Solar energy

[Jay-qu]

So it is possible to "beam" energy into earth's atmosphere? Would it have any effect on the ozone layer?

There are certain wavelengths of EM that that the atmosphere is virtually transparent so thats not much of a problem, possibly some issues with refraction if your beaming on an angle - but that just comes down to some calculations.

[ronthepon]

So what exactly are the wavelengths that may be useful for direct beaming?

Radiowaves? Never, in my guess...

[Jay-qu]

we have radio telescopes on the ground yes, so thats a fair bet :hyper: some forms of microwave and infrared are blocked - I had a great image of this I will have a look for it :(

[Kayra]

Hmm, I did not realize diffraction was such a major issue. ;)

 

I was only considering capturing raw sunlight in a 100KM diameter reflective umbrella. Aimed at earth and capture it using a 1 KM diameter reflective umbrella.

 

Energy leaving the sun should be something like 300 GWH. About the amount of electricity the entire planet uses today. You could suffer considerable losses and still have a fair amount of power.

 

Beaming raw sunlight through the atmosphere as straight sunlight would likely cost you an additional 20% of the remaining power. Limitations in existing materials would demand that this energy be split up and sent to multiple locations in order to harness it.

 

Conversion in space to Microwave is another option that has been studied rather rigorously. (http://en.wikipedia.org/wiki/Solar_power_satellite) One of the issues I have with this sort of technology is that it will rely on Solar cells. A technology that is far from ready and whos lifespan is still indeterminate. you can not spend vast amounts of money on a power generation system that will last 8, 10, 12 years, decreasing in efficiency each year.

 

Any suggestions on how to send the raw sunlight that far? What it's losses would be? If the total that reaches the earth orbital reciever is less then 10% then it would be the same as building the 100 KM diameter umbrella reflector right here in earth orbit.

[cwes99_03]

Have any of you seen Sahara with Matthew McCaunaughy (sp?)? If you haven't check it out and you'll see the actual use of the sun's heat energy ability on earth solar oven style.

[Kayra]

Have any of you seen Sahara with Matthew McCaunaughy (sp?)? If you haven't check it out and you'll see the actual use of the sun's heat energy ability on earth solar oven style.

 

Yep

And the 10,000 motorized mirrors that all have to be moved to face the sun. Surfaces that get scoured by sand constantly. Maintenance on a system like that has already proven to be substantial.

 

Imagine if you had that capability, but it came straight down on the system. 24/7/360 (it would be obscured a few days out of the year during equinox. Few hours each day). No massive mirror farm that had to be constantly aligned. practically no moving parts at all.

 

In fact, there would probably be enough energy (if it could be focused tight enough) to create a fast ignition inertial fusion system.

[Jay-qu]

If the light from the sun is focused then it helps with the diffaction issue, thing is the distance between earth and sun is not constant, nor will it be between the sender and receiver, so the focal length of such a system would have to be some how variable..

[learnin to learn]

this is getting interesting!!!!!:shrug: Jay-qu are you planning on working for NASA when you get out of school?

[Jay-qu]

I dont know about NASA.. do they pay well :hihi: nah really whatever I can get in the industry!

[ronthepon]

If the light from the sun is focused then it helps with the diffaction issue, thing is the distance between earth and sun is not constant, nor will it be between the sender and receiver, so the focal length of such a system would have to be some how variable..

 

Won't the whole issue be resolved if we package the energy in some concentrated power holding battery or something, and send it to earth?

 

Then the dangers of missing targets, heating of atmospheres, diffraction, and all that can be forgotten!

 

Huh? HUh? HUH?

[Jay-qu]

yup that does sound much better, but uses energy on the journey, also its not instantaneous "energy when we need it" kind of solution - but none the less meritable.

[Kayra]

I dont know about NASA.. do they pay well :hihi: nah really whatever I can get in the industry!

 

Jay, what would be your best guess on what % of the energy would make it to earth if the following were true.

 

Collector placed in polar solar orbit inside Mercury orbit. Expect continious supply of 10 kW/m². At 100 KM diameter that gives us almost 8 billion square meters for a total energy available of 8* 10^17 watts.

 

If we focus this energy at a 1000 meter reflective collector in earth Geo orbit, how much energy could manage to make the trip?

 

 

Not looking ot hold you to it, I was just curious :lol:

[Jay-qu]

If it is focused correctly and all is captured at the other end then the losses will be minimal during the trip - main losses will be in the sender and collector set up - 8*10^17watts is a lot of energy to be going through a 1km (I presume diameter) its going to cause a bit of heat.

 

You want a figure -well Im not really sure but maybe 99% will make the trip and there will be a bit more lost at each of the collector and sender, maybe 90% total.. :hihi:

[Qfwfq]

Now matter how safe a reactor on Earth is, it produces long term radioactive waste and there's no really satisfactory solution that ain't expensive.

[cwes99_03]

If the light from the sun is focused then it helps with the diffaction issue, thing is the distance between earth and sun is not constant, nor will it be between the sender and receiver, so the focal length of such a system would have to be some how variable..

 

Well, not exactly. The distance between the earth and the sun can be treated as infinite due to the distance between the earth and this space mirror.

 

The real issue with getting a mirror to reflect light from the sun down to earth is to keep it in a stable orbit, that is if you really want to have it there 24x7x365. And this ain't no little bathroom mirror. You'll have to calculate in the push of the solar wind and put it high enough on earth's rotation of axis to provide 24x7 coverage. That is unless you plan on using a system of mirrors in deep orbit (still don't have to worry about focal lengths here I don't think) that will collect the light to a central point for reflection to the earth, but that increases the number of guidance computers.

 

Thank goodness for people at NASA who are willing to do nothing but calculations all day long.

[Kayra]

 

The real issue with getting a mirror to reflect light from the sun down to earth is to keep it in a stable orbit, that is if you really want to have it there 24x7x365. And this ain't no little bathroom mirror. You'll have to calculate in the push of the solar wind and put it high enough on earth's rotation of axis to provide 24x7 coverage.

 

I beleive that Geosync orbits can be set up to have Line of Sight on the sun for all but the 2 equinoxes. For those periods of time, you lose 1-3 hours a day.

[Kayra]

If it is focused correctly and all is captured at the other end then the losses will be minimal during the trip - main losses will be in the sender and collector set up - 8*10^17watts is a lot of energy to be going through a 1km (I presume diameter) its going to cause a bit of heat.

 

You want a figure -well Im not really sure but maybe 99% will make the trip and there will be a bit more lost at each of the collector and sender, maybe 90% total.. :esmoking:

 

90% is more then I dreamed.

I was concerned. While the collector at the sun would be highly reflective, it is not exactly the most stable surface. (being a stiff cloth like material.)

 

I had also assumed that the earth point would end up more like a large fuzzy circle, with the highest energy in the middle. If the beam can be kept colminated so that 90% of the energy is within the collector area, that would be.. amazing.