Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Assistance on building energy unit with alternators

  1. Sep 1, 2010 #1
    If someone could assist me with some information re: the following it would be very much appreciated. I am planning to build an energy system for my home to address the drastically increasing power bills we have been getting as a result of the unusually hot weather lately. Problem is I am not very well educated in regard to the electrical side of things.

    What I envisage is a series of alternators connected together that will have sufficient output to accommodate all of the home’s energy needs, basically the same as the main city power supply does now. Instead of using wind turbines (which are far too expensive for me to consider, and of course rely totally on the wind and need to accommodate its fluctuations) I figure that I can achieve the same end result by using a series of alternators.

    As the local power supply is 220-240 volts I guess I need, say 4 alternators of 60 volts each, or 3 x 80v. Problem is I have no idea what I need as far as wattage and amperage is concerned but do know that the present consumption is around 1400 units per month.


    Now what I need to understand before I start is:
    1. How do I calculate the output and usage requirements.
    2. If I connect these alternators in series will I get the 240 volts of AC electricity.
    3. What will the amperage of each alternator need to be
    4. On various appliances that I have there is mention of ‘Hz, amps and watts’, do I need to concern myself about this or is that something that is regulated by each individual appliance..
    5. How I can regulate the output to accommodate the fluctuating power requirements. ie: say for example if all the lights are switched off and no air conditioners are turned on the energy output would be just sufficient to run what ‘is’ switched on, such as freezer, fridges, fans and so on. Then as more energy is required when lights and airconditioners or an electric stove etc are turned on the output is automatically increased to suit…. I have worked out a way to provide a driver for the alternators that keeps them running at the required constant speed so I guess it will be that driver that needs to be regulated.
    6. Will I need to have a printed circuitboard made to accommodate all of this regulating.

    OK that’s about all I need to find out to begin this project. Needless to say there will be other questions as I progress and I would really appreciate some help with them when the time comes.
    Graham
     
    Last edited: Sep 1, 2010
  2. jcsd
  3. Sep 1, 2010 #2

    russ_watters

    User Avatar

    Staff: Mentor

    This is a big undertaking you are proposing, but first things first: what will spin the alternators?
     
  4. Sep 1, 2010 #3
    Thanks for your note. So that I don't risk making a complete fool of myself I will just say for the moment that the driver will be powered by town supply energy (that might change later) and it will not need a lot of energy to do that. Once I have completed the project and have it functioning as I believe it should I will provide here full details, including a video of the entire thing, so anyone else who would like to give it a try can do so. The immediate aim is to find out how to do what needs doing. The driver being regulated to send the alternators around at the varying speeds required at any given time would probably be the simplest approach. But then it might not be. I really have no idea if that or regulating the alternators would be best.

    I look fwd to further helpful responses.

    Graham
     
  5. Sep 1, 2010 #4

    Zryn

    User Avatar
    Gold Member

    Correct me if I'm seeing it wrong, but are you proposing to use the town electricity supply to run a motor to run a generator in order to make electricity at a much cheaper rate than the town electricity supplier, in order to save money?
     
  6. Sep 1, 2010 #5
    Thanks for this note: Yes, at least initially, this is basically the principle. A small driver run on town power supply (small energy consumption; about the same as a 20" fan. 80w, 40 amp) will provide the motion of the series of alternators (no belts or chains necessary) that will produce the enegry needs for the entire house.
     
  7. Sep 1, 2010 #6

    Zryn

    User Avatar
    Gold Member

    I'm no expert at this, but I believe conservation of energy dictates that you will never get out more, or even equal to what you put in, due to system losses. Not taking into account the price/time to buy/setup/maintain this system, you will need more electricity to run it than it will produce for you. People like Solar/Wind/Hydro because its a free energy input, so anything you can get out of it is a bonus.

    If you want to use energy in the off peak times to run this setup and then store the energy for peak usage then that may work, aside from the cost/size of storage devices, and the noise pollution in the morning. This is akin to how hydro power plants work.

    Giving an overview of the components will allow for more comments into the systems feasibility, which is the first step before you need to know about ratings/values.
     
