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Space based Solar Power
April 20, 2009 3:38 PM   Subscribe

Space-based Solar Power beamed down to earth sounds pretty far out, but the technology is further along than many suppose, the sun never sets in space, and space is a Saudi Arabia of unlimited energy for the nation with the technology to harness it. PG&E (California) in conjunction with SolarEn has announced a 200MW space solar project to be up by 2016.
posted by stbalbach (87 comments total) 11 users marked this as a favorite

 
Energy is everywhere - in sunlight, in wind, in mountain streams, in temperature gradients of all sorts wherever found, in coal, in fossil oil, in radioactive ores, in green growing things. Especially in ocean depths and in outer space energy is free for the taking in amounts lavish beyond all human comprehension. Those who spoke of "energy scarcity" and "conserving energy" simply did not understand the situation. The sky was "raining soup"; what was needed was a bucket in which to carry it. - Robert Heinlein, Friday
posted by Joe Beese at 3:42 PM on April 20, 2009 [7 favorites]


Demo video although the sound is really, really low on that clip.
posted by GuyZero at 3:43 PM on April 20, 2009


As noted on a related Slashdot post, that same orbiting Space Power Plant could have the capabilities to disrupt hurricanes.
posted by filthy light thief at 3:44 PM on April 20, 2009


Joe Beese - we just need to design the right sorts of buckets.
posted by filthy light thief at 3:45 PM on April 20, 2009


This has to be a hoax.
posted by dunkadunc at 3:45 PM on April 20, 2009


Robert Heinlein, Friday

Remind me if Friday was written before or after Heinlein lost his mind.
posted by GuyZero at 3:47 PM on April 20, 2009 [1 favorite]


Come on people. Hasn't anyone played Sim City? Sure, the pollution-free power is great, but what about the associated disasters?
posted by Serial Killer Slumber Party at 3:50 PM on April 20, 2009 [3 favorites]


I don't see any problems with a really long extension cord
posted by rainman84 at 3:51 PM on April 20, 2009


GuyZero: "Remind me if Friday was written before or after Heinlein lost his mind."

After.
posted by Joe Beese at 3:52 PM on April 20, 2009


rainman84: "I don't see any problems with a really long extension cord"

That's actually the second way, with a space elevator cable. It's further out than microwaves, but people are working on it.
posted by stbalbach at 3:55 PM on April 20, 2009


AskMe, a few days ago: Solar power in space?
posted by ssg at 3:57 PM on April 20, 2009


From the AskMe link

... the Solaren service for PG&E, the signal would be tightly focused, aimed at a receiving station in Fresno, Calif.

... right next to your house, sir. Nothing to to worry about. Nope.
posted by R. Mutt at 4:09 PM on April 20, 2009 [1 favorite]


I think everyone who's played sim-city understands why this is a bad idea :P
posted by delmoi at 4:13 PM on April 20, 2009 [3 favorites]


... the Solaren service for PG&E, the signal would be tightly focused, aimed at a receiving station in Fresno, Calif.

... right next to your house, sir. Nothing to to worry about. Nope.


Plus, Fresno's air quality is horrible. Would this hinder the strength of the signal or is it negligible with regards to the rest of the atmosphere?
posted by JauntyFedora at 4:15 PM on April 20, 2009


This has to be a hoax. Nope. It may never happen - the NIMBY issues are through the roof - but it's a very real plan.
posted by Tomorrowful at 4:16 PM on April 20, 2009


the NIMBY issues are through the roof

In this case, quite literally.
posted by yoink at 4:17 PM on April 20, 2009 [3 favorites]


Nice. Stage II civilisation here we come.


well not quite.
posted by ST!NG at 4:18 PM on April 20, 2009


So that's what Lazlo Hollyfield was working on in Real Genius.
posted by mrmojoflying at 4:25 PM on April 20, 2009 [3 favorites]


DoD says itll be a 'game changer'
posted by sponge at 4:40 PM on April 20, 2009


Does this mean we can back to really diabolical James Bond villains now instead of water barons and newspaper magnates?
posted by adamdschneider at 4:43 PM on April 20, 2009 [3 favorites]


