A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Space Science » Technology
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

"Reinventing the Solar Power Satellite" paper



 
 
Thread Tools Display Modes
  #11  
Old May 16th 04, 02:44 PM
Alex Terrell
external usenet poster
 
Posts: n/a
Default "Reinventing the Solar Power Satellite" paper

Ian Stirling wrote in message ...
Robert Lee wrote:
I was wondering if you worked out how high the price of oil has to be in
order for an SPS project to be profitable.


This is going to be as contraversial as the Drake equation.
There are so many possible variables.
What do you pick for launch cost?
Is it $6000/Kg, or $30/Kg launched by some sort of tether.
Are you using near-term 200W/Kg solar panels, or are you assuming
thin-film manufacturing breakthroughs, solar-dynamic, or...

What is the size of the recieving arrays, how close are they
together, how big are they, can you use the land under them, do you
need to keep aeroplanes out, ......

All of these are variables.
It's quite easy to generate numbers that vary by a factor of at least
a thousand.


Do we use direct space launch, which would be the cheapest for a few
GW, or do we go and capture NEOs, which would be much cheaper for a
few Terawatts?
  #12  
Old May 18th 04, 07:12 PM
Iain McClatchie
external usenet poster
 
Posts: n/a
Default "Reinventing the Solar Power Satellite" paper

Robert I was wondering if you worked out how high the price of oil has to
Robert be in order for an SPS project to be profitable.

That's the energy component. You also have to know the price of land.

Solar cells on the ground in Arizona might generate about 300 KW per acre.
Call it 6 hours a day (it's more, but the amount decreases off noon), sell
it at $.04/kWH, for $26k a year. A quick google found land in Arizona
("Just 1 hour from Phoenix!") for $2000/acre, and I would guess it can be
had for less, especially in Mexico. If you can pay off the land with a
month's operation, I think the dirt is a good cheap orbit for an SPS until
launch costs drop to $1/lb and you can build a reliable power satellite
in 1 ounce per square foot.

I really wouldn't even worry about putting the land to other uses. Even
the absolute amount of land available does not appear to be a large
problem, as 150 square miles would generate enough power to run California,
and 800 would take care of the difference between day and night operation
across the entire U.S., eliminating those pesky "peaking" issues.

Then, of course, you have to compare transporting energy via thousands of
miles of wire, which is a well-understood problem (buying rights-of-way),
versus transporting that energy tens of thousands of miles via microwaves,
which have seen less deployment due to much larger losses, complexity, and
issues with things getting into the beam (which I think are somewhat
analagous to right-of-way issues).

So never mind space, building and installing cheap solar cells is *the*
problem. Happily, we're only an order of magnitude away (for cells I can
buy today from realgoods.com), and probably a fair bit closer than that
for large commercial systems. Manufacturing problems are much easier
problems than negotiating with despotic thugs and their terrified citizens
in, you know, the mideast.
  #15  
Old May 24th 04, 12:45 AM
external usenet poster
 
Posts: n/a
Default "Reinventing the Solar Power Satellite" paper

Geoffrey A. Landis wrote:
Geoffrey A. Landis wrote:
For any of you with an interest in Solar Power Satellite (SPS, or SSPS)
concepts, I finally received NASA Technical Memorandum copies of my
papers "Reinventing the Solar Power Satellite" and "Peak Power Markets
for Satellite Solar Power" from the Houston IAF Congress... NASA
TM-2004-212743


Or, for those who prefer electrons, I realized it's available on the
Glenn server as a PDF file: http://gltrs.grc.nasa.gov/cgi-bin/GLTRS/
browse.pl?2004/TM-2004-212743.html


As I understand it, your SPS plan is predicated on ground solar cells
supplementing around local noon the SPS's peak power generating times
at 0900 and 1600. The SPS transmits its power to the ground solar
installation, which also would have rectennas to capture the microwave
beamed energy.

That's an interesting idea, but perhaps I'm missing something. Why beam
microwaves at all? You have a perfectly good ground solar installation,
and according to Henry Spencer PV cells are fairly efficient (~50%) if
the wavelength is well matched to the type of cell, so a space-based
dichroic mirror array might be an equally valid form of power beaming
to the ground while reducing terrestrial heating as compared to a
simple mirror. The design would likely look like the dihedral array
in figure 9, albeit with the dihedral pointing in the opposite direction
to bounce light to the ground installation.

Eliminating the microwave transmitters would reduce orbital mass while
reducing ground-based cost by doing away with rectennas, not to mention
calming public fears about RF leakage outside the ground receptors.

Comments?


Francois.

  #17  
Old May 28th 04, 10:16 PM
Charles F. Radley
external usenet poster
 
Posts: n/a
Default "Reinventing the Solar Power Satellite" paper

"Robert Lee" wrote in message ...

One other thing comes to mind, if you are pumping energy into the
atmosphere, it seem that you maybe
producing waste heat as well, that could also play a role in global
warming, so you would still have to find a
way to remove the CO2 and Methane for the atmosphere in order prevent
continued global warming.

Of course, the decrease in CO2 emissions could offset the waste heat
produced. I guess someone would
have to do the math to find out.


Global warming is not caused by waste heat, it is caused by the
greenhouse effect. Greenhouse gases, e.g. CO2, traps natural heat
coming in from the sun, and prevents it from being radiated back to
space.

The amount of solar energy trapped in this way is at least thousands
of times greater than all the waste heat humanity is creating.

I did the calculation once a few years ago, I will see if I can find
the data. I say thousands to be conservative, it could be more, I do
not remember.

The solution to global warming is to stop emitting greenhouse gases.
That means eliminating fossil fuels, or sequestering all the CO2
underground.

Once that is done we are free to generate as much waste heat as we
want, it will simply be radiated out into space along with the
re-radiated solar energy, with no detectable net change to the overall
temperature of the planet.
  #18  
Old June 24th 04, 09:35 PM
external usenet poster
 
Posts: n/a
Default "Reinventing the Solar Power Satellite" paper

Iain McClatchie wrote:
Francois a space-based dichroic mirror array might be an equally valid
Francois form of power beaming to the ground while reducing terrestrial
Francois heating as compared to a simple mirror.

This was covered right here fairly recently.


Quite, quite. I got here just recently, and on your recommendation
re-read the older posts. Thanks.


What you're missing is a limitation of ordinary optics: nothing that
simply reflects or diffracts sunlight can make a spot in the sky appear
brighter than the sun. The crucial function of the photovoltaics +
microwave transmitter is that they make a spot in the sky with huge
power per steradian.

[...clear & concise technical explanation why my idea is full of beans...]


Much appreciated.

(wait! This is Usenet! Civility Not Allowed! YOU PESSIMISTS IGNORE
THE TRUE GENIUS BEHIND MY REASONING! GALILEO EINSTEIN!! BOOGA BOOGA!)

There, that should restore the natural order.


Cheers,
Francois.

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Zubrin's panning of space solar power in Entering Space TomRC Technology 10 February 25th 04 12:26 PM
Scientists Report First-Ever 3D Observations of Solar Storms Using Ulysses Spacecraft Ron Baalke Science 0 November 17th 03 04:28 AM
Voyager Spacecraft Approaching Solar System's Final Frontier Ron Baalke Science 0 November 5th 03 07:56 PM
Voyager 1 Approaches Solar System's Outer Limits Ron Baalke Science 0 November 5th 03 07:53 PM
ESA Sees Stardust Storms Heading For Solar System Ron Baalke Science 0 August 20th 03 08:10 PM


All times are GMT +1. The time now is 05:01 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.