mr2peak wrote: Really guys? I'm having trouble believing anyone is taking this thread seriously. I think we're being trolled.
Nope, no troll. I was thinking about wind turbines, and the idea popped into my head. Obviously, I'm not the engineer here, so I figured that if it were really that easy, it would already have been done. That's why I come to GRM to find out the real answers to my questions.
That's why I ended the post with "tell me why I'm wrong..."
Wind turbines are the bane of my work existence. Whoever thought they should be hooked up to the grid should be flogged.
Am I the only one old enough to have had a set of lights on my bicycle powered by a generator? Flip that lever and shift down a gear to pay for the illumination with speed.
Am I the only one old enough to have had a set of lights on my bicycle powered by a generator? Flip that lever and shift down a gear to pay for the illumination with speed.
Three letters that would have changed your childhood: L E D
Many of as already do have alternators in our wheel hubs.
Just so happens that they like to call them 'ABS sensors'
One system that can work for converting combustion into electricity and then into motion (kinetic energy) is if you have a combustion powerplant that is very efficient at producing energy from a cheap fuel but only with a very limited powerband (e.g. jet turbine). You then hook that into an alternator to charge batteries to run an electric motor that is very efficient at converting electrical energy into momentum across a very wide powerband, but has a power source that tends to be heavy for the amount of energy stored.
BobOfTheFuture wrote: Many of as already do have alternators in our wheel hubs. Just so happens that they like to call them 'ABS sensors'
that explains why new cars don't get much better mileage than they did 25 years ago- the extra drag is making the engine work harder..
novaderrik wrote:BobOfTheFuture wrote: Many of as already do have alternators in our wheel hubs. Just so happens that they like to call them 'ABS sensors'that explains why new cars don't get much better mileage than they did 25 years ago- the extra drag is making the engine work harder..
Most of the gas mileage struggle is due to weight and accessories! I have a 1991 (22 years..sue me) Escort with as little stuff as legal from the factory. 33/50 mpg are pretty normal, but...I'm willing to bet that a similar HP engine (100 HP) from today would show an increase in gas mileage.
Bruce
egnorant wrote: Most of the gas mileage struggle is due to weight and accessories!
Yes!
My old '88 626 weighed around 2700 lbs. and routinely got 36 mpg highway. A '13 Mazda 6 weighs around 3200 lbs. and gets 30 mpg highway. This is progress?
Beer Baron wrote: One system that can work for converting combustion into electricity and then into motion (kinetic energy) is if you have a combustion powerplant that is very efficient at producing energy from a cheap fuel but only with a very limited powerband (e.g. jet turbine). You then hook that into an alternator to charge batteries to run an electric motor that is very efficient at converting electrical energy into momentum across a very wide powerband, but has a power source that tends to be heavy for the amount of energy stored.
gas turbines (what you really meant I think) are efficient if they are big. They are inefficient if they are small. Even the biggest versions you can find (9 series) are only getting the efficiency they get (very very good, near 60%) because of the combined cycle plants they are in, and not just the gas turbine itself.
Maroon92 wrote: If the wheels are already turning, then why would it cause any additional drag to have them generating electricity at speed?
The best way to demonstrate this is to hook an alternator up to a bicycle thru one of those 120v inverters. Then pedal it with no load... then try to make coffee. You would be surprised how much effort it takes to pedal 1500 watts.
Giant Purple Snorklewacker wrote:Maroon92 wrote: If the wheels are already turning, then why would it cause any additional drag to have them generating electricity at speed?The best way to demonstrate this is to hook an alternator up to a bicycle thru one of those 120v inverters. Then pedal it with no load... then try to make coffee. You would be surprised how much effort it takes to pedal 1500 watts.
That's why the turbines and generators for hydroelectricity need the potential energy of a huge lake behind them channeled through a comparatively small tube to spin them to supply electric power. It takes EFFORT to spin those magnets when everybody is sucking power from the grid. Check out the size of these:
RossD wrote: Think of an airplane.
What if I put that airplane on a Large treadmill that matched it's forward speed? Would it ever take off?
This discussion was a fascinating and very educational read. This is why I love GRM.
that explains why new cars don't get much better mileage than they did 25 years ago- the extra drag is making the engine work harder..
LOL
What if I put that airplane on a Large treadmill that matched it's forward speed? Would it ever take off?
LOL
nocones wrote:RossD wrote: Think of an airplane.What if I put that airplane on a Large treadmill that matched it's forward speed? Would it ever take off?
it would if the Mythbusters were the ones doing it...
then something would explode.
It would happen even if the Mythbusters weren't testing it. Air speed is not ground speed. I really don't understand why that was even taken seriously. It's a grade school science fair experiment at best. Now, the "best way to deal with a grenade" testing, that was fun...