Is this gonna be like that short story is Asmov's collection I, Robot with the Cartesian robot who keeps an energy beam right where it needs to be during a solar hurricane?
posted by sciurus at 4:43 PM on April 20, 2009


oh god. there was a book i read in probably 6th grade, that was about this satellite that collected solar energy and beamed it back down to earth using microwaves. i distinctly remember a part of the book when the beam goes out of control and a field of corn starts popping. does anyone recall this book?
posted by Mach5 at 4:50 PM on April 20, 2009


Space-based solar played a central role in Dr. O'Neill's plan to colonize L4 in The High Frontier. However, all the plans I see for this stuff usually center around building the heavier elements from material in space, either from the moon or near earth asteroids. It was considered the case for a while that high launch costs made launching a solar array impractical. As far as I know, that hasn't changed, so either SolarEn thinks they have a way to make very light solar power satellites, or they expect launch costs to go way down.

Also, these things don't produce a death ray as in SimCity. From what I understand, the beam is somewhat, though not significantly, more powerful than a microwave communication link, and at a similar frequency. The worst this could do is give you a bad "sunburn" if you accidentally wandered into the beam.
posted by heathkit at 4:53 PM on April 20, 2009


SBSP and its enabling wireless power transmission technology could facilitate extremely flexible “energy on demand” for combat units and installations across an entire theater

From sponge's link. This makes me smile. That's a rather understated way of saying "we'll burn you fuckers with a GIANT DEATH RAY FROM SPACE. GAME OVER BITCHES."
posted by Justinian at 4:57 PM on April 20, 2009


the beam goes out of control and a field of corn starts popping

What delicious destruction.
posted by filthy light thief at 4:57 PM on April 20, 2009


Also, these things don't produce a death ray as in SimCity.

Don't ruin my fun.
posted by Justinian at 4:58 PM on April 20, 2009


Is this more or less plausible than generally available fusion power? I need to plan my city...
posted by patricio at 5:01 PM on April 20, 2009


> the beam goes out of control and a field of corn starts popping

"Aw, nooo, the corn! Paul Newman's gonna have ma legs broke!"
posted by The Card Cheat at 5:03 PM on April 20, 2009 [4 favorites]


First Tang, now this! In truth, all good things come from space.
posted by yeloson at 5:05 PM on April 20, 2009


Their intentions are good and their faces shine with the pure crystalline light of limitless possibility. What could possibly go wrong?
posted by ZenMasterThis at 5:06 PM on April 20, 2009 [1 favorite]


On a hot summer day, California power usage peaks at about 40 gigawatts. 200 MW is ½% of that.
posted by Chocolate Pickle at 5:07 PM on April 20, 2009 [1 favorite]


As I wrote in another, similar post, we can harness solar power right here, right now. What matters then is the cost and the benefits. And the benefits of being in space don't yet outweigh the costs. Better to plow your money into improving the efficiency of the here and the now.
posted by Cool Papa Bell at 5:11 PM on April 20, 2009


Does this mean we can back to really diabolical James Bond villains now instead of water barons and newspaper magnates?


Now that I have taken control of Solaren satellite, I will redirect its energy beam to major world cities: New York, Paris, Berlin, Beijing, Moscow,
unless I am paid

One MILLION Dollars!
posted by eye of newt at 5:11 PM on April 20, 2009


This would be a lot easier if we did it on the Moon. Just more stable, you know? Plus, we have all of the materials we need right there. We can just send up some self-replicating robots who will build this for us. Oh, wait.
posted by adipocere at 5:21 PM on April 20, 2009


"I know you don't smoke weed, I know this; but I'm gonna get you high today, 'cause it's Friday; you ain't got no job... and you ain't got shit to do." - Smokey, Friday.
posted by Marisa Stole the Precious Thing at 5:21 PM on April 20, 2009


I Really like this idea and I like it even more when the recivers are offshore, on the side of a mountaintop, in the desert or .... hmm on a landfill come to think of it Yucca mountain if it ever gets built may have one of the worlds largest energy substations.
posted by Rubbstone at 5:22 PM on April 20, 2009


I'm rather skeptical - the project fights against a couple of laws of physics - primarily radiant energy loss, proportional to the square of the distance between transmitter and receiver.

