More on the PG&E/Solaren SBSP plan [Update]

I didn't realize that the Next100 site is actually run by PG&E. Here is their original announcement: Space Solar Power: The Next Frontier? - Next100.

So Solaren must find money do all the testing and development of the system, deal with all of the regulatory issues, etc. all by 2016. Quite a few hurdles there to leap.

A couple of other articles about all this:
/-- Space-Based Solar Power — PG&E Says Yes, if No Money Down - Greentech Media: Green Light
/-- PG&E Seeking Solar In Space! Seriously - Earth2Tech

A Google search on Spirnak brought up this patent: Weather management using space-based power system. Modifying hurricanes via space energy beams seems pretty far out, so to speak. The part about describing how a "control system maintains alignment of the free-floating elements" sounds interesting, though.

In conventional systems, the connecting structures can comprise a majority of the weight of the systems. For example, some known systems utilize a transmit antenna in space having connecting structures that are many kilometers long and weigh millions of metric tons. The excessive weight of connecting structures can result in increased launch costs. Further, the excessive weight can strain system components, possibly impacting the alignment, operation and performance of the system. Thus, the weight of electrical and mechanical connections can be a limitation on the maximum size system that can be profitably implemented. Further, the positioning, orientation, and efficiency of system components can be improved, particularly system components that are not linked together with connecting elements.

[Update Apr.14.09: Alan Boyle has a report on the PG&E/Solaren agreement: PG&E makes deal for space solar power - Space/msnbc.com.

Solaren's director for energy services, Cal Boerman, told Alan:

Solaren's plan called for four or five heavy-lift launches that would put the elements of the power-generating facility in orbit. Those elements would dock automatically in space to create the satellite system. Boerman declined to describe the elements in detail but noted that each heavy-lift launch could put 25 tons of payload into orbit.

"We've talked with United Launch Alliance, and gotten an idea of what's involved and what the cost is," he said.

]

Posted 04/13/09 | 15:31:15 by TopSpacer | Filed under: Space Technology

Comments

I was going to start humming the "monorail" tune from the Simpsons, but the fact that they are only signing a contingency contract where they aren't putting any money down may make this less of a scam. The bit that they're supposedly contracting to buy electricity at similar rates to other renewable sources also helps protect them from getting ripped off...so I guess the best way to put this is as an interesting PR stunt that isn't likely to cost PG&E anything.

I just wonder if any other utilities are going to follow suit. If they're able to sign enough contingency contracts, they might actually get enough money to try...I just don't see how they plan on making the business case close using existing launch vehicles.

~Jon

Posted by Jonathan Goff at 04/13/09 15:56:17

Hi Jon,

"I just don't see how they plan on making the business case close using existing launch vehicles."

Yes, hard to see how Solaren could get within a factor of 10 of terrestrial solar. They must have some tricks beyond just minimizing structures to give them the confidence to take the project this far. Even so, won't be believable till they have a prototype system working.

- Clark

Posted by TopSpacer at 04/13/09 19:26:38

The best solar cells can deliver only 500W/kg. And structure, power conversion and antennas are going to halve that.

I have no idea what magical technologies these guys are using, but you can't build a 200MW plant with four 25000kg launches using todays gear.

Posted by Chris at 04/14/09 03:04:43

Inflatable mirrors, or lightweight deployable ones, and concentrator solar cell arrays, can improve the power to weight ratio over planar arrays. The big SPS studies don't seriously consider planar arrays, they're all concentrators of one sort or another.

The question is whether these people have any idea how to build those and have them function reliably enough and last long enough to be economically viable.

200 megawatts at 5 cents a kilowatt hour (order of magnitude for wholesale price in California, may be 30% low) is $10,000 per hour, $240,000 per day of operation, about $87 million per year.

At 10% cost of money, that's paying interest on 4 EELV mid-heavys. But not ongoing operational costs, capital costs of the satellites themselves, etc.

