Darkness photocells

Scottech · 10th October 2009, 01:22 PM

I have a small postcard sized photovoltaic panel attached to my window and I am impressed by the fact that every day there is enough daylight to charge some Nicad cells to operate a small portable radio.

This set me thinking that there is daylight every day but not always wind every day to power a 'wind turbine'. I then thought why cannot we have the equivalent of a photovoltaic panel which would work in the darkness? (i.e. negative light!).

I then realised that outer space which is very visible at night has a very low temperature, -55 degrees C I believe, but Google tells me that some parts are at -270 degrees Celsius (all the better!). So why can we not get some energy by exploiting this low temperature property which is available every night?

Thinking back to about 65 years ago when I found interest in the thermodynamics course which I did at Glasgow University, I remember having it regularly impressed on me that all Heat Engines require a 'source' and a 'sink'. I reckon that outer space should make a good sink and that there are plenty of sources on our planet which would make a good source, such as the sea or a river whose temperature is much above outer space.

It is relatively easy to extract heat from such a source but how to dump it to the sink in outer space is a problem.

It then occurred to me that a large parabolic light (and infra-red) reflecting mirror pointed into a clear sky at night should have a very low temperature at its focal point, which it may be possible to exploit as a sink. Between the source and sink could be placed some suitable heat engine of which the are many varieties and whose theories are now well known. A mechanical refrigerator working in the opposite direction using freon etc., may be possible, the mechanical output of the engine could be used to generate electricity.

An alternative method would be to use thermocouples with the hot junction in the sea/river and the cold junction at the mirror focal point.

Such devices would pump heat from the planet to outer space and would possibly upset the politician’s taxing bonanzas by generating global cooling, unless they can find a suitable way to tax it too.

Roll on the tokamak and the ITER project!

I have typed this article with 'tongue in cheek', but it might be an interesting project for more intelligent thought until someone invents the dark photocell!

Dilb · 10th October 2009, 01:27 PM

You basically want to run a heat engine between the earth at ~300K, and deep space, at ~2K. Consider the cost of a solar powered heat engine, and think of the difference compared to using the sun at ~6000K and the earth at 300K, particularly in terms of the Carnot efficiency limit.

jasonpatterson · 10th October 2009, 10:58 PM

So you want to concentrate darkons and use them for power, basically? It's an ambitious idea, but I think you can do it if you're sufficiently persistent.

Dancing David · 11th October 2009, 06:07 AM

Originally Posted by Scottech

It then occurred to me that a large parabolic light (and infra-red) reflecting mirror pointed into a clear sky at night should have a very low temperature at its focal point, which it may be possible to exploit as a sink.

Um not sure what you are thinking here, if on the earth's surface it is going to be at the ambient air temp, the mirror is not going to do anything about that.

Linking a thermocouple to space would be problematic.

Arthur C. Clarke discusses using thermocouples in the ocean and land surface in a book.

Andrew Wiggin · 11th October 2009, 11:31 PM

Originally Posted by Dancing David

Um not sure what you are thinking here, if on the earth's surface it is going to be at the ambient air temp, the mirror is not going to do anything about that.

Linking a thermocouple to space would be problematic.

Arthur C. Clarke discusses using thermocouples in the ocean and land surface in a book.

What David said. Providing a thermocouple with a free view of the sky doesn't make it radiate heat till it assumes the temperature of the sky. The parabolic reflector doesn't help much, except as far as it increases the angle from which the thermocouple can see the sky. You can cool it a little bit this way but the local heating from the air its in contact with overwhelms that effect. You're much better off as well using the temperature difference from something really hot like concentrated solar light to ambient temperature than the much smaller difference from ambient temperature to whatever you can cool the thermocouple to by exposing it to darkness.

Now, if you COULD extract energy from darkness, you'd probably be able to make money from figuring out how to reverse the process. I'd buy a 'dark bulb' that absorbed all light and made the room dark when it was turned on. I'd pay GOOD MONEY as well for a bulb that only illuminated things worth looking at.

A.

Horatius · 12th October 2009, 10:39 AM

Originally Posted by Andrew Wiggin

I'd pay GOOD MONEY as well for a bulb that only illuminated things worth looking at.

A.

Isn't that just a spotlight?

