Space-based Power Generation

dlkf writes: "There is an article on Space.com that talks about some of the benefits, costs and current research relevant to using satellites to generate and store power. This surplus of power could then be beamed via laser or microwave to earth or other satellites."

Comments

hasn't this already been done?

[niall111]

in Sim City 2000? Microwave power plants!

microwave?

[mr.ska]

This surplus of power could then be beamed via laser or microwave to earth or other satellites.

Gee, and I thought cell phone radiation was going to fry my noodle. At least this way I'll keep warm...

Why bother when there are better alternatives!

[GodLessOne]

For a tenth of the cost we can cover several square miles of the nevada desert with solar arrays. This will produce ten times the power without the problems of beaming the power back to the ground.

This will also avoid the problems of the orbiting solar arrays regularly being hit of the collection of space junk that we have deposited in orbit over the years.

Now if these were feeding power to city sized orbiting habitats then it might be a much more interesting idea.

Just imagine a bemoth fluster of these! :)

Re:Why bother when there are better alternatives!

[ch-chuck]

Only thing that bothers me about taking energy from sunlight is that the existing energy is a part of the natural environment. Recall that energy is neither created or destroyed, just transformed from one kind & place to another (usually with losses and inefficiencies) - so if you take 1GW of power from the desert and sent it to high concentrations of metropolitan areas, that will contribut to 'desert cooling' and more urban 'heat island'.

If there's one thing we learn from the history of technology, no matter WHAT you do, the luddites with dreams of happy, pastoral family farm livin' will be agin' it. I have magazines from the 20's where some blatering idiot is blaming the then rainy season on all dem newfangled, high powered radio transmitters, sending kilowatts of power out into the aether.

Re:Why bother when there are better alternatives!

[shaunak]

"For a tenth of the cost we can cover several square miles of the nevada desert with solar arrays. This will produce ten times the power without the problems of beaming the power back to the ground."

Do you have any solid 'figures' to back this claim up?

When it comes to the photo electric effect, E = hv
Now, when it comes to E, as v increases, E increases.

Here on the earth, we do not recieve most high frequency radiation (think Ultra Violet, think Cosmic) which is available in abundence in Space.

Consider that thought for a moment.

Re:Why bother when there are better alternatives!

[Telek]

Why bother when there are better alternatives!

Because there aren't, really...

How about this as a reason:

According to an April 2000 article in the Electric Power Research Institute (EPRI) Journal, photovoltaic arrays in a geostationary Earth orbit (at an altitude of 22,300 miles) would receive, on average, eight times as much sunlight as they would on Earth's surface. Such arrays would be unaffected by cloud cover, atmospheric dust or by the Earth's day-night cycle.

So not only do you get sunlight all the time, but you can also beam this energy to low orbiting satellites, higher satellites, spacecraft, lunar bases or use it to propel spaceships and interplanetary probes. There's many a good reason to use microwave based power stations, but right now it's far too expensive (due to launch costs)... Once the launch costs come down this will become a real possibility.

Re:Why bother when there are better alternatives!

[angel'o'sphere]

Uh, hum ....

Rated interesting :-) but wrong.

A space stationed power generator will by very effective in relation to a ground based.

By fabricing everything in space (yes yes, for that we would need a source for the needed resources, e.g. the moon and it is a much bigger undertaking ) it can be made unlimited big.

A lot of constructive problems we had on ground fall away. (No need to have something taking the weight of the constructin etc.)

Allways directed to the sun, so more yield.

Combination of power generation with the cooling system (if one is needed).

New thin film technices, e.g. not based on silicon , but paint like, would only require a thin sheet to be painted in space.

Bigger problem: the ground station receiving the beam.

Also: military abuse of the beam.

Regards,
angel'o'sphere

Re:Why bother when there are better alternatives!

[Hard_Code]

Even better - wind power is proving pretty efficient without the nasty side effect of having to create awkward solar cells, creating/disposing toxic chemicals, etc.

Wind power is a viable alternative but the government, heavily lobbied by the status-quo energy industry, just wont throw money into alternative technologies, like it does into petroleum based research & development etc.

Re:Why bother when there are better alternatives!

[Taurine]

Why does the government always want to mess up any good plans for renewable energy? Here in the UK we are starting to make progress with this sort of thing. A town near where I grew up has an enormous windmill which generates most of the energy needs of the town, which is cool. Off the coast of Scotland there is a wind farm with hundreds of these things, but the company operating them is thinking of getting out of the business, because they currently lose 60% of their revenue due to a new government rule that says if your energy source doesn't produce a reliable, steady amount of energy, you cannot sell it at the same rate as a reliable steady one. Which means of course that fossil fuel and nuclear power plant generators get paid a lot more than wind farms, hydroelectric dams and factories that generate electricity with heat exchangers off their normal machine cooling systems. Will they ever get a clue while there is still oil and gas in the North Sea?

Re:Why bother when there are better alternatives!

[markmoss]

a new government rule that says if your energy source doesn't produce a reliable, steady amount of energy, you cannot sell it at the same rate as a reliable steady one. In a free market, you CAN'T sell something that is available now and then at the same rate as if it was assuredly available when needed. It's worth more if it's there when I want it, than if it's only there when you happen to have it. The only reason for such a gov't regulation would be that they were already regulating the market too tightly.

Re:Why bother when there are better alternatives!

[Dyolf Knip]

Here on the earth, we do not recieve most high frequency radiation

Do you have any figures on how the extra high-frequency rays improve solar cell performance?

Re:Why bother when there are better alternatives!

[Dyolf Knip]

Theory is a wonderful thing, but often it has nothing to do with real life. Lemme rephrase my question. Do you have any figures on how high frequency rays affect solar cells that we manufacture today? I know they receive more light, but I'd like some stats on the 'quality' of that light affecting performance. To say it theoretically improves it, while true, doesn't quite cut the mustard. Graphs, charts, statistics, anything.

Re:Why bother when there are better alternatives!

[markmoss]

The space junk is spread out pretty thinly. You'll have less trouble with it than with keeping earthside solar panels clean, especially in cities and deserts. (Of course, in northern Michigan where I live, the solar panel will be perfectly clean, it just has a foot of snow on top. 8-)

Once it a while, something will hit at 10,000 kph and blast a hole right through a solar panel or a mirror. This happens because to make this worthwhile, you'd have miles of solar collectors. But it won't affect your generating capacity noticeably, because the rest of the panels or the mirror will still be working (mirrors would be very thin metal, or aluminized mylar, not glass), and it's miles across. 20 years of this isn't going to reduce your capacity as much as a few days dust accumulation in Nevada.

One thing I don't know about though: what is the effect of hard radiation (cosmic rays, solar wind, etc.) on solar panels? I hear that solar panels are expected to last 20 years on Earth; is the much greater exposure to radiation hard enough to re-arrange the crystal matrix a bit going to make space-borne panels shorter lived, or will the lack of rain, wind, and crud going to make them longer lived?

