Can Electric Cars Convert Kinetic Energy Back into Electrical Energy?

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Discussion Overview

The discussion revolves around the concept of converting kinetic energy back into electrical energy in electric cars, particularly through mechanisms like regenerative braking and potential alternative methods such as using air pressure. Participants explore the feasibility and efficiency of these energy recovery methods while considering the implications of energy conservation laws.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether kinetic energy can be converted back into electrical energy while the car is moving, suggesting the use of a generator to achieve this.
  • Another participant explains that regenerative braking in hybrid cars does indeed convert kinetic energy back to electrical energy, but emphasizes that the energy recovered is always less than what was originally put in.
  • A participant proposes the idea of using air pressure to spin a generator as a means to recover kinetic energy, expressing curiosity about energy efficiency.
  • Another participant counters that using a windmill to extract energy from the air would increase drag on the car, requiring more energy to maintain speed than would be recovered, and suggests focusing on reducing drag instead.
  • It is noted that while extracting kinetic energy through a generator slows the vehicle down, it is more efficient than wasting energy through traditional braking methods.

Areas of Agreement / Disagreement

Participants generally agree that while kinetic energy can be recovered, it is not possible to double the energy due to inherent losses in the system. There is a lack of consensus on the practicality of alternative methods like using air pressure to generate energy.

Contextual Notes

Participants acknowledge the limitations of energy recovery systems, including losses in generators and the impact of additional drag on vehicle efficiency. The discussion highlights the complexities involved in energy conversion and recovery in automotive applications.

Who May Find This Useful

This discussion may be of interest to those studying energy efficiency in transportation, electric vehicle technology, and concepts related to energy conservation and recovery systems.

hwall95
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Just out of curiosity, electric cars produce movement through converting electrical energy into kinetic via magnetic field and magnets, etc; would it not be possible to convert the kinetic energy back into electrical energy while the car is moving. I know the Law of Conservation of Energy says that all sums of energy must be the same both before and after, but if a generator were to be placed to use the kinetic energy acting upon to car to convert it to electrical energy could you not convert most of the kinetic energy back into electrical energy while the car still moves. Sorry i don't know if I've explained it very well. Basically I am asking unless the generator slowed the rotational force placed upon the axle down how come you can't double the energy?
 
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Yes, that is how regenerative breaking works in today's hybrid cars. Except you can't increase the energy, you always get back less than you put in.
 
So the act of using the rotational force of an axle like generator slows it down? What about if they were to channel air through a car and use the force and pressure of the air to spin a generator would they be able to recover the kinetic energy spent in moving the car forward and gather it up again? Sorry if i sound stupid, I'm just trying to think of ways that we could like use energy more efficiently.
 
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Using a windmill to extract energy from the air passing through/over a car would increase drag, meaning more energy is required to push the car through the air. More energy than you capture with the windmill. There would also be losses in the generator. Overall you are better off not using a wind mill and concentrating on reducing drag.

There are times when you want to slow down. A cars brakes waste all the KE the car has gained by turning it into heat. However instead of brakes you can connect a dynamo to the wheels and collect the energy...

http://en.wikipedia.org/wiki/Kinetic_energy_recovery_system

a.k.a. KERS See also Formula 1 racing cars

The extra load of the dynamo/generator acts like a brake and slows down the car.
 
hwall95 said:
So the act of using the rotational force of an axle like generator slows it down? ... Sorry if i sound stupid, I'm just trying to think of ways that we could like use energy more efficiently.
Yes, it slows it down, as does any means of extracting KE. However, it is more efficient than throwing the energy away in the brakes. That is why all hybrid vehicles use the idea.
 

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