I'm not convinced. I'd rather not have my brain fried* neither by microwave nor infrared lasers.
*some may argue that this wouldn't make any difference so I include any other parts of my body and belongings.
European space company EADS Astrium has revived an old idea, that of space-based solar power generation. The company says it could have a 10-20kW demonstration spacecraft in orbit "in the next five years". The BBC reports on speculation by company executives yesterday, but it is acknowledged that without funding, probably from …
Thought about using laser beams to zap down energy some time ago, makes sense but there is no telling what kind of impact it would have as it passes through the atmosphere and would you trust environmental analyst's to come up with a reliable answer these days? Would mean limitless free power but we have plenty of options for that already, just no way of making limitless amounts of money from them. Would also give the owners the option of zapping stuff with laser beams from space....
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It's a series of effects - space W/m2 is only about 150% of terrestrial W/m2. Then, double it because space collectors will work for 24 hours instead of 12. Then, factor in weather on earth which reduces terrestrial collection by a random but large amount. This pushes Space Solar Power (SSP) to much more efficient levels.
Also, SSP can be shifted to different places very easily - just build a new collector elsewhere and aim the beam (and hope you don't miss).
While efficiency is moderately improved, counting in the lack of clouds, W/m2, and 24hour ops, then balancing that with beam loss and conversion; the main win is that it could actually be built. NIMYism (or as covered in a recent Reg article BANANA) means that there is little/no chance that solar power fields on earth will be built in any usable quantity.
That this kind of technology will take off is when we have automated/robotic space-based manufacturing capability, using materials obtained from either mining on the moon or the capture of a NEO. Preferably this would involve self-replicating robots capable of churning out solar panels without much human intervention. They'd also need to be capable of maintaining the arrays once built.
And transmission back to earth would be better done using some kind of tether rigged with superconducting cables - else the transmission losses just make the whole scheme even sillier.
Launching the equipment from Earth would be madness using our current disposable rocket technology. Better to spend the money on developing fusion, or building terrestrial solar arrays...
There are serious downsides, its just they don't want to advertise them. (Its also nothing to do with accidental death rays and cost etc).
For a start, while this one they talk about is just a small prototype, a final system, to make this form of power generation financially viable, it will need to be generating at least 100MW of power, much more likely nearer 1GW to pay for it all, as space is so expensive to work in. Any less power generation capacity isn't going to earn enough money to pay for all the hassle of getting it up there, and operating it on a daily basis, much less paying for all the research and construction costs. Also what their company is likely to want to do is replicate this technology, so many countries can use this form of power generation. Then it becomes more financially viable for a company, but still a very expensive system for each one built.
But here is the key fundamental flaw:
That means, for each satellite system we will be introducing an extra 100MW to 1GW of IR fired through our atmosphere. Now multiply that say even just 100 times as they sell the technology to many other countries. At that point you have around 10GW to 100GW of extra IR fired at the planet, that would not otherwise enter Earth's atmosphere. 100 generators is nothing. It could easily go to 1000 systems sold. For a start each on their own will definitely cause local weather influences, but now add up their total effect on the planet. That means all the satellites working together, are effectively acting like a gigantic Fresnel Len pointed at the planet. That much extra IR power is going to cause global environmental impact.
Another way to think of it is to imagine say each 1GW as 1 million 1kW electric fires all pointed at you, held in a giant array 1000 x 1000 electric fires. That many for each Gigawatt of power heating the planet, more than it would other wise experience. Now imagine many Gigawatts of additional IR power all over the planet. Thats a lot of extra IR hitting the planet.
So I don't think this is such a viable solution for power generation. Plus thats before you add in the additional serious problem that some countries most definitely will also try to weaponise it. You can bet they will want to build these as laser platforms, to torch enemy positions (crops, buildings, radio transmitters etc..) whenever they wish. That could be the real unspoken additional goal, as weapon construction is financially far more viable than power generation. Which would also explain how they could fund such space work. It would also mean the power generation story could even just be a PR smoke screen, for where they see real money from this technology.
In reference to the potential of transmission beams heating the atmosphere, as long as the solar panel is kept between the Earth and the Sun (ie as long as it casts a shadow on the Earth), then no extra energy is reaching us. No energy is created in the process, and it was all heading our way anyway. In fact, if it could be transmitted in a form which is less prone to heat the atmosphere it passes through (higher frequency or transmission cables etc) then there would be less atmospheric warming than without the panel.
