Human power converted to stored energy

Discussion in 'The Projects Forum' started by Ibnbat, Oct 5, 2015.

  1. Ibnbat

    Thread Starter New Member

    Oct 5, 2015
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    Hi, some will see in my introduction (common thread) that by far I am not an electronic/electrical specialist, curious to promote the science to my kids though.
    This thread is about optimising human ability to accumulate usable/stored electricity, would it be for transportation assitance or powering house appliances or modestly charging phones...

    Chapter 1:
    is about my eldest son last year under graduate starting a small school project trying to find out if a capacitor can help taking varied charge to transfer charge into a small 12v lead gel battery.
    He is working with his physics teacher and simulating human pedal charger with generator source volt pattern over 5mins 8-9-10-12-9 volts held for a minute each.
    The man is to check if (a) the battery charges equaly with and without "pumping" volts through a capacitor (b) the batterie heats up marginally more with and without the intermediate capacitor.
    Nb: for the moment the circuit is basic, with a regulated power source we hope is protected, switch, capacitor and battery. A lazer heat sensor gun to monitor component temp.
    We are not sure of the relevance of the test, whether it will be conclusive with componants not really optimal for the test.
    The first challenge was to discharge the lead acid battery ideally to 7-8v.... It keeps coming up by itself....

    Chapter 2:
    Trying to use the k-tor pedal charger 120v dc or 12v dc 20w output to charge a supercapacitor bank that charges a car battery

    Chapter 3:
    Scale up further the charger to use 500W 12v dc motor with two pedal cyclist to charge a an electric vehicle type Renault Twizy or "Fine mobile" Twike through an appropriately sized supercapacitor bank.

    Chapter Z:
    Consider this setup to experiment a trip in Buthan or Africa and an alternative to offer a way to supply a portable device capable to generate power to help people not grid connected but capable to paddle, eventually time shared nimble transport for a few goods and driver 30-40km away at moderate speed.

    Help is welcome on chapter 1 for now, all comments especially constructive would help first focus on testing the technical side. Not overly stopped by the utopist economical perspective of chapter z for now.
    The cost of the testing will be a challenge we plan to address ourselves when the decision to invest comes.
    Feel free to send technical guidance for now.
    Cheers
    Francois and kids
     
  2. nsaspook

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    Last edited: Oct 5, 2015
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  3. tcmtech

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    Most people in good physical shape can produce about 1/10 HP or roughly 75 watts continuously but can do short duration peaks well above that. I used to be able to do about 1000 watts for roughly 10 seconds in college.

    As for charging a battery there is nothing to gain by running it through a capacitor transfer first. Go directly from the generator to the battery it's the most efficient method of converting mechanical effort into stored battery power.

    For what to do with the power just consider your initial source and how much time and physical effort the person is willing or capable to put into charging a battery and that will tell you your at best amount of stored energy you will have to work with.

    Personally human power is not good for much more than charging hand held items and powering low power devices that only draw a few tens of watts at most which means that for a nimble 30 -40 KM drive in a small vehicle you had better either have one person who doesn't mind peddling a generator bike for a few days near non stop ahead of time or you have a group of people willing to peddle the generator bike for that duration.

    Small vehicle power demands are measured in kilowatts and your human power source is only good for tens of watts so there is a considerable time involvement required to make the small amount of people power add up to basic minimal machine power.
     
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  4. Ibnbat

    Thread Starter New Member

    Oct 5, 2015
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    J
    Thanks Nsaspook,

    Indeed so much a human can produce with his legs hence the ultimate target of 500w for two people cycling fits the information on the link you kindly sent me.
    The supercapacitor intention is there to address the non continuous or fluctuating production of the legs.
    Direct elelctric transport propulsion with legs is not my intention. I am considering a elderly person could charge little every day by gentle paddle charge or supported by younger legs to prepare a single weekly trip to sell his product to the market or any other weekly matter to attend or power home appliances...

    Yes the battery discharge may affect the lifecycle if taken too low. It maybe a sacrificial small 2.36Amp 1.2Ah 12v batterie

    I really appreciate your input thanks.

    Cheers
     
  5. Ibnbat

    Thread Starter New Member

    Oct 5, 2015
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    Thanks tcmtech,

    Indeed not pressured by time, i have a Twike seating two people. Basically a double two very light and nimble.
    Usually used the weekend and mgetting full 80km charge in 80min from the grid 10amp wall socket , liPo4 batteries gearing up to 35deg.
    Away from the grid it should be possible trikle charge without
    heat loss following battery can take from legs without creating much battery heat (waste) but body heat (healthy).