However, I think that an SPS built now would use the much cheaper technology of using a mirror to focus sunlight on a boiler, which runs a steam turbine. Cosmic rays won't hurt a steam plant, although the crew is going to need good medical insurance...

Re:Why bother when there are better alternatives!

[markmoss]

Shaunuk, you mixed so much good and bad physics mixed together it's hard to tell where to begin. Individual photons do get more energetic with shorter wavelength (blue-er light), and if you could build solar cells tailored to each wavelength, the higher the energy the higher the voltage per cell.

But the number of photons in sunlight at each wavelength drops with increasing wavelength through most of the visible spectrum. So the red light has the most available power. Don't even consider the cosmic rays and other radiation in space, for power they compare to sunlight like a gnat to a supertanker.

But the second problem is the way solar cells work. They are semiconductor diodes, arranged so that an incoming photon of sufficient energy will knock an electron from the positive (anode) to the negative (cathode) end. All the electrons put together form a current flowing from the cathode. (Of course, they better go through something and come back to the anode for you to get any current or power...). Each color or wavelength can push an electron across a different voltage, but the photocell only works at one voltage. So photons that are too red are wasted completely because they lack the energy to make the electron go, and ones that are too blue have excess energy beyond what the electron absorbs. The result is that you have to design your photocell for some sort of compromise voltage, probably about 1.5V corresponding to a particular wavelenght of red. (Of course, they put a bunch of cells in series to make 12V or higher outputs from the panels). Even if everything else worked at 100% efficiency the inherent losses from energy mismatch will never allow a cell like this to get better than maybe 30% efficient.

UV light would just waste more of it's energy. One UV photon would at best impart to one electron the same energy as a red photon does, with the rest of the energy wasted. It's more likely that big a mismatch would just keep the photon from being captured at all--it would reflect or be absorbed as heat only.

I can think of two ways to work around this. One is to use a prism or diffraction grating to split the light out into different wavelengths, illuminating a set of photocells with different working voltages. This would certainly raise the efficiency with respect to the light entering the device, but it would be expensive, and I'm not sure you could make the separation work without restricting the light entry to a slit -- and blocking light outside the slit certainly won't give you much efficiency overall. Or maybe you could make a stack of solar cells, each one transparent to the wavelengths preferred by the cells below. Assuming this transparency is possible, there's a problem with cost -- as long as the semiconductor is the biggest cost of the panels, it will be far cheaper to just cover more square feet with inefficient cells than to stack up cells for higher efficiency.

Re:Why bother when there are better alternatives!

[markmoss]

What I want to know is: why solar cells? It seems to me it would be much easier to make a space-based heat engine.

You forgot one more advantage: steam power plants routinely run at over 30% efficiency, higher than solar cells. All you need is a big mirror to focus light on the boiler, a big radiator in the shadow of the mirror, and the steam plant in between. And you can make the mirror extremely thin, there is no wind and very little gravitational/accelerational forces, and you just keep the mirror stationary (or stabilized by spinning about the optical axis) to keep it pointed at the sun. On Earth, a solar steam plant requires bracing the mirror against wind and gravity, and then mounting the whole shebang on a giant turntable to follow the sun. Or maybe you have a giant array of small steerable mirrors, but it's still very expensive, possibly more than an immoveable array of solar panels that would collect the same average power. In space: it's lighter than the solar panels (real thin mirrors...) so if you are lifting it from earth it's much, much cheaper. If you are building from space-mined materials, you've got a lot fewer factories to lift into orbit to build the steam plant.

hmmmm

[thrashncarry]

let's all pray that Nasa's aiming is a darn site better than the military or we'll all be fried :) ... time to get those anti-laser suits for my cats i think

Re:hmmmm

[.sig]

Well, we've already seen how well NASA does lately. If they mess up the unit conversions on this one we may accidentally lose a city block or something instead of an unmanned mars rover.

Hopefully they'll test a few low power 'tracer' shots before beaming down anything big.

Japan seems to think it's worthwhile...

[tomknight]

...after all, why else would they be planning on having one in the pretty near future?. This is interesting becasue Japan's not really afraid (it seems) to use nuclear power, and the satellite power is considerebly more expensive per kilowatt hour.

Tom.

Bad Idea...

[redcliffe]

Some reasons why this would be bad:

- It would be more cost-effective to build a solar power station 10 times larger on the ground

- It could cause atmospheric problems, heating etc. What if a plane flies through the beam, would it's electronics get mucked up?

- The reciever station would be massive anyway

- It would be better to give every house a solar roof

David

Space Junk a problem?

[tsetem]

I remember watching Discovery channel where they discussed the space junk floating out there. I would think that would be a major hinderance to having a reliable power supply. With all the junk out there, and a (presumably) rather large satellite, it's just asking for problems unless there is a lot of armor to protect it with.

I think even the ISS is a target, but they have some major shielding to protect the areas that are most likely to get hit.

That brings up another question, how does the armor effectively deal with the space junk, without creating more junk out there after absorbing the impact?

Re:Space Junk a problem?

[spyderbyte23]

I remember watching Discovery channel where they discussed the space junk floating out there. I would think that would be a major hinderance to having a reliable power supply.

Well, you don't put it in low earth orbit where the junk is; you put it in geosynchronous orbit or, better yet, one of the Lagrange points, where it can be tended by the residents of O'Neill colonies. (I have now posted this link twice in two days. Funny old world.)

Re:Space Junk a problem?

[Dolly_Llama]

A question from the astronomically illiterate: The short google search i did on lagrange points all talked about points in the earth-sun system. Would it be possible to have lagrange points between the earth and the moon, or does the sun just fuck it up? Conversely, wouldn't the moon's revolution (around the earth, not in the Heinlein sense) move these points in a 3 body lagrange system?

is that so? Let me go out and take a look...

[jason99si]

So what happens when something doesn't work right? Are they going to take a quick skip into the outer reaches of our atmosphere to cold boot the power server? Something nice about power generation on Earth, you can walk there. (or at least use a ladder).

On the plus side, a new Incredible Hulk movie is coming out, there could be an interesting cross marketing campaign... hey.. wait a second...

Re:Radiations would kill us all

[rm-r]

Microwaves are themselves a form of radiation, in the ovens they stay 99% inside and don't reside in the food after cooking. Microwaves cook food because the waves 'excite' water molecules, so I really don't fancy our chances if this beam were to astray, being 70% water....

will we be reading this again 25 years from now

[hagbard5235]

This was first seriously proposed by
Gerald K. Oneill of Princeton University in
1975! It was feasable ( and even profitable )
then, but the capitalization was to high for
any organization on earth but the US Government
to undertake. The only reason we haven't done
it already is because of a defect of will, a
myopy of purpose, and inability to look further
ahead than the next election.

