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PG&E will work with a startup company to try and develop technology to generate solar power in space

California utility Pacific Gas & Electric hopes to work with the Solaren Corp. startup that will help generate electricity from solar-powered satellites that are in orbit around Earth.

It appears this is the first time space solar power will actually be used on Earth, despite the fact that it has been discussed by researchers for many years.  The necessary underlying technology is available, even though companies haven't developed a system of this magnitude yet.

The company is looking for state approval to sign a 15-year agreement with Solaren, but it's unknown when state legislators will discuss the matter.

"Emerging technologies like space solar face considerable hurdles," according to paperwork filed for the California Public Utilities Commission.  "PG&E believes that potential, significant benefits to its customers from a successful space solar installation outweigh the challenges associated with a new and unproven technology."

Specifically, Solaren will utilize 850 gigawatt hours of solar power in the first 12 months -- which is expected to be in 2016 -- while the overall number is expected to double in 2017 and forward.  Utilizing solar panels in Earth's orbit, the power will be converted to radio frequency energy that can be received by a custom receiving station that will be located in Fresno County, California.  

Once at the receiving station, it will be converted to electricity and distributed through PG&E's state power grid.

Solaren will be responsible for receiving the necessary federal, state and local permits and approvals, while also working with government agencies and university researchers to further its technology for PG&E.  PG&E will purchase the power at an agreed-upon price that is similar to other renewable-energy purchases, but the specific monetary numbers weren't released.

Both state and the U.S. federal governments are asking companies to develop more renewable energy sources, though development hasn't been as fast as some lawmakers want.

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Here's my concerns with that ...
By Chris Peredun on 4/14/2009 9:33:40 AM , Rating: 1
quote:
Specifically, Solaren will utilize 850 gigawatt hours of solar power in the first 12 months ... the power will be converted to radio frequency energy that can be received by a custom receiving station that will be located in Fresno County, California.


First concern is how much loss will be inherent in that conversion/transmission/conversion process - is that 850GW at generation or "end result to the line?"

Second concern is what happens to anything that gets between "Point A" and "Point B." 850GW/yr boils down to about 27kW transmitted a second.

Will pre-cooked birds be falling out of the skies over Fresno?




By rdeegvainl on 4/14/2009 9:49:42 AM , Rating: 2
I'd love me some roast duck on a picknick, but never have the time to prepare one for those spur of the moment events.


RE: Here's my concerns with that ...
By Proteusza on 4/14/2009 9:54:58 AM , Rating: 3
Did you ever play Sim City 200? They had a microwave power plant that used pretty much the exact same principle, only it had a possible disaster attached to it - every now and then, the beam would miss the dish.

Yeah, its a good point though, with energy of that magnitude being beamed down, how wide an area do they expect it to cover at ground level? Could it slice the wings off an aircraft? Fascinating stuff, and it could be a good and clean source of energy, but I'm very keen to know more about how they plan to get the energy down to the ground without a giant power cable.


By ninus3d on 4/14/2009 11:09:21 AM , Rating: 2
Slice the wings of an aircraft?
If it had even anything close to that it would have been put into war use ages ago!

I want a space lasercannon!


RE: Here's my concerns with that ...
By Radnor on 4/14/2009 10:15:26 AM , Rating: 2
Interesting POV.

It will put McD's and KFC out of business.

On a more serious note i hope this kind of investments lead to the space elevator. Or some reusable form of space "elevation"

11Km/s is nice and all. But hey, it isn't all that cheap.


RE: Here's my concerns with that ...
By randomly on 4/14/2009 10:16:28 AM , Rating: 5
No, the energy density of the microwave beam will actually be quite low so it won't be frying birds or people. Typical designs call for around 200 Watts/sq. meter maximum, or about 20% the intensity of sunlight. Transfer efficiency from satellite to ground will be in the 70%-80% range. Most of the losses will be as heat in the microwave generators on the satellite and the diodes in the Rectenna (rectifying antenna) on the ground.

However the antenna sizes in orbit and on the ground have to be very large. With a 2.45 Ghz microwave power link (12 cm wavelength) and the solar satellite in Geosynchronous orbit of 36,000 km with a 1km diameter orbital antenna the ground antenna needs to be ~4.3 km in diameter to pick up the main power lobe. It will need to be even larger to pick up the side lobes and deal with aiming errors. The minimum antenna sizes are fixed no matter how little energy you actually transfer because they determine how focused the microwave beam is. So even if you build a low power system you still have to build huge antennas.

Going to higher frequency microwaves will allow you to reduce antenna sizes, but conversion efficiency starts to really drop above about 5-6 Ghz because of diode losses.

It's a very cool and 'spacey' idea. However the whole concept makes no economic sense at all without launch costs that are orders of magnitude cheaper than the $10,000 / kg currently available. You would need launch costs at least 100 times cheaper.

It's a huge waste of money with the current state of technology and launch costs and only benefits the company getting the taxpayers money. It's an irresponsible allocation of funds and I would categorize it as a scam. If PG&E spends any money on this it will only be to the extent of the 'Green' Marketing/PR points they can squeeze out of it before it's quietly abandoned.

You'd get at least 10 times better value out of building a concentrated thermal solar power facility, and actually useful amounts of energy.


RE: Here's my concerns with that ...
By MrTeal on 4/14/2009 10:53:30 AM , Rating: 2
Do you have any links showing 70-80% end to end efficiency with beamed RF? I would have though the atmospheric losses alone would be much higher than that, unless they've come up with some cool new way of doing it.


RE: Here's my concerns with that ...
By randomly on 4/14/2009 4:37:45 PM , Rating: 2
Using Magnetrons, Klystrons, Gyrotrons, or distributed solid state amplifiers (depending on frequency and other design constraints) you can achieve an 80%-90% DC to microwave conversion efficiency. Rectennas can also achieve efficiencies in the 80%-90% range when converting microwaves back to DC power on the ground. That puts the potential overall efficiency of the power transfer by microwaves in the 70%-80% range.

Atmospheric losses are not very high at 2.45 Ghz, but increase at higher frequencies due to absorption by oxygen and water vapor. This is partly why frequencies in the 2.45 Ghz to 5.8 Ghz range are usually the proposed.

Here's a paper on the subject that covers some of the issues.
http://www.sspi.gatech.edu/wptshinohara.pdf


RE: Here's my concerns with that ...
By Shadowself on 4/14/2009 7:37:07 PM , Rating: 3
DC to microwave conversions can be as high as 98% on some space qualified hardware. That is NOT where the losses are. The losses are in the high voltage conversions to run the DC to RF conversion equipment. The BEST ones right now are about 60% efficient for an overall efficiency -- of the best systems out there -- of less than 60%.

Now assuming that they can get that up to about 70% over the next several years (a HUGE IF) then that will big a big move forward.

However the conversion on the receive side is still pretty poor. The RF to DC conversion is still much less than 50%.

Thus the DC to RF to DC efficiency is less than 30% today and will probably be less than 40% when this thing is supposed to be operational.

While the S-band and C-band frequencies don't see much atmospheric loss in satellite links (typically less than 1.0 dB), these bands are very crowded. I doubt anyone could get an exclusive authorization in any of these bands.


By randomly on 4/14/2009 11:33:43 PM , Rating: 2
I'm not aware of any high power DC to microwave conversion technology that is even close to 98% efficient. If you can provide a reference that would be helpful.

I believe you are making several errors in your assessment. There is no need to do any high voltage DC conversion to run the microwave generators. They run can run directly off the DC voltage supplied by the photovoltaic array. Even if DC power conversion was necessary you can certainly do better than 60%, I've designed DC-DC converters with over 90% efficiency, and achieving over 80% efficiency is trivial.

Crossfield amplifiers are over 76% efficient. Magnetrons such as those used in microwave ovens are commercially available with 75% efficiency. A multistage collector Klystron is a little over 80% efficient.