    Lets continue on the optimum electrical setup compenant specifications sto measure the charge that can be obtained ref chapter 1 .... to Z

    Thanks for your input
    Cheers
     
  6. nsaspook

    AAC Fanatic!

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    I see very little chance of a system like this being popular. Humans being lazy by nature would rather sit in the dark with a drink and smoke than pedal an hour for a light in the room.

     
    Last edited: Oct 6, 2015
  7. tcmtech

    Well-Known Member

    Nov 4, 2013
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    I looked up the specs for the Twike vehicles and they still take a considerable amount of power.

    The specs sheets I see say they have a 336 volt 20 - 45 Ah battery and use a 2 KW charger unit.

    Given that if yours takes 80 minutes of 2 KW charging that works out to around 2670 watts of power being put into the battery which after factoring in typical expected charging losses and conversion losses that adds up to an input of around 3000 watt hours being needed.

    To get 3000 watt hours of human power that's ~40 hours of continuous peddling at the typical 75 watt value a good healthy human can support. Now if the person doing the generating is old, weak, out of shape, lazy, of less than average build and fitness or just has a life and job that requires their primary time day in and day out that time to recharge the battery becomes even longer.

    I don't know about you but I have far better things to do than ride a generator bike for 40+ hours of vigorous pedaling just so I can take a drive for a hour or two.

    I hope this gives a practical comparison of just how useless us humans are when compared to even a small efficient vehicles energy needs. As I stated earlier unless the power demand is less than a few tens of watts total people power is pretty useless unless you have a huge amount of time to dedicate to nothing else but making electricity. :(
     
  8. Papabravo

    Expert

    Feb 24, 2006
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    This is analogous to the vain hope that useful amounts of free energy can b harvested from all the RF energy in the surroundings. When the result is femtowatts the enthusiasm level fall like a brick in a rainstorm. What's a femtowatt you say?

    https://en.wikipedia.org/wiki/Orders_of_magnitude_(power)
     
  9. Ibnbat

    Thread Starter New Member

    Oct 5, 2015
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    Guys, guys, guys,
    The test i am refering to show a healthy person can sustain 2-3 hrs idling 300-400w leg output.
    If what i have been told supercapacitors can do by acting as a "bucket" taking all the energy they can take without dissipating heat that can utube into a battery without forcing, dissipating energy you end up in theory by charging that Twike within 4-5 hours.
    Whilst we could spend time looking at the bottle half full and half empty I am keen to get all this modelled and scalled up so we sort it out with facts.
    Those electric vehicle are really nimble and don't take much to go 80kph say less on hilly terrain, make sure you check by yourself.
    I am very keen to get your feedback, whether it is not going toward a celebration of the initiative is not the main issue, seeing is believing. What I see as fossil fuel or you'd note it is what I made my living last 40+ year is that it is not going to last for ever and does not come for free although for the moment it looks cheap, another way to hook everyone into it for a bit further. The fuel we get is at much higher cost then what our wallet tells us come and see this in the Middle East by yourself. Only a small portion of the world population gets access to the majority of resources.
    It does not look sustainable to hold migrants away and explain them they cannot reach what we have access to. It is not going to hold them back for long just by gates.
    Fact is i can only share few decades leaving in non-developped countries in few words and i cannot dream in convincing you with those few words. You are allowed in having a different opinion.
    Well the challenge i put myself into is not pretty probably but I wish to take to the bottom with facts.

    Shall we get back to the technical drawing board as we have a chance to get all this action studied, measured at school so we may end up at least getting kids at least paying more respect for fossil fuel when they'll understand the intensity of energy it bares until they get any better discovered to help all on earth.
    Ref. "the crude (oil) awakning" 2006 documentary available only is just a tad pessimistic
     
  10. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    Don't forget that human energy does not come from nowhere. All you have here are a series of very inefficient energy conversions with substantial losses at every stage; you are essentially inventing an extremely inefficient bicycle.

    Why do you think supercapacitors will make any difference? You seem to have jumped to this conclusion with no factual basis.
     
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  11. Alec_t

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    Sep 17, 2013
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    His physics teacher should know that to charge a 12V battery the generator needs to produce a good bit more than 12V.
    Supercapacitors offer no advantage, since you have to charge them up and that requires peddling even longer!
     
  12. Ibnbat

    Thread Starter New Member

    Oct 5, 2015
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    This project assumes indeed you have more time to paddle to charge than the need for transportation and that to reduce of early death human have to exercise no less than 20mins per day.
     