When will we, the citizens of the United States,
have the vision to demand these sorts of
projects from our government? Oneill's initial
proposal had an estimated 20 year pay back time, for
the first powersat. Subsequent powersats would
have been much cheaper. If the proposal Oneill
made had been taken up seriously in 1976, and taken
say 2 years to get it's political legs so that
actual work began in 1978, and it took ten
years to build, we would have had cheap abundant
energy by 1988.

Given cheap abundant energy it would be feasible to
produce, for example, metal hydride or fuel cell
powered cars. Given a 10 year ramp up and phase in
for those technologies we would have in 1998
been largely petroleum free ( at least for
power ).

Does anyone question that this would be a better
place to be... and we could be there by now, if
only we had the vision, and the will.

I remember this...

[Rob.Mathers]

from SimCity2000. I based my entire city's power grid on 4 of these things. Then the microwave beam missed, and blew up two of the other power plants.

Re:highlander

[32xts]

Wonder why the bots from the Matrix never thought of doing this?

They have probably never seen Highlander 2. Not that many people have.

Why not use the acres of urban tarpaper?

[SgtChaireBourne]

There must be millions of square kilometers of flat rooves in the world's cities. Since most are neither generally accessable nor designed for regular activties, they'd make an idea place for solar arrays. You could even use DC instead of AC due to the proximity, but that would be a bother. In hot areas, the shade would help lower the temperature of the upper floors.

Re:Why not use the acres of urban tarpaper?

[Mr. Slippery]

Think about all the pollution in the cities, the dust would cover the arrays, and we would have to hire a lot of people to clean the arrays.

So when the window washers come by, they also do the solar array on the roof. Cleaning gunk off glass surfaces in urban areas is a solved problem.

Why on earth do we not concentrate on energy saving instead of producing more and more energy?

We definitely need both.

Re:Why not use the acres of urban tarpaper?

[NaturePhotog]

This is or was under consideration in San Francisco. The idea was floated during the height of the energy crisis here in California, to put acres and acres of collectors around the city on roofs. However, the idea seems to have fallen by the wayside, in part because the cost, the energy crisis has eased considerably, and the other events in the country.

Re:Why not use the acres of urban tarpaper?

[markmoss]

If we _are_ going to solar power collected on Earth, then covering rooftops is definitely the way to go. It's been a long time since I did the calculations, but the way I figured it (1) we'd need less than 50% of the total roof area in the US, and (2) blocking the sun from that much undeveloped land would be a massive ecological disaster... (There is life even in the Nevada desert.)

But it's very expensive. Solar cells cost over $1/watt the last time I looked. And 1KW of solar cells gives you far less than 1KW of delivered power most of the time -- they are rated for peak power, which is aimed directly at the sun at noon on a clear day on a mountaintop in the tropics. I did some datalogging with a small solar panel where I live this summer; in a Michigan summer, clear days give you the equivalent of 2 hrs/day at full power. Many days aren't clear, some are so cloudy that I never got enough current to measure. Overage, I think a 1KW panel around here will collect 1KW-hour per day in the summer. Winter is going to be a lot worse. I'm also testing a small windcharger -- it didn't collect enough energy to notice in September, October is shaping up a little better, and maybe it will give a decent power output when the winter storms start hitting...

California would be better, and Tucson AZ might get 5KW-hour/day. Most American homes use considerably more than that, so you need several KW of collector. Then you also have to store the energy for night-time use. In a house-sized system, that storage is batteries, so you also need a batter charger and inverter to convert from and to AC. I'm told that the overall cost of a solar power system (panels, batteries, electronics, and wiring) for one house is $20K to $60K, and that is if you cut your power usage well below average and use either a back-up generator or a connection to the power grid for prolonged storms. (In northern Michigan, we'd probably be on back-up power Oct-March, unless another $20K into windchargers would give us winter power.) Or you can pay the power company about $100/month. It only makes sense if (1) you are an eco-freak, or (2) your house is so far back in the woods you have to pay $10K or more to get a power line hooked up. But then you also have to buy the massive inverter needed to power a well. (You can't run a 4 inch submerged pump from 24 or 48VDC -- the wiring needed would be too thick. You need 240V to bring the current down.)

If you are putting solar panels on city/suburban rooftops and connecting them to the grid, then the costs are probably lower. Each place needs an inverter that will sync to AC already on the lines -- in mass production that's not much more expensive than the inverter needed for stand-alone operation. There has to be one big energy storage system, but on a large scale there are cheaper options than batteries. For instance two ponds, one on top of a hill, one at the bottom. Pump water to the top in the daytime, and let it flow back through a turbine at night. Or convert excess electricity to hydrogen, and store it or pipe it to someplace less blessed with sunlight, then burn it in gas turbines, fuel cells, or even a converted coal plant.

But notice that in any of these cases, the final stage is still as costly to build as a conventional (fossil-fuel or hydro) electric system, plus someone has to pay for all those solar collectors, and inverters. The economics isn't there until either fuel gets more expensive or solar cells get much cheaper.

So how is a solar power satellite going to beat this? It will stay at peak power 24 hours a day, so you get 6-12 times as much energy as from the same solar panel in L.A. and reduce the requirement for night-time storage and backup power, but that's not nearly enough to make up for the launch costs.

However, an SPS does not have to use expensive semiconductors for energy conversion. Use a big mirror (e.g. a balloon with one half clear, the other half aluminized) to focus the sun on a boiler. The mirror stays pointed just by pointing the power plant at the sun and then spinning it around the mirror axis. (Pointing the microwave antenna at a fixed spot on Earth could be a problem -- maybe use phased arrays?) The only heavy parts of this system are the boiler, turbine, and condenser. Big steam plants get well over 30% efficiency, and this is better than any solar cell I have heard of. You could do this on earth too, but you've got to turn that big mirror to follow the sun, brace it against winds, etc., so it's pretty costly, although at this time it would be definitely cheaper than launching a much lighter SPS into space...

What would really make it economical would be to mine the materials and build the SPS in space. And the enthusiast's real goal is to get that mfg capacity up there -- because then they could build pretty much anything needed to colonize space. And if some earth-based gov't thinks they have to pay taxes...oops, lost control of that beam for a few minutes, sorry.

Re:Why not use the acres of urban tarpaper?

[Dyolf Knip]

But it's very expensive. Solar cells cost over $1/watt the last time I looked. And 1KW of solar cells gives you far less than 1KW of delivered power most of the time -- they are rated for peak power

No kidding. Normal solar cells just aren't economical yet. So, what are some other methods for getting power from the sun? There's mirror/boiler combos, solar chimneys (particularly nice since they run at night as well), and what else?

Then you also have to store the energy for night-time use. In a house-sized system, that storage is batteries, so you also need a batter charger and inverter to convert from and to AC

Not neccesarily. Flywheels or water electrolysis could be used instead of chemical batteries. They don't have to be replaced every few years and aren't hazardous if and when you throw them out.

What would really make it economical would be to mine the materials and build the SPS in space

Duh. Building anything really big in space by bringing the components out of Earth's gravity well is just stupid. Not until launch costs are cut by several orders of magnitude would it be remotely economical. Don't hold your breath waiting for NASA to do that...

