Space-based Solar Power

[ihwip]

I recently read about how the Pentagon wants a 5-10MW power generator in space. This would be the method where solar power is collected and beamed to Earth via microwaves.<br /><br />Couldn't they use such a microwave device to vaporize targets from space? I am assuming that they are going to use a focused transmission to increase efficiency. Wouldn't this qualify as weaponizing space?

 

[annodomini2]

Given its government and military nothing would surprise me, logic's sound depends on the operating frequency. <div class="Discussion_UserSignature"> </div>

 

[vulture2]

I was at the last Solar Power Satellite Conference over 20 years ago. Unfortunately there are serious economic and technical obstacles. Costs were based on assuming a very large and fully reusable shuttle fleet. The cost of the power was still very high, so it was assumed no alternative energy source would be available. The problem with SPS is that is that there _are_ alternatives and because the mass that must be launched is large, it is simply much less expensive to generate power on the ground.

 

[billslugg]

At microwave frequencies, beam dispersion due to diffraction results in a power density on the ground that would do little harm.<br /><br />I don't understand what the attraction is in space based power, other than military needs for troops in the boonies. I mean, you get 1kw/m^2 here on the ground and only 1.3 up in space. What is the big deal? <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

 

[webtaz99]

Near-constant sunlight with no losses due to weather. <br /><br />1kW/m^2 is for noon in Death Valley. Most places get less. <br /><br />Oh yeah, in space, you can make REALLY BIG collectors - cheap. <div class="Discussion_UserSignature"> </div>

 

[comga]

"Oh yeah, in space, you can make REALLY BIG collectors - cheap. "<br /><br />No you cannot. You can make structures with low mass per unit area, under some circumstances. They still are incredibly expensive. <br /><br />Elsewhere I have posted a quick-and-dirty cost estimate for an 8.2MW solar power plant being built in southern Colorado. By my estimate, for the $25M to $50M it costs, we could put up something perhaps the size of half basketball court, if one were very clever, and if we stick to low Earth orbit. In GEO we would get something perhaps a big as a ping-pong table, again assuming extreme cleverness.<br /><br />Space is still frightfully expensive. <br /><br />(Just read that the plant south of Alamosa will cost $60M. Still can't launch much for that price.)

 

[docm]

And Solucar is building a 300MW solar tower/heliostat near Seville, Spain that'll power most all of the city. Build a bunch in the Sahara, Australia and the US desert southwest and you could power a good portion of the planet. <div class="Discussion_UserSignature"> </div>

 

[kelvinzero]

Im looking forward to that. Perhaps building these vast collectors in the deserts could also be combined with efforts to trap soil there. Living off oil we are little more than bussards fighting over a dead cow.<br /><br />However even with massive ground based solar collectors on earth we are still limited to the tiny fraction of the sun's energy that falls on the earth just as life has been for billions of years.<br /><br />What is exciting about space solar power is that it is open ended. Once it reaches the break even point where it returns more money than it costs then we can build massive space infrastructure without ever begging for money again. The process will be exponential because the more power you collect the faster you can build, and the faster you can build the faster your array of power collectors can grow. There is no reason to stop ever.<br /><br />'Power' doesnt just mean electricity for running your electric razor either. It all goes into the pool of energy available for life on earth, for example by freeing up more ground for crops, even growing crops under sunlamps as dope growers already do. This makes it the most important evolutionary step for earth life since it first appeared.

 

[webtaz99]

What's expensive about aluminized mylar (or similar stuff)? I wrote "collector" in the sense of mirrors, not solar cells. <br /><br />And I still don't see why folks look at this as a contest between ground- and space-based solar. Obviously, we will have both. <div class="Discussion_UserSignature"> </div>

 

[nexium]

If your aluminzed mylar has an average mass of one gram per square meter (including what ever keeps it flat or parabolic, and facing the correct direction) = one ton per square kilometer which is expensive to LEO and very expensive to GEO orbit. So now you have a converging beam of 1.3 gigawatts of sunlight a kilometer wide, which will start diverging in a few kilometers. You need more mass to turn it into electricity and still more mass to get the energy to Earth's surface. Solar pumped lasars, may soon be available to shave a few million dollars off the total cost, but the desert photovoltaic panels are competitive or cheaper. Neil

 

[nexium]

Hi Kelvin: I'm hoping for large scale soon, but removing the soil from the photovoltaic panels, will be costly if the soil gets traped on the sun facing surface. Hopefully the array will behave like a snow fence with the soil collecting underneith. How do we keep near by children from playing on our photovoltaic array and the scaffolding for cleaning and repairs? Neil

 

[webtaz99]

I would suggest that you guys start your own "Ground Based Solar" thread. <img src="/images/icons/rolleyes.gif" /> <div class="Discussion_UserSignature"> </div>

 

[publiusr]

Space based solar forwards technology for solar asteroid deflection missions--solar sails of great size--etc.