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Beamed Space Solar Power Plant To Open In 2016?
Eric_S writes "Anybody who managed to get a decent city going in Sim City 2000 remembers the microwave power plant; now it seems like a real-world equivalent might be coming up on the horizon.
The Pacific Gas and Electricity Company, per this 'interview' with the CEO of Solaren on their affiliated site, announced PG&E's plans to buy 200MW of base-load power from a Solaren beamed space solar power plant by 2016." I wish the skeptic in me would be quiet.
Because you haven't run the numbers on the beam power density. The Microwave beam is wide, because it's trivial and cheap to make a huge ground antenna, and because agriculture can be carried out under the antenna. THe beam power density can be held down to just a few times noon sunlight power, and still deliver plenty of energy.
That way, both airplane and albatross are safe to transit the beam area.
Don't take life too seriously; it isn't permanent.
But this hare-brained idea will heat the atmosphere
Fail.
Most power generation schemes are *heat engines.* The typical efficiency is less than 40%. Microwave transmission starts at 50% efficiency, and is likely to get better. For the same amount of electric power, you're going to have less waste heat than with coal, nuclear, or natural gas power plants.
This is a dupe of http://science.slashdot.org/story/09/04/14/0317236/PGampE-Makes-Deal-For-Solar-Power-From-Space. They announced this in April.
Hell, the linked interview in summary is in the original story from MSNBC.com. This submission contains nothing new to add...
Based on Wolfram Alpha the Earth gets about 1.3 kW per square meter. with the earth being 6.4*10^6 m radius with find the area facing the sun is pi*r^2 = 1.28*10^14. Multiplied by the power gives 1.67*10^17 W hitting the earth. Now since the power company wants to sell 2*10^8 W of power we can conclude that the extra energy reaching the Earth would be in the region of 0.0000001%.
It's not just the lack of night, but not having the atmosphere block out a lot of light before it hits your solar cells.
Sim City was fiction. The microwave beams here aren't concentrated enough to be useful as any sort of weapon, either purposely or accidental. The frequencies choosen need to be transparent to water (since it'll have to cut through a lot of it to get to the surface), and the "beam" is spread over a wide area to make simple rectenna receivers possible.
Not a typewriter
Personally I think that geothermal energy is still a method of energy production that has yet to be tapped on a more massive scale.
Strictly speaking, you are correct, geothermal is a method that hasn't been tapped on a massive scale (outside of a few places like Iceland). Problem is, there are issues with induced earthquakes with geothermal. Google Basel Geothermal for an example...
A house divided against itself cannot stand.
Folks like the US military are interested. It's expensive to ship fuel for generators to remote outposts. At those prices for power, SPS are competitive. You also get to remove one logistics vulnerability.
A bit more subtle: The transmitter is using a phased array, and the locking phase is a reflection of the signal from the ground. This is a completely fail-safe system: It doesn't have a machine that says "reference signal gone": if the reference signal disappears, the beam turns into a glow by the laws of physics, not by any allegedly safe automation. And the beam can *only* be aimed at something with an appropriate reflector, so even a mad scientist cannot redirect the beam to a city.
Consciousness is an illusion caused by an excess of self consciousness.
The problem with that is the cold end - it is actually rather difficult to dump heat in space, since you are rather well vacuum insulated. You need a very big radiator, shielded from the sun (presumably by your primary mirror). Which brings the mass required back up again.
Consciousness is an illusion caused by an excess of self consciousness.
If we build it, Scotty will come!
Arguing with an engineer is like wrestling a pig in the mud. After a while, you realize the engineer enjoys it.
Actually, no, it won't heat the atmosphere significantly.
"Atmospheric heating from microwave loss" is another word for "atmospheric attenuation". The trick is you choose microwave frequencies that are not significantly absorbed by nitrogen, oxygen, and water (dihydrogen monoxide), and that knocks out your atmospheric attenuation problem right there.
This is Physics 102, people.
Your real losses are going to be in beamforming and beam wander. You fix beam wander by using a BIG receiving antenna (which also lets you use low power density in the beam: win-win).
Either a "few times noon sunlight" is a lot, or it isn't.
You can't bash the idea as both "dangerously hot/bright" and "too cold/dark for practical use".
Sun at noon can easily generate temperatures over 40C - if a "few times" that is 2.5 or higher, then you're over boiling point of water.
You can harvest that energy using 19th century means - like steam engine.
That WOULD be quite dangerous, though. No need to argue there.
If "few times" is lower than 1.5 - those are temperature extremes observed in nature. Granted, in places like Death Valley or Libya but still - up to 58C is natural.
A tad uncomfortable, but unless you plan to step into the ray naked and just stand there for prolonged periods of time - quite harmless.
If it is somewhere between 1.5 and 2.5, that is in the area of boiling eggs (and other things made out of protein, like skin).
Probably very uncomfortable conditions for living creatures but quite usable levels of energy.
Hey! If you can boil an egg, you are surely getting enough energy to do some other things. Again, you don't need to go further than 19th century - just substitute water for something that boils at lower temperature.
And besides, nobody forces you to stick to the 19th century. So, those energy levels are quite usable.
Even just 100% of noon sunlight is a lot - considering that modern solar is way bellow that. And we ARE using solar.
