# Power generation via thermal differences

1. Nov 5, 2005

### primalchaos

As part of a science project, my professor is having us come up with an original way of producing electricity, with an emphasis on new frontiers and space travel. Here's what I came up with.

It occured to me there must be a way to exploit the temperature difference between the base of a space elevator and its orbital top for power purposes. I know solar power would be easier, but I'm trying to come up with something original here.

Taking a page of meteorology, the reason wind exists is that cold air sinks and hot air rises. As air moves away from the equator and higher into the atmosphere, it becomes colder and heavier. Similarly, as air moves toward the equator and toward the Earth's surface, it becomes hotter and lighter. This causes changes in pressure that creates the eternal loop of our planet's wind cycle.

Now, let us assume we have a space elevator. Take two large tubes (let's say about 10 feet in diameter) and run them side by side along most of the length of the elevator. Then connect them at either end and make them airtight/vacuumtight. Fill them with a stable and plentiful gas, like Nitrogen. A single element being involved will probably make the physics easier to work out.

So, we have one end of the tube sticking out into space, and the other end down near the surface of the Earth. That's a huge temperature difference. The air at the top of the tube will be extremely cold, and will want to move downward, while the hot air near the bottom will want to move upward. And as hot air move upwards, the ambient temperature will chill it, and the reverse with the cold air moving downwards.

Exaggerate this effect by implementing a valve system that only lets air pass one way through either of the tubes (one down, one up). This should create a fairly powerful wind force by manipulating the temperature differences.

Stick in wind turbines modified to work in the tube. And you have a endless power source that uses no resource other than the temperature differences created by the sun, and has no toxic side effects.

Tell me why this wouldn't work, or a way to use the same idea but better. There has to be a way to harness the temperature/pressure differences on a space ribbon for power.

2. Nov 8, 2005

### steve9983

There isn't any air in space. There's nothing to flow down the tube from space.

Also, the same principles that keep the atmosphere from going into space will stop air from flowing up the tube.

To take advantage of temperature difference, you would probably want to look at the Peltier-Seebeck effect:

http://en.wikipedia.org/wiki/Peltier-Seebeck_effect

3. Nov 8, 2005

### .:JimmY:.

Well at theoratical level it is much true but not very practical. coz temprature is same throughout the the space (as is required in the experiment) unless u r talking abt creating something that expands frm a planet to planet coz there we have huge temprature differnce.
Consider creating something using solar wind, 'm not sure yet .

4. Nov 8, 2005

### .:JimmY:.

u prolly don't know what u r talking abt, no offence though.
And the peltier-seeback effect won't be any helpfull in the cause

5. Nov 11, 2005

### steve9983

Jimmy... you might concider hitting up the english language usage forum.

6. Jun 9, 2011

### emkay4597

I think it would work except for your valving sytem. You need to insulate one at the top, and the other at the bottom.

7. Jun 9, 2011

### Drakkith

Staff Emeritus
I am unsure how effective this would be. Have you taken into account the effect of elevation on gas density? That would affect the flow of hot and cold gas in your tubes.

8. Jun 9, 2011

### cjl

It would only work if the temperature gradient were larger than the adiabatic lapse rate, and I doubt that would be the case.

9. Aug 30, 2011

### Free_Soul_Man

10. Aug 30, 2011

### Drakkith

Staff Emeritus
I don't see why not. Did you have a question?