... and when its not between the Earth and the Sun, ie. its to the side of the Earth, then I'm right and you are wrong. (So you are getting very near a straw man argument by misrepresenting me).
Plus for it to be able to provide power then it needs to send that power to a fixed building base station which therefore needs to be in geostationary orbit and so moving with the Earth, therefore moving in and out of shadow and at times it will result in the satellites at the edge of the Earth so to speak, with respect to satellites facing towards the sun. Therefore *at times* the satellites won't be between the Earth and the Sun while they are collecting *additional solar power*.
In addition, it can also be said that all non-renewable power sources are also adding to the overall heat energy on the planet, in the same way this harvesting of additional solar power is added to additional heating of the Earth. (I don't want to get into the whole global warming debate as thats not my point. I'm only discussing total *heat* energy on the planet).
For example if we burn coal, then we generate heat. Simple. (Also fission could be used to generate heat). All of this heat is additional heat that wasn't there before. Simple and note, no energy is created in the process. Its simply a conversion, yet it does add to the total heat on the Earth. We use heat to drive generators to create electrical power and then in turn the electronic devices dissipate that electrical power as heat. That created heat is going into the environment at some point and its additional heat. After all cities have recognized micro climates, so they do effect the environmental conditions. (I'm not making judgments as to good or bad effects, its simply that it does affect the environmental conditions is my point).
Some of that heat radiates away from the earth and greenhouse gases help trap more of that heat etc.. but the point is, when we put in more heat, we are making matters worse. So my point stands, this space based solar power generation is adding to the heating problem, not solving it. Still it doesn't generate greenhouse gases, so its better in that respect.
Anyway I suspect its all academic because as I hinted, I don't think this is about power generation at all. The more I think about it the more it sounds like a military PR smokescreen lie to hide their true desire to build a weapon. Its exactly the kind of lie they would use. Cheap, clean, high tech futuristic power source. Trust us, we won't point it at anything else.
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As the Director of R&D of a solar cell company. And this kind of "solar power in space with energy beamed to Earth" stupidity just drives me crazy. Ground based photovoltaics are marginally economical and, at best, marginally ecological. The whole focus of the entire industry is to drive costs (including BOP) down, and to eliminate/minimize environmental wastes. The only way to make photovoltaics orders of magnitude less economically & ecologically viable so is to rocket them into Space. The higher (and unflitered) solar flux in orbit (as compared to Earth's surface) is just not very large (much less than x1.5 in the wavelengths that matter for solar power generation), and even if positioned to never be in Earth shadow, you only gain another factor which is less than 4 when averaged over a day..
But where is the benefit of space PV panels?
PV panels on earth = inefficient. but only one stage of energy conversion
PV panels in space = more efficient, but then have to convert to some other form of radiant energy, squirt to ground, extra losses from inverse square law, passage through atmosphere etc, more losses from converting back to electricity (again) = very, very inefficient
There is a lot more area for solar collection up there than down here. Perhaps a satellite could have an array 100m x 100m , beaming down this energy to a location on earth say 10m x 10m
That would still present a control problem, there would be a fair push on the panel from the incident sunlight , and focussing a tight beam from geostationary orbit onto a small target is going to be difficult. Handling high levels of electrical power seems to need very heavy equipment as well, how do we get that into space?
And what happens if something files through the beam?
Track your satellite here : http://science.nasa.gov/Realtime/jtrack/3d/JTrack3D.html
1) Put satellite in space
2) Convert light energy into electricity
3) Convert electricity into light
4) Send light to earth
5) Convert light energy into electricity
Surely you could do better with mirrors and optics to skip steps 2 & 3? I know, there are probably advantages when it comes to wavelengths etc, but then again the photovoltaic cells really arent that great yet anyway. Focus sunlight into a concentrated beam and send it to earth, bypassing the middle man
What we really need is a giant 'leccy cable into space... Anyone got a spare extension cord?
(1) Can simple solar collectors (ie focussed mirrors) be used instead of PV ? These might be far cheaper to scale to large areas).
