Naked Science Forum
Non Life Sciences => Technology => Topic started by: greenslime on 22/03/2010 18:20:35
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Since we are getting a new washing machine I have decided to use the old washing machine motor in my experiment to generate electricity.
What I plan to do is hook up my bike to a static stand and connect the rear wheel to a pulley kind of system to the washing machine motor to generate electricity to charge a 12V Car battery which I will then connect to an DC/AC inverter to see what I can use it for. See diagram for hopefully a clearer picture of what i mean
What kind of calculations do I need to work out and what kind of things should I be aware of?
Thanks
P.S the diagram sucks because i tried to do it using the touchpad on my laptop. It wouldnt have been much better though if i used a mouse
[diagram=579_0]
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Steal be inspired by this product idea (http://www.econvergence.net/electro.htm).
You need a 12 vdc regulator option if you are going to charge a battery, charge (or run) a PowerPack or power a 12 vdc appliance. When you pedal sometimes you pedal hard and sometimes less hard. This means that the voltage fluctuates. Without a 12 vdc regulator you may damage batteries or appliances you are trying to charge or run.
http://www.econvergence.net/electrofaqs.htm
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Not a bad drawing for a touchpad. It's hard enough with a mouse!
I think I see a wee prolem with your idea though. If the motor from your old washing machine is the kind I think it is, it won't work as a generator.
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An car alternator from a scrap-yard perhaps ? (could also be the source of the rectification and voltage regulation components).
http://en.wikipedia.org/wiki/Alternator#Automotive_alternators
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An car alternator from a scrap-yard perhaps ? (could also be the source of the rectification and voltage regulation components).
http://en.wikipedia.org/wiki/Alternator#Automotive_alternators
I think that would work. It's all about "excitation", so you might need to start off with some charge in the battery.
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Q. What things do I need to know before making my own electricity?
A. electrolyte spilled from from a car battery can burn a hole in carpet. [:I]
http://en.wikipedia.org/wiki/Lead_acid_battery#Maintenance_precautions
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Not a bad drawing for a touchpad. It's hard enough with a mouse!
I think I see a wee prolem with your idea though. If the motor from your old washing machine is the kind I think it is, it won't work as a generator.
Oh right, I thought if you just reversed the way the motor spins it produces electricity instead of using it. Okay, so I would need to use a car alternator instead, presumably that would keep everything DC right and then all I would need to do is hook up the inverter to the battery to "invert" it to AC?
The battery I was thinking of is like a leisure battery, 12V 110Ah or something along those lines.
How would I be able to test how much energy I produce from cycling and is there an instrument I can buy which tells me when I am charging the battery? Perhaps a volt meter or something?
Thanks
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... I would need to use a car alternator instead, presumably that would keep everything DC right and then all I would need to do is hook up the inverter to the battery to "invert" it to AC?
Alternators (dynamos) are AC, their output needs to be converted to DC (rectified) and regulated to charge a car battery.
To power a device designed to run off mains electricity (110V/240V AC) from a car battery (12V DC) you need an inverter.
Now the bad news, apart for the considerable expense involved in constructing this contraption, you'll only get about a quarter of the energy from the battery that you expended on the bicycle. The alternator is only about 50% efficient, and charging then discharging the battery about the same. 50% of 50% is 25%. If you used the electricity generated immediately you would avoid the 50% loss involved in charging-discharging the battery,
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Now the bad news, apart for the considerable expense involved in constructing this contraption, you'll only get about a quarter of the energy from the battery that you expended on the bicycle. The alternator is only about 50% efficient, and charging then discharging the battery about the same. 50% of 50% is 25%. If you used the electricity generated immediately you would avoid the 50% loss involved in charging-discharging the battery,
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What does that mean? Does it mean you charge the battery but when you go to use the battery it isn't fully charged or it has lost some of its charge?
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The conversion of energy from one form into another is not 100% efficient.
Your conversions :-
Kinetic Energy (cycling bike) to
electrical Energy (output from alternator) to
Chemical Energy (charging battery) back to
Electrical Energy (discharging battery to power a device).
With each conversion usable energy is lost from the system via heat*, chemical changes, noise.
[* Batteries heat up when they are charged or discharged].
Efficiency of automotive alternators is limited by fan cooling loss, bearing loss, iron loss, copper loss, and the voltage drop in the diode bridges; at part load, efficiency is between 50-62% depending on the size of alternator, and varies with alternator speed
http://en.wikipedia.org/wiki/Alternator
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Aw man that sucks big time.
So is there an alternative to automobile alternators?
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I'm not saying your concept won't work, evidently it does (http://www.youtube.com/watch?v=UazEMopbzBc&feature=related),
but you'll only get about a quarter the energy you expend on the bike from the battery.
Converting one form of energy to another is never 100% efficient.
and, to quote Scotty from Star Trek [:)] , "Ye cannae change the laws of physics".
Other Videos ...
Note no battery, voltage not rectified or regulated either.
again direct use from generator (no battery).
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Scotty from Star Trek is Scottish? [:o]
Hmmm...So would there be any possible way to improve efficiency at all?
What about multiple motors connecting to the same regulator, battery etc?
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Scotty from Star Trek is Scottish? [:o]
There's a clue in the title.
Hmmm...So would there be any possible way to improve efficiency at all?
What about multiple motors connecting to the same regulator, battery etc?
Each motor has the same efficiency 50-60%,
if anything multiple motors will reduce efficiency: the overheads will be larger than using one big dynamo.
Dynamos do not create energy, they convert one form of energy (kinetic) into another (electric).
First law of thermodynamics
Energy can neither be created nor destroyed. It can only change forms.
