CNN takes a look an energy long shot that could change the game on climate change: space-based solar power. The idea is to launch satellites covered with solar panels up into geosynchronous orbit, where the sun is always shining, and beam the power back down to land-based receivers. A 2007 Pentagon study concluded that "a single kilometer-wide band of geosynchronous Earth orbit experiences enough solar flux in one year to nearly equal the amount of energy contained within all known recoverable conventional oil reserves on Earth today."
The article focuses on the obvious problem: cost. Back in the '70s when the U.S. was looking at this seriously, NASA concluded getting all the infrastructure up into space would run about $1 trillion.
That's a lot. It's only about a third of what we'll end up spending on the Iraq war, though, and if it buys basically limitless clean electricity, it will be a bargain. But NASA has blown it before, and betting $1 trillion is a bit much.
What I want to know is: Are massive microwave beams of power shooting through the atmosphere not cause for worry? Think of the birds!
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Comments
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sindark Posted 7:01 am
03 Jun 2008
The costs associated with the rocket launches could be more efficiently directed towards building more renewable power stations on the ground. The greenhouse gas emissions associated with all those launches also need to be considered.
a sibilant intake of breath
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sunflower Posted 7:21 am
03 Jun 2008
To take science fiction further afield, we can imagine solar powered robots on the moon building more solar power robots on the moon building more solar robots...
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GreenEngineer Posted 7:38 am
03 Jun 2008
First of all, the advantages are limited: You get more solar exposure time, and higher intensities of radiation. I don't have the numbers ready to hand, but I think the advantage over a terrestrial, equatorial PV array located in the desert are about a factor of five. That's not trivial, but it probably doesn't justify the enormous cost associated with putting the thing in orbit. And that doesn't allow for losses in the conversion to microwaves, transmission to earth, collection, recovery or distribution. The real advantage would likely be less than a factor of three. At that point, you'd be better off just deploying more terrestrial panels (and investing heavily in efficiency).
Another thing to bear in mind is that geosynchronous orbit is a whole different animal than LEO (low earth orbit), where the space station and the shuttle hang out. LEO is ~200 miles up. Geosynch is 22,000 miles up. Getting from LEO to GEO isn't really that big a deal, because as Heinlein said, once you're in orbit, you're halfway to anywhere in the solar system. But the fact is that we have no roundtrip capacity to GEO currently: we send satellites out there on a one-way trip, but that's about it. 99% of what we do, we do in LEO.
We also have very little experience with on-orbit construction. Most things are assembled as far as possible on the ground, and then sent up. On-orbit work is minimized, because it's expensive and dangerous. Every EVA (spacewalk) is practiced multiple times on the ground (in a neutral buoyancy tank) before it is performed in space. Imagine building a skyscraper for which every contractor must first rehearse every single move on the ground multiple times before actually performing the work. Obviously, we'd need a new approach to orbital construction before we could attempt something like this, but the process of developing that expertise would take years, and the cost can not be credibly estimated.
Then there's the cost to orbit. This is the big one, the first barrier that gets in the way of everything else. Shuttle rides cost about $10,000 per pound to LEO. (That was in 1998; it's probably higher now.) Russian rockets are cheaper, ~2000-3000/pound. But practical space industry, you need to get it down to around $100/pound or less. If you want to build the parts on the ground and ship them up, you need to get even cheaper. (For less than $100/pound to orbit, you're probably talking about a beanstalk, which is a whole other order of project). The other option is mine and refine an asteroid and fabricate the array in space. That requires less total lift, but requires building an entire industrial infrastructure in space.
I think that solar power satellites have the potential to be a great source of power for an advanced civilization which has regular cheap orbital access and a developed space industrial base. There are lots of environmental advantages to putting industry in space: unlimited hard vacuum, plenty of thermal gradients (in the sun, it's HOT; in the shade, it's COLD), lots of solar power, and little concern about environmental contamination. But as a species, we're not ready to do that yet. It's cheaper to move our dirty industries to China instead. If we had stayed on track after about 1970, we might now have orbital habitats and industries, and be ready to seriously consider a project of this sort. But, alas, we've made no forward progress in manned space development in 40 years; our capabilities to do something like this are substantially LESS than they were 40 years ago. And when you're staring down the barrel of peak fossil energy is not the time to start down this path -- no matter how much money (and how many lives) you throw at it, it simply takes longer than we have.
Solar power satellites are a technology for an advanced technological civilization. To get our current, juvenile civilization through the coming crises, we're going to have to focus on more prosaic solutions (and hopefully do some growing up along the way). But the potential of such technologies is one of the reasons that I don't worry about energy supply in the long term. The energy's out there -- we just have to go get it.
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GRLCowan Posted 7:51 am
03 Jun 2008
The plan was for the microwave beams to be about half as dense (in terms of watts per square metre) as zenithal sunlight, so that birds would not be inconvenienced. If it were winter, they might congregate. I don't know if anyone worried about that.
--- G.R.L. Cowan, H2 energy fan 'til ~1996
http://www.eagle.ca/~gcowan/boron_blast.html
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guido Posted 7:58 am
03 Jun 2008
My conclusion; it is absolutely possible, it can absolutely happen, and DoD supports this.
Cost of lift is an issue, and one other but despite this NASA studies show it could deliever at $.04 per kH.
The super guru of this is Marty Hoffert, at MIT!!!
guido
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PermieWriter Posted 8:48 am
03 Jun 2008
There's a wonderful filk song by Leslie Fish called "The Light Ships" that posits that all industry has moved out to orbit: "The Earth is clean as a springtime dream, no factory smokes appear. For they've left the land to the gardener's hand and they all are circling here." Beautiful image, but we're just not there yet. Not to mention the birds, global heating and other factors.