(2) How big are the power converters ? Depending on how good the infrared beam is at punching through clouds it might be a plus in terms of not needing to build large grids. Being able to redeploy somewhere else in the event of a power failure for example, or moving electrical power via a wire from Australia to Europe for when the wind doesn't blow isn't feasible, but moving a downlink from a satellite might be.
I've always wondered, why has no company offered a big city to take over its public lighting service.
Mirrors in space could keep paris or london lit 24h/day for next to nothing! No need for full daylight, an improved twilight would be fine. This seems to me to be the perfect way to bootstrap the "energy from space" business...
"Space-based solar power is a potentially unlimited resource"
By the time we've completely encased the Earth in a shell of orbiting solar panels, we'll have not only exhausted this "potentially unlimited resource", but possibly also caused some minor side-effects to boot.
A *lot* of work has been done (mostly by NASA) on the use and deployment of Space Power Satellites. The comments made suggest very few people have read it. Let me summarise.
They went with microwave because electricity -> microwave generation is *highly* efficient. 80-95% is common. *High* efficiency in electricity -> laser is IIRC 32%.
Work has been down using Microwave oven grade magentrons, The cheapest high power generators (by a large margin). Cost matters on this scale.
The microwave power level was chosen to be in line with the microwave safety level and bird safe to fly through the beam.
Ground aerials were designed to be *kilometers* on a side but the aerials are *not* opaque and can allow crop growth or grazing beneath it.
*All* designs planned to used phased array techniques to focus the beam (to this low power level) witha low power "back channel" to keep it locked. No return signal and the magnetrons de-phase to even lower levels.
Modern solar cells are a *lot*more efficent with IIRC the record being about 43% (3 layer types)
BTW it is nonsense that PSP only work during the day. Above c800Km they are in *permanent* sunlight. The phased array lock on would allow them to "walk" the beam backward, however multiple satellites would be needed for 24/7 power. OTOH 1 sat could supply a pulse big enough to re-charge off-grid sites with on-site storage
Like Iridium satellites they would still need to be replaced regualrly. The original designs incorporated plans for cell re-annealing by travelling electron guns to reduce solar radiation damage.
Launch costs are a *huge* part of any concept. While launch costs run $15-20 000/Kg the price of electricity froms such an array is likely to be *huge*.
The studies conclude the *only* reasonable options were to mine the moon (transported by mass driver from the moon and processed in orbit) or lowering the launch cost by 100x at *least*.
BTW With a 43% light -> electricity 32% electricity -> laser and another 43% for light-> electricity conversion at the ground with a 1300W m^2 sunlight level that needs 260000 m^2 to give 20Kw, or roughly 26.81 Hp.
I'd forgotten that PGE had put a deal on the table. Note the technology. Solar conentrators on the sats and *microwave* beam down. It was the laser transmission idea that made this a non-starter.
I like concentrators. They increase collector area for *potentally* very little mass (hyperthetically a metallised plastic sheet with inflatable ribs could work and deliver 100x basic solar level to the cell or more). Depending on the tech cells can respond very well to concentrated sun light as long as the heat is dumped. A 43% efficient cell still has to dump the other 57%.
Note I've presumed they would go for the top end cell type which are a *lot* more expensive than any of the types your'e likely to see on Earth. Good modelling of the costs of various technology types (and substituting one for another) are *critical* to making a viable business case with the fewest launches (stil likely the biggest cost element).
Note that Solarem are a *long* way from delivering actual power to the grid. Worst case would be they need just 1 good launch (BTW packing a sat delivering 200MW at the ground station outlet in a single launch would be an *awsome* engineering feat and would leiminate a number of tricky problems), it fails and they have no launch insurance to build and launch a replacement.
I'll wish them luck. A working sat delivering real power to a real grid would change quite a lot of peoples perceptions. But it won't be easy.
"Each one that goes up carrying PVs will probably spit out more energy than the panels would collect over their entire working lifespan."
No. It takes *roughly* 60Mj to put 1 Kg in orbit (roughly kinetic energy of mass + potential energy of mass) . An array of 200MW collects 200Mj per *second*. It will therefor recoup the energy spent by the rocket to transport it up fairly quickly.
Mine's the one with the Physics text book in the pocket.
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