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THE Solar Power & Space Thread (merged)

Discussions of conventional and alternative energy production technologies.

THE Solar Power & Space Thread (merged)

Unread postby fecteau » Thu 19 Aug 2004, 13:21:53

Solar power satellites have been discussed for decades. I think it's time we
start looking at them seriously. It's unfortunate that NASA has dismissed it so easily: http://www.wired.com/news/technology/0, ... story_top5

On the other hand, ESA is interested enough to have a conference on the subject: http://www.congrex.nl/04c15/

As a long time space entusiats, I believe SPS can play and important role in
the post oil peak economy. Developing the technology for SPS could also be the driving factor that keep the economy growing.
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Orbital peace platform laser

Unread postby guest » Thu 19 Aug 2004, 16:27:07

This reminds me of a bit from (I believe) Robocop 2 or 1 (paraphrasing):

"Thousands died this morning as a malfunction on the orbital peace platform laser accidentaly fired into a crowded neighborhood."

All these solar sattelite articles conveniently neglect the astronomical amount of energy it takes to put even 1 kg of material into geostationary orbit.

And if you mention that, then proponents suggest building vast factories on the moon to make all of this stuff. Yeah, THAT'S going to happen in time for peak oil problems.

It would be much wiser to invest our time & energy into conservation, flexible electric grids powered by wind & solar (where as the amount of power produced falls the price increases for consumers and big power drawing pieces of equipment power down accordingly) and crop-waste-to-ethanol production.
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Re: [Solar 7] Solar Power from Space

Unread postby rerere » Thu 19 Aug 2004, 20:19:24

fecteau wrote:Solar power satellites have been discussed for decades. I think it's time we
start looking at them seriously.


Please explain how you plan to take watts of 'power' from space will NOT add to the heat load inside the planets atmosphere?

Because your plan will add heat energy inside the atmospheric envelope. In addition to being an orbital weapon system.
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Unread postby Devil » Fri 20 Aug 2004, 02:09:10

Dammit! We can't manage energy on the earth's surface successfully, so how can we manage it from space? :( Thank God, I'll be dead before any such hare-brained scheme could doom us to further misery.
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Unread postby Licho » Fri 20 Aug 2004, 04:38:36

Japan plans SPS in longer term. With several hundred megawats of power. It's gonna be using microwaves (not laser), with intensity on Earth just a bit higher than that of cellular phones. Therefore, antena reciever has to be big, but you can still use space below antena (it allows about 1/2 of light to come through).
Plan suggest, that it should pay itself in similar time like nuclear plant.

And regarding heating of Earth - that's a minimal problem. We don't have global warming because of heat we produce by burning fossils/using any kind of energy, but because of CO2.
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Unread postby Devil » Fri 20 Aug 2004, 05:40:26

Licho wrote:Japan plans SPS in longer term. With several hundred megawats of power. It's gonna be using microwaves (not laser), with intensity on Earth just a bit higher than that of cellular phones. Therefore, antena reciever has to be big, but you can still use space below antena (it allows about 1/2 of light to come through).
Plan suggest, that it should pay itself in similar time like nuclear plant.

And regarding heating of Earth - that's a minimal problem. We don't have global warming because of heat we produce by burning fossils/using any kind of energy, but because of CO2.


Just apply a little elementary physics and some modicum of commomsense.

1) Tell me how you are going to generate "several hundred megawatts" of microwave power. To generate 1 kW of CW microwave power (not pulsed) is already a challenge. I don't believe we have the technology for even a single MW.

2) Bearing in mind the inefficiency of CW TXs at those frequencies, I would imagine that, for a 500 MW space station, you would need about 4 to 6 km2 of solar panels to power it. How are you going to get them up there?

3) As such a station would need to be in geostationary orbit above the receiving dish, it will be in the dark for half the time.

4) How do you overcome atmospheric diffraction changes?

5) It is simple physics that if you increase the radiation energy into the earth's biosphere, so the latter will become warmer. However, half a dozen such stations would not make much difference.

6) What will you do with all the roast birds that will fall to earth (not to mention aircraft that inadvertently pass through the beam

7) How will you perform maintenance on a geostationary device using thermionic components?
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Just use solar panels on earth

Unread postby rerere » Fri 20 Aug 2004, 09:24:15

Licho wrote:Plan suggest, that it should pay itself in similar time like nuclear plant.


But nuke plants CAN NOT afford the insurance, that is why in the US of A Congress limits their liability via the Anderson bill. So nuke plants do not 'pay for themselves'.

Licho wrote:And regarding heating of Earth - that's a minimal problem. We don't have global warming because of heat we produce by burning fossils/using any kind of energy, but because of CO2.