Your efficiency numbers on the receiver end are also wrong. Working Rectennas have been built and tested with RF-DC conversion efficiency higher than 84%. Some engineering studies indicate that over 90% efficiency may be possible.

William Brown achieved a JPL certified DC power in to DC power out overall efficiency of 54% with a high power microwave link, and that was 40 years ago.

The band most often proposed is the microwave oven frequency of 2.45 Ghz. The other often cited frequency is 5.8 Ghz. These are both ISM bands, allocated for Industrial, Medical, and Scientific RF field use and any communications device using them must accept interference generated by ISM equipment.

Unfortunately I think every single point you made is in error.

The problems are in the economics of the scheme, not the engineering.


RE: Here's my concerns with that ...
By MrPeabody on 4/14/2009 11:00:47 AM , Rating: 5
There has to be a "rectenna" joke around here somewhere.


By DeepBlue1975 on 4/14/2009 1:13:44 PM , Rating: 5
I heard those will only be used to establish a communication link with Uranus


RE: Here's my concerns with that ...
By eetnoyer on 4/14/2009 12:08:42 PM , Rating: 2
"Most of the losses will be as heat in the microwave generators on the satellite..."<\i>

So, if they're generating so much heat in space, exactly how are they going to dissipate it? Conduction and convection are out (in any significant amount). That only leaves radiative loss. To dissipate that significant an amount, that's gotta be some really high temperature capable equipment.


By eetnoyer on 4/14/2009 12:10:01 PM , Rating: 2
Screwed up the flag. Man, do they need an edit function here.


RE: Here's my concerns with that ...
By Schrag4 on 4/14/2009 10:56:31 AM , Rating: 4
I hate to nitpick (or do I?), but it's not 850GW/y. It's 850GW Hours /Y, which boils down to:
850GHW / (24H * 365) = ~97 MW

And it's not 'per second' as you stated. It's 97 MegaWatts at any given point. It's 97MegaWattSeconds per second. Or 97MegaWattHours per hour. Or 97MegaWattYears per year. Make sense?


By MrBungle123 on 4/16/2009 11:00:03 AM , Rating: 2
I just did a quick google search for how much solar panels weigh and went with the first thing I found so take this with a grain of salt but it should be good enough for illustrative purposes.

I found some panels that put out 205W and weighed 18Kg each.

97M / 205 = 473170 panels required
473170 * 18 = 851073 Kg total weight

it currently costs about $10,000 per Kg to put something into orbit. so...

851073 * 10000 = $8,510,730,000 required just to put these things in space.

we buy power by the KWhr so lets figure this out.

$8.5 Billion / 97000KWhr = $878048 per KWhr

say we assume the design life on these satellites is 15 years

$878048 / 15 = $58536 KWhr....

and thats excluding the cost of the conversion station on the ground just to keep the numbers "conservative"... Yay I can heat up a hot pocket in the microwave and it will only cost me as much as a used car!


RE: Here's my concerns with that ...
By mmcdonalataocdotgov on 4/14/2009 12:19:04 PM , Rating: 2
Here ARE my concerns...

Anyway, who cares about loss in the system? That is only pertinent when using non-renewable resources to generate power. Now, making it more efficient in subsequent generations would be a desireable goal.

Also, who uses a conjunction with an infinitive as in the article's subtitle? TO develop, not AND develop. Am I right, grammar nerds?


By MrPickins on 4/14/2009 1:10:36 PM , Rating: 2
quote:

Anyway, who cares about loss in the system? That is only pertinent when using non-renewable resources to generate power. Now, making it more efficient in subsequent generations would be a desireable goal.


Sure, in a purely research situation. This is a public utility company we're talking about. The cost for the inefficiency will go straight to the consumer.


RE: Here's my concerns with that ...
By MrTeal on 4/14/2009 1:26:59 PM , Rating: 2
From Wikipedia, on the ISS solar panels

quote:
Each of the Solar Array Wings are 34 m (112 ft) long by 12 m (39 ft) wide, and are capable of generating nearly 32.8 kW of DC power.[3] They are split into two photovoltaic blankets, with the deployment mast in between. Each blanket has 16,400 silicon photovoltaic cells, grouped into 82 active panels, each consisting of 200 cells, and each cell is 8 cm² with 4,100 diodes.[2]


Each of these SAWs took one shuttle mission to send to the ISS, and they produce 32.8kW of power. To get the original 97MW would require almost 3000 panels of similar size and materials. The payload on a satellite launcher might be higher, but you'd still need a unbelievable number of launches to put this system in space.

You don't think the efficiency is a big deal, when losing even 20% in the beaming and conversion process would mean hundreds of extra launches at tens of millions each?


No details on cost...
By Schrag4 on 4/14/2009 9:18:28 AM , Rating: 2
850 GWH over 12 months works out to:
850GHW / (24H * 365) = ~97 MW

Double that the next year to less than 200 MW. How much does it cost to get all this equipment into space? How about the ground station? I guess cost doesn't matter...




RE: No details on cost...
By MrTeal on 4/14/2009 10:58:37 AM , Rating: 1
To collect 97MW in space, with a solar constant of 2366W/m^2 and 40% panel efficiency (ignoring conversion and beaming losses), would require 100,000m^2 of solar panel.

I'd guess it won't be cheap. The entire idea seems a little impractical at this point in time.


RE: No details on cost...
By MrTeal on 4/14/2009 11:38:37 AM , Rating: 2
Oops. I knew I should have double-checked that before posting. Solar constant averages 1366, not 2366. So, closer to 175,000m^2 of panel would be needed. And that's expensive triple junction space grade panels, at tens of thousands of dollars per m^2. Double or triple that area for the polysilicon panels that would be needed because you can't get another types in a reasonable price range or quantity.


RE: No details on cost...
By stromgald30 on 4/14/2009 6:08:17 PM , Rating: 2
This idea has been thrown around since the 80s and maybe even before. It wasn't practical according to the studies done in the 80s, and it's still not practical now. It's just another "great" idea that politicians picked up on and decided to support. Unfortunately, now tax dollars are being spent on "developing" it, which is really disappointing.


RE: No details on cost...
By Shadowself on 4/14/2009 7:49:12 PM , Rating: 2
A 40% panel efficiency for space solar cells is probably a bit high. Space qualified solar cells typically lag ground based solar cells by 5-10%. Then you have to drop some for the panel inefficiencies (string redundancies, diode losses, packing fraction, etc.). Right now, even for cutting edge systems you're lucky if you get near 30% for a total panel efficiency. It extremely unlikely it will approach 40% by the time this system is supposed to launch.

The number I've used for years is 1358 W/m^2. Also, even at GSO you have the eclipse periods (when the Earth is between the satellite and the sun around local midnight for about a month before and after the equinoxes each year). These eclipse periods vary in duration depending on the date during the year, but can be 90 minutes or more.

About cost, I haven't priced a full up space based power system (not just the solar panels) recently, but the last time I did (around 2000) a full system cost about $600 to $700 per watt. Yes, per watt. NOT per kilowatt.

Let's make the crazy assumption that they to $100 per watt. That's on the order of $10 Billion dollars for the power part of the satellite system. Now add on top of that the cost for the satellite structure and control systems -- not to mention launch costs!


RE: No details on cost...
By Ammohunt on 4/14/2009 1:49:49 PM , Rating: 2
I agree pie in the sky comes to mind...meanwhile nuclear power is a proven technology and safe.


RE: No details on cost...
By Hulk on 4/14/2009 2:54:58 PM , Rating: 2
Yummy... high altitude pastry!

(i.e. pie in the sky)


RE: No details on cost...
By stromgald30 on 4/14/2009 6:11:52 PM , Rating: 2
Exactly. Nuclear is so much better than fossil fuels and can be implemented NOW. Wind, tidal, and geothermal are also other clean sources that need to be expanded upon.

Solar may be the most ideal source of power since it comes from a source that is inexhaustible with respect to any human time frame, but the technology/efficiencies just isn't there yet.


RE: No details on cost...
By Viditor on 4/15/2009 5:37:14 AM , Rating: 2
At 194MW/hour and $0.12/kwh, that's 0.12 * 194000 * 24 * 365 = $203.9 Million/yr.

While nuclear will certainly be a part of a balanced solution, the very soonest a nuclear plant could be built and put on-line is 10 years from now.


RE: No details on cost...
By mars2k on 4/15/2009 6:47:52 AM , Rating: 2
Am I missing something here? Why are we importing energy from outside the atmosphere.
Isn't the object of all our efforts to utilize new sources of energy to allow the earth to reflect a little energy back into space.
I know the net gain over what would normally hit the surface of the earth is small.
There was, however, a time when the the total amount of gasoline we used on the planet was quite small.
I'm not sure we need to get this good at collecting solar energy to be really effective in achieving our real objective.


RE: No details on cost...
By Starcub on 4/15/2009 10:48:19 AM , Rating: 2
quote:
Isn't the object of all our efforts to utilize new sources of energy to allow the earth to reflect a little energy back into space.

For the purpose of combatting global warming? Yes, that was my perspective as well. Likewise, I'm not sure what effect it would have in the net, but it does seem to be a desirable goal.

Despite the fact that solar looks like the only clean renewable source capable of meeting the worlds energy demands, I would tend to agree with the other commentors and say that we should concentrate on terrestrial tech right now. In addition to cost/practicality, I'm not sure about the safety aspects of something like this.


earth orbit?
By kattanna on 4/14/2009 10:08:14 AM , Rating: 4
quote:
Utilizing solar panels in Earth's orbit


and just what orbit is that?

with a low earth orbit like the space station uses.. those panels will be zipping around the planet once every 90 minutes and only able to send their power for a couple minutes once every orbit.. and thats IF they can get a proper orbit so that each orbit actually crosses over where the receiver station is.

at a geosynchronous orbit, while allowing for 24/7 power, would make the beam coming back so broad as to lose much power as im doubting they are going to be able to confine the beam spread from such a distance. plus.. anything passing between it and the earth.. like other sattelites could very well be disrupted by such powerful radio waves.

then.. there is the launch costs. the shear 100's to 1,000's of millions of dollars could be better spent on ground based solar arrays, if it HAS to be spent on solar at all.




RE: earth orbit?
By Etsp on 4/14/2009 10:51:45 AM , Rating: 1
Perhaps it stores energy for those 89.5 seconds it isn't directly above the antenna, and then releases it all at once...


RE: earth orbit?
By stromgald30 on 4/14/2009 6:18:15 PM , Rating: 2
Um, the orbit is 90 minutes not seconds. For a 90 minute orbit, about 50 to 55 minutes is in the sun. Roughly 35-40 minutes is in eclipse. The time that the satellite would be in view is about 15 minutes, and you still only get about 2 good (within 15° of being directly over head) passes per day. So you'll be storing a TON of energy that needs to be transmitted in a few minutes.

The alternative would be to have hundreds of ground stations, but that just increases the cost and pollution expelled in constructing this ridiculous system.


RE: earth orbit?
By casteve on 4/14/2009 10:55:02 AM , Rating: 2
Hey Fresno, you can stop worrying about cell towers and health concerns now. The side-lobe energy from this monster will take care of your problems :)

This was a boondoggle in the 80's, it's a boondoggle now. The cost of launch will kill it....and if it doesn't, the footprint all of the launches leave in ozone layer loss should.


All I'm thinking of right now...
By jaericho on 4/14/2009 9:43:01 AM , Rating: 5
is SimCity 2000.

Tho' the premise does sound very interesting.




By Starcub on 4/15/2009 10:50:14 AM , Rating: 2
I think the Air Force traded the F-22 for this.


Safe, and who is gonna pay?
By KITH on 4/14/2009 2:33:08 PM , Rating: 2
California is going to be bankrupt, who is paying for this venture?