What orbital profile will they use? Geosynchronous (required to stay over the same spot on earth) puts you 22000 miles up, and puts the satellite into the earth's shadow for a portion of it's orbit - at night, when you might find said power quite useful back down here.
posted by Nice Guy Mike at 5:22 PM on April 20, 2009 [1 favorite]


Also, outside the very crucial realm of science fiction stories, this is a huge issue in the American southwest. The areas chosen by solar companies tend to be pristine desert that's -- solar plants scrape miles of living desert down to a giant flat lot, and then the mirrors are installed, and then the necessary water is pumped out of the desert aquifers. A lot of water.

(A bunch of these solar farms are planned for donated conservation land in the Mojave, not exactly the intended use. Feinstein is rushing to introduce a bill that would protect a big chunk of desert along old Route 66 between Mojave National Preserve and Joshua Tree National Park from renewable energy use, while setting aside a lot of disturbed/distressed desert lands -- old ag fields, etc. -- for ready-to-go solar farms.)

The BLM land where solar companies want to build these solar farms also tends to be far away from big transmission lines, modern highways and other infrastructure, such as cities with housing and schools and stores and hospitals for the workers and their families.

So, as expensive as it might be to put your solar panels on a satellite, it might be less expensive than years of court battles over endangered species, and massive local infrastructure costs, and the energy you get is steady and not subject to weather, seasons, etc.
posted by kenlayne at 5:24 PM on April 20, 2009 [2 favorites]


Sol Invictus
posted by shoesfullofdust at 5:25 PM on April 20, 2009


What orbital profile will they use? Geosynchronous (required to stay over the same spot on earth) puts you 22000 miles up, and puts the satellite into the earth's shadow for a portion of it's orbit - at night, when you might find said power quite useful back down here.


Geosynchronous satellites are only "eclipsed" by the earth for about 45 minutes a year. The earth looks pretty small from 22,000 miles away and these orbits are inclined to match the earth's axial tilt. So almost all the time when the satellite is behind the earth (from the point of view of the sun), it will be below or above it far enough not to be in the earth's shadow.
posted by FishBike at 5:27 PM on April 20, 2009 [3 favorites]


a chunk of a sentence somehow vanished in here. After "pristine desert that's" should be "loaded with habitat for various endangered critters such as the Desert Tortoise."
posted by kenlayne at 5:27 PM on April 20, 2009


Forgot to say, and I should have previewed - what Cool Papa Bell said.

Even if you don't want to go for Photovoltaics, there's always focussed solar water heating, which the Spanish are pushing ahead with.

You want to help power California? Build a few solar plants in southern California and Nevada and back them with rapid-cycle gas turbines.
posted by Nice Guy Mike at 5:27 PM on April 20, 2009 [1 favorite]


Space for power? Naw. PV panels on land get 170W/m2 and the space based downlink is at 300W/m2. Why spend the effort to go to space for 2x the benefit?

Space as a military 'high ground' - that is change I believe they'll spend money on.

the energy you get is steady and not subject to weather

Err if the microwaves can screw with hurricanes and microwaves have a history of being disrupted by water vapor - exactly how is "the energy not subject to weather"?
posted by rough ashlar at 5:29 PM on April 20, 2009


Looks at the facts: very high power, portable, limited firing time, unlimited range. All you'd need is a big spinning mirror and you could vaporize a human target from space.
posted by Lazlo Hollyfeld at 5:32 PM on April 20, 2009 [6 favorites]


On a hot summer day, California power usage peaks at about 40 gigawatts. 200 MW is ½% of that.

Which is to say its alot, given that there are 278 Power plants in California right now.
posted by Rubbstone at 5:35 PM on April 20, 2009


Read the article closely, and you see that PG&E is committed to buying power from Solaren...IF they overcome all the technical obstacles and produce marketable electricity.

Big IF. I didn't notice anything actually involving PG&E actually committing money.

So basically, all this is, is a PR piece, to convince people that PG&E is forward looking, and that they are coming up with "innovative high-tech solutions" to produce a solution to the climate change problem. Without actually having to do anything. It doesn't address the huge development costs, or the cost of moving materials to orbit.

This is a perfect example of how a single puff-piece can result in a huge amount of hype. PG&E gets lots of pro-ecology press, and Solaren may be setting up something where they lure in investors for a project that will be the energy equivalent of the Moller flying car.
posted by happyroach at 5:42 PM on April 20, 2009 [1 favorite]


Years ago, as a kid, on saturday mornings, I would go with my dad to his engineering office. He had stacks of engineering magazines going back to the late 1950's - that I would flip through looking at the covers.