Re:Why not use the acres of urban tarpaper?

[markmoss]

I forgot flywheels, yes those could be effective energy storage for a household. There are some dangers with the high-energy flywheels (having one crack is like having a little accident with a lot of TNT), but in a fixed installation you just put it underground with a vertical spin axis and if it breaks the ground absorbs the fragments. Wonder if they have the frictional losses low enough to hold through one of our five-day storms? How would flywheels scale up to city-size storage?

I mentioned hydrogen for large-scale systems, from water electrolysis of course. Turning it back into electricity isn't cheap on a household scale. AFAIK, fuel cells cost something like $20K minimum, and a motor-generator big enough to let you run your house normally is probably over $1K, under 30% efficient, and requires repairs frequently. On a city-wide scale, I think the water/gravity system can be 80% efficient, better than batteries and much better than fuel cells. But that is only if you generate and use the power within a few miles. If San Diego wanted to sell excess solar power to Seattle, electrolyzing hydrogen and sending it by pipeline would be best

Re:Why not use the acres of urban tarpaper?

[markmoss]

Actually, the best orbit for beaming to one spot on the ground is not just geosynchronous but geostationary: above the equator & 24 hour period. Because the Earth's axis is tilted, the orbit is at 40,000 miles radius, and Earth is only 8,000 miles in diameter, the satellite rarely passes into the Earth's shadow. At the equinoxes, it will be shadowed when it goes around the far side of the Earth, but that's only a couple of hours a day or less for a few days. So for that couple of hours (which would probably be around midnight), you have to draw power from some other satellite in a slightly different orbit, turn on your hydrogen-burning back-up power turbines, or simply declare a "blackout holiday". The rest of the year, the satellite is "above" or "below" the poles while transiting the far side.

Re:Why not use the acres of urban tarpaper?

[esonik]

dust would cover the arrays

ever heard of rain ? (not so good vor Nevada desert, I admit)

However, the radiation from the stars gets a lot lower the further away we get from them

isotropic radiation (i.e. from stars) falls of with 1/r^2 (r = distance to star). However, I would expect satellites to emit directed beams (think Laser), not isotropic - the losses would be much lower.

Why on earth do we not concentrate on energy saving instead of producing more and more energy?

It's stupid to "put all eggs into one basket". Better to proceed in both directions.

Re:Why not use the acres of urban tarpaper?

[NaturePhotog]

It's apparently still being considered, as it's on the upcoming ballot as Measure B in San Francisco.

Re:Radiations would kill us all

[Faulder]

The wavelength (frequency) of the microwaves is what makes it excite water. I'm sure they would not be using the same wavelength to transmit energy from space to earth. Clouds and water vapor in the air would affect it.

Re:Bad Idea... Perhaps not

[conan_albrecht]

I recently discussed this idea with a planetary scientist. We did a little research and here's what we came up with:

1. The microwave beam does not disrupt any planes, etc. because they are made of metal. Even a small amount of metal shields microwaves in the frequency that would be used -- same reason that metal won't heat in your home microwave -- it just reflects the light waves.
2. Organic beings that come into the focused beam cone are not affected much by the beam. Microwave s only sink into your skin about 1-2 inches. At most it raises your body temperature one or two degrees. Of course, people won't normally be inside of these beam cones anyway.
3. Earth-based solar stations have to put up with night. Orbital solar arrays only have a few hours of blackout each year. Most of the year they can beam the microwave down 24 hours per day, even in geosynchronous orbit over a country like Japan.

It may not be the best alternative for countries such as the U.S., but it makes more sense for smaller countries such as Japan that have almost no natural energy resources.

My $0.02.

Ok for Japan, not feasible for us

[N3P1u5U17r4]

It should be noted that the initial proposal by Japan to meet its Kyoto emission targets was to install an additional 20 nuclear plants. This caused a major outcry and stimulated increased attention to Space-Based Solar Power. Importantly, the prices for electricity are sufficiently high in Japan that a workable Space-Based Solar Power system might be developed with launch costs much higher (1000 $/kg) than would be feasible for North America.

Sounds Like A Maxis Idea To Me!

[Self Bias Resistor]

Kind of reminds me of SimCity 2000, where Microwave power allowed you to beam energy from space into the satellite dish of the power plant. My question is, what happens if they miss? Ooops, there goes half a residential district!

Re:Sounds Like A Maxis Idea To Me!

[Jeremi]

My question is, what happens if they miss? Ooops, there goes half a residential district!

Well, as I recall from the last go-around of this topic on slashdot, the collector array would contain a small, directional transmitter that the satellite would look for. If the satellite didn't "see" the transmitter in the center of its target area, then it would cut power. This technique would keep the system fail-safe.

The other safety measure was that the beam would be unfocused enough that by the time it reached earth its footprint would be fairly large, and hence the power would be diffuse enough not to cause fires or instant death (tm) to anyone who happened to be under it. It wouldn't be pleasant, but it wouldn't be dangerous either.

1982 World's Fair, Knoxville, TN

[GMontag]

This OLD idea (se parent to this post) was dusted off 19 years ago for the World's Fair in Knoxville, but never implimented. There was some discussion that birds flying through the beam could be fried or something.

Also, as far as putting a narrow/small footprint on the ground, that technology is in use today. The satellite imagery downlink for the US military has a very small footprint. You can receive it at the Ft. Belvour, VA PX (right by the ground station), but if you get over to Davidson Army Airfield you are out of the footprint. Good luck decrypting the signal if you are not supposed to be receiving ;-)

Problems with solar power

[wiredog]

OK, several posters have said "Why not just use solar cells?". Here's why:

Solar power is not quite ready yet. If you live in an area, such as the desert southwest of the USA, that gets lots of sun, then solar can work. The initial cost is higher than other power sources, but people do it. The maintenance factor is a problem as well, since most solar power systems require batteries for storage. My previous employer looked at solar quite seriously because the line power, in Cedar City Utah, sucked. Brownouts were common. It turned out to be cheaper to replace equipment on a yearly basis than to put solar cells and a battery bank in.

If you live in an area such as the northwest of the USA then you can forget about solar. There are too many cloudy days.

Putting a bank of solar cells in the Nevada desert would work for Nevada, but distributing it beyond Nevada would be difficult.

The cloudy days and the distribution problems apply to SPS as well. The price of solar is going down, and in the desert areas it will probably be a better solution than SPS. In a few years.

Re:Problems with solar power

[TonyJohn]

Even on a cloudy day, the earth receives a load of power from the sun. (In strong sunlight about 1kW/square metre, in cloud at high latitudes it can go down to 300W/m.m). It is possible if you cover your roof with solar tiles to generate (on average) the same amount of power as you consume. With the current low-cost of electricity (which does not take into account the cost of the carbon emissions), the economics are poor though.

