Taking energy from the atmosphere...

  1. Our atmosphere is continously being heated and energized by the sun. Has anyone ever actually developed an engine able to take this energy directly from the atmosphere or if not, why nobody was able yet to make one?
     
  2. jcsd
  3. dav2008

    dav2008 624
    Gold Member

    We have solar cells that take sunlight and convert it to electricity.

    We have windmills that take wind and convert it to electricity.
     
  4. yeah, but solar cells are actually taking energy from the sun light, but traveling through earth's atmosphere sun light will leave a lot of energy in the atmosphere I suppose. If a person gets energy directly from the upper atmosphere one gains much more free energy. Such energy could be more effective than direct sun light. And windmills, they work using wind (oh, what the knowledge :rofl: ) and it cannot be accessible from every place of the world at any time. Sun for example always lights.
     
  5. russ_watters

    Staff: Mentor

    Energy is only accessible if it is in motion from a source to a sink. So warm atmosphere sitting still does not provide a source of energy. Wind is thermal energy in motion and is the closest you can get to what you suggest.
     
  6. Of course it's possible to directly extract the thermal energy in the atmosphere. Just set up a stirling engine with its warm piston in the atmosphere and the cold piston in a bucket of ice.

    Just go figure why most people aren't doing this as we speak...
     
  7. Since the ground level is warmer than high altitude I would put the hot piston on the ground and the cold one at high altitude. In fact weather does exactly this.
     
  8. Cliff_J

    Cliff_J 789
    Science Advisor

    Given the much higher density of water, using the wind-driven waves on the oceans as a source of energy seems to be a much less expensive solution than capturing the wind itself. Of course, there's just those pesky problems of building something large-scale in a very hostile environment....

    Russ's point is spot on: If you could store the energy somehow (forget the atmosphere and lets say you just use the infrared spectrum of the sunlight on a black surface to heat water) then you could extract some of that energy as you discharge it back into the atmosphere.

    Now, how about efficiency? With such a small temperature differential, you're not going to get much energy per unit of area. Even with nuclear reactors or a gasoline engine in a car or a river dam with a hydroelectric plant, the larger the differential the easier it is to increase efficiency.

    So to power a typical home, you'd need an area closer to the size of the lot or larger. With a high efficiency home at a low lattitude, the use of PV solar cells and infrared hot water heaters (to use in showers) can capture more energy in a day than it uses. As long as you can handle paying $.25-35 per kWh of electricity, this is a reality today.
     
  9. russ_watters

    Staff: Mentor

    I hope that was sarcastic, but can't really tell.....where does the ice come from?
     
  10. Your freezer! Just use a generator connected to the stirling to power the freezer. Then you get free energy! (Yes, that was sarcastic :rolleyes:)

    Anyway, the point is that you always need some kind of difference to convert energy from one form to another. A heat engine needs a temperature difference, a wind generator needs a pressure difference, a hydro plant needs a gravitational potential difference, an electric heater needs a potential difference.
     
  11. In the novel Atlas Shrugged , John Galt invented a motor that ran on the electric charge in the atmosphere , I suppose a kind of static electricity accumulator.

    Lightning occurs when this static charge concentrates in clouds and a diiference in potential exists between the cloud and the earth.

    On a smaller scale can we accomplish this task artificially , and what might its output in work be ?
     
  12. Q_Goest

    Q_Goest 2,949
    Science Advisor
    Homework Helper
    Gold Member

    Lightning has been considered. There's an article in Wikipedia about it that says:
    I wonder how much hydrogen could be produced by electrolysis of water from a single lightning strike. I seem to remember that being looked at once.
     
  13. I dont think that 30 degree C air really has that much energy available. Like mentioned, the solar cells are likely the most efficiant way to convert the sun energy.
     
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