And that CO2 is still going to trap the additional heat load of this orbiting solar platform scheme. Every watt of eventual electrial power will become a part of a BTU of heat. That heat will be trapped by the already existing CO2 as you have noted.

Once every man made structure on this planet, wind machines are in use AND the energy needs are still unmet, then this obiting solar platform idea should be considered for implementation. Otherwise, it is nothing more than picking the pockets of citizens by the Governments for the benefit of global corporations.
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Unread postby Licho » Fri 20 Aug 2004, 13:33:41

Devil wrote:1) Tell me how you are going to generate "several hundred megawatts" of microwave power. To generate 1 kW of CW microwave power (not pulsed) is already a challenge. I don't believe we have the technology for even a single MW.

We don't need CW, plan calculates with normal 2450MHz transmitters similar to microwave owens :-) There si probably going to be array of them on sattelite.
The problem is, that you need large array of transmitters, to limit divergence of rays.

2) Bearing in mind the inefficiency of CW TXs at those frequencies, I would imagine that, for a 500 MW space station, you would need about 4 to 6 km2 of solar panels to power it. How are you going to get them up there?

Yes, one of the major problems. It calculets with modular design and many normal launches, but nothing undoable, just very costly.
If we are going to build large ammount of such things, it's really much much cheaper (energy wise) to launch material from Moon, or build space elevator :-)

3) As such a station would need to be in geostationary orbit above the receiving dish, it will be in the dark for half the time.

Erm, check the orbits :-) It's not in shadow 1/2 of day, in fact it's in light 24/7 ! (Just rare do eclipses though happen).

4) How do you overcome atmospheric diffraction changes?

Diffraction affects MW minimally, and happens at relatively low altituted. Rectifier antena will be bigger than neccesary and probably of ellipse shape and will handle tiny changes.

5) It is simple physics that if you increase the radiation energy into the earth's biosphere, so the latter will become warmer. However, half a dozen such stations would not make much difference.

Yes, but just compare this energy to total solar energy we receive. Really, several GW change nothing..

6) What will you do with all the roast birds that will fall to earth (not to mention aircraft that inadvertently pass through the beam

Intensity near Earth is going to be just about 20-30mW per square cm (5mW can leak from MW owen by US standards), it won't kill anything. Birds can fly over it.

7) How will you perform maintenance on a geostationary device using thermionic components?

Biggest problem. Maintenance and servicing costs will be huge. SPS will receive constant damage from sun, space junk and micrometeorites..
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Unread postby Licho » Fri 20 Aug 2004, 13:37:29

Regarding the orbit - don't forget that GEO orbits are over equaor. But axis of Earth is tilted, and GEO orbit is 36 000 km high, so SPS won't enter Earth's shadow..
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Unread postby fecteau » Fri 20 Aug 2004, 19:11:04

Licho, Thanks for responding to most of the nay sayers comments.

One that you did not address is SPS versus earth base solar and wind power.
All have a place in our future. However I believe that once established, SPS will provide more and cheaper power.

As for "how to get it up there", have a look at the following link re"space elevator"
http://www.space.com/businesstechnology ... 40629.html

Another proposal would build the collectors on the moon, not on earth orbit:
http://fti.neep.wisc.edu/neep602/FALL97 ... ure36.html

We don't have a shortage of ideas. What's needed is the leadership to move
our society away from it's hydrocarbon addiction
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Unread postby neo » Sat 21 Aug 2004, 13:08:43

The earth atomosphere absorbs about 40% of the solar energy on average; but the percentage really varies from place to place. Here in Arizona there is almost no humidity and clouds, I belive the percentage should be much smaller. And the SPS also have some transmission loss due to converting electicity to microwave, the microwave being absorbed by the atomosphere, and converting it back to electricity. If we can cover half of Ariona desert with solar panel, we can easily meet the electricity needs for entire US. It will be way cheaper than building it in space. Of course the key is to make cheap and efficient solar panel, and it is already in progress.

My local power supplier SRP already provides solar power generated electricity at the rate of 525 kW ( http://www.srpnet.com/environment/renewable.asp ). Hope they can expand this project. I do believe solar power is our savier and hold the key to our future. I am a senior engineer at a big semiconductor company and I'm looking into ways to make solar cells from defected wafers.
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Unread postby nero » Sat 21 Aug 2004, 14:31:14

Would space based energy be useful if instead of sending it down to earth as pure energy instead you send down to earth finished products. heres my suggestion. You go capture an asteroid :) and use solar energy to mine and smelt the darn thing then send down to earth payloads of refined metals as slow meteorites.
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Unread postby Licho » Sat 21 Aug 2004, 19:36:47

Sun does not shine 24/7 on Earth and atmosphere absorbs significant ammount of energy. It's far more efficient to transmit it from space, even with relatively low efficiency conversion to MW and back. (Microwaves on this frequency loose only minimum energy in atmosphere). However, building costs for such thing are hug. Countries like Japan, don't have many excellent sites for ground solar farms, that's probably why they consider such extravagant plans. Some european scientists want to build solar plants over northern Africa, due to lack of suitable places in europe..