You don't have to have batteries - you can remain connected to the grid, and sell or buy electricity as needed. Not good if you are trying to survive a brownout though.

Re:Problems with solar power

[The Panther!]

The maintenance factor is a problem as well, since most solar power systems require batteries for storage.

This is a little off the beaten path, but I was told by a friend who worked in Dallas of a company who was trying to reduce their energy costs. That company installed a very large tank of water on the top of their building, several stories high from the description, and used energy off the grid at night (non-primetime energy costs per KWH) to heat the water, then would reclaim it during the day back into electricity.

I don't know how efficient their reclamation scheme was, but I'm sure it didn't hurt to have the sun out 300 days a year to warm the tank while extracting energy from it. Seems that solar might benefit from a similar approach, using a natural battery of sorts. Obviously, this is only reasonable for large installations, but terrestrial solar doesn't seem to be feasible on an individual basis anyway.

And asphalt....

[BillyGoatThree]

This is entirely theoretical since there isn't any way I know of to make a solar panel that could support the weight of a car. But I did the calculations once to figure out how much roadway would be needed (at around 1% eff) to power a home. Not very much. The nation's highways have enough square meterage to provide all the electricity we (residential users) need.

We could also just build covered roadways. That would save wear and tear on the roads themselves PLUS we could use regular 15%-20% eff panels, thus entirely powering the nation with plenty left over.

Alternatively, use the thermal energy already IN the road. You know how hot asphalt gets in the sun? Put a little steam turbine (or a thermoelectric generator) every few meters. You'd get at least enough power to charge a battery for the street lights.

Energy is literally pouring out of the sky. The only reason it costs so much is that we are stupid.

Could be nice

[Diabolical]

Off course this could be nice. Let's think about it. In a few years it is very likely we run out of fossile fuel to use in our powerplants.

An array of solar power sattelites could solve alot of problems. Not only in the remote area's. What to think of the dense population area's where there is not enough place for several acres of solararray's?

The possibility of miss targeting a beam could off course be bad. But the only other solution we would have is to cut back on our powerconsumption which is likely only to increase in the next eons...

If we could use these space based arrays to power both space and earth powerplants we would indeed have an abundance of power.

The only real drawback would be: Who will be maintaining these things..? corporations will most likely be too money hungry and governments would probably be too power hungry.. a consortium could be the answer but again.. power trips would be the problem there as well.

As long as people are involved there will be advantages and disadvantages for any kind of solution.

Back off of our Desert!

[hawk]

It's a common misconception that the Nevada desert is a wasteland. Guess what: It's not. There is a rather intricate ecosystem. Covering the desert wipes out this system.

On top of that, we'll probably fight you on it. We're already getting a recklessly designed dump. No, it's not the dump we object to; it's the slipshod way it's being handled. A nuclear depository 100 miles from my house doesn't bother me. A repository run by that band of chuckleheads does.

The law for the the dump ordered the DOEto study a list of sites (provided in the law) and to build a dump at the safest site. Guess how many sites are on the list? If you said "1" you were correct.

So yes, we are suspicious of *anything* pushed by the feds. If Nevada is in charge of the plants, maybe. If it's a federal project, prepare for a very long fight.

hawk, displaced Nevadan

Re:Back off of our Desert!

[sam_handelman]

It's a common misconception that the Nevada desert is a wasteland. Guess what: It's not. There is a rather intricate ecosystem. Covering the desert wipes out this system.

This is true. Furthermore, there's the power transmission problem. Until we get room temperature superconductors, only California can benefit from Nevada's ecological destruction. Beaming the power from space is about as feasible as killing people with orbiting laser satellites.

The only real wasteland is in the open ocean. It doesn't look real different from other stretches of ocean but if there's no algae, you can cut off the sun (it only penetrates about 40 meters anyway). You float the things on the water. It's the only ecologically sound place to put them, and there are stretches of this sort of ocean comparatively close to all of the world's coastlines, which is where most people live.

Re:Back off of our Desert!

[Dyolf Knip]

The only real wasteland is in the open ocean

That's right, I remember reading about some guys who dumped a whole bunch of some iron compound into otherwise 'dead' ocean trying to encourage a bloom. Here's link number one grom Google.

O'Niell O'Shmeal

[Iron Sun]

Sorry, but I think you've been buying into a bit too much hype.

This was first seriously proposed by Gerald K. Oneill of Princeton University in 1975! It was feasable ( and even profitable ) then

No, it wasn't even remotely profitable in the 70s, just as it is not (quite) profitable now. When O'Neill made his calculations in the mid-70s, he projected several future technologies that would make his schemes affordable, the foremost being cheap, reliable, regular access to space. In 1975, the space shuttle was 7 years away from its maiden flight, and everybody believed the bullshit about the fleet flying one mission per week with perfect safety. This has not proven to be the case.

Until we get a 10-fold reduction in launch costs, and launches are handled more like airport departures, then schemes such as this will remain prohibitively expensive. I want it as much as the next geek, but I'd rather focus on what concrete steps we can take in the next 5-10 years. Cheap access is the breakthough tech.

Does anyone question that this would be a better place to be... and we could be there by now, if only we had the vision, and the will.

Of course it would be a better place to be. World peace would be nice too, but we're going to need a bit more than abstract notions of vision and will to get us there.

This whole line about 'lack of will' is one that I see quite frequently on /. from starry-eyed, impatient idealists who want to holiday on the Moon RIGHT NOW. If you try to explain about economics, technological development, or engineering project turnaround times, they frequently have problems accepting this. Not wanting to believe that they may have to wait a while to get all Buck Rogers, they cast about for the real reason, and latch on 'political will'. It was politicians that cut short the Apollo program, so it's politicians fault that there isn't currently a lunar Hilton.

Umm, no. Lack of funding (as well as bureaucratic inefficiency) may be retarding the rate of advance, but we can't blame Washington because we don't have a warp drive yet. Let's take things one step at a time. As soon as such projects become economically feasible, you can bet your bottom dollar someone will come forward with a business plan.

WHY THIS GOT MODDED AS TROLL

[Medievalist]

Somebody obviously ripped this off from some other site, without attribution. That's not really a problem on /., where plagarism is seen by some as a god-granted right ;^), but then the copier edited the text near the end to insert a bunch of racist nonsense.

It looks like the bigot is hoping you'll clip it and copy it yourself and spread his or her lunacy under your own name. The text chosen is long and appears mostly correct to lull you into the trap.

This stuff is becoming more common on /., and it's really sad that some morons have nothing better to do with their time. Good job Mr. Moderator, thanks for reading it all the way through.
--Charlie

Superconductors!

[BillyGoatThree]

Since we are talking about non-existent technology, I see no reason not to include unproven techniques.

No, I didn't take traffic into account, mainly because it varies so much from area to area. In urban areas obviously there is significant traffic but I've also driven across vast stretches of Wyoming where mile after mile you see literally nobody. Since my assumptions were pulled from my ass to begin with I decided I could ignore traffic. If that makes you uncomfortable, just assume that in the worst case 50% of the road is covered....and that the asphalt generation system is 2% instead of 1% efficient.