  8. Sep 2, 2010 #7
    Thanks again: I understand what you are saying here, however I can see no connection to this principle in this case when we consider that the driver is using a very small amount of energy from the grid and it turns (via means that do not require actual contact between the driver and the production end. It is basically an alternative to the wind that drives wind turbines, but consistent rather than varying) a series of alternators that will produce sufficient energy to run the entire house. So we are using 40 watts to produce 50 (or more) times more watts and that production is not involved at all in running the driver. Therefore we get many times more than what we give. No concerns about off peak or otherwise, No batteries involved. No noise pollution; no more noise than several electric fans running at one time. We have that in our homes all the time and don't even notice it. The fridge turns on and off, the airconditioner hums when it's on, but none of it is what one would call noise pollution; rather 'white noise' that we take no notice of.
     
  9. Sep 2, 2010 #8

    Zryn

    User Avatar
    Gold Member

    Again it may be all in my understanding, but humor me ;).

    Could you then use that (40x50=2000) 2kW to create (2000x50=100000) 100kW, that 100kW to create 5MW, that 5MW to create 250MW and so on and so forth (given enough room and equipment)?

    I mentioned the principle of conservation of energy before because I believe that this process is impossible.

    Wind/Coal/Sunlight/Gravity/Methane/Tides/Biomass/Oil/Nuclear/Geothermal etc are all sources of energy that come from somewhere external. You propose to create your own source of energy without using much initial energy, correct? I believe this comes back to conservation of energy again.
     
  10. Sep 2, 2010 #9
    Hello again and thanks for your further insight.
    The wind/coal/gravity etc are all external forces and they are able to be used to produce energy. Agreed and fully understood... Now, what we will have here is an external force in fact (the driver), and that force is not using any part of the energy produced by the mechanism; it is using the town supply... The mechanism is a separate entity altogether that is connected to the house distribution box that runs everything in the house from the energy that it produces. The driver is run by the town supply and that is the only thing that it is connected to. It provides the force, just like wind provides the force for the wind turbine. Once that force turns the alternators they produce the required energy (just as the turbine does) and that is fed into the house electrical system. The town supply will be, for all intents and purposes, disconnected from the house distribution board other than to be used to provide for the driver. I can not see how this can be considered to be conservation of energy. As I see it, the driver would have to be also connected to and be driven by the mechanism for that to be the case. I stand to be corrected if it is otherwise, but that's how I interpret it.
     
  11. Sep 2, 2010 #10

    uart

    User Avatar
    Science Advisor

    Ok it looks like everyone else here is, like me, suffering from FEDES today. (Free Energy Debunking Exhaustion Syndrome).
    :uhh:
     
  12. Sep 2, 2010 #11

    Averagesupernova

    User Avatar
    Science Advisor
    Gold Member

    No uart, I think it's true. I read somwhere that they have one or two hamsters running in a wheel at most power plants. Then they just use the scheme mentioned by the OP in this thread to get the 'real' power out of the plant.
    -
    Ok, seriously plutointer are you familiar with conservation of energy at all? Do you understand back EMF in electric motors? Are you familiar with torque requirements of generators and alternators when an electrical load is placed on them? Are you familiar with current demand of an electric motor when a mechanical load is placed on it?
     
  13. Sep 2, 2010 #12

    russ_watters

    User Avatar

    Staff: Mentor

    plutointer, you seem to be under the incorrect impression that it takes no torque or power to spin an alternator. It does: a 1 kw alternator requires at least 1 kw of input mechanical power to make it spin.

    What you propose would violate conservation of energy and won't work. As a rule of thumb, most engineering problems involving energy of any kind start with a conservation of energy based analysis.
     
  14. Sep 2, 2010 #13

    Zryn

    User Avatar
    Gold Member

    The driver being run by the town supply can not create more energy than it uses. This is conservation of energy. There is no such thing as a separate entity when looking at energy. Energy has to come from somewhere, and it has to go somewhere, and it has to all add up. In this case it does not.

    If you were able to do what you are proposing, then anyone else could do it too, and we would all have free unlimited energy.

    Its a nice idea though (and one that's been around for a long time), but no such luck.
     
