Buy an air-tight container. When the atmospheric pressure is high, open the box and "store" the high pressure. Then when the atmospheric pressure is low, you have a a pressure differential between the inside of the box and the outside. Make a small outlet for the high pressure air to escape and use the air flow to drive a wind turbine.T-- lubbit, Jun 25 2001 Atmos clock http://www.jaeger-l...n/collection10.htmlRuns off atmospheric temperature/pressure changes. Baked in 1926. [rmutt, Jun 25 2001, last modified Oct 06 2004] Wind Cave http://www.wind.cav...l-park.com/info.htm [bungston, Oct 04 2004, last modified Oct 06 2004] Cave energy storage http://www.sandia.g...l/NR2001/norton.htmFor bung [Worldgineer, Oct 04 2004, last modified Oct 06 2004] You'd be better off just letting the wind (how exactly do you think air pressure changes, anyway?) drive the turbine. Thermodynamics and all that.-- bookworm, Jun 25 2001 Bookworm:
Yeh, but
1) Wind is not reliable (right place, right time)
2) Wind only works outside
3) Wind-ows.-- lubbit, Jun 25 2001 Air pressure changes are hardly reliable, either.
1.4 W-h per cubic meter doesn't sound like a lot. How frequently can we assume the pressure will fluctuate? Once a week? Large sealed containers and the space to store them are not cheap.-- egnor, Jun 25 2001 Pressure is pervasive though, unlike wind. I wouldn't like to say that I was "better off" letting the wind do it, that's my point.
Anyway, I hear large containers can be very attractive these days...-- lubbit, Jun 25 2001 In the 18th century, a British clockmaker was selling "perpetual motion" clocks that ran on barometric pressure. More info can be found at: http://www.marcdatabase.com/~lemur/dm-cox-merlin.html-- antiquark2, Jun 25 2001 As noted by antiquark2, there are devices such as clocks which do indeed power themselves using changes in ambient atmospheric pressure. It is important to note, however, that the actual amount of energy that can be obtained in this way is extremely small; fortunately, moving balanced hands at a slow continuous rate around the face of a clock requires almost no power.-- supercat, Jun 25 2001 This sounds like a macroscopic take on Maxwell's Demon - the thought experiment whereby an 'intelligent' gate on an otherwised sealed box is supposed to be able to defy the laws of thermodynamics by selectively letting in only air molecules with greater than a certain threshold velocity. It turns out not to violate the laws, although I forget exactly how - something to do with the entropy cost of the intelligence in the gate, I think.
I'm betting that the cost of measuring the atmospheric pressure and opening and shutting the box would eat up almost all of the stored energy, which is already pretty small, as others have pointed out.-- gravelpit, Jun 26 2001 [gravelpit]: No, it's nothing like Maxwell's Demon. The amount of energy you gain may not be worth it, but it definitely is there; as others have pointed out, clocks are able to power themselves via this technique.-- egnor, Jun 26 2001 Okay, I've gotta try this now..heh. I'm not sure, but wouldn't the container have to be proportionately stronger as the pressure differential increased so that it wouldn't rupture?-- Legend, Jun 29 2001 How about an abandoned mine shaft or some such for storage?-- phoenix, Jun 29 2001 Tall buildings would be perfect, particularly in the summer. Put intake ducts at the bottom of the building and outlet ducts at the top. Fresh, cool air is drawn in at the base of the building, absorbs the heat inside, rises to the top and exhausts through roof-top vents. Wind turbines could be installed in both the intake at the base and the outlet at the top.-- wrinklehead, Jun 29 2001 I was working on an idea with a landmass network of large pipes or tunnels to utilize the pressure difference between high and low pressure areas. There's usually one of each on large continents and the force (wind) could drive large turbines between the correct openings.-- FarmerJohn, Nov 07 2002 It is well known that large caves often have wind blowing out of them or sucking into them. An example is Wind Cave (see link), which moves 1,000,000 cubic feet of air per hour. This is caused by temperature differences and changes in atmospheric pressure. The cave in this example serves as the box, with the difference that it is big enough that the pressure will not equilibrate immediately.
A windmill mounted in a cave entrance would work just fine.-- bungston, Mar 20 2003 bung, They've done something like this for energy storage. See my link.-- Worldgineer, Mar 20 2003 Ok so the amount of power is tiny, a barometric powered watch sounds really cool, I want one. Aslo could other low power devices run on barometric pressure? calculator? just a thought-- tedhaubrich, May 26 2004 random, halfbakery