In any process in an isolated system, the total energy remains the same.
http://en.wikipedia.org/wiki/Laws_of_thermodynamics#First_law
Using many dynamos will not extract more energy from the rotating wheel than a single dynamo.
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Being not a Star Trek fan I did not know lol.
Thanks RD for your help.
Just going back to the energy conversion thing is it possible to store electricity in a battery that doesn't use chemicals (if they exist) So it just goes straight from Kinetic to Electrical?
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I was always hoping Scotty would say,
"The warp drive's completely buggert Captain!"
Apart from his less than authentic accent, you could tell he was not really a Scottish engineer because he didn't liberally sprinkle his sentences with expletives.
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Your pedalling madly on the bike will produce around 50W of usable energy supply to the alternator ( or whatever you connect to the pedals to extract power) with a peak of around 150W if you go all out, though this will not be sustainable for long. With typical efficiency the energy stored will probably be around 15W, just about enough to charge a cellphone battery with an hour of pedalling, or charge your laptop battery in around 5 hours of steady pedalling.
Nice way to lose weight in snowed out UK, and will keep you warm when the power is out and you need to light a small CFL lamp, but pretty much not going to be the means to liberate yourself from paying your local supplier for power. Solar would be a better idea, even with it's poor overall efficiency, the input power is only dependant on sunshine and how much you want to buy in terms of surface area to collect direct light.
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... it possible to store electricity in a battery that doesn't use chemicals (if they exist)
Work also is done when charging a capacitor (http://en.wikipedia.org/wiki/Supercapacitor#Technology), (which is "a battery which doesn't use chemicals"), again you don't get all the energy out that you put in.
Don't abandon your project because it is physically impossible to make it 100% efficient, just be aware of what is practically possible.
... a peak of around 150W if you go all out
A bit pessimistic, this guy (http://www.youtube.com/watch?v=OSJ0CeBYG0s&feature=related) manages at least 300 Watts going flat out,
(powering incandescent AC lamps direct from generator, no rectification, no regulation, no battery).
... you could tell he was not really a Scottish engineer because he didn't liberally sprinkle his sentences with expletives.
Simon Pegg (the latest Engineer Scot) did say he almost swears in the 2009 Star Trek Movie, but is cut-off mid expletive ...
" a-woa tee f ".
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Did I split an infinitive by saying "liberally sprinkle"?
Sounds a bit like "boldly go".
Yes, you might be able to produce about one horsepower (around 750 watts?) but not for very long.
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Soooo...all in all would it be worth it? Would the monetary cost of creating the device get anything back? So, if it takes £1,000 to build would you get that £1,000 back eventually through electricity saved? My first thoughts on this are probably yes over like a century. But then my second thought is that it probably isn't even worth it because no matter how much we try to save energy the blasted energy companies keep putting the costs up.
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The retail price of electricity in the UK is currently* about 10 pence per Kilowatt hour.
To match that you'd have find someone who would pedal your stationary bike for about three pence an hour.
[* pun not intended]
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I'm sure you could make one for a lot less than $1000. But even if the capital cost was zero, you'd have to think about the cost of the initial energy source, which in your case would be the food you consumed to produce the electricity, then you would have to compare that with the price of electricity in your area.
You might discover it's not very attractive from a simple economic perspective. However, if you needed the exercise anyway, you might look at it very differently, and consider it free electricity.
I always thought it might be a good idea to only power TV sets from from stationary bicycles. That way we'd all be getting some exercise while we were watching the TV. I don't think we would have to pedal too hard to power a modern TV either. We could easily apply the same idea to computers.
This might be a really good thing for kids who refuse to exercise [:D]
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Another site on this concept ...
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http://scienceshareware.com/bicycle-generator-faq.htm
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Oh yes. Not plasma TV's either. I think LCD would be best.
What I really do like about this idea is that people would be able to really appreciate just how much energy they were wasting by leaving stuff switched on when it could be off. We really have little clue about what a kilowatt-hour actually is, and how little we really pay for it.
When you've produced a kilowatt for an hour by pedalling, you'll know all about it. I suspect only really fit cyclists would actually be able to crank out a kW for any length of time.
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Hmm. To be honest I think exercise equipment should be incorporated into places like gyms where they just have rows and rows of cycling machines, cross trainers, treadmills etc. That way the electricity would soon build up right?
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Hmm. To be honest I think exercise equipment should be incorporated into places like gyms where they just have rows and rows of cycling machines, cross trainers, treadmills etc. That way the electricity would soon build up right?
Not really. It might result in some "economies of scale" in terms of the equipment, but it would not make any difference in terms of the energy being expended by the people providing the power. They could all just as easily be at home.
The silly thing is that, as far as I know, all the power that people generate on those exercise machines is simply dumped into the gym in the form of heat. Then, they have to run air conditioners to remove the heat from the gym!
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Hmm. To be honest I think exercise equipment should be incorporated into places like gyms where they just have rows and rows of cycling machines, cross trainers, treadmills etc. That way the electricity would soon build up right?
Someone has beat you to it ...
... The gym is the first human-powered gym in the U.S.
Adam Boesel, a personal trainer and the owner of the gym came up with the unique idea. He describes, "We're just harnessing that extra energy that they put out anyway. For people, that's a no-brainer. They say it's there, you might as well capture it."
Mr. Boesel is no mental slouch either. He helped to rig up the gyms spin bikes with weedwacker motors and truck alternators to provide juice to the gym's systems.
http://www.dailytech.com/Green+Gym+Debuts+Powered+by+Exercisers/article12788.htm
It's still only a (very) few hundred Watts per punter while they're maxed-out on on the equipment.
i.e. it's a gimmick: this would only supply a fraction of the energy the gym uses: the gym is not entirely "human-powered".
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Well....I suppose waste not want not.