  15. Sep 2, 2010 #14
    Hi, thanks for your response. No I am not familiar with any of that but realise that there would be such a thing/s to consider. But let me explain what I'm thinking of here and see if we can make it work somehow. Several alternators (or generators with a converter added) are connected together in series, they have a disc that has blades around the edge (like a fan) attached to the end of their axle (you know, the bar thingo that is in the middle of the coil thingo and sticks out the end of the alternator). A portion of the discs (fan) are fitted into a pipe (I guess about 3" - 4" in diameter) meaning they are all in line and will turn as a force is applied. The output is fed into the house electrical system. The town supply is disconnected from the house system, all but for driver. At one end of the pipe there is said driver. It produces a steady flow of wind that moves down the pipe and spins the discs. As there are several alternators (or generators) they each produce energy but the driver produces only the steady flow of wind and needs only the energy from the mains to do that. Like the energy that is produced, it has to go somewhere, so as it is getting there it is turning the discs. Does that make sense? can we make it (or something similar) work?
    I look fwd to your further enlightenment.
     
  16. Sep 2, 2010 #15
    Hi, thanks for your response. No I am not familiar with any of that but realise that there would be such a thing/s to consider. But let me explain what I'm thinking of here and see if we can make it work somehow. Several alternators (or generators with a converter added) are connected together in series, they have a disc that has blades around the edge (like a fan) attached to the end of their axle (you know, the bar thingo that is in the middle of the coil thingo and sticks out the end of the alternator). A portion of the discs (fan) are fitted into a pipe (I guess about 3" - 4" in diameter) meaning they are all in line and will turn as a force is applied. The output is fed into the house electrical system. The town supply is disconnected from the house system, all but for driver. At one end of the pipe there is said driver. It produces a steady flow of wind that moves down the pipe and spins the discs. As there are several alternators (or generators) they each produce energy but the driver produces only the steady flow of wind and needs only the energy from the mains to do that. Like the energy that is produced, it has to go somewhere, so as it is getting there it is turning the discs. Does that make sense? can we make it (or something similar) work?
    I look fwd to your further enlightenment.
     
  17. Sep 2, 2010 #16

    Zryn

    User Avatar
    Gold Member

    What has led you to believe that such a setup is feasible?
     
  18. Sep 3, 2010 #17
    What you are trying to do is analogous to the old schoolboy bicycle idea; if I put a generator on the front wheel and a motor on the back wheel as the motor turns the wheels the generator will provide power to turn the motor etc etc. Won't work, can't work, sorry.
     
  19. Sep 5, 2010 #18
    Thanks again Joe, I really appreciate your input here. Sorry I have been a few days responding to this. Been upcountry.

    OK, now, If only one generator is attached to the front wheel then I can appreciate that there would be a problem with the 'conservation of energy' principle. However, I am going to put three generators on the front wheel and three on the back wheel and I am also going to take further advantage of the forward motion of the bike when it is mobile by fitting to a plate attached to the bike frame under the handlebars four more generators with rotors (just like a wind turbine) that will turn with the force of the air as I pass through it. Also, I am going to attach a large battery to the tray at the rear of the seat above the back wheel and have all the energy generated directed to a charger for that to keep it full at all times, and to that battery I am going to attach the motor (that will comfortably operate with the energy from just two or three of those generators) that will drive the bike. I'll also have sufficient to power the lights, the sound system, the miniature DVD player and whatever else I can logically fit on to the bicycle...... Would this then overcome the 'conservation of energy' principle problem?

    Now, let's take this general idea and apply it hypothetically to the house power supply project:

    First I borrow my wife's vacuum cleaner (she is totally unaware of this of course). This appliance has a small intake opening (about 2" in diameter) at one end. Inside there is a filter bag and then a much larger motor - say about 8-9" in diameter - that has a fan attached which sucks the air and dust etc in. The intake gets filtered and then clean air is exhausted from an outlet hole of the same size as the intake opening but at the other end of the unit. It consumes say 60 watts of energy.