To this day there is one that I still think of. (Engineering News Record, maybe?) It was different from the others because it didn't have some machine, computer, or skyscraper on it. It had HUGE, perfectly round, man-made lakes on the cover. Speed boats skimmed across the surface. People were happy.

As my father explained, it was an issue about using controlled nuclear explosions for cool things like man-made lakes in the desert.
posted by R. Mutt at 5:44 PM on April 20, 2009 [3 favorites]


So if I get this right, our plan to prevent global warming involves taking a giant lens and focusing more light from the sun at the earth?
posted by pwnguin at 6:09 PM on April 20, 2009 [3 favorites]


I hope this isn't a front for some crazy-ass military project to zap targets from space, because this just screams "dual use".
posted by amuseDetachment at 6:34 PM on April 20, 2009 [1 favorite]


Why hasn't anyone built any of those solar supertowers that required no water? The idea was (IIRC) that you build a huge concrete tube, put greenhouses/collecting mirrors at the bottom, and the hot air then goes up the tube due to the temperature differential, thus generating constant wind, thus powering turbines?
posted by sonic meat machine at 6:47 PM on April 20, 2009


"The worst this could do is give you a bad 'sunburn' if you accidentally wandered into the beam."

Not even that. Most of the antenna farms I've read about for these things have cheap land costs because they are mixed use. You can still grow plants and raise animals underneath them.

"This would be a lot easier if we did it on the Moon. Just more stable, you know?"

The moon is a) an order of magnitude farther away and b) isn't in a geosynchronous orbit.
posted by Mitheral at 6:49 PM on April 20, 2009


You can still grow plants and raise animals underneath them.

And that delicious smell? A pig farm.
(+6 degrees Kelvin bacon)
posted by hal9k at 7:00 PM on April 20, 2009 [4 favorites]


Geosynchronous satellites are only "eclipsed" by the earth for about 45 minutes a year.

I really ought to have double-checked this before I wrote it instead of after. It's more like 70 minute 'eclipses' apparently, which happen every day for a few weeks in the spring and few in the fall. Source.

So still for most of the year, this isn't a problem, and when it does happen it's not during peak demand times of day or year (around midnight, and not in the hottest part of summer or coldest part of winter).

And if one was to have many solar power satellites, as appears to be necessary to do a lot of good, one would space out their orbits so that they don't all get eclipsed at once. More traditional power plants have to have scheduled outages for maintenance and so forth, so it's not like this would be a new type of problem.

I think launch costs are still way to high for this to make any economic sense though. It'll be interesting to see if this turns out to be just another way to suck up grant money of some kind, and will disappear without a trace once the funding goes away.
posted by FishBike at 7:02 PM on April 20, 2009


It seems to me that no one has taken into consideration the other practical application of this technology; the use as a focusing lens against the gigantic ants ( Them! ) spawned by our foolish nuclear tests in the fifties.
posted by digsrus at 7:21 PM on April 20, 2009


"I'd put my money on the Sun and Solar energy. What a source of power! I hope we don't wait til oil and coal run out before we tackle that." Thomas Edison
posted by P.o.B. at 7:21 PM on April 20, 2009



So if I get this right, our plan to prevent global warming involves taking a giant lens and focusing more light from the sun at the earth?


Yes. What's the problem? You focus it on a specific plant that converts it into useful energy. It's not like they are going to focus it on the polar ice caps. Focused means focused, it doesn't mean generalized sun all over the planet, which is what global warming is.
posted by spicynuts at 7:35 PM on April 20, 2009 [1 favorite]


On a hot summer day, California power usage peaks at about 40 gigawatts. 200 MW is ½% of that.

Well, hell, that's that. Let's keep burning oil and coal.
posted by Blazecock Pileon at 8:05 PM on April 20, 2009 [5 favorites]


Yes. What's the problem? You focus it on a specific plant that converts it into useful energy. It's not like they are going to focus it on the polar ice caps. Focused means focused, it doesn't mean generalized sun all over the planet, which is what global warming is.

The 'conversion' of 'useful energy' will become infrared. Heat. Hence the need for fans in the machines that bring you to Metafilter.

Resulting in more overall heat within the atmosphere of the planet.
posted by rough ashlar at 8:40 PM on April 20, 2009


Lazlo Hollyfeld said: Look at the facts: very high power, portable, limited firing time, unlimited range. All you'd need is a big spinning mirror and you could vaporize a human target from space.