Mit der Dummheit kämpfen Götter selbst vergebens
Yes, invulnerable. There's a huge difference between hitting a satellite in low earth orbit and geosynchronous orbit, which is a few times higher up and which requires a lot more delta-v to reach.
You are right, the Solaren CEO does say it would be in geosynchronous orbit.
My bad. I was wrong, you were right.
"The agriculture ministry is not in charge of Gundam" - Japanese ministry official.
Didn't anyone read the NSSO's report on Space Based Solar Power? Especially the part about "SBSP cannot be constructed without safe, frequent (daily/weekly), cheap, and reliable access to space and ubiquitous in-space operations." Unless their business plan includes developing that kind of access they have no chance of success. It's daunting even with it, SBSP is hideously expensive to get started, in part because it's co-dependent with low-cost space access which doesn't yet exist.
Luckily, I do, after a quick Wikipedia check on the Sun...
Actually, that's 1.368 kW/m^2 in orbit. In the form of sunlight.
I presume you're surprised by now, since it's not, in fact, "a few (at least) orders of magnitude higher"?
"I do not agree with what you say, but I will defend to the death your right to say it"
If you're talking about attitude of a spacecraft in orbit, then as a matter of fact, there are purely electric systems: magnetic torquers. Lots of satellites use them, including Hubble.
Changing electrical energy into thrust? You got it. Space agencies have been using it for years. And, as an added bonus, it makes a neat blue glow when you do it!
End of lesson. You may press the button.
No, they cause all the transmitters to drift out of phase, so that instead of a coherent beam, you have a wide-angle glow. Transmission is done by a phased-array antenna, as used on most modern radar systems. If these all transmit in a carefully calculated phase relationship, interference directs all the energy into a tight beam. If the phase between the transmitters is random, which it will become if not positively locked to a reference beam, all interference disappears and the energy is dissipated in all directions. All you have to do is ensure that the reference phase is derived not from on board, but from the ground: when the reference beam disappears the transmitters lose phase and the beam broadens into nothing. The transmitters will probably lose lock easily anyway, but you can deliberately unstable if you want. To start the system requires someone on the ground to fire a fairly powerful beam from the target area up to the satellite; to maintain it requires a well-aligned reflector.
Consciousness is an illusion caused by an excess of self consciousness.
That ionizes Xenon gas to produce the thrust, you still need the fuel which is the gas. That is changing electrical energy and a fuel into thrust.
I want a purely electrical one, no gas, nothing consumed like ablating a surface.
Plus the ion engine dont have enough newton impulse to do station keeping for a satellite. at least the last time I looked at them they did not.
Do not look at laser with remaining good eye.
Maybe we can build them safely, but maintenance is another issue. This is the same plant that almost went postal in 1985. See http://www.cleveland.com/powerplants/plaindealer/index.ssf?/powerplants/more/1095759100318143.html for just one reference.
Try looking at the energy densities per square millimeter. That 200 MW beam is spread out quite a bit.
Understanding the scope of the problem is the first step on the path to true panic.
Somehow I think I'm being trolled, but let's clear these up anyhow.
1. With the horror stories about living near power lines, and cell phone usage, what possibke problems could a massive beam of energy blasting from overhead cause?
As those are all false, it's a non-issue.
2. Terrorist with a simple transmitter causing the beam to come down into a nearby city.
Terrorists with a transmitter with enough power to focus a basically harmless beam into a nearby city instead of, I don't know, just using a bomb to blow shit up are hardly a credible threat. Nice movie plot, though.
3. How to you intend on using a power beam to adjust a satellites position, without blasting random sites on the earth? I doubt you can make manouver as necessary without pointing the beam in all directions.
Physics not your strong point? Don't feel bad, most people aren't physicists. But you should avoid expressing strong opinions about what's physically possible when you lack any understanding whatsoever of the mechanism being discussed.
4. You have your power at the equator. Now what? Load it on a boat it to Canada where it's needed? 2000 miles of wire with minimal losses?
The power recieving station does not need to be directly beneath the satellite, though lattitudes as high as Canada start to be an efficiency problem, LA shouldn't be a big deal.
5. If you're worried about global warming right now, how will you feel about massive amounts of energy pumped into the atmosphere every day? You cannot send a beam through the air without affecting it. ...
OK, being bad a physics is no excuse for this one. All power used becomes heat in the environment. The sum of all power used by humans is a very tiny fraction of the total solar energy that hits the planet naturally. It's a complete non-issue. Buring fossil fuels have a very leveraged effect on global warming (if you believe the hypothesis) because of the CO2 released - the waste heat is nothing by comparison. So if you care about global warming, shouldn't you support/I. the 1x heat option over the 10000x heat option?
Socialism: a lie told by totalitarians and believed by fools.
Your math is wrong, you are forgetting that you are dealing with sqare units (the common notation for square units is rather confusing which doesn't help). There are 10000 square centimeters in a square meter and 1000000 square meters in a square kilometer. You also seem to be in a bit of a mess with the units of various figures.
200,000 W = 200,000,000 mW
200,000,000 mW / 50 (mW/cm^2 )= 4,000,000 cm^2
4,000,000 cm^2 = 400 m^2
sqrt(400 m^2/3.14) ~= 128m
so a 128m diameter receiver, not small but not massive either.
note: i'm known as plugwash most places but i screwd up registering that here somehow in the past and now can't register