    I then pop over the my next door neighbour with a power lead and ask him if I can plug it into his power supply and borrow some energy to run the vacuum cleaner. For the sake of this exercise let's say he is happy to do that. I then take a 30 metre long pipe (actually a square section would be more practical) and, after removing the filter bag from the vacuum cleaner to allow the air to pass though without any restriction, I attache the vac' outlet to this pipe. I switch on the vac' and run down to the other end of the pipe. Sure enough there is a steady strong flow of air coming out the end. It must do that because it is being produced constantly by the vac' and has to go somewhere. Right?.

    That ascertained I then take one alternator/generator/turbine (hereinafter called generators) that is capable of generating 60 watts of energy. To the shaft of that I attach a disc, around the circumference of which I have attached a series of blades. I cut a slot into the top of the pipe and partially insert said disc. I then make a hood and cover the disc to ensure none of the flowing air escapes from the pipe. I then attach the generator wires to a gauge so I can confirm the output and from there to a light (or something that will consume maximum 60 watts). Once again I switch the vac' on and instantly the disc begins to spin, the generator starts generating and the gauge shows 60 watts; the light is shinning brightly. I run down to the other end of the pipe and sure enough the air flow is the same as it was before. (how can it be otherwise? )

    60 watts however will not power my house so I repeat the process of attaching generators, one every meter along the top of the pipe and one every meter between them along the bottom of the pipe. ie: one generator every 50 cm; total number 60; all with a maximum output of 60 watts.. Total capacity 3,600 watts.

    Now I disconnect the town power supply cables from the house distribution box. I attach all of the generator wires to a transformer/converter/regulator (or whatever is required to end up with the energy needs of the house at any given time). I attach the resulting output to the house distribution box and switch the vac' on.

    All the generators start to spin; all of the gauges indicate 60watts being generated; the vac' is functioning normally (consuming 60 watts of my neighbour's town supply). I run down to the end of the pipe and sure enough the air is flowing as before. It has nowhere else to go. The house power switch is then turned on and the lights and fridges and freezers and airconditioners etc start functioning normally.

    Then I get a bright idea (another one).. Whilst looking at the vac' using power from my neighbour's supply I think: "I will have to pay him for that energy, but what if I can get it for FREE?"...... I rush off and purchase another vac' (same size, same model and same brand, same 60 watts consumption). I also buy a 'Y' junction and a one way valve the same size as the outlet pipe of the vac' (say 2" in diameter). I fit the valve to vac' #1 so that the air can come out but it can't go back in and I then connect the outlet pipe to one arm of the 'Y' junction. I fit the leg of the 'Y' to the 30 metre long pipe and I connect vac' #2 to the other arm of the 'Y'. I then connect vac' #2 to my own home supply (but I don't turn it on - yet).

    All set, I turn on vac' #1. Everything starts functioning as expected. I then switch off vac' #1 and at the same time switch on vac' #2. Same output same result, only difference is that the 60 watts that vac' #2 is consuming is coming from the 3,600 watts being produced by the overall mechanism. I now have perpetual FREE energy.. I roll up the power lead and thank my neighbour for his generosity...

    Now, Jo, all this makes perfect sense to me, but then what do I know? Your further comments will be very much appreciated.
     
  20. Sep 5, 2010 #19
    Let's try a method of reasoning that I was taught at college, put a line around it.
    Imagine your vacuum cleaner and tube with the generators placed in a sealed room, going into the room is a power cord plugged into your nieghbour's mains and attached to the vacuum cleaner, on the power cord is a wattmeter (Win). Coming out of the room is another cable attached to your house and trying to run fridge, lights aircon etc, on this cable is another wattmeter (Wout).
    Is it possible for Wout to be greater then Win?
    If so, where are the extra watts coming from?
     
  21. Sep 5, 2010 #20
    I like to think of it like this:

    Main gives you 100% of your requirement
    The alternator uses this energy to turn itself. However, it can only output 90% of the energy it uses, now you have 90%. Then repeat how many times you have alternators in series (say 3 in series)

    90% of 100% then 90% of 90% then 90% of that = ~73% of the energy you put in, meaning you have a loss of about 27%

    Then you disconnect the main, and your fan (powered by the alternators spinning from inertia) pushes air, and the fans on your alternators pick up this pushed air. But they can only use 25% (probably less?) of what the fan is attempting to push. So right away, you're getting

    25% return. You have a loss of about 27% every time (from earlier on the main), so your alternators return 73% of this 25%. Repeat.

