Why not rooftops covered with infrared LEDs? an abstract in IEEE suggested ....

[Hank Roberts]

Ray Pierrehumbert thought this notion sounded interesting, a while
back at RC; at the time all I'd seen and all he'd seen was an IEEE
abstract. I mentioned it at RC quite a while ago, and haven't seen
anything more about it.

The IEEE article seemed to be thinking about big infrared lasers (yes,
I think they'd have to be bicycle/hydro/solar/wind powered to make a
net improvement -- you don't want to generate any net excess heat to
power such a device!)

http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1392156

Ray's inline replies in these comments:
http://www.realclimate.org/?comments_popup=307#comment-14306
http://www.realclimate.org/?comments_popup=307#comment-14322

At the rate at which light-emitting diodes are improving, it might
soon be possible to make rooftops not just white, but actively
narrowband emitters, to lose heat in one of the infrared windows.

I was hoping some astronomer would start looking in those bands --
maybe it would be a way to locate life elsewhere. Has anyone reported
an exoplanet with very narrowband IR signature?

Maybe we could be the first ...

[James]

On Jun 6, 8:35 am, Hank Roberts <ankh...@gmail.com> wrote:
> Ray Pierrehumbert thought this notion sounded interesting, a while
> back at RC; at the time all I'd seen and all he'd seen was an IEEE
> abstract.  I mentioned it at RC quite a while ago, and haven't seen
> anything more about it.
>
> The IEEE article seemed to be thinking about big infrared lasers (yes,
> I think they'd have to be bicycle/hydro/solar/wind powered to make a
> net improvement -- you don't want to generate any net excess heat to
> power such a device!)
>
> http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1392156

Sounds utterly barking to me - why waste all that energy rather than
using it for something meaningful (like substituting fossil fuels, for
example).

Mind you I can't see the full paper which may provide some plausible
arguments..

James

[Michael Tobis]

Ah, the giant air-conditioner idea again.

Why infrared in particular?

Ray is a science fiction reader. He finds things interesting without necessarily finding them plausible.

I think Ray's first comment is pretty much the same as James' one. It's an awfully roundabout way at the problem. Some snark from me: it does qualify as geoengineering, because the planet is not actually zero-dimensional. The neglect of the actual circulation of the atmosphere is pretty standard stuff in geoengineering, as if global mean temperature were the problem rather than a symptom of the problem.

I am not interested in solutions that don't address forcings and you shouldn't be either. Trying to do an atmospheric energetics fix with a reverse forcing is solving the wrong problem and won't work.

mt

[Hank Roberts]

I don't have the full paper either; perhaps someone reading here does
have IEEE access, or knows where this was discussed if it was.

On the microcosm, the reason is to rapidly remove heat from a
spacecraft by radiating it away. The ISS uses big flat radiator
panels rather than a 'cooling laser' because they can afford the huge
surface area required -- on the global scale, to emit through the
atmosphere would require wavelength control.

I suppose the same question applies to painting roofs white -- all the
energy of making and applying the paint or new roofing material could
be used differently too.

Heat that's already at the infrared level is mostly waste now, hard to
scrape it up somehow into thermodynamically useful energy. Can a
range of infrared be captured and used to emit in an IR window band?

Some infrared photovoltaic material is being worked on
http://www.google.com/search?q=infrared+photovoltaic


Maybe there'd be a way to use that kind of material to tune the
wavelength and re-emit IR in a window band.

That's what led me to wonder about using roofing material rather than
giant lasers -- the roofs have to be replaced every few decades
anyhow, whether with bright white or with something that is bright in
one of the IR windows.

Hey, it's science fiction -- the idea is to get rid of low-value heat
by getting it collected in a wavelength that will exit through "IR
window" bands.

A 'rogue wave' material -- something that from time to time will
collect enough energy from all the lower waves around it into one
larger wave tuned for the IR window. Paint or roofing material that
glows or sparkles in IR window frequencies when it gets warm.
http://scholar.google.com/scholar?q=%22Nature+Materials%22++infrared+photovoltaic

Of course the IR astronomers working in those windows would hate the
idea.

Hell, the visible light astronomers are going to hate the idea, now
that I look into it.

You've seen the huge blindingly bright LED billboards now going up
along freeways?

Imagine what the advertisers are going to do with sprayable paint-on
LEDs (sigh).
http://www.nature.com/nmat/journal/v8/n6/abs/nmat2459.html

[Michael Tobis]

I tried my IEEE membership number to no avail. I don't have the
relevant subscription.

It leaves me guessing which subsociety actually has access. Quite
plausibly there is no paper at all and only an abstract, as is often
the case at proceedings like this.

But a little googling got me to this:

http://parisetech.com/technology.html

and this:

http://parisetech.com/ECTecPaper.pdf

I think if you contact him he will ask you for money.

mt

[eugene nordell]

Hi: Tx for reply, I guess my instant reaction was that it would take far more total area than just roof tops to accomplish anything that it would likely be futile.  It appears to me that all of the re-radiated "Waste" Heat from UHI still contributes to Global (atmospheric warming) with much of it being re-radiated back to us.  That, unless there are specific sub-bands within the
infra-red band that would re-radiate most energy out into space without intercept in lower troposphere???  I'm not familiar with specific frequency bands at infra-red, having worked mostly from low L-band (1 Ghz) up through K-Band on the order of 14- 16 Ghz??  Just zero experience with infra-red stuff.  I am not familiar with frequencies of re-radiation of gas molecules except for oxygen which I believe to be in the range of L-Band; 1Ghz+/-?

