I have been hearing mention lately of orbital solar power generating stations. Is this just idle talk from those who read too much Popular Mechanics or have there been recent breakthroughs that bring it closer to practicality?
Thanks,
Rob
I have been hearing mention lately of orbital solar power generating stations. Is this just idle talk from those who read too much Popular Mechanics or have there been recent breakthroughs that bring it closer to practicality?
Thanks,
Rob
I haven’t heard about it recently, but this idea has been in the works for about forty years. I tremember going to lecturesc about it in the mid-1970s. The biggest holdup was the inefficiency of the solar cells back then. I recall people saying that we’d have these wonderful organic-based cells with as much as 80% efficiency of conversion. That didn’t happen.
So, what are we left with? A extension cord hundreds of miles long?
Here’s a recent news article about space solar power, but it doesn’t mention any breakthroughs or renewed interest, and in fact states that NASA is currently not doing any work in this field.
http://news.yahoo.com/s/space/20090225/sc_space/spacesolarpowercrowdbetsonobama
Also, I understand launch cost has been going up in recent years, not down.
No. Power (in this case, electricity) can be transmitted wirelessly. Here are a few wikipedia links to get you started if you’re interested. Wireless Energy Transfer and WiTricity.
The idea was originally (and most recently,. as I heard it a few years back) to send the power down via microwaves to a rectenna on the ground (or floating in the ocean). Critics suggested sending huge amounts of power down via microwave would result in a great many cooked seagulls, so the proponents suggested spreading the beam as large as possible.
Which is a very inefficient process, necessitating an even larger installation.
I dunno… It seems to me that while getting a fairly large solar installation into space is doable, if not very feasible with current technology, beaming the power back to earth safely would be a whole new ballgame.
Relevant Wikipedia article
You’ve got me there. I was just presenting an alternative to an enormously long extension cord, inefficient though the alternative may be.
Note that WiTricity is irrelevant to this, since that effect depends the source and receiver being relatively close together (relative to the sizes of both devices). Radiation-based methods (basically, microwaves or lasers) can in principle work, but would be extremely dangerous with any practical set of parameters.
That, and regular maintanence, too. Right now we can barely keep the ISS going, and who knows if we can keep Hubble up. The cost of keeping a SPS going right now wouldn’t make the energy worth it.
Everything comes down to how much it costs to send people & material to and from space, and that doesn’t seem to be getting any cheaper.
Is there potentially anything that makes space-based solar generation worth the extra expense and technical hurdles not faced with terrestrial solar power plants?
Well, the advantage is that the atmosphere absorbs a significant amount of solar energy before it reaches the surface, and that the amount absorbed is unpredictable (depending on clouds and such). A solar plant in orbit wouldn’t have that problem. Whether that’s worth the whole host of other problems such a plant would have, well, that’s a different question.
You’ve been whooshed. I was speaking tongue-in-cheek, but I sometimes get too obscure for my own good.
Unless that’s a mis-link, the article’s talking about getting energy to the satellite, from the atmosphere. Not connecting to Earth at all. On the other hand, here’s a real extension cord.
It depends upon what you mean by efficiency. Solar cells have a number of efficiencies.
First there is the efficiency with which photons are absorbed, this does not necessarily give rise to an electron or electron-hole pair and various thermodynamic processes can either re-emit the photon or cause it to generate heat and therefore be lost (as far as making electricity is concerned anyway).
Once a charge carrier pair is created there are a number of ways that they can re-combine and be lost as heat etc. Plus there are a couple of parasitic resistances to be taken into consideration.
It is then possible to calculate the total efficiency for the cell (for a certain wavelength range of light depending upon the band gap of the material ~1.14eV for Silicon IIRC and various values for organic polymers).
Organics unfortunately have not yet achieved their potential and the best efficiency I’ve read about to date is around 7%, whereas silicon is around 40% in the lab and about 28% commerically (IIRC). Plus silicon doesn’t degrade as fast as polymers. I would think that either a silicon or a multilayer silicon-germanium cell would be the best type to put into space for this purpose, but couldn’t say for certain as I currently work on polymers (the potential for increase in efficiency is better as silicon is approaching its theoretical limit).
I’d like to see it done but don’t know if we could do it yet.
Well, the fact that they are in sunlight 24 hours a day is an advantage, compared to ones on earth that are dark (non productive) at night. That right there just about doubles their efficiency.
Although it is unlikely that they would be in sunlight for 24hrs as presumably they would need to be in geostationary orbit over a collector of some kind and therefore would spend the night away from the sun.
If a the European Union microwave power downlink went off target would it cause the Cooking of Provincial France?
And, if it would, what sauce would you serve it with?
Well, it IS France, after all…sauce is God there.