    By the second turn, your alternators have stopped.
     
  22. Sep 5, 2010 #21
    Hi again Joe and thanks for your further input but I am still not able to understand why the vacuum cleaner doesn't turn the alternators right to the last one along the line. The air it is providing from the exhaust end is moving along the pipe and as it moves it is (as I see it at least) turning all of the alternators in turn and as they turn they must produce energy. Right/wrong?.

    Do you mean that the vac' would stop producing the air flow because of the resistance it encounters with the discs along the pipe because they require some of it to be spun? Do you mean that the air flowing down the pipe would slow down to a point where it would not spin the discs? If that is the case where does to air flow to? If it is being produced at a constant rate by the vac' it has to go somewhere. Why then could there not be more energy flowing out of this room than is flowing into it? The vac' would be, in this case, the equivalent of the wind that drives wind turbines (wouldn't it?).
     
  23. Sep 5, 2010 #22
    Thanks for your input mate. I would agree with you if it was the mains that were being used by the alternators to turn 'themselves', however that is not the case here. The vac' is being powered initially by the next door neighbour's mains and is sending air under force down the pipe. That air is what drives the alternators. As I understand it all of the alternators would be spinning at the same pace because the airflow would be constant speed, meaning that they would all be outputting the same amount of energy. If one was powering the other and then that one was powering the next, all the way down the line, then I can see how your theory would be correct, but in this case they are all being powered by the one air flow from the vac' and all are independent of each other. I'm not sure if connecting them in series would be the way to go or if combining their individual output would be the best and then transforming it to what is needed. But, if all of the alternators are being turned by the constant airflow then they must all be spinning at the same pace and as such generating the same amount of energy. The only way that this would vary (as I see it) is if the airflow was not applying the same force to each disc. If that is the case then where is the air going? Does the vac simply stop outputting?
     
  24. Sep 5, 2010 #23
    Plutointer and Wetmelon
    Forget for a moment the mechanism of how it is done. If you have a box with an electric power supply going in measured as Win and electric power coming out measured as Wout; is it possible for Wout to be greater then Win?
     
  25. Sep 6, 2010 #24
    The vac' "wind energy" needs to be converted to electrical energy. So conservation of energy says that the amount of electrical energy taken from the generator is equal to the energy taken from the wind energy. In a closed pipe the wind energy would only lose energy if the airflow reduces, in this case the air velocity. In other words a generator "brakes" the air flow, and the air speed on the top of the turbine is higher than on the bottom. Putting more generators behind each other will cause the air flow of each turbine to be different, and rotational speed different causing frequency to differ on all generators.

    Other problem is quite significant, since there are a limit to how much air you can accumulate in a straight pipe, at some point the airflow into the pipe must be equal to airflow out of the pipe. For a equal diameter pipe, air needs to be compressed to maintain airflow if energy is taken form the air, and dependent on speed and size your pipe would mostly "choke up" making it hard to get air down the pipe and turbine to stall.
    Solution, after the turbine, the diameter of the pipe must increase to maintain the airflow, without compressing it.

    Have you ever tried thinking of why no hydro electric powerplant uses your idea?
     
  26. Sep 6, 2010 #25

    russ_watters

    User Avatar

    Staff: Mentor

    Ok, that's enough of this. We don't play "debunk my perpetual motion machine" games here, especially when people aren't willing to learn how science really works. The necessary advice is what I and others have told you already:

    Conservation of energy is real and is used as a tool for analyzing devices. So if you think you've found a way to make Eout > Ein, then clearly you've violated conservation of energy and you shouldn't be trying to make the device work but instead be trying to find your error.

    And your error was pointed out to you: when you put a bunch of turbines in series, adding more turbines reduces the energy harvested by each of them. So if you have a single 60 watt turbine and you add a second identical turbine, now you have two 30 watt turbines (approximately).

    Thread locked.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook