April 15, 2009
California Utility To Buy Solar Satellite Power?

Space solar power beamed to Earth with microwaves might start providing electric power in California by 2016.

Now Solaren Corporation, a startup based in Manhattan Beach, CA, is trying to get the idea off the ground. It's working with the California utility Pacific Gas and Electric (PG&E), which intends to enter into a power-purchase agreement with the company. If the agreement is approved by regulators, starting in 2016, the utility will purchase 200 megawatts of power from Solaren at an undisclosed price--that is, if the startup can get a system into space and working by then. The company has already selected a site in California for the receiving station; it hasn't said exactly where, but it will be close to a PG&E substation and won't require long-distance transmission lines.

For transmitting the power down to Earth the article mentions both microwaves and lasers. Are lasers practical for this purpose? In that case wouldn't another photovoltaic array be needed on the surface to convert again to electricity? Granted, that array would receive a very focused beam of light. So the area needed would be much smaller.

Also, does anyone know the conversion efficiency for microwaves into electricity?

It is hard to judge the odds of this getting off the ground (both figuratively and literally) by 2016.

Share |      Randall Parker, 2009 April 15 10:26 PM  Energy Solar


Comments
Brett Bellmore said at April 16, 2009 4:30 AM:

Proposals I have seen, (This was a while back.) for laser space power would have involved a sunlight pumped gas laser, no solar cells in orbit. And solar cells can be very efficient dealing with laser light, since you can match the band gap precisely to the wavelength of the laser. Finally, of course, a laser power satelite could be a lot smaller, and still achieve a decent beam size.

OTOH, microwave space power could involve highly decentralized satelites, which every small panel having it's own antenna, together forming a huge phased array. And sine microwave recievers don't have to block sunlight much, you can still farm underneath them. But the satelite does have to be a lot larger, to get the beam size down. Oh, and I think they got up to about 80% receiving efficiency on tests a while ago.

Wolf-Dog said at April 16, 2009 5:45 AM:

But what is the danger that the beam might be improperly aimed on a big city by mistake? Can it be used as a weapon also?

Clark said at April 16, 2009 7:02 AM:

NASA/JPL carried out a wireless power transmission test in 1975 with the Goldstone antenna in which they achieved 82.5% efficiency for 34kW over 1.5km.
video.google.com/videoplay?docid=-6412618572057686135
en.wikipedia.org/wiki/Wireless_energy_transfer

A lot of development in microwave technology has gone on since then so efficiencies should improve. Yes, the distance to GEO is a lot farther but there don't seem to be any fundamental reasons that similar efficiencies can't be achieved if the transmitter and rectenna are sized appropriately.

"Can it be used as a weapon also?"

No, as explained in this article
www.technologyreview.com/blog/energy/23381/
the energy density will be a sixth of noon time sunlight.

Michael said at April 16, 2009 9:56 AM:

Best that Solaren Corporation negotiate with Diane Feinsten as I strongly suspect that wherever they wish to place their receiving station she will have an objection

Neuroskeptic said at April 17, 2009 5:05 AM:

The video game Sim City 2000 included this technology, and it was a very good way of generating power for your city, but sometimes it would go wrong and set your city on fire...

bbartlog said at April 17, 2009 5:05 AM:

It is hard to judge the odds of this getting off the ground (both figuratively and literally) by 2016.

On the contrary, you can pretty easily judge the odds to be zero. A government crash program or someone with billions of dollars at hand could do it in that timeframe; a startup company, not so much.

Orbital Electrician said at April 24, 2009 2:21 PM:

"Can it be used as a weapon also?"

Well, almost everything can be used that way. Even a knife I use for spreading the butter. For more information see "Particle Uplink Cannon" in C&C Generals, which shares similar concept.

Anyway, if you read more on that subject, you discover that it's possible to design such a systems in a very safe way. Like using low-power microwave beams for example. They've done studies on it back in 70's.

Solar energy is the best available energy source by now. Did you know that all Earth's energy of fossil fuels available, passes the Earth every 2 days as radiation (visible and not) from from the Sun?

So let's build a proper, safe Solar Orbit Powerstations:)

Take care.

Siphon said at September 20, 2009 1:24 PM:

In order to be safe, the microwave beams would indeed have to be very low power. But then you'd use more land for the receiver compared to land based solar panel space requirements!

The notion that space based solar power can compete with land based solar power is rather absurd. This is a serious case of NIMLY! (Not In My Lifetime). I suspect some overzealous space solar power scientists are trying to get more attention from the media since no rational investor would give them significant amounts of money.

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