Regarding safety and wireless power transmission, I believe Tesla wanted to it for shooting down planes...




RE: Safe, and who is gonna pay?
By Smartless on 4/14/2009 3:26:55 PM , Rating: 3
Yeah they kinda are... Last I heard they were going to cut 30% of their teachers. They're also renting space in Oregon for windfarms. Interesting state I must say.


RE: Safe, and who is gonna pay?
By Spuke on 4/14/2009 4:55:39 PM , Rating: 2
30% was just the LA School district. They get all of the press because they take 15% of the states budget.


Roast duck not on the menu
By bohrd on 4/14/2009 9:55:46 AM , Rating: 3
..What happens when you stand in front of your radio? Do you get cooked? No?

If the wavelengths are long enough, which I'm sure they are, ducks you and even planes won't notice.

Yay for science!




RE: Roast duck not on the menu
By bohrd on 4/14/2009 10:19:49 AM , Rating: 2
If there is interest, look up Tesla (the guy not the car company) he wanted to do wireless power 100+ years ago using radio frequency.


bullet points
By Old Man Dotes on 4/14/2009 11:50:05 AM , Rating: 3
Launch costs , like anything else, go down with economy of scale, unless the Government is running the show. With civilian launch systems right at the edge of availability, expect to see dramatic cost decreases Real Soon Now due to orders-of-magnitude increases in civilian launches.
In-transit losses are effectively nil when the power itself is free; all that sunlight is simply going to waste right now. And solar power generates no greenhouse gases, no toxic waste in landfills, and no noxious fumes to fill up the Los Angeles basin with brown air.
Space industry generates high-tech jobs. I don't know anyone other than religious fundies and Luddites who would have a problem with that.




RE: bullet points
By JediJeb on 4/14/2009 5:38:13 PM , Rating: 2
quote:
And solar power generates no greenhouse gases, no toxic waste in landfills, and no noxious fumes to fill up the Los Angeles basin with brown air.


True, but how much will be generated by the manufacturing of so many panels? Also unless they are using H2/O2 as rocket fuel, how much polution is generated by all the launches it will take to put the array into orbit? Only way to prevent this would be to establish asteroid/lunar mining for materials and build an orbital assembly plant.


Can't wait to see...
By hoosierE on 4/14/2009 9:48:09 AM , Rating: 1
what happens when birds and planes fly through a 97 MW microwave oven...

Ooh...
Aaah...
Oh!




RE: Can't wait to see...
By AnnihilatorX on 4/14/2009 11:37:02 AM , Rating: 2
Passenger: Excuse me this potato bake is not hot enough. Oh wait it is now. By the way who turned the air con down?


All I know...
By DeepBlue1975 on 4/14/2009 1:20:23 PM , Rating: 2
Is that solar energy has always been, is and will be a "bright" idea.

As a side news, I've heard a new song is making quite a hit on the radio "Total eclipse of the satellite dish".




Watch Gundam 00 much?
By wingless on 4/14/2009 4:06:22 PM , Rating: 2
Somebody has been watching a little too much Gundam00. Google it. Need I say more?




Deathray in space.
By toyotabedzrock on 4/14/2009 5:12:02 PM , Rating: 2
I'm just glad there gonna be microwaving, I mean powering homes on the west coast and not the east coast.

If I remember correctly Japan used this same tech during WWII to try and create a death ray.

How many years has it taken NASA to deploy all of the solar panels to the ISS




Instead of RF Transmission...
By ChuckDriver on 4/14/2009 5:51:50 PM , Rating: 2
let's attach some conduit to the shaft of the space elevator and send the electricity down a wire. We can do it 50 years after everyone has stopped laughing.




Worst website ever
By Captin Crunch on 4/15/2009 6:49:31 AM , Rating: 2
I'm not sure some lame Tron graphics and a flashing catch phrase really screams legitimate opportunity.

http://www.solarenspace.com/

that is a fail.




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