  13. Ibnbat

    Thread Starter New Member

    Oct 5, 2015
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  14. Ibnbat

    Thread Starter New Member

    Oct 5, 2015
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    Science has few facts, lets check if we read the same books, mechanical efficiency is around .5 and electrical efficiency .8

    Can we assume supercapacitor have near to no internal resistance, no (negligible) heating-up during charge and discharge, batterries heat up under heavy charge and discharge therefore supercapacitor offer best storage for regeneration braking and re-powering into propulsion for the specific driving style of an EV, this leads to challenge to demonstrate on this project that (super)capacitors also help level out irregular human generated energy as a buffer to charge a battery smoothly without forcing it.
    Presently I have the experience of driving a TWIKE which battery temperatures vary from 25 to 35deg just over 10km urban traffic - those are facts.

    This project assumes indeed you have more time to paddle to charge than the need for transportation and that to reduce of early death human have to exercise no less than 20mins per day... to live longer, avoid degenerating diseases [...] a smoker would not understand what a cancer survivor may believe in.

    All good feedback not worry, I am keen to put all possible concept to a real test and measure.
    I am trying to save experimental time by using the most advice to select and assemble appropriate components setup, and you are welcome to help.
     
  15. atferrari

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    I recall an article maybe from more than 20 or 30 years ago (USA) about a man driving everything at home with a bicycle specially adapted to that. It seemed that he spent most of the bloody day, pedalling. Oh, yes, he was in very good shape, except that special look of prophet, beard et al, preaching in his own desert.

    I like the idea of riding a bike to go nowhere. Oh yes!

    Après ça, overunity mon pot...
     
    Last edited: Oct 6, 2015
  16. tcmtech

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    You are dreaming. The top pro cyclists in the world cant even sustain that power output for much more than around 10 minutes and are pretty well drained after that.

    http://education.polarusa.com/consumer/powerkit/Article2.asp

    You are not grasping the reality and relation to mass times speed equals power and the power required to move one of those Twikes is substantial when compared to what the average human can produce for any amount of time.

    Again your facts are off.

    Just because super capacitors have very low internal resistance that does not make them substantially better for anything at the power levels a human produces and certainly not cost effective for the microscopic power gains you would be seeing plus their added weight and electronics to make them work in any type of battery charging applications.

    Cancer survivor or not human will does not trump the laws of physics. 20 minutes of exercise is good for you. 8+ hours of hard repetitive labor every day is not.

    I am getting the very strong impression you do not have a good understanding of applied physics and energy conversion or the realities of how much power it takes to do any type of work plus on top of that you seem to not follow the concept that many of us here, on forums like this, have very solid applied backgrounds in the physics, electrical applications and general sciences of what you are referring to.

    We know how to calculate energy usage and how to factor that out towards the application of electrical power conversion and we also know how to equate those energy conversions to different sources like human power verses watts, Kilowatts, Horsepower and battery capacity along with how those forces are involved in moving masses at different speeds all while factoring in the real world efficiency looses in each stage of energy conversion.

    If you want our advice on how to make the conversions of one source of energy into another the most efficient as possible we are happy to help but if you keep insisting on things we know to be not true you all you will get is criticism and laughter at your expense.

    Given that for what you are talking about the holy grail for you of converting variable human power to charged battery power would be a basic MPPT (Maximum Power Point Tracker) battery charger unit like what is commonly used in solar panel and small wind generator systems that are primarily charging and maintaining battery systems.

    https://en.wikipedia.org/wiki/Maximum_power_point_tracking
    and
    http://www.solar-electric.com/mppt-solar-charge-controllers.html

    are worth reading to give you an idea of how MPPT works and how it improves efficiency in battery charging when the power source has variable output.
     
    Last edited: Oct 6, 2015
  17. wayneh

    Expert

    Sep 9, 2010
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    It borders on immoral to waste human food just to make stored energy. That is the big picture here. You are not capturing energy from a free source, you are buying food for a human and then wasting about 75% of the calories in the conversion to mechanical energy. Then you waste some more making, storing and retrieving electricity. It would be far more efficient to just buy vegetable oil and burn it in an engine. And since you don't need it to be edible, it might as well be fuel oil.
     
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  18. tcmtech

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    So did we chase this guy away being we insisted on applying rational scientific sense and math to his idea? o_O
     
  19. wayneh

    Expert

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    That usually does it. :cool:
    Now, a mechanism for regenerative braking on a bicycle would be interesting.
     
  20. tcmtech

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    Either that or he got one of those pedal generators set up and tried to do his 300 - 400 watt continuous output for a few hours straight to prove us wrong and now he is lying somewhere dead of a heart attack or stroke. :rolleyes:
     
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