How long have you been waiting to use that?

You get the popcorn I'll get the key to Jerry's house.
posted by Bonzai at 9:06 PM on April 20, 2009


the beam goes out of control and a field of corn starts popping

The cows think that it is snowing and freeze to death...so sad.
posted by Jumpin Jack Flash at 10:56 PM on April 20, 2009 [2 favorites]


On a hot summer day, California power usage peaks at about 40 gigawatts. 200 MW is ½% of that.

Well, hell, that's that. Let's keep burning oil and coal.


While I'd never suggest that we shouldn't pursue this sort of thing, it's what we should have been doing years and years ago. There's a very real chance that, unless some really revolutionary technology that no one could have anticipated comes along, we're just fooling ourselves into thinking we can avert multiple climactic catastrophes. 1/2% of the output of California power usage on a hot summer day just isn't that revolutionary. Let's hope whatever research is going into this lays the groundwork for real solutions, fast.
posted by treepour at 11:06 PM on April 20, 2009


1/2% of the output of California power usage on a hot summer day just isn't that revolutionary. Let's hope whatever research is going into this lays the groundwork for real solutions, fast.

So you're saying that because a single satellite, the first of its kind ever to be built, doesn't immediately meet all of California's energy needs by itself, this isn't a real solution? You know, this isn't going to be the only one ever made if the idea works out. Or the most efficient one ever made. You might want to wait with the doom and gloom and see what happens with this.
posted by Sangermaine at 12:10 AM on April 21, 2009 [5 favorites]


Adipocere, I think you meant Mother of Storms

I don't remember Heavy Weather having replicating moon machinery, it was all about weather "hacking" and a big storm.
posted by Megafly at 12:43 AM on April 21, 2009


I'm rather skeptical - the project fights against a couple of laws of physics - primarily radiant energy loss, proportional to the square of the distance between transmitter and receiver.

That loss is only if the beam radiates in all directions from a point source. The inverse square part is related to the same amount of energy being spread out over a sphere of radius r. In this scheme, the beam of energy would presumably be tightly focused like a LASER (the intensity of which, you'll recall does not fall with 1/r^2).
posted by !Jim at 2:31 AM on April 21, 2009 [2 favorites]


And then, there's this.
posted by sfts2 at 2:58 AM on April 21, 2009


This is insanity.
posted by Eugenek at 3:56 AM on April 21, 2009


You're right. Dammit, I do that every frikkin' time.
posted by adipocere at 4:53 AM on April 21, 2009


and their faces shine with the pure crystalline light of limitless possibility.

I worry that what you see may actually be the beginnings of flop-sweat.
posted by Devils Rancher at 4:59 AM on April 21, 2009


Remind me if Friday was written before or after Heinlein lost his mind.

After he lost his mind (Friday ends up marrying her rapist) but before he lost his ability to write.

Also, the search for alternative energy isn't really about a lack of energy (except that oil is running out). It's about searching for something clean. Yes, obvs, we could go with coal....if we want to die choking and covered in black dust in 50 years.
posted by DU at 5:36 AM on April 21, 2009 [1 favorite]


200MW by 2016!

The biggest issue is that it's way too little, way too late.

It's also
-hugely expensive. The cost of getting materials on site is huge, as is the cost of assembly.
-it's very insecure. In order to maintain or repair it you need to have a very expensive very complex transport system readily available. Even if you have this you need the right weather to be able to get there. This is one of the major additional costs of offshore wind compared to onshore and you just need a boat for them...
-it's inefficient; the transmission losses are pretty significant
-it's dangerous. (Yes, you really could pop those cows)
-it's not a solution godammit! Unless the focusser is shadowing the earth then you are adding energy to the environment. Accepted; you are reducing CO2 emissions, but most of the energy you collect will be released as heat.

However; this has succeeded in its primary function. It's got attention, and it's got people talking. Unfortunately it's also detracting attention from viable solutions and derogating the renewables industry.