10th October 2009, 01:22 PM	#1
Scottech New Blood Join Date: Oct 2007 Location: Edinburgh Scotland Posts: 6	Darkness photocells I have a small postcard sized photovoltaic panel attached to my window and I am impressed by the fact that every day there is enough daylight to charge some Nicad cells to operate a small portable radio. This set me thinking that there is daylight every day but not always wind every day to power a 'wind turbine'. I then thought why cannot we have the equivalent of a photovoltaic panel which would work in the darkness? (i.e. negative light!). I then realised that outer space which is very visible at night has a very low temperature, -55 degrees C I believe, but Google tells me that some parts are at -270 degrees Celsius (all the better!). So why can we not get some energy by exploiting this low temperature property which is available every night? Thinking back to about 65 years ago when I found interest in the thermodynamics course which I did at Glasgow University, I remember having it regularly impressed on me that all Heat Engines require a 'source' and a 'sink'. I reckon that outer space should make a good sink and that there are plenty of sources on our planet which would make a good source, such as the sea or a river whose temperature is much above outer space. It is relatively easy to extract heat from such a source but how to dump it to the sink in outer space is a problem. It then occurred to me that a large parabolic light (and infra-red) reflecting mirror pointed into a clear sky at night should have a very low temperature at its focal point, which it may be possible to exploit as a sink. Between the source and sink could be placed some suitable heat engine of which the are many varieties and whose theories are now well known. A mechanical refrigerator working in the opposite direction using freon etc., may be possible, the mechanical output of the engine could be used to generate electricity. An alternative method would be to use thermocouples with the hot junction in the sea/river and the cold junction at the mirror focal point. Such devices would pump heat from the planet to outer space and would possibly upset the politician’s taxing bonanzas by generating global cooling, unless they can find a suitable way to tax it too. Roll on the tokamak and the ITER project! I have typed this article with 'tongue in cheek', but it might be an interesting project for more intelligent thought until someone invents the dark photocell!

10th October 2009, 01:27 PM	#2
Dilb Muse Join Date: Oct 2004 Posts: 558	You basically want to run a heat engine between the earth at ~300K, and deep space, at ~2K. Consider the cost of a solar powered heat engine, and think of the difference compared to using the sun at ~6000K and the earth at 300K, particularly in terms of the Carnot efficiency limit.
Dilb Muse Join Date: Oct 2004 Posts: 558

10th October 2009, 10:58 PM	#3
jasonpatterson Philanthropic Misanthrope Join Date: Apr 2009 Location: Macedonia, OH Posts: 908	So you want to concentrate darkons and use them for power, basically? It's an ambitious idea, but I think you can do it if you're sufficiently persistent.
	__________________ Sandra's seen a leprechaun, Eddie touched a troll, Laurie danced with witches once, Charlie found some goblins' gold. Donald heard a mermaid sing, Susie spied an elf, But all the magic I have known I've had to make myself. - Shel Silverstein

11th October 2009, 06:07 AM	#4
Dancing David Penultimate Amazing Join Date: Mar 2003 Location: Central Illinois Posts: 18,357	Originally Posted by Scottech It then occurred to me that a large parabolic light (and infra-red) reflecting mirror pointed into a clear sky at night should have a very low temperature at its focal point, which it may be possible to exploit as a sink. Um not sure what you are thinking here, if on the earth's surface it is going to be at the ambient air temp, the mirror is not going to do anything about that. Linking a thermocouple to space would be problematic. Arthur C. Clarke discusses using thermocouples in the ocean and land surface in a book.
	__________________ Resolve then, that on this very ground, with small flags waving and tinny blast on tiny trumpets, we shall meet the enemy, and not only may he be ours, he may be us.- Walt Kelly wow Mr.Philospher, you need some custard poured over your head mayhaps? -kittynh "Exhibit 1338A as to why the Politics forum is "where rational thought goes to die."-Carlitos Last edited by Dancing David; 11th October 2009 at 06:08 AM.

11th October 2009, 11:31 PM	#5
Andrew Wiggin Muse Join Date: Aug 2009 Location: A small planet named for it's dirt. You'll find it filed under 'mostly harmless' Posts: 578	Originally Posted by Dancing David Um not sure what you are thinking here, if on the earth's surface it is going to be at the ambient air temp, the mirror is not going to do anything about that. Linking a thermocouple to space would be problematic. Arthur C. Clarke discusses using thermocouples in the ocean and land surface in a book. What David said. Providing a thermocouple with a free view of the sky doesn't make it radiate heat till it assumes the temperature of the sky. The parabolic reflector doesn't help much, except as far as it increases the angle from which the thermocouple can see the sky. You can cool it a little bit this way but the local heating from the air its in contact with overwhelms that effect. You're much better off as well using the temperature difference from something really hot like concentrated solar light to ambient temperature than the much smaller difference from ambient temperature to whatever you can cool the thermocouple to by exposing it to darkness. Now, if you COULD extract energy from darkness, you'd probably be able to make money from figuring out how to reverse the process. I'd buy a 'dark bulb' that absorbed all light and made the room dark when it was turned on. I'd pay GOOD MONEY as well for a bulb that only illuminated things worth looking at. A.
	__________________ "Everyone takes the limits of his own vision for the limits of the world." - Arthur Schopenhauer "New and stirring things are belittled because if they are not belittled, the humiliating question arises, 'Why then are you not taking part in them?' " - H. G. Wells

12th October 2009, 10:39 AM	#6
Horatius NWO Kitty Wrangler Join Date: May 2006 Location: Ottawa, ON, Canada Posts: 12,283	Originally Posted by Andrew Wiggin I'd pay GOOD MONEY as well for a bulb that only illuminated things worth looking at. A. Isn't that just a spotlight?
	__________________ ``Horatius,'' quoth the Consul,``As thou sayest, so let it be.'' And straight against that great array Forth went the dauntless Three. For Romans in Rome's quarrel Spared neither land nor gold, Nor son nor wife, nor limb nor life, In the brave days of old.(1) GENERATION 8: The first time you see this, copy it into your sig on any forum and add 1 to the generation. Social experiment.