Eat what you grow, grow what you eat
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rmcleod Posted 9:11 am
03 Jun 2008
http://entropyproduction.blogspot.com/2006/07/solar-power ...
I'm guessing that's a trillion measured in 1970s dollars.
--
entropyproduction.blogspot.com
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Wolverine Posted 9:42 am
03 Jun 2008
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GreyFlcn Posted 10:51 am
03 Jun 2008
Which is the real killer, even if you didn't care about cost.
Besides which, whats so wrong with SolarThermal+Storage?
Get a bunch of those overlapping, plus a bit of hydro/natgas for midday super-peaks, and you're set.
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GRLCowan Posted 12:26 pm
03 Jun 2008
It should be "do we want to do this?" To which all good environmentalists would answer a resounding "NO!"
Well, I suppose. But we could properly encourage others to do it.
--- G.R.L. Cowan, H2 energy fan 'til ~1996
http://www.eagle.ca/~gcowan/boron_blast.html
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JChan111 Posted 3:39 pm
03 Jun 2008
The last I looked at the officially released budget profile for NASA, they are slowing down shuttle funding and the Space Station hardly gets public funding support. Programs are going begging for money based on highly public news items that can be found in Nature, or Science.
So my first question to your question would be a retorical ...and who's going to pay for this grand idea? It all often comes down to money. Tne technical hurdles with enough money thrown at it ..maybe as much as we've spent in Iraq already? might have orbited such a system by now. But for anything less, it wouldn't make a dent in our energy outlook in my opinion. Nice try ..keep dreaming closer to earth for a higher density power source.
-JChan
http://www.atomicmotor.com
-JChan
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katakanadian Posted 2:50 am
04 Jun 2008
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GRLCowan Posted 3:45 am
04 Jun 2008
From http://climate.weather.com/blog/9_10884.html
A gallon of gasoline yields about 2500 kilocalories of energy when it is combusted. The CO2 that comes from that gallon, added up over the lifetime of its climate impact, ultimately traps about 100,000,000,000 kilocalories of unusable and unwanted waste greenhouse heat.
I don't think we are going to leave the CO2 up for the whole time it would stay up if we had no effective way of removing it. But the one-to-100-million ratio of the thermal effect of non-CO2-emitting energy versus CO2-emitting is instructive.
Also, a terawatt from space solar plant is just a terawatt, just a 0.001-percent rise in Earth's heat budget; a terawatt from thermal plant on Earth is of course a 0.003-percent rise.
--- G.R.L. Cowan, H2 energy fan 'til ~1996
http://www.eagle.ca/~gcowan/boron_blast.html
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GreenEngineer Posted 4:22 am
04 Jun 2008
</sarcasm>
I hope I don't have to point out to everyone else that that comment is shining example of why the green movement remains fragmented and prone to spend more time on infighting than progress.
There is more than one acceptable vision for the future. Pre-judging and condemning others' visions -- especially while knowing so little about them -- is not a basis for building an effective movement.
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GRLCowan Posted 4:56 am
04 Jun 2008
--- G.R.L. Cowan, H2 energy fan 'til ~1996
http://www.eagle.ca/~gcowan/boron_blast.html
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Russ Posted 5:06 pm
04 Jun 2008
Are the growth ideology and the ideology of self-justifying technological intensification compatible with good stewardship of the earth and its resources?
has been by now definitively answered NO.
Yet we still have all these technocrats whose contention is similar to that of semi-reformed Iraq war supporters: "The idea is still good/beautiful/righteous, it's just the execution that's been bad. Now we know what we're doing, and we won't make the same mistakes that everyone before us made."
But we've heard all that before. I'm struck by this similarity between totatitarians and the "technology will save us" crew, that neither believes there is any such thing as physical or cognitive (let alone moral) limits in the universe, only political limits. Literally any problem is simply a matter of mustering the political will to overcome it. So they don't see the fundamental insanity of a proposition like this.
Where's the fossil fuel energy going to come from to build all this and send it into space? Where's the financing? As we speak normal coal plants become less viable by the month, and projects are being cancelled left and right. Yet even though it costs $millions to send each packet of Tang into space, they're somehow also going to magically send the metal shavings of god knows how many rapist mines up there.
Which leads to another physical impossibility - where is even the most hideous further ravaging going to yield even the most miniscule fraction of the metals this would take?
Oh, that's right - they're planning to mine asteroids. I forgot.
So: impossibility upon impossibility, insanity upon insanity, depravity upon depravity, to keep building this ever more top-heavy, ever more precariously swaying Tower of Babel....
....to where? To do all this - WHY?
So that man can still have Hummers and hedonist air travel and suburban sprawl and all the rancid electronic toys which help evade having to actually live.
Whatever arenas of legitimate dispute there may be, we do not have one here. I'll leave aside the spirituality and aesthetics of the matter, though I personally believe that environmentalists have strong feelings here as well. But this much must be part of any meaningful definition: Environmentalists are willing to acknowledge the limits of the possible, and are not willing to further destroy the earth trying to push those limits, all for the sake of material goals far in excess of any need.
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Tasermons Partner Posted 6:14 pm
04 Jun 2008
Probably enough for several good sized cities, equvalent, easily.
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Payton Chung Posted 6:00 am
30 Jun 2008
(Just being a little silly here.)
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