Generating Electricity with Air

Discussion in 'The Projects Forum' started by Ruben Becerra, Jan 15, 2011.

  1. Ruben Becerra

    Thread Starter New Member

    Jan 11, 2011
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    Hi Great Minds,
    I am in the process of choosing a generator that will be able to generate electricity to go directly to the grid. I know my generator needs to be no more than a 5hp. Also, most common hook up is single phase and 240v. Does anyone have any suggestions for best producing motor? P.S. I will be generating the 5hp with an air motor.
    I have a prime mover that has plenty of potential energy being used to capture and compress all the air I'll need.

    Thank you in advance.:)
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    Sounds like you are in Europe, with 240VAC 50Hz as line voltage. The USA has some laws concerning being able to sell electricity back to the grid (as a form of storage), but I wasn't aware of other parts of the world doing it.

    So if you don't mind my asking, what part of the world are you?
     
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    I would recommend a three phase industrial induction motor as the generator.

    You can direct connect the generator to the grid and use the AC mains to power it 'on'. When it is running steady you can give your air motor some juice and get the motor into generator mode by trying to turn it faster than its already running. It won't turn faster, but it will start to produce electricity -THAT IS IN SYNC with the grid power.
     
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  4. Wendy

    Moderator

    Mar 24, 2008
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    Aren't you assuming his power meter will spin backwards? I've heard a lot of models don't support this. If you can't get the credits, what is the point?
     
  5. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    I am confused by the original post. Sounds to me like the OP is trying to produce electricity with compressed air???

    Unless you have an almost infinite source of compressed air, you need to compress it somehow.

    Sounds to me like another over unity scheme to me.
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    Windmills use air, I had assumed that is what he was talking about. I still do until stated otherwise by the OP.

    They spin whether they are in use or not. Might as well sell some of that back to the power company.
     
  7. t06afre

    AAC Fanatic!

    May 11, 2009
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    What will be the energy source driving your prime mover?
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    Well, 5hp is 746W x 5 = 3,730 Watts. If you had a really efficient generator (let's just pie-in-the-sky it at 90%) that would be around 3,360 Watts. That's about enough to run a refrigerator and hot water heater, but not both at the same time.
     
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  9. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Jet aircraft have a backup generator that is essentially a wind turbine. When onboard power fails, it pops out the side to keep the minimum critical electronics running.

    The problem with this is it creates drag and slows down the airplane, so electricity is much easier to generate at the source, the engine.

    The reason I am talking about jets, is they are the only thing I can think of that have a continual, high pressure, high volume airflow. Even then the power harvested can only run the "basics" for fly by wire.
     
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  10. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Best solution, aside from buying something proper, is to find someone with an old backup generator that the engine has failed on and harvest the alternator from it. Automotive alternators are always an option but there's an ideal speed they prefer.
     
  11. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    air motors are notoriously bad for speed control, which you'll need to match the utility, else they kick you off and penalize you if you disrupt thier service.
     
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  12. Ruben Becerra

    Thread Starter New Member

    Jan 11, 2011
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    Wow.

    Thank you for the response.
    I will answer the questions asked.
    I am in Texas - Yes some folks around here would like to think its another country.
    My prime mover is the conversion of mechanical energy from roadway traffic. Rotations would turn compressors.

    I have been told that the best thing to do was get a generator 3600rpm from a "gas generator" I've also heard the other suggestions. I'm buying things and was hoping for a resounding singular direction. Still, I appreciate the feed back. It really means a lot to me.

    Thank you all for your contribution.
     
  13. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Can you post a sketch of how you intend to implement this on a road?

    Ken
     
  14. wayneh

    Expert

    Sep 9, 2010
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    Unless you're intentionally adding resistance to the traffic (something the drivers would frown upon), there won't be any "free" energy to extract. the work available to you from mechanical energy is force times distance. What force are you hoping to use, gravity? The distance - of road compression? - will be inches or less? Puffs of wind from passing vehicles?

    I suggest a thorough energy balance before investing much effort in this.
     
  15. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    Not to mention TXDOT getting upset for tearing up their roads.

    I guess some people never heard of the saying, there ain't no such thing as a free lunch. :)
     
  16. Wendy

    Moderator

    Mar 24, 2008
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    I don't know, a long line of gas station signal tubes.

    Just, not in my neighborhood please. :D
     
  17. BillB3857

    Senior Member

    Feb 28, 2009
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    Linear peristaltic pump?
     
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