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Orbiting Solar Panels Beam Energy From Space

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didymus7
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Re: How much power, indeed ... logistics, and the cost?
didymus7   3/27/2014 1:15:31 PM
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I was surprised that the most important aspect was ignored in the article.  How do you get the energy from space to earth?  The atmosphere is a very lossy conductor.  Then again, you'd need to either set aside a large area for a receptor, or the beam has to be very narrow. 

Now, what happens if a flock of birds flys through the beam?  Is there a special on fried 'chicken' at McDonalds?  Does everybody's TV flicker?  Then there are clouds.

Now, how about the orbit of these things?  If it's not geo-synchronous, you'll lose contact at least half the day, then another half, the beam is going though even more atmosphere due to a poor angle.  If it is to be geo-synchronous, do the satellites always see the sun, or will there be blackouts?

It seems to me a lot of things have to be thought out before you start designing hardware.

naperlou
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Blogger
Re: How much power, indeed ... logistics, and the cost?
naperlou   3/27/2014 1:46:30 PM
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Hank-4: death rays are exactly what this would become.  This is probably the main reason it will not be done.  I have seen examples of technicians working on large radar systems on Navy ships.  Generally there is a bar placed in the mechanism that stops the antenna from rotating.  In rare cases something happens to this and there have been cases where the technicians have been fried.  What will happen with such a large source in space?  As for fried bird, that is a real possibility.  Just look at the latest concentrated solar power (CSP) plant built.  It is responsible for killing lots of birds already, and that is just from mirrors.  We also have the problem with wind power killing birds. 

On the price issue, I fully agree.  There is no way this is 10 cents per Kwh.  Jaffe is supposedly a spacecraft engineer.  He should know that this is not in the realm of possibility. 

What this whole thing strikes me as is an attempt by NASA to get involved in solving the energy problem.  They would want to do that becuase it is getting more attention than space exploration.  Energy is a DOE responsibility and they have the expertise. 

SiliconGraybeard
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Silver
Death Rays From Space? Not So Much...
SiliconGraybeard   3/27/2014 4:38:45 PM
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This is a rather old idea; I remember talking about when I was in school, so over 35 years ago, but I think it was an old idea then. The system design has been done so that it all works out on paper, it's safe for birds or small planes flying through the RF fields, or kids who'd wander into the antenna fields. IIRC, C band (approx 4-6 GHz) worked out well. I've seen design approaches that start with acres of solar cells on the moon, because the weak gravity of the moon provides advantages. It also has the disadvantage of two weeks of darkness out of every four weeks. I think satellites, in deep space worked out best.

 

The beam can be as strong or as weak as you want it to be. Microwaves can be focused very well; high gain antennas that can be deployed in space have been in use since at least the late 1970s and reaction wheels for stablizing the satellites are probably older than that. The safe power exposure level of RF for the general public is around 1 mW/sq.cm, so the receiving antenna array has to be large: think square miles, not square meters. (Fun fact: the lowest power limit the FCC issues is 200 uW/sq.cm for the FM broadcast band, where the average person is close to 1/4 wavelength tall and so a very effective receiving antenna. Just sit down to tune yourself out of band.)  Above some fairly low frequencies, you get lower losses by transmitting through the air than by trying to use cable.  It's the reason the phone companies went to microwave links on towers decades ago.

 

In fact, think square miles of solar cells, square miles of antennas, and the "Microwave Power Amplifier Designers' Full Employment Act". The questions about whether it can be done technically are over. Of course it can. The rough questions are whether it could be done without massive amounts of government spending, when virtually every government in the world is on the verge of default from overspending as it is.

 

Daniyal_Ali
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Platinum
Re: how much energy
Daniyal_Ali   3/28/2014 6:16:38 AM
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I agree with Lou too. Do get the answers from Jaffe and share them with us when you get time. Being actively involved in the Renewable Field myself i can say this with great confidence that at the end, the cost effectiveness and overall output yield is the only thing that settles the issue of implementing something at a larger scale or rejecting it completely, even if the idea is unique.
Perhaps as time passes we will be able to manufacture a better technology to cater such ideas with much cheaper and environmental friendly solutions. The main slogan of Solar Panels is to produce environment-friendly energy, isn't it ironic if we use Solar Panels to generate beams that result in harming the environment?
I am eagerly looking forward to more details about this project which would make things clearer.

Trenth
User Rank
Gold
Re: how much energy
Trenth   3/29/2014 2:22:25 AM
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I hate to be so negative, but this is a terrible idea, and seems like just a way to get money from the taxpayers to make space based death rays.

 

From placing panels in space you gain, 4x over ground based if you can keep it out of the earth and the moons shadow.

You lose at least that much converting rf and back. You lose 75%. You have to keep the RF below about 100 watts per meter squared, that's only 50Watts after conversion. Earth based solar panels would produce 200Watts dc/4 or about the same 50W, and they would do it on our rooftops, without the 10,000 dollars per lb it costs to launch sufficient space! As for getting solar power during a hurricane, that's some fancy pr. just convert wastes to fuels and use them in your backup generators and peak generators when you need it.





Other folks have pointed out this could make a great death ray from space too. I agree. That's why the Navy is backing it.  

shehan
User Rank
Gold
Re: Complicated yet simple
shehan   3/31/2014 10:28:48 PM
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I was wondering how the harvested energy is transferred from space to earth. 

shehan
User Rank
Gold
Re: Complicated yet simple
shehan   3/31/2014 10:34:15 PM
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@Elizabeth – harvesting energy from the sun is one good way to ensure we use renewable energy. Sun has enough power to power up the entire world. The difficult part is to harvest the energy and transfer it to the earth. 

shehan
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Gold
Re: Sci Fi to Reality
shehan   3/31/2014 10:36:20 PM
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@Elizabeth  - yes the so called death beams could be very harmful to humans, we might need to create corridor for the beams to travel and ensure that no humans are kept in the area where the beams are received.  

shehan
User Rank
Gold
Re: how much energy
shehan   3/31/2014 10:37:27 PM
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@naperlou- I am sure we are taking about much energy, I mean much energy than we harvest from earth. 

shehan
User Rank
Gold
Re: how much energy
shehan   3/31/2014 10:39:20 PM
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@naperlou- It all depends on the heat the sun generates and the closer we could reach to have the solar panels. We should also ensure that the panels could bear the heat. 

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