> Date: Sat, 6 Jun 2009 17:31:45 -0500
> Subject: [Global Change: 3222] Re: Why not rooftops covered with infrared LEDs? an abstract in IEEE suggested ....
> From: mto...@gmail.com
> To: global...@googlegroups.com

[eugene nordell]

I have read that some believe the majority of the "waste" heat is a product of blacktop roads, roofs, etc., which absorb a broad range of frequencies and re-radiate it at much lower frequency band.  If that is the case(?), a simple white paint with correctly selected constituent elements, For Example-whitewash as specified in NASA specifications for painting shelters of temperature measuring thermometer; would reflect most of the incoming rays and not store them as blacktop roads and black roofs apparently do and re-radiate them as much lower frequencies. Thus, the white surface would send most of the heat back into space. As a test, just feel a car painted pure white and compare that to a black pointed car; but be careful on a bright, sunny day re burning of hand, especially in southern US or even closer to equator!  However, paint selection would be subject to NOT making a slick surface on roads, that would be disastrous, especially in rainy conditions.  Also,glare might prove very limiting.

> Date: Sat, 6 Jun 2009 09:08:23 -0700
> Subject: [Global Change: 3221] Re: Why not rooftops covered with infrared LEDs? an abstract in IEEE suggested ....
> From: ank...@gmail.com
> To: global...@googlegroups.com

[James Annan]

Hank Roberts wrote:

> I suppose the same question applies to painting roofs white -- all the
> energy of making and applying the paint or new roofing material could
> be used differently too.

Sure, but at least the effect is free, whereas LEDs need powering...from
somewhere. I realise that this does not necessarily guarantee it's a
better alternative, but it's a pretty strong indicator. I also think it
is well established that white roofing is economically better than free
in areas where airconditioning is a significant cost.

> Heat that's already at the infrared level is mostly waste now, hard to
> scrape it up somehow into thermodynamically useful energy. Can a
> range of infrared be captured and used to emit in an IR window band?

My point exactly. All a bit moot in absence of any idea what is actually
being proposed.

James

[James Annan]

Michael Tobis wrote:

> http://parisetech.com/ECTecPaper.pdf
>

Sorry, didn't realise you had actually found the paper until I did some
googling myself and got to the same point. I believe it's a form of
perpetual motion machine. In particular, the "cooler" relies on
radiating away energy in order to create a temperature differential
which can be used to generate sufficient energy to radiate away the heat
that passes through the generator.

As such, I'm surprised it hasn't made a bigger splash with the denialists...

James

[Don Libby]

From: "James Annan" <james...@gmail.com>
Newsgroups: gmane.science.general.global-change
To: <global...@googlegroups.com>
Sent: Sunday, June 07, 2009 8:21 PM
Subject: [Global Change: 3226] Re: Why not rooftops covered with infrared

LEDs? an abstract in IEEE suggested ....

Michael Tobis wrote:

HA HAR HAR! Thanks for a good laugh to start the day off. :-)

My own favorite crackpot scheme along these lines is to generate electricity
with IR photocells inside a power plant exhaust stack. I suppose you could
feed it directly to rooftop IR LEDs to re-radiate as heat, with
thermodynamic losses all along the way. The only possible use for the
scheme would be to shift the IR wavelength to a band that is not already
saturated. I'm foggy on the physics of what happens to the beam after it
leaves the LED, but isn't there a very thick blanket of molecules to
penetrate before reaching the black body of space? Maybe that's why
superior crackpots prefer lasers - more punch to get through the fog.

-dl

[Michael Tobis]

Let's work from Parise's estimate that direct heating from US
automobile traffic could be counteracted by 0.7% of the area of Texas
or roughly 1900 sq mi. That is that counteracting all direct US energy
consumption could be balanced by about 25000 sq mi = 65000 sq km for
29000 TWh.

Divding by the number of hours in a year, the total emissions must average
3.31e12 W over a surface area of 6.5e10 m^2 or 50 watts per square meter.

I have to admit if the stuff were free and worked this well it would
be better than white paint.

One problem is that anthropogenic greenhouse forcing is much more
effective than direct heating.

Leaving aside capital costs, to counteract global warming due to 550
ppmv CO2 equivalent (4 W/m^2 global) would require 1/12 of the earth's
surface to be covered in this stuff. Or about 1/3 of the land surface
area.

Then you have to consider whether it would work in the daytime or
under cloudy conditions or (as described briefly in the white paper)
in humid conditions. Accounting for various inefficiencies and
practicalities, then, we essentially have to pave the earth in Parise
devices to preserve life as we know it, which seems a bit
contradictory.

That all said a device that could passively generate 50 watts of
infrared per square meter would surely be enormously useful for other
reasons. Perhaps there are some other problems with the design?

mt

[James Annan]

Michael Tobis wrote:

> That all said a device that could passively generate 50 watts of
> infrared per square meter would surely be enormously useful for other
> reasons. Perhaps there are some other problems with the design?

Like I said, it's a perpetual motion machine. Other than that, yeah it's
all peachy. Energy too cheap to meter etc etc.

Surprising the patent office didn't spot it as they are supposed to be
on the lookout for these things. OTOH perhaps one could argue that it
isn't technically a true perpetual motion machine, but it's close enough
(unless I misunderstand something, which is always possible).

James

[Hank Roberts]

Good grief. Nighttime solar cell; same inventor:
http://www.freepatentsonline.com/5936193.html
http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=870653