Re:Bad Idea... Perhaps not

[Telek]

Not to mention that the concentration of solar energy is 8x in orbit that of what it is on the surface of the planet, and it's a constant feed not disrupted by weather or atmospheric conditions...

Re:Radiations would kill us all

[Telek]

2.45GHz and 10GHz would be common wavelengths based on past studies. Your microwave operates at ... oh 2.5GHz!

But fear not! There's more to the microwave science than meets the eye.

You see, in order for microwaves to do anything, they have to be absorbed into something and not re-emitted

This only happens when you have something in a liquid state... Otherwise, for example, when microwaves pass through steam they will excite the water molucules by causing them to vibrate madly, but as soon as the microwaves have finished passing through them the molecules stop vibrating, and nothing changes. The only way that you will get it to heat up a lot is if, in the process of causing those molecules to vibrate, those molecules rub against other molecules and transfer some kinetic energy. This can only happen effectively in liquid states.

If it's in a gaseous state and you have a constant beam that will continue to excite the water molecules in it's path, but due to winds and the fact that once you heat up a gas it will expand and move around on it's own you won't have a very large problem. If it's raining or you have a very dense cloud that's about to cause a storm, then you might have a problem, but under normal circumstances you'd be fine.

I remember reading somewhere that a good analogy was to think of them like this: imagine an object floating on water as waves pass by. The object will bob up and down but once the waves have passed there is no appreciable net change in energy to the object. However now imagine that this object was sitting right next to a fixed object, like a boat and a dock. As the boat bobs up and down it will rub up against the dock and friction will cause the dock to warm up. Same deal here.

Re:Radiations would kill us all

[Telek]

Actually I just remembered something else. Ironically the frequency that it used is not the resonance frequency of water (if it was it'd boil off the surface of your food and not cook the insides!). It's slightly off so that it will weakly be absorbed by the water molecules so it can penetrate the food and cook the insides as well. After about 2 inches of penetration the entire microwave will have been exhausted.

Re:Space Junk a problem?[OT]

[spyderbyte23]

Would it be possible to have lagrange points between the earth and the moon,

The Lagrange points are present anywhere you have one body orbiting another, though only L4 and L5 are stable enough for real permanence. (My astronomical knowledge is rudimentary; anyone with real training is welcome to jump in.)

Did you see the movie _2010?_ (It was the sequel to _2001._)The monolith at Jupiter is parked at, I believe, the L2 point in the Jupiter-Io orbital system.

Or, alternatively, you mention Heinlein. Did you read _Friday?_ The idea of space colonies at L4 and L5 comes up tangentially there, as does the idea of collecting solar energy in space for transmission to Earth.(If you haven't read _Friday,_ read it. It's one of his most fun books.)

Re:Space power 1000+ times more expensive (Zubrin)

[connorbd]

IIRC (and I might not) Zubrin might be considered a bit daft by some scientists (I know his name is in Voodoo Science by Bob Park somewhere, but I don't remember exactly where), but he's got to be right about this...

I can't believe anyone takes the idea of space-generated power seriously anymore. It *could* work, mind you -- but how many failsafes would you have to pack into the system to prevent it from cooking a bird, or part of a small town, or an airplane?

/Brian

If you only knew....

[Orne]

"But but but... its cheaper to build solar panels on the ground!"

1. There is no nighttime in space. There are no clouds in space, no atmosphere to dilute the sun's energy, no birds to fly by and crap on the panels. That means 24h efficiency.

2. Yes, you COULD build a 10-square-mile solar panel farm in New Mexico, but you wouldn't even be able to get the current out of state before line-losses, frequency problems, and other transmission problems ate all of your energy.

Its like you could build several dozen nuclear plants in Nevada, enough to power the ENTIRE North America on nuclear alone, but you couldn't build a power grid transmission system strong enough to move the power to where it is consumed.

Re:Radiations would kill us all

[Telek]

So in other words, we're not going to be beaming power to Seatlle anytime soon.

Unless of course we opted to use something a little off the frequency of water, say 2.3GHz or 10GHz instead. It's a pretty wide spectrum...

But we ain't gonna be beaming power soon cuz it costs so damned much to lift if off the planet! =(... Not to mention that it'd take at least 5-10 years to build.

Re:Geosynchronous lesson... for the millionth time

[Russ Steffen]

Who said the earth station has to be directly below the satellite. A geostationary satellite can see half the planet. It might be less efficient, but there is no reason why the beam couldn't be aimed above or below the equator.

And, by the way geosyncronous orbits are not over only the equator. By definition, they cross the equator every 12 hours, wandering north and south at the same longitude. A geosynchronous satellite with a 90 degeree inclined orbit sits above a point on the equator - the term for that is geostationary. All geostationary orbits are geosynchronous, not all geosynchronous orbits are geostationary. Verstehen Sie?

Re:Cheap Power

[HiThere]

I doubt that it would be that cheap. Generation costs would be considerably less, possibly. But surely that wouldn't decrease administration costs.

Space solar power will happen

[wronkiew]

As nuclear and fossil fuels become harder to find, beaming solar power from space will become feasible. When that happens, the companies and governments which have developed the necessary technologies will reap the rewards. An analysis of NASA's attempts to do so can be found at http://www.nap.edu/books/0309075971/html/. This is the document mentioned in the Space.com article. Check out The SSP Monitor for more space solar power information

Cost per kilogram to orbit

[Animats]

It costs about $20,000/Kg to put stuff in orbit with the Space Shuttle. Unless and until that comes way, way, down, building anything big in orbit is out.

Great does this mean...

[ACK!!]

Can I hack the damn satellite and fry my neighbor with laser beams from space? Could I microwave the cats next door that seem to be in heat 365 days a frickin' year?

One screw up and instead of sending energy to power a few hundred houses they toast into a crispy crunchy mass. Yum...The future's so bright right now.

Ozone

[bandannarama]

Seems like that much energy passing through the atmosphere would generate a fair amount of ozone from oxygen molecules absorbing some of the energy. I guess this might be fine at high altitudes where ozone is pretty depleted, but at low altitudes it's just another pollutant.

I might be completely out in left field. Anyone out there know whether this would be an issue?

Re:Ozone

[Catbeller]

The power density per cubic meter is too low to do much of anything, if microwaves are used. No, I don;t have the numbers, but this engineering was done to death back then in the '70's.

Re:Cheap Power

[Dyolf Knip]

If power were really dirt cheap (approaching $0) what ramifications would we face?

You'd rather keep an artificial scarcity of energy to protect ourselves from the ramifications? What if the majority of those ramifications are extremely good? The media industries are trying to do this with music and whatnot, look how well they're succeeding.

Would we see the current power industries (like oil and nuclear) moving to protect their interests?

