I have read about people being asked this question before but I never anticipated hearing it myself. Yesterday a neighbor asked why, as technically advanced as we are, we couldn't create a mechanism for electric vehicles to charge themselves as they were being driven using the momentum of the vehicle. This from a really nice guy who is a very good neighbor. The answer seems so terribly obvious to me that I am at a loss as to how to explain it to someone without a science background in a way he will understand without being rude or demeaning. I offered examples of comparisons but they didn't seem clear enough to make my point. Assistance, please.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
How do I explain this?
- Thread starter Beasts
- Start date
I see that comment all the time in comments on EV articles, and it's almost always accompanied by conspiracy theory nonsense about how "THEY" won't allow that to happen, because it would prevent "THEM" from charging people money for recharging.
So a couple of ideas for answering this.
People get this idea because they think that generators just spin freely and generate energy without taking force. So they see something spinning, like the wheels of the car, and think they can add however many generators of whatever size they want and just collect free energy from it, without affecting the movement of the wheels or requiring any extra input energy.
But suggest this idea. Have you ever been to one of those hands-on science museums? Have you been to the display where they have a stationary bike with a generator on it, so you can see how energy is generated from force? You get on the bike, and pedal, and it lights up a light bulb. But then as you connect a 2nd bulb and a 3rd bulb, it gets harder and harder to pedal because there is more load, and you're having to put in more force to generate more energy output.
Another thing is to remind people that generators and motors are strictly energy CONVERSION devices. They don't produce energy out of nothing. It is taking rotational kinetic energy and converting that amount (minus losses) into electrical energy. So any electricity you want to collect out must come from EXTRA rotational kinetic energy put in! The other part is to remind them that this is a closed loop system. It is having to take extra energy from the battery, to convert through the motor into kinetic energy, to then convert back through a generator into electricity, to then put it back into the battery. It's not gaining anything from anywhere. It's just doing two conversion steps in a circle. And in each conversion, nothing is perfectly efficient, so at 90% efficiency, you're taking 1 unit of energy, converting it and getting 0.9, and then converting it again and getting 0.81. Great--you just wasted energy while gaining nothing.
So a couple of ideas for answering this.
People get this idea because they think that generators just spin freely and generate energy without taking force. So they see something spinning, like the wheels of the car, and think they can add however many generators of whatever size they want and just collect free energy from it, without affecting the movement of the wheels or requiring any extra input energy.
But suggest this idea. Have you ever been to one of those hands-on science museums? Have you been to the display where they have a stationary bike with a generator on it, so you can see how energy is generated from force? You get on the bike, and pedal, and it lights up a light bulb. But then as you connect a 2nd bulb and a 3rd bulb, it gets harder and harder to pedal because there is more load, and you're having to put in more force to generate more energy output.
Another thing is to remind people that generators and motors are strictly energy CONVERSION devices. They don't produce energy out of nothing. It is taking rotational kinetic energy and converting that amount (minus losses) into electrical energy. So any electricity you want to collect out must come from EXTRA rotational kinetic energy put in! The other part is to remind them that this is a closed loop system. It is having to take extra energy from the battery, to convert through the motor into kinetic energy, to then convert back through a generator into electricity, to then put it back into the battery. It's not gaining anything from anywhere. It's just doing two conversion steps in a circle. And in each conversion, nothing is perfectly efficient, so at 90% efficiency, you're taking 1 unit of energy, converting it and getting 0.9, and then converting it again and getting 0.81. Great--you just wasted energy while gaining nothing.
Upvote
0
henderrj
Active Member
Last night I was at dinner with my brother, a tech genius. He was all excited about a project he'd seen online. The guy had a fountain with a little stream with three waterfalls. So he puts three generators one at each waterfall. That way they generate enough electricity to keep the stream going indefinitely. When I pointed out that that would make it a perpetual motion machine, he couldn't see it. "Oh no, they have three generators so it's not like that" Sorry, loss in this world is real. You can't have something for nothing. Same with electric cars.
Upvote
0
Another couple of things I forgot to mention that I hear from people. A lot of people think that manipulating the ratios with different gearing is somehow a magical way around the physics, so it can somehow multiply or duplicate the energy.
And the other one is that a lot of times it's not about the conspiracy theory, but people think we are objecting because it is simply a very difficult problem that hasn't been solved YET. They say things like, "Well people thought _______ was impossible 100 years ago, but we solved that!" It's hard to convince them that this IS NOT simply difficult. It is really, literally impossible. It's not that it's not known how to do it. It is fully completely KNOWN exactly why this CANNOT EVER work at all--provable with equations and everything.
And the other one is that a lot of times it's not about the conspiracy theory, but people think we are objecting because it is simply a very difficult problem that hasn't been solved YET. They say things like, "Well people thought _______ was impossible 100 years ago, but we solved that!" It's hard to convince them that this IS NOT simply difficult. It is really, literally impossible. It's not that it's not known how to do it. It is fully completely KNOWN exactly why this CANNOT EVER work at all--provable with equations and everything.
Upvote
0
Yes, that is another good thing to point out. This process is energy conversion. If you are taking it out as electricity, that means by definition, it is taking it away from the motion of the car to convert it. So you can recover energy that was already in the motion of the car, which slows it down, and that's better than just wasting it. But you can't collect it while it's still there in the car's motion. It can't duplicate like that.
Upvote
0
Ostrichsak
Well-Known Member
What you are describing is a perpetual motion machine and the basic premise defies known physics. You need energy to overcome the forces of gravity and wind resistance due to a body at rest remaining at rest unless acted upon by an outside force. No conspiracy theory. Physics 101.
Upvote
0
Excellent!! My thanks to all of you for all of your contributions. Our neighbor seems like someone who really wants to understand so I'll give it my best.
I must add that during our conversation we discussed the advances in farm machinery and he described a serious new tractor a friend had just purchased and mentioned that it had 585 horsepower. I couldn't help but casually point to our S LR and tell him it has 670 horsepower. And that leads me to another question - would a diesel engine with the same horsepower as an electric motor have more or less torque or would that ratio somehow vary. I believe that gas engines develop less torque than comparable diesel engines but I don't know how diesel compares to electric except that the electric torque is available immediately. Inquiring minds....
Thanks again
I must add that during our conversation we discussed the advances in farm machinery and he described a serious new tractor a friend had just purchased and mentioned that it had 585 horsepower. I couldn't help but casually point to our S LR and tell him it has 670 horsepower. And that leads me to another question - would a diesel engine with the same horsepower as an electric motor have more or less torque or would that ratio somehow vary. I believe that gas engines develop less torque than comparable diesel engines but I don't know how diesel compares to electric except that the electric torque is available immediately. Inquiring minds....
Thanks again
Upvote
0
Similar threads