I don't know if this has been put into practice, but I've heard a clever proposal to integrate the alternator, flywheel and starter with an electric motor. Starter is easy enough to understand. So is alternator, and it could also provide regen braking. To replace the flywheel, little bursts of power (or little drops in the drag, I guess) could smooth out the pulses. Package it in the current flywheel location and you've cleaned up your install. Might be one of those solutions that is more complex than what it's replacing without much benefit though.
So to clarify your post, Mr Tanner, you are thinking the electric motor would replace the flywheel through some type of software or electrical programming that would offset the pulses (like noise cancelling headphones)?
I figured the weight of the motor would do it.
Keith Tanner wrote: I don't know if this has been put into practice, but I've heard a clever proposal to integrate the alternator, flywheel and starter with an electric motor.
In the case of automatic transmissions - it could just be part of the trans packaging itself. Neat idea but... aside from the ability to dynamically change the rotating mass of the flywheel - it is a lot of added static sprung weight and expense for the motor, bearing and engagement wizardry for a lateral functionality wise.
Although it resembles Porsche's regenerative flywheel solution in packaging and that worked pretty well.
The Prius already integrates the starter into one of the electric motors. IIRC the flywheel contains the magnets for regen braking as well. I think it uses the 12v battery and conventional alternator only to get the 'starter' to initially move and to run the 12v accessories like the lights radio etc.
Keith Tanner wrote: It would happen even if the Mythbusters weren't testing it. Air speed is not ground speed. I really don't understand why that was even taken seriously. It's a grade school science fair experiment at best. Now, the "best way to deal with a grenade" testing, that was fun...
I'm assuming (or hoping very hard) that it was only ever brought up here as a reference to the absurdity of the Mythbusters episode.
Now I did once make the mistake of reading the Mythbusters forum surrounding that episode. 
Giant Purple Snorklewacker wrote:Keith Tanner wrote: I don't know if this has been put into practice, but I've heard a clever proposal to integrate the alternator, flywheel and starter with an electric motor.In the case of automatic transmissions - it could just be part of the trans packaging itself. Neat idea but... aside from the ability to dynamically change the rotating mass of the flywheel - it is a lot of added static sprung weight and expense for the motor, bearing and engagement wizardry for a lateral functionality wise. Although it resembles Porsche's regenerative flywheel solution in packaging and that worked pretty well.
The transmission in the hybrid Suburban etc is done that way. The reason was the unit can be used behind different engines. GM, Mercedes and Chrysler developed it together, the initial applications were the Suburban and the Durango.
Keith Tanner wrote: It would happen even if the Mythbusters weren't testing it. Air speed is not ground speed. I really don't understand why that was even taken seriously. It's a grade school science fair experiment at best. Now, the "best way to deal with a grenade" testing, that was fun... I don't know if this has been put into practice, but I've heard a clever proposal to integrate the alternator, flywheel and starter with an electric motor. Starter is easy enough to understand. So is alternator, and it could also provide regen braking. To replace the flywheel, little bursts of power (or little drops in the drag, I guess) could smooth out the pulses. Package it in the current flywheel location and you've cleaned up your install. Might be one of those solutions that is more complex than what it's replacing without much benefit though.
There's so much perpetual motion talk in here, I almost missed this actual concept discussion. Just so you know, Keith, GM already had this in production about ten years ago for their first series of hybrid trucks, before the "dual mode" system they use in production now. They called it the "Parallel Hybrid Truck" but it was really a very mild hybrid; it used a flywheel generator/starter combo in between the standard transmission and engine on the 1500 trucks. These trucks had no alternator or starter as we know them normally, and they shut the engine off when the vehicle was at low speeds. It's a pretty slick system except that it uses some lead acid batteries instead of modern NiMH or lithium, which would be leaps and bounds better. The trucks even had an inverter to provide 120V power for construction sites, no generator required...you've already got a V8 generator in your truck!
Edited to add a picture:
Bryce
For those thinking there's "free" electricity just because a thing (like a wheel) is spinning, didn't you ever ride one of these at the science fairs as a kid?
http://www.youtube.com/watch?v=KmJoXPHkH9I
It takes energy to make energy! If you add a generator load on a device, that device has to get the energy from somewhere to generate more energy...no free lunch.
Bryce
I like the truck implementation. It's quite possible that I heard about it when this was first introduced on the trucks.
I've noticed that autos don't really use flywheels - maybe the torque converter weighs enough for that. So it would make sense that it would be easier to integrate on an auto.
As for perpetual motion machines, I worked with a couple of friends on a science fair project addressing this in high school. I made the machines, they had to explain why they wouldn't work. Most fun science fair ever.
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