about how wind turbines, electric vehicles, and generators work. And so, I did my research about the three topics.
Generators
The operation of a generator is based on the principles discovered by Faraday. He found that when a magnet is moved past a conductor, it causes electricity to flow. Generators convert mechanical energy into electrical energy, by capturing the power of motion and turning it into electrical energy by forcing electrons from the external source through an electrical circuit. Many generators are gas-powered and are generally used to supply backup emergency power at home and farms, whereas wind turbines use natural sources like motion.
Wind Turbine
The wind blows past a turbine, its blades capture the kinetic energy of the wind and rotate which turns it into mechanical energy. The rotation of the blade turns an internal shaft connected to a gearbox, which increases the speed of rotation by a factor of 100. That spins a generator that produces electricity, which is then usually stored in a battery or is used to supply power to an electric grid.
Modern Electric Vehicles
I chose a Tesla Model S to study efficiency improvement with added wind turbines. The Model S uses AC induction electric motors, which achieves an efficiency of 93% and has an overall energy conversion efficiency of 70-75%. Also, the Model S is the most aerodynamic production car in the world right now with a drag coefficient of just 0.208. Components of the turbines could be stored in the front, since the components of the vehicle are in the back/under the vehicle.
So how much electricity can we generate?
To calculate wind power we follow this formula: P = 0.5 × p × A × Cp × V³ × Ng × Nb.
Calculations
(Calculating for a radius of 3 inches)
Why is my efficiency so low?
Because of the Betz Limit, and inefficiencies within the system. The Betz law means wind turbines can never be better than 59.3% efficient. This law is often simply explained by considering that if all the energy coming from wind movement into the turbine were converted into useful energy then the wind speed afterward would be zero. But, if the wind stopped moving at the exit of the turbine, then no more fresh wind could get in — it would, to be precise, be blocked. So, to keep the wind moving through the turbine, and to continue getting energy, there has got to be some wind movement on the surface with energy left in it. There must be a 'sweet spot,' somewhere and there is, which is the Betz limit at 59.3%.
Overall gain/loss
Since I have 2 turbines in my design, I need to double the amount of electricity I am generating, so 11.974 × 2 = 23.944 W.
The Tesla Model S has a battery that can use up to 100 kWh. This means it can use 100,000 W for one hour. The estimated range of the Tesla Model S is around 640 km on one charge (1 kWh can go 6.4 km).
So, hypothetically, the range with the two turbines would increase, right? (adding the little power generated to recharge the battery while driving). Sadly, no. That's because we have 3 different problems with this concept (issues listed from least concerning to most).
Problems with the Concept
First Problem
The average wind turbine begins to produce power at wind speeds of about 4 m/s (9mph or 14.48 km/h). The average wind turbine also stops producing power at wind speeds of about 25 m/s (56mph or 90.12 km/h). That means my car turbine needs to have something to stop the incoming force once the car reaches speeds above 90 km/h. If the wind turbine spins too fast, it will experience mechanical damage and will fail to create electricity.
This problem has many methods to overcome it, since it is a very miniscule issue.
Second Problem
When I implement my two turbines, with them come two generators and many other components that makeup turbines. By adding this, the overall mass of the car increases by a significant amount. When you increase the amount of mass, the coefficient of drag will also increase. When the coefficient of drag increases, fuel efficiency decreases. When fuel efficiency decreases, the range will end up decreasing.
Therefore, the range would not increase with two turbines.
Is there a solution?
You're probably thinking, what if we could manage to decrease the weight to an amount where it wouldn't affect the coefficient of drag by a lot. Hypothetically, yes. Theoretically, no. That's because we have a third problem.
Third Problem
Since the turbines are getting powered by the wind that is created by the movement of the car (using the car's power). It essentially is reusing energy/creating its own energy. The battery powers the car to move forward (which uses energy); the turbines pick up the wind once the car gets to a high-speed; the energy produced is then transferred back to the battery; therefore, the energy that was stored in the battery before it is looped right back to where it began. This process would actually go on forever if both the turbine's and car's efficiency was 100% which we already know is not possible, but the big problem with that is it violates the first and second laws of thermodynamics. In order to power the Model S even a little more than 6.4 km/1 kWh, we would need to get something from nothing, and we cannot create our own energy. This is because the total amount of energy and matter in our universe stays constant.
Why does it not work?
The first law of thermodynamics is the law of conservation of energy. It states that energy is always conserved. It means that energy can be neither created nor destroyed. Instead, it simply changes from one form to another. To keep a machine moving forever we would need to reuse the energy without any loss. This would be impossible with the fact that a turbine can't even have an efficiency of over 59.2% and cars can't have an efficiency of 100%. If the car was capable of pulling this off, it would be considered a perpetual motion machine, which is a hypothetical creation. The second law of thermodynamics also makes this impossible, it states that the entropy of a system always increases. Since we are reusing energy in my design, it would have to produce work without energy input, the system would move into a state of disorder, the more energy is transformed, the more of it is wasted. A wind-powered car would have to have energy that was never wasted and never moved toward a disordered state. Proving, you can't get something from nothing and cannot create your own energy.
Results
This concludes the hypothesis:
Contrary to the general belief that wind machines on a car should generate electric power, I have figured it is not true.
If wind turbines were added to any EV, then the efficiency and range would decrease rather than increase.
Past creations
I bet you're thinking, "so how come I've heard of wind-powered cars before?" Well, the answer to that is simple, because they have been made before.
But, as I proved up top, they would be pretty useless compared to today's commercial vehicles. To accomplish a wind-powered car, we would need 3 things.
First, to generate the thousands of watts a car needs to work, we would need to attach a huge turbine to the top of the car along with a mast as well. This ordeal itself would turn me around from buying it. Also, it would be very expensive, have a ton of safety issues, and wouldn't function as an everyday use vehicle.
Second, we would need to follow the wind since we dictated it's not possible to use the opposing wind-generated from the vehicle itself moving. This means the vehicle would only work at high speeds if wind speeds were high, which kind of ruins the use of a modern-day vehicle.
Third, we would need a very small and nimble build. This is because since the wind can't power much, we need a high fuel efficiency. The only way to get that is with a low drag coefficient, meaning the vehicle would need to be really tiny.
Being completely real, this would be those most impractical invention ever.
Future work
Since I learned wind-power has a very small amount of implementations, and a very limited range in where it can work. There is not much that is possible with production wind powered cars.
Design
This is an image of what I wanted my vehicle to look like:
Work Cited
- International Journal of Scientific Research Publications. "Research Paper February 2012."
Available at: ijsrp.org/research_paper_feb2012/ijsrp-feb-2012-06.pdf - Lenovo News. "Chinook Wind-Powered Cars: Future of Travel."
Available at: news.lenovo.com/chinook-wind-powered-cars-future-of-travel/