So I was talking about this at work using heat energy....

[Kalidurga]

I was thinking about global warming actually and had a thought that perhaps we can use this problem as part of the solution. Of course, everyone looks at me like I am nuts when I propose things like this. But, I was thinking heat is energy and if there is more heat energy via global warming perhaps we could transfer much of that energy into running machinery and even us it for cooling our homes. So, I did a bit of a search found this on my first try.

http://www.green-energy-news.com/arch/nrgs2009/20090029.html

[Sherman A1]

1. Thanks for posting

A very interesting concept. One that I had also thought of in passing along the way, but really couldn't turn the fleeting thought into anything like a useful idea, even just to start a discussion.

This IS really something and something that we should as a society pursue as the heat is an endless source of power.

I would as an aside add that we should find some means of capturing all the Hot Air that is circulating in Congress and at least get something productive from it. :rofl:

A big :thumbsup:

[HysteryDiagnosis]

2. This is somewhat related to your topic, close enough for horseshoes and hand

grenades they say....


http://www.popsci.com/cars/article/2011-03/shockwave-generating-wave-discs-could-replace-cars-internal-combustion-engines

[madokie]

3. The Amish around here use heat to run their propane powered refrigerators

We've had a propane powered refrigerator for years that works fine even though it hasn't been used in years. It is smaller than the average home refrigerator of today but back when it was made it wasn't so small then in comparison to what people had in their homes. I've often wonder why we don't harness the waste heat we have all around us to generate electric by heating a refrigerant to drive a turbine. Using a refrigerant is not much different from using water to make steam to drive turbines and the beauty of the system is it would be a closed loop and require very little waste heat to be released into the atmosphere. I'm still convinced that all the waste heat that is due to the dark roads, parking lots, roofs, the air conditioners in the summer, heaters in the winter, auto and truck exhaust is all adding to the temperature of the earth, albeit a little mind you but every little bit is some.
Thanks for the links

[jeff47]

4. Because using heat energy requires a heat gradient

There has to be a "warm" side and a "cool" side. With heat from global warming, there is no cool side.

[madokie]

5. Sure there is a heat gradient

exhaust from a car engine for example is hundred of degrees where the ambient temperature is 120 or so at most, way less most places most times.
Anything else you want to try to make this sound like it is a waste of time? :hi:

Heat gradient does not mean a hot and a cold as such it means heat and a lesser heat, dummy. Just kiddin' about the dummy part but you get the picture I'm sure :-)

[jeff47]

7. Except that gradient isn't due to global warming

Global warming is, as the name implies, global.

In fact, global warming makes it harder to use your proposed gradient because the ambient temperature is higher, reducing the gradient.

[madokie]

9. Global warming has nothing to do with what the subject here is

You are wrong and anything you say is not going to change that. You said there has to be a heat gradient where there is none and I corrected you. Nothing more or nothing less. When a car exhaust for instance is several hundreds of degrees and the ambient temperature is maybe a few degrees hotter than it was a few years ago matters not to the subject at hand. The exhaust of an auto engine going down the hiway at 60 miles an hour is enough to turn the exhaust manifolds red hot so there is plenty of heat gradient between that and the outside air. Geeeze Louise.
Pick a subject you know something about why don't you cause you don't have a clue here and all you wanted to do was rain on the OP's parade, face it.
Peace
have a good afternoon

[caraher]

10. No, he's not wrong

The OP said, "I was thinking about global warming actually and had a thought that perhaps we can use this problem as part of the solution." Global warming has everything to do with the subject of the original post

The idea being explored was whether the heating of the atmosphere could be tapped as an energy resource, and the short answer is no. Your examples of extracting work from a temperature difference *rely* on using the atmosphere as a heat sink, and while you also point out correctly that a few degrees on average won't make a huge difference in the efficiency of these devices, the effect of a warming atmosphere nevertheless goes distinctly in the wrong direction to be a help.

Your particular examples of using "heat" are really examples of burning a fuel to drive a heat engine. None of them tap ambient thermal energy in the air; they all use the air as a dump for waste heat.

One can certainly drive a heat engine using the temperature difference between air and the ground, or between air and seawater. That would be closer to the spirit of what the OP proposed; however, because the temperature differences are so small the thermodynamic efficiencies of such devices is tiny. So we could squeeze a little work out of the "extra" ambient energy caused by atmospheric warming, but not enough to make an enormous difference (especially once you factor in the energy cost of building the machinery required to make it work).

Welcome to DU, Kalidurga. Your article has good ideas in it, but in all those cases what's really proposed is harvesting energy from industrial and other activities we currently just release as waste heat. This kind of thing can and should be done, but is not something that a warmer atmosphere helps.

[madokie]

11. As I said. Using an auto engine for an example

"exhaust from a car engine for example is hundred of degrees where the ambient temperature is 120 or so at most, way less most places most times.
Anything else you want to try to make this sound like it is a waste of time?"
Who I was replying to was not correct, I'm sorry.

ETA: So that hundreds of degrees of heat from the auto exhaust to the ambient air is a heat gradient.

[madokie]

6. Welcome to DU

I hope you stick around :hi: :hug: You can add a lot to the discussions :-)

[TalkingDog]

8. When will they make a waste heat converter small enough for a politician's mouth?

Earth's energy problems? SOLVED

[Bill USA]

12. well, with Global warming comes greater air turbulence (more extreme storms) and this means

that wind power would have a bit more energy to extract from the air, due to higher wind speeds on average. that's one example of what you are talking about. It's a marginal difference, but it would be a function of greater energy (heat) in the atmosphere.

[Ready4Change]

13. An idea in there, perhaps with some confusion on terms.

Global warming isn't due to the heat that comes from cars exhaust pipes or factory smoke stacks. It is due to materials in those exhausts, which get into the atmosphere and then cause that atmosphere to trap a bit more of the heat that the Earth would otherwise radiate into space. (Heat which originally comes from the sun, and which outweighs what our cars and factories put out by a heavy margin.) The over all average temperature change due to the materials we add is actually very small. But since it effects such a large area, the energy it represents can make large changes in weather patterns, making them more extreme. Thus global 'warming' can result in deeper cold and heavy snow falls, because making those more extreme than normal takes more energy. In other words, global 'warming' can make it colder at times, and should be called something like 'global energizing' instead.

However, that doesn't negate the idea of, for example, using the heat in a cars exhaust that would otherwise be wasted. Note, however, that your car already uses some of that. You catalytic converter gets very hot, helping to clean up the exhaust. So whatever you do needs to be 'downstream' from that. Also note, whatever you do which uses that heat will cool down the exhaust, which will make it more dense and heavier, which will make your cars engine work a bit harder. (Takes more work to push heavier gases out the exhaust pipe.) And it gets worse if you stick heat exchangers into the exhaust flow, making that flow turbulent. Better to extract heat via some sort of wrap around the exhaust pipe. You still make the air denser, and may collect less heat, but at least you aren't adding turbulence.

Now, can you do something with that heat? I dunno. Use the difference between it and the ambient air to run a sterling engine? Concentrate it to boil a closed loop of water to run a little turbine generator? I dunno if that could work. And if it did work, I dunno if you would recover enough power to make loading the car with the weight of the equipment worthwhile. Pushing that weight around makes the engine work harder, which costs fuel. It's a numbers game, and I don't know the numbers.