[rant]

I work in the renewables industry and I've seen numerous pie-in-the-sky (sic) ideas like this. It's the kind of thing which sounds great, really sci-fi, but anyone with any sense can see that it's totally unrealistic and it'll never be a viable solution. We are faced with a real problem here people! Unless we can get some real traction on it and put some real money into solving it then we are screwed! The entire industrial revolution (ie the hugh progress of the past 300 years) has been based on the earth's reserves of concentrated stored energy. Not only are these running out, but using them is also impacting the world we rely on. Unless we can replace all the oil, all the coal and all the nuclear that we are using then we are going to not only face pre-industrial technology but also trying to live in a dirty, inhospitable world.
There is a lot of energy out there; it can be hugely cheap and completely sustainable but we need to be realistic in how we access it.
There needs to be investment in transmission; by definition most environmental energy is in inhostpitable places; too hot, too windy, too stormy. Currently there are not served by power transmission. Putting in this infrastructure is going to be contraversial.
We need to focus on developing available technology to access the easiest resources in the most efficient way. Onshore wind power is a mature technology, offshore needs some development. There are currently quite a few marine devices, both wave and tidal, but there are a few clear leaders. Solar is just finding it's market (probably as much small scale, as much as industrial).



[/rant]

Strewth. Needed that.
posted by BadMiker at 6:10 AM on April 21, 2009 [1 favorite]


(Wipes off spittle from up-thread)

We will need a bunch of alternatives. That includes wind, wave, tidal, solar. Also conservation. Also nuclear. Spaced based may not be part of that mix, but there does need to be an effort to replace fossil fuels. Otherwise the future looks hot and messy.
posted by Midnight Skulker at 6:25 AM on April 21, 2009


As my father explained, it was an issue about using controlled nuclear explosions for cool things like man-made lakes in the desert.

Operation Plowshare - The peaceful atom (video).
posted by odinsdream at 7:19 AM on April 21, 2009


They should match this up with the space elevator and some big copper wires.
posted by no_moniker at 7:45 AM on April 21, 2009


What would beaming that power back do the ozone layer?
posted by Saturn XXIII at 7:49 AM on April 21, 2009


Metafilter: Doesn't produce a death ray as in SimCity.
posted by cereselle at 7:53 AM on April 21, 2009


Eugenek : This is insanity.

This. Is. Solar!
posted by quin at 8:45 AM on April 21, 2009


Also, isn't all the byproduct heat at the receiving station rather the point of all this? Steam turbines run on that heat, that's how many nuclear power stations work. Seems like a feature, not a bug.
posted by FatherDagon at 9:04 AM on April 21, 2009


Operation Plowshare

This book goes into pretty good detail about Teller's enthusiasm for this project and how ridiculously close we got to some of those basically insane ideas actually happenning. There was, from what I can recall, (It's been about 3 years since I'v read it) an internecine war between Teller's lab in Berkeley and some of the other bigwigs at Los Alamos who were a little more distrustful of the Awesome Atom™.

At any rate, he was barely stopped.
posted by Devils Rancher at 9:37 AM on April 21, 2009


We need to start accepting solar and wind farms in our backyards and rooftops.

We also need to ban Hummers and leafblowers. Except maybe for wind-powered leafblowers.
posted by Foosnark at 12:25 PM on April 21, 2009


Also, isn't all the byproduct heat at the receiving station rather the point of all this? Steam turbines run on that heat, that's how many nuclear power stations work. Seems like a feature, not a bug.

I believe the idea is to generate the power up in space and transmit it back down to earth via laser or microwave. From what I've read, the beam isn't actually dangerous (i.e., no exploding cows), though how that works I haven't a clue.

So, yes, it would marginally increase the total heat-output on earth--but by a pretty minute amount (by definition it can't be more than the total solar energy falling on the collector arrays of the space station itself--pretty minute compared to the total solar energy falling on earth--and its atmosphere--itself). Being completely greenhouse-gas free (except, of course, for development and initial implementation) arguably makes up for that.
posted by yoink at 1:32 PM on April 21, 2009


The current project is 200MW. This is very small. As comparison, in the Netherlands there are plans for building a 8000 MW windfarm in the Northsea. Why go to space to build such a small installation.

In the orginal document they talk about the potential of 212 TW years, or 1,857,120 TWh. This is huge. However, the current project will only produce (assuminging an uptime of 99.9%) of 200 MW x 24 hours x 365 days = 1.75 TWh.
posted by jeroen8 at 2:00 PM on April 21, 2009


You know, this is all predicated on cheap access to space. Which is a great goal by itself. This way we get cheap access to space AND all the power we'd ever need.