Well of course they would. I wouldn't like them for it, but I could certainly understand their motives. But really, too fscking bad for them. Adapt or die, it's the oldest law on the books.

Foretold by Isaac Asimov...

[matusa]

A great hope of science fiction writers is for one of their hypothetical futures, or some aspect of them, to come true.

Asimov used rings of satellites transmitting power vie Microwave to the earth in many of his stories.

He'd be happy to see this.

Re:Foretold by Isaac Asimov...

[Catbeller]

Asimov was totally won over by Gerry O'Neill, and all the rest of the SPS/Space Colony proponents. And for good reason; all the numbers added up, there was no downside, and we built a space-based industry in the bargain that could move out into the rest of the system at will.

He added the tech into his new SF stories, so that's why you see the SPS bounding in from nowhere around '78 or so.

Note: the SPS, if built from lunar materials, is a tremendous idea. It was researched to death in the '70's and '80's, so the engineering prelim is done. But to be viable, it must be built from lunar materials. Launch costs are ridiculous if one decides to build on Earth and shuttle to orbit. (Though Boeing et al are hot for that notion, not surprisingly).

Before SimCity 2000. . .

[emrys79]

A lot of folks have noticed that this idea was in SimCity 2000. But decades before Maxis published SimCity, Robert Heinlein had used the idea in one of his future history short stories. Of course, he also had a gigantic nuclear power plant 1/4 the size of Arizona (or something like that) that he moved into space as well, right before it blew up. . .

distributing power

[Tumbleweed]

> Putting a bank of solar cells in the Nevada desert would work for Nevada, but distributing it beyond Nevada would be difficult.

Don't be silly - we already have an international power grid (we're connected to Canada, not sure about Mexico). Power selling between areas goes on all day, every day, and has for years. Yes, there is inefficiency (and lots of it) in the distribution, but it's already in place.

Re:distributing power

[wiredog]

Canada sells to the northern tier and New England, which are close by, not to, say, Georgia. Yes, Nevada could sell to Texas, which could sell its power to Georgia. But going mostly solar would be difficult as you would then be trying to send voltage from Nevada to Maine.

Remember, too, that solar is DC, which has trouble going long distances.

SSP pretty secure from terrorist attack

[GPS Pilot]

I have many friends living near Three Mile Island, so when I heard on the news there was a "credible threat" against it (which was later discredited) I was pretty concerned.

That points up a benefit of Space Solar Power: Space Solar Power and nuclear energy are the two forms of power generation most benign to the environment. BUT, it's virtually impossible for terrorists to attack a SSP satellite. And if some future terrorist does aquire anti-satellite weapon, blowing up a SSP bird would have far fewer consequences than blowing up a nuke plant.

Re:Space Solar Power: A Fresh Look

[Antaeus Feldspar]

Where the worthwhile portion of the parent comment was plagiarized from.

Lunar Materials for Construction

[Baldrson]

Satellite Solar Power has been studied since the 1970s. The NRC among others rejected it then primarily due to the launch costs, which have not declined appreciably during the intervening years.

This study by government or government-selected authorities ignored the radical option of lunar construction materials that, if properly used, could comprise almost all the mass of the satellites for a fraction of the transportation costs due to low lunar gravitation and absence of atmosphere on the lunar surface to interfere with techniques for lofting materials that would be impractical through atmospheric drag.

Space Studies Institute was the early leader in these studies of SSP-from-nonterrestrial-materials, and its founder, the late Gerard K. O'Neill had this to say about the option:

Space Studies Institute

The World's Energy Future Belongs in Orbit

by Dr. Gerard K. O'Neill
Trilogy January/February 1992

...

To make solar power satellites (SPS) practical and economical, we do not need any new science; we only need to apply what we are already doing in the more advanced industries: robotic production, computer control, and the replication by robotic machines of some of their heavier, simpler components. We do need one more thing: materials. It is neither practical, nor economical, nor environmentally acceptable to lift from the Earth by rockets the thousands of tons of materials needed to build an SPS that would supply Earth electricity equal to the output of ten nuclear power plants.

Let the Moon Pitch In

Fortunately, we do not have to. We were given something unique in our solar system: an enormous moon, orbiting tantalizingly nearby, and containing on its surface just the materials we need. Lunar soils contain 20 percent silicon for solar cells, and about 20 percent metals. Much of the rest, surprisingly enough, is oxygen. The moon has two other great advantages as a source of materials: its gravitational pull is only one-sixth of the Earth's, and because of its small diameter, the moon's gravitational grip is less than a twentieth of the Earth's.

The moon's second advantage is it has no atmosphere. The combination of the moon's weak gravitational grip and its vacuum environment makes it practical to locate electric mass accelerators on its surface which would be capable of lofting a steady stream of small payloads to a precise collection point high in space.

Such machines, called "mass-drivers," were tested nearly a decade ago under the sponsorship of our small, quiet, nonprofit foundation, the Space Studies Institute (SSI). Mass-drivers were shown to obey their computer design programs within one percent - no new science there - just straightforward engineering. Since then SSI has sponsored laboratory research on making useful products from ores similar to lunar soils.

Can SPS Technology Deliver?

As people concerned about our environment and about the world we leave to our children we should question proposed solutions to major physical problems. As fossil fuels, nuclear energy, ground-based solar, and other conventional sources of energy all fail to make sense in the world.

First of all, there is plenty of energy in space. Even in a narrow band 25,000 miles above the equator, where a satellite can maintain a fixed orbit, plenty of solar energy streams by constantly to supply far more than enough energy for the Earth of 2050.

What of the conversion on Earth? It was demonstrated years ago. The antennas convert the radio waves with an efficiency so high that less than 100 watts of waste heat goes into the environment for every 1,000 watts that goes into power lines. For coal or nuclear the numbers are: 1,500 watts waste, 2,500 watts total; for ground-based solar they are several thousand watts waste plus another thousand to make up the total - different from an Earth without solar cells - because solar cells absorb more heat than the ground they cover.

Transmission is the question that deserves continuing research: How to send the low-density radio waves from an SPS to antennas on the Earth. I have satisfied myself that transmission does not involve significant risks. But I invite you to do your own research. One of the best sources on the subject is The Microwave Debate by N.H. Steneck (MIT Press).

The points that seem to me most important about radio transmission of energy are that people would not be in the beams; that for fundamental physical reasons the beams could not be intentionally or accidentally redirected; that their intensity would be comparable to sunlight; that unlike the massive shielding around a nuclear reactor, the only shielding necessary would be a layer of household aluminum foil; and that, unlike the present irreversible dumping of 5,000 megatons per year of fossil-fuel carbon dioxide into the atmosphere, or the generation of long-lived nuclear wastes, the SPS system would leave no chemicals or radioactives behind if our descendants decided to turn it off.