Nero: I don't think that there such thing as "slow meteorite" :-)
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Unread postby Devil » Sun 22 Aug 2004, 02:18:54

I'll believe it when I see it, and that will be from six feet under, if ever! Even if it were to materialise, I could never hope to pay the cost price for that energy.
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Beam It Down: How the New Satellites Can Power the World

Unread postby JohnDenver » Fri 24 Sep 2004, 09:13:18

Interesting article on a new approach to power satellites.

"The new communications satellites will orbit at an altitude of only a few hundred miles. Instead of hovering above a spot on the equator, low-orbiting satellites zip around the globe in as little as 90 minutes, tracing paths that oscillate about the equator, rising and dipping as many as 86 degrees of latitude. Because they are closer to the earth's surface, the solar collectors on the satellite can be a few hundred meters across rather than 10 kilometers. And because the microwave beams they generate would spread out much less than those from geosynchronous satellites, the ground rectennas could be correspondingly smaller and less expensive as well. By piggybacking onto these fleets of communications satellites--and taking advantage of their microwave transmitters and receivers, ground stations, and control systems--solar power technology can become economically viable."

http://www.spacefuture.com/archive/beam ... orld.shtml
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Unread postby Jack » Fri 24 Sep 2004, 16:14:32

Neat idea---one would think that it would be an ideal way to generate power in isolated areas instead of using long transmission lines.
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Unread postby Concerned » Fri 24 Sep 2004, 17:02:48

Sounds ok but prohibitively expensive.

How many satellites do you need in orbit to produce say 2%-5% of global power consumption how much will each satellite cost. How much energy to build and maintian such a system.

Personally it sounds like a big energy sink, nice theory but impractical.

The solutions we should be pursuing are more efficient use of existing fossil fuel resources and bio fuels such as that being developed at Iogen. http://www.iogen.ca/

Long term we need to focus more on fusion power spend less money of weapons more on research into energy. My 2c worth.
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Unread postby small_steps » Fri 24 Sep 2004, 19:54:43

Jack wrote:Neat idea---one would think that it would be an ideal way to generate power in isolated areas instead of using long transmission lines.


Sounds a hell of a lot like wind power, generate it away from the demand, and damn, how do you get the energy from where it is collected to where it is utilized..... umm.... an electric transmission line. Wait, they proclaim to solve one of the problems of wind, and use the same damned senario to argue for their pet project.


Also, from that article:
Scaling up to higher power levels would be straightforward, entailing simply the deployment of a larger amount of solar-collecting area in space. Power would be transmitted through the infrastructure of transmitters and receivers that will then be in place for the satellite communications systems. In this regard, microwave transmission has a decided advantage over conventional cable methods of transmitting power. A microwave system that is 80 percent efficient at sending 1 kilowatt will still be 80 percent efficient at sending 1 megawatt. This is fundamentally different from an electric utility transmission line, where you need thicker, and costlier, wires to carry more power. If too much power is put through a cable, it will melt the insulation.


Electrical Transmission lines are not insulated, unless they are underwater, etc.
Distribution lines in urban areas, maybe, not transmission lines- too damned expensive
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Unread postby Guest » Sat 25 Sep 2004, 09:53:56

This proposal is so full of holes it seems to me a distraction from addressing the issue of sustainable energy supply.

One such glaring hole is persuading the public that it's a good idea to have gigawatts of microwave energy being beamed at receivers on the planet from hundreds (thousands?) of satellites, any of which are liable to stray or get knocked off course, potentially irradiating God knows what population centres.

Another is the utterly prohibitive cost of public liability insurance against such an event.

A third is the predictably untenable money, energy & CO2 expenditure per unit of power supplied.

In the absence of global economic growth post peak I don't see who exactly is expected to bankroll such whimsy. In case anyone hadn't noticed, America is heading for bankruptcy. Broke. No credit-worthiness. Bust.

For me this sort of proposal is a further evidence that while one major chunk of the space industry is for military escalation, another is for distracting the population from the damage being inflicted on the only significant vessel we're ever going to have: namely the earth.

The propaganda appears to be: "Why give a damn - when we've wrecked this planet we'll go find another one !"

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More efficient than power lines

Unread postby Ted » Sat 25 Sep 2004, 16:55:52

Beaming power through space via microwave or laser is clearly more efficient than passing it through the atmosphere, and much more efficient than using power lines.
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