Cheap cold air from the atmosphere

Hi, why don’t they send a balloon up with a pipe or hose attached to where the cold air is and suck it down into the buildings/hotels etc…? wouldn’t that save tons on ac costs?
virtually yours

Well, that would pretty seriously impact air travel. In fact, giant balloons tethered to the ground have been used as an air defense in the past. It creates, basically, a giant spiderweb in the sky. That’s a very bad thing.

Due to heat transfer through the walls of these very, very long pipes, the air would be pretty much at ambient temperature by the time it got to the ground.

Unless you insulated the pipes.

Which would be expensive.

And heavy.

Which would require the balloons to be very big to hold them up.

Which would be even more expensive.

And even if the pipes were insulated, the air would heat up as it moved downwards. The pressure increases as the air gets to lower elevations, and when air gets compressed, it gets hotter (see adiabatic heating, by which a gas that is compressed exhibits a higher temperature, even in the absence of any heat transfer). In other words, your air would actually be pretty warm by the time you pumped it all the way down to the buildings on the ground even if you had perfectly insulated pipes.

The answer is yes, it would drastically reduce AC costs. It would however drastically increase a number of other costs, as mentioned above, and would introduce a myriad of logistical problems.

Are you high? Or are you just looking for a leg to pull? Serious question, because I can’t fathom how - outside of a child’s mind, or that of a stoner - this question would come into the world.

Was it a cool anime cartoon? Comic book? Video game? Pray tell what was your inspiration?

Moderator Note

Uber_the_Goober, insults are not permitted in General Questions. This is also verging on an accusation of trolling. No warning issued, but don’t do this again.

Colibri
General Questions Moderator

It isn’t a hopeless idea… Jack McDevitt, in one of his science fiction novels, has helicopters raise high tubes of this sort to produce convection engines. Similar convection engines using the temperature difference between surface water and deep water have been seriously proposed.

it’s more practical to do the opposite, ie drill into the earth. like this: http://en.wikipedia.org/wiki/Geothermal_heat_pump

A geothermal heat pump, ground source heat pump (GSHP), or ground heat pump[1] is a central heating and/or cooling system that pumps heat to or from the ground.

It uses the earth as a heat source (in the winter) or a heat sink (in the summer). This design takes advantage of the moderate temperatures in the ground to boost efficiency and reduce the operational costs of heating and cooling systems, and may be combined with solar heating to form a geosolar system with even greater efficiency. Depending on latitude, the temperature beneath the upper 6 metres (20 ft) of Earth’s surface maintains a nearly constant temperature between 10 and 16 °C (50 and 60 °F)

There’s no need to be rude about it. There’s actually a nearly analogous system called OTEC, except that instead of cold air from high atmosphere, it pulls cold water from the deep ocean. The systems aren’t very common yet, but they are practical in some situations. It’s not at all a stoner idea.

Getting cold air from the upper atmosphere may be more difficult, but not entirely impossible. It might be better to use a working fluid like helium to transfer the heat. You could use nested pipes for insulation. Ideally, the system would be self-pumping; you would want the heavy, cold air to fall by itself, and using that energy to pump warm air back up to altitude.

I tried to fashion an air-conditioner for my boat on this principle (in reverse). It was many years ago, I was young and knew little of heat transfer, physics, etc.

I had an old cabin cruiser and tried to assemble an air conditioner out of an 12V fan, a small car radiator, some hose, and a small 12V underwater pump. My reasoning was that water below 8 feet (or so) in a lake is always pretty cold. I would pump this water up, through the radiator, and overboard. The fan would blow thru the radiator and I would have a nice a/c that could run on the batteries. Obviously this wouldn’t work underway, but I wanted to try it anyway.

Turns out you need a lot of water to do this, and moving it from 8 feet below requires a bigger pump, and more battery, and a bigger fan, and… well you see where this went. There just isn’t any way to change the temp of a large volume of air without a lot of energy. :rolleyes:

Ok ok, I see your point. It was needlessly rude.

I’m still baffled at how this question could come about. To me, that’s the more interesting discussion.

If this worked, one would expect a larger pipe to be more effective, right? Now picture making your pipe larger and larger, until eventually the pipe encompasses the whole planet: That should surely be the most effective system possible for exploiting this. But if you think about it, that’s already exactly what we have: The entire atmosphere acts like one huge pipe. And if that’s the most effective system possible, then surely any pipe we could actually construct couldn’t be any more effective.

No not high just thinking high…altitude that is… I have seen the high altitude tethered surveillance balloons and wonder if they could have used a hollow tube attached to the side of the tether and using vacuum suck down the cold air… as someone mentioned they use the sea for something to this effect and the ground, so why not the air… there are mountains and tall buildings to fly around or over and also no fly zones… ie military etc… and even the existing high balloons have to be navigated around…
lots of ideas were laughed at and later turned out to be great inventions and helped out the world tremendously… I take your comment as a great compliment… it indicates I am thinking outside of the box, and have unique ideas…stuff you never heard of before…not tipping my own hat and trying to say this as humbly as possible: that is the stuff geniuses are made of… thank you so much…
virtually yours,
virtually yours

The air would have to increase in pressure as it was forced towards the surface. Compression would cause it to heat up.

My building is 14 stories about 250,000 sqft. The supply fans for the cold deck are 100 Hp and there are two of them. On hot days when the building goes to “full cooling” a third 100 hpfan kicks in. I run about 54 degrees on the cold deck. I have no reserve cooling and in some of the offices onthe sun side of the building the temp can climb about the buildings 72 degree sepoint. The pipes would have to be very large to move that much air.

Walt and Leigh Richmond postulated the concept in 1970 in their story “Shortstack.”

This is essentially the opposite of an air conditioner. An air conditioner sitting outside the building compresses air so that it heats up then releases it into the building where is expands and cools. We would instead be taking cool air and compressing it which would cause this:

But that aside, the air temperature is only 5 degrees cooler per thousand feet of dry air, and only 3 degrees for humid air, so what altitude would you expect to pull air from? 10,000 feet? 20,000? And things can vary locally so if you’re expecting 60 degree air at X feet, you may not get it. Then what happens if there’s a temperature inversion, a weather event where the air is warmer at altitude?

Not quite. The air in a buildings supply fans may increase to 2 to 3 inches of pressure. that is less than 0.2 PSI.

Oops, I played a little fast and loose there. It actually compresses refrigerant outside, then as it depressurizes and cools inside, it pulls heat from the air.

as I already said, systems like this exists but into the ground, which is much more practical. Check out ground source heat pumps.

If you used a fluid like water instead of air (no issues with compression) and heat exchangers, I could see this working - if only you could get away with 10,000+ foot pipes (insulated very well!).