SPS Stuck in Bureaucratic Morass

You and I know that satellite power aided by the use of construction materials from the lunar surface is an idea that is still almost unheard of, much less the subject of national debate, as it should be. Indeed, those most seriously studying SPS are Japan and Europe. Why does this conspiracy of silence exist? The reasons are partly unfamiliarity: three-dimensional thinking is often unwelcome in a two-dimensional world. Oddly enough, it is often more unwelcome to people who think of themselves as experts than to people who have a general, rather than a specialized education.

Institutional barriers and the normal behavior patterns of bureaucracies explain the rest of the "why". Since shortly after World War II the generation of scientists who contributed so greatly to winning that war have championed nuclear power. Though that generation is well into retirement now, it remains a powerful force in advising the government. It is joined by the heavy industries which see (or used to see) nuclear power as a market opportunity.

Fusion power research has gone on in large part because governmental science agencies like the National Aeronautics and Space Administration, the Department of Energy, and the National Science Foundation are extremely responsive to the scientific establishment. That establishment is led by such organizations as the National Academy of Sciences. The academy is made up of intelligent and highly qualified scientists, but as a body it is very conservative. Indeed, one of my colleagues high in its councils once described it as an "Old Men's Club." Fusion power research has been supported for some 40 years because, literally, generations of scientists have worked on it as graduate students, then gone on to positions of authority, and finally risen to positions where their recommendations arc heard with respect by government agencies.

In the bureaucratic format, satellite power has no natural home and no built-in constituency. NASA, now a timid, fearful NASA made up of aging pre-retirees rather than the young tigers who made Apollo work in just eight years, would be frightened out of its skin by a tough, make-it-work assignment with a tight budget and a tighter time scale. And NASA's charter doesn't cover energy. The DOE? Its charter doesn't include space. The NSF? Satellite power isn't science, it's engineering.

That's why research support toward satellite power has been left largely to the Space Studies Institute, a small foundation supported by thousands of private citizens -much as the organizations of the environmental movement are supported. Environmentally concerned citizens and groups, and SSI, should be talking. Their concerns are the same and their goals are the same. Since the governmental-scientific establishment in the United States is making no useful move toward a serious review of satellite power as a practical alternative, it may well be that concerned citizens are the only force that can bring about the necessary action. We as citizens have often succeeded in "Stop!" actions. Let us review, carefully and with open minds, whether SPS is something that we may want to "Start!"

Re:Space power 1000+ times more expensive (Zubrin)

[Catbeller]

Nay, no, uh-uh, nope. The fallacy of the fallacy, as it were, is that we launch 10,000 tons of metal per powersat.
Yes, that is insane, absurd, impossible. That's why the aluminum and silicon must be moved from the moon via mass driver (railgun to you yunguns) to Geosych, where it could be melted, smelted and made into yummy struts and solar panels.
Launching the powersat from Earth would be ludicrous, tho it makes NASA and Boeing/Lockheed/Whatever deliriously happy -- dozens of launchers, billions of dollars in contracts, sky's the limit.
Solution: move a small mining plant (manned, essentially a shack and some dozers) to the moon, build a railgun, launch the raw materials to Geosync, process the materials, and build the powersat from construction shacks manned by a few dozen men.
Any other way is impossible.

Re:Space power 1000+ times more expensive (Zubrin)

[Catbeller]

Can't cook a bird. Can't even heat a glass of water a degree.
Look, the microwave beam should be attenuated over a square mile or so. At that power density, birds are safe, fish are safe, you are safe. A tinfoil hat would block anything that could remotely hurt anyone.
As a comparison, think of billions of pounds of oxides dumped into the atmosphere by our cars and power plants, every year. Dead lakes in the Northeast from midwestern coal plants. Acid eating the ruins of Roma and Greece. Global warming from the greenhouse gases. Even nuke plants produce waste that is politically and physically dangerous.
Powersats are clean, efficient, eternal, and almost 24/7. The question is, how do we afford notto build them?
BTW, I givethese answers, not as an opinion, but from my studies of the engineering done back in the '70's and '80's. The questions were covered back then to anyone's satisfation. It was just too hard an idea for Americans to understand, since they don't breathe science and engineering the way geeks do.

Re:Been there done that

[Catbeller]

Um, no, I believe that the power satellite, a giant breeder reactor, produced safer fissionable materials than that which the sat used itself, and the safer materials were shipped to Earth for use in safe nuke power plants. The Sat, using much more dangerous fissionables, eventually exploded.
I remember the stories: "Blowups Happen", and "The Man Who sold the Moon".
The idea of solar sats beaming power to earth was done back in the sixties, by a Russian scientist, and no, I don't remember the name.
But it was Gerry O'Neill and the rest of the merry engineers in the L5 days who put lunar mining, orbital colonies and factories, and powersats together as a gestalt, and they get the kudos.

Re:Radiations would kill us all

[(H)elix1]

I'm not sure if I should make a snide PR rating comment about 2.45 gHz, or say we could push it up to 2.5 gHz if we could only up the voltage a bit....

Re:Radiations would kill us all

[Telek]

then might there not be unexpected resulting effects which have nothing to do with direct mechanics such as heating?

Absolutely, but if you've climbed up top and are lying in the middle of the collecter dish, what did you expect? =)

Most systems would utilize some failsafes, like say the satellite must be receiving a constant ACK beam back in return from the ground station, and the nanosecond it looses the feedback signal it cuts the power.

Having said that, you're not going to install a microwave power plant in your backyard... These will be out in the open somewhere where minor trajectory mistakes wouldn't bake a city. And with the aforementioned system in place anyways, you've got a reasonably safe system. I'm sure that they have thought of several other safeguards as well.

vulerability?

[jafac]

A solar power station that Human civilization relied heavily upon would be the FIRST target I would take out if I were an invading alien fleet.

Or a disgruntled ex-math professor living in a shack in North Dakota. (okay - exactly HOW to take it out would be a challenge).

the other question is - solar cells are 15% efficient? I would hope that they could improve that before shooting them into space.
And HOW long do these solar panels last? 20 years tops? Could a station like this even be built within the lifespan of it's collectors?

Space dust?
Micrometeors?

These guys watch too much star-trek.

Industrial effort for moon factories enourmous

[Goonie]

Solution: move a small mining plant (manned, essentially a shack and some dozers) to the moon, build a railgun, launch the raw materials to Geosync, process the materials, and build the powersat from construction shacks manned by a few dozen men.

Hmmm. How many off-earth factories do we have right now? How much R&D will be needed to design the first off-earth factory? How many launches from Earth will it require to keep those few dozen workers fed, clothed, and supplied with all the parts, tools, and other things they need to do the job (notably carbon to process the silicon, something present only in miniscule quantities on the moon). For fsck's sake, obtaining water on the moon isn't exactly easy (there might be some at the poles, but if so it'll be located in craters that never see the sun). Oh, and where are you going to get the power to extract bulk quantities of aluminium?

Now, none of these problems are insurmountable, given enough effort However, all that effort strikes me as a *very* expensive and long-termexercise. By the time it becomes feasible, one wonders whether fusion power will have been perfected and all this effort to be irrelevant.