And you can't beam 200 MW down to earth continuously from LEO, as the satellites are orbiting too fast. If they're rad-hard they can do it from Molnya orbits with reasonable time efficiency and steerable antennas. Or you can stick the whole assembly in geosynch orbit. But the payloads to Molnya or GEO compared to LEO are lousy.

I need to see an architecture sketch and some business plan numbers. Case doesn't seem to close right now.

Posted by George William Herbert at 04/14/09 10:58:59

Ummm - what would happen if the beam went astray?

Posted by Question at 04/14/09 11:40:14

"Ummm - what would happen if the beam went astray?"

Some RFI and a hefty fine from the FCC.

Posted by Matt Wronkiewicz at 04/14/09 11:48:53

"Ummm - what would happen if the beam went astray?"

Both microwave and laser beams would be phase locked onto the ground receivers; the antennas/mirrors can't form a beam (i.e., focus on a spot) without that. Being that is part of physical law, it can't fail.

After I wrote the above, I checked to see what Wikipedia may have:

"A commonly proposed approach to ensuring fail-safe beam targeting is to use a retrodirective phased array antenna/rectenna. A "pilot" microwave beam emitted from the center of the rectenna on the ground establishes a phase front at the transmitting antenna. There, circuits in each of the antenna's subarrays compare the pilot beam's phase front with an internal clock phase to control the phase of the outgoing signal. This forces the transmitted beam to be centered precisely on the rectenna and to have a high degree of phase uniformity; if the pilot beam is lost for any reason (if the transmitting antenna is turned away from the rectenna, for example) the phase control value fails and the microwave power beam is automatically defocused. Such a system would be physically incapable of focusing its power beam anywhere that did not have a pilot beam transmitter."

Posted by Gary C Hudson at 04/14/09 11:57:04

PV and ULA means that you are 1000X the cost per installed watt required.

Posted by joseph.burris@att.net at 04/14/09 12:23:35

Looks like this is all about answering investors who as "If you can make the power, will anyone buy it?" So PG&E is making it easier for them to raise capital.

Posted by Karl Gallagher at 04/14/09 12:40:11

"PV and ULA means that you are 1000X the cost per installed watt required."

That just means (sort of) that you need to concentrate at 1000:1 with thin film reflectors.

;)

I agree that this is way premature, however, give the current cost of space transportation.

Posted by Gary C Hudson at 04/14/09 16:09:23

A demonstration satellite would certainly be interesting. How about a power beaming demonstration from ISS?

Posted by Tom D at 04/14/09 18:08:05

"A demonstration satellite would certainly be interesting. How about a power beaming demonstration from ISS?"

I would have to agree here. The ISS has the largest single power source ever put into orbit, and the power system is essentially complete. While the reserve power for the ISS isn't all that huge, there certainly is some power to spare for a relatively brief demonstration test.... and some first-hand knowledge of some of the logistical issues that come from performing maintenance on such a large power-array in space.

Virtually none of the proposals regarding space-based solar power even cite experiences on Mir, Skylab, or the ISS... where the picture isn't nearly so clear cut and bright as the space solar power proponents would have you believe. Issues like the failure of the Skylab array deployment, stuck rotors, and other mechanical breakdowns have been documented in the operations of the ISS... including some instances where having astronauts available to bang a hammer on the equipment sometimes can make a difference. Astronauts literally saved the day with Skylab, and is a sort of proof that astronauts have utility in space.

BTW, I'm not convinced that the environmental impact of this power source is worth the effort... and treating this as a "green" power source completely ignores the significant energy loss from beaming the power to the Earth. Most of the "lost energy" from the transmission is absorbed into the atmosphere in the form of heat. Don't tell me that such atmospheric heating is negligible to the environment, when the alternative is building a coal plant spewing out CO2 that supposedly also has a negligible impact for global warming. The same arguments apply in both cases.

Posted by Robert Horning at 04/15/09 10:04:26

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