We'll never see this.
posted by mikelieman at 2:22 PM on April 21, 2009


I have a tough time seeing how the energy cost of putting something into space can be compensated by the gain you get from going to space -- at least for now.

A one-square-meter panel at Earth's orbit would see about 1400 J/s, i.e. 1400 Watts. (That is just the solar flux here -- i.e. the total solar luminosity, divided into the total surface area of a sphere at our orbital distance.) So for every 1 m^2 panel you put in space, you can power let's say 15 lightbulbs. That's if the panels you have are perfectly efficient, and if the energy is beamed efficiently back to Earth, and carried efficiently from wherever the giant space-collector-of-doom dish is to your lightbulbs.

A quick search suggests that the US uses between 5x10^10 and 5x10^11 W at any one time. (Wikipedia has, in some places, numbers that range even higher than that, ~10 kW/person; my sense from glancing at a couple of other sources is that that can't be right, at least not if we're talking about "bought and paid for" energy. But anyway, for this estimate we'll take the smallest plausible number.) So (taking that lowest plausible number) you'd need about a 5 km^2 panel floating in space, at perfect efficiency, to deliver the energy needs of the US today.

On the one hand, that's kinda cool -- 5 km^2 isn't blot-out-the-sky huge. But it is still so vastly beyond the scope of anything we have yet put in space that it seems, well, not so practical for the foreseeable future. Put another way: a ground-based panel could be a lot less efficient and still seem like a better option.

(I started to type something about how the energy cost of putting an object of this size into orbit was probably comparable to the total amount of energy you'd get from it, ever. But that might not actually be true -- it costs something like a million J per kg of material you want to send to space; that's assuming you lift it with perfect efficiency. If your hypothetical space solar panel is very light and very thin, and your hypothetical delivery vehicle is really efficient, you could plausibly still come out way ahead. It still costs a lot less energy to just build the thing down here, though.)
posted by chalkbored at 3:58 PM on April 21, 2009


My thoughts:

-How efficient can such an (electromagnetic) coupling be? Is that 200MW what the satellite produces, or is it what gets received down here on Earth?
-So as not to be dangerous Earthside, the beam's supposed to be wide enough that it won't pose any huge danger- requiring a huge rectenna.

This whole plan seems unnecessarily complex and expensive. I like the idea of developing alternative energy sources, but it would seem to me that there would be a better dollar/megawatt ratio if the money was to be spent on something down here on Earth, probably massive sea-based wind turbines.

I wonder what radioastronomers are saying?
posted by dunkadunc at 4:17 PM on April 21, 2009


Put another way: a ground-based panel could be a lot less efficient and still seem like a better option.

Ground-based panels have practical problems of their own. Like they stop working suddenly and unpredictably when clouds block out the direct sunlight. They don't work at night, and the night is quite long on the ground. They don't work very well at extreme latitudes especially in the winter.

Part of the appeal of putting them in space is that sunlight is almost constant, and the times when it's blocked by the earth are 100% predictable and can be planned for without having to have all sorts of spinning reserve online. I think the number I have seen is there is about 7 times as much solar influx available in space as there is on the ground, once you allow for night and typical weather.

Beaming power to the ground means you can beam it to locations that might not have a lot of sunlight, without having to haul it a long way through cables that lose much of it to transmissions losses.

It's going to be interesting to see if putting solar power satellites into geostationary orbit is an easier engineering and economic problem to solve than large-scale energy storage, which would make a lot of the practical problems with ground-based solar less of an issue.

Or we could use somewhat unpredictable power sources like solar and wind power to run synthetic hydrocarbon production processes instead of trying to distribute electrical power from them directly. Then huge amounts of reserve generating capacity won't be needed to make up for the sudden shortfall--when the power stops, so does the process. Use this to replace fossil fuels in aircraft and other vehicles, where the energy density of fuel is important, and hydrocarbon fuels still looks awfully tough to beat.
posted by FishBike at 5:26 PM on April 21, 2009


Remember in Transmetropolitan when Spider offhandedly mentions how the world's energy problems were a distant memory since they "wired up Mercury" with solar panels? That was great.
posted by Uther Bentrazor at 6:52 PM on April 21, 2009


Here's a google video on ways to solve the energy problem for the next 100 years. It's from a year ago, but it covers the basic engineering approaches.
posted by pwnguin at 11:17 PM on April 21, 2009


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