August 6, 2008

The Only Realistic Solar-Power System for the Planet

Hatched by Dafydd

In response to Dave Ross' post below... actually, we could power the entire planet's energy needs in perpetuity by solar power alone.

But only if we generate that power via vast solar arrays in high Earth orbit (HEO) and beam the power back to the ground.

The idea of solar-power satellites has been kicking around since at least the 1970s; Jerry Pournelle popularized it greatly back then (I presume he still supports the idea today). It would require a number of technological breakthroughs -- each of which would be a huge boon to Mankind in itself:

  1. A much, much cheaper way to put a pound of payload into low Earth orbit (LEO). It currently costs between $50,000 and $100,000 a pound on the soon-to-be-defunct Space Shuttle, somewhat less on disposable rockets, and we have no idea what it will cost on whatever eventually replaces the STS. We need to bring that down by three orders of magnitude to $50 - $100 per pound.

    Possibilities abound. My favorite is a laser-launching system, where a ground-based laser shoots an intermittent, high-energy laser beam into the combustion chamber of a rocket; this superheats the air that has been sucked into the chamber, causing it to expand out the nozzle. The advantage is that the rocket need carry no onboard fuel, thus making it tremendously more efficient. You need to complete boost before leaving the bulk of the atmosphere, of course; and you might not be able to launch through heavy cloud cover.

    (A "space elevator" is a really cool idea, but it could only be built out of Bolognium -- i.e., some unreasonably strong material that doesn't exist yet. And the "Ferris wheel" launcher is too dangerous, in my opinion.)

  2. An inexpensive way to boost payload from LEO to HEO. This is probably the easiest technology of the batch, requiring just a booster pack that can attach to payload in LEO, then navigate itself back down (or else bring payload down from HEO to LEO).
  3. Building a permanent mining, separating, refining, and smelting facility on the Moon. This is the only way to get sufficient raw materials to build solar-power satellites without taxing the capacity of Earthbound mines and refineries.

    This doesn't require much in the way of technolgical breakthroughs, given 1 and 2; but it does require burying the facility underground, to avoid cosmic radiation; and it requires quickly setting up the facility to extract oxygen from the lunar soil, so the workers can breathe without having to deplete whatever oxygen through brought with them. It also requires a truly spectacular recycling system, as workers must also, for the most part, consume their own, er, output.

  4. We need to build a launch facility on the Moon to send up the raw materials or manufactured items that we will need to build the satellites. This is a perfect opportunity for a linear-accelerator launcher, since the Moon has no atmosphere -- and since we're not going to be launching living creatures that way, so we can up the acceleration to 200-300 Gs.
  5. We need to perfect building very large structures in open space... because it makes no sense to build a solar array (say, 2,000 square miles) on the ground -- even the Moon -- and then launch it into orbit. We should use the launcher (4) to launch either very small components (but they cannot be fragile), or better yet, just raw metal and crystal; each larger structure can be built in orbit, in "freefall," where gravity is not a serious problem.

    The biggest problem here would be cosmic radiation: Either the facility would have to be deeply coated with lunar dust; or if you want to be more elegant, you can use the idea of T.A. Heppenheimer: Put a huge static postive charge on the hull to push away the big, slow, dumb alpha particles that cause the most damage... and then set up a strong magnetic field to push away the electrons that would otherwise be attracted to the positively charged hull.

  6. Finally, we have to decide how to broadcast the power back to Earth.

Each of these technological breakthroughs is admittely difficult; but nevertheless, none is impossible. And none even requires a significant scientific breakthrough: The science is there -- all that's left are the engineering details.

The advantages of a solar-power satellite system are obvious:

  • It collects power "day" and "night," since it's never in the Earth's shadow (or at least rarely and not for long);
  • Each satellite can be as big as necessary to produce enough power for our needs; the only limitation is that if you make any structure big enough, it will collapse under its own gravitational mass. But "big enough" is way bigger than we would ever need here;
  • It would allow us to dramatically reduce petroleum usage, along with coal... thus going a long way towards reducing world air pollution -- which is actually energy wasted. If we can invent a really, really good battery, we could reduce pollution even further;
  • And of course, the required technological breakthroughs will be tremendous boons to the American economy, as well as the economies of all our trading partners... as would the very process of developing them in the first place: Technology creation drives jobs.

Since we're adding more energy to the ecosystem, we might need to find a way to reduce the amount of energy that comes to Earth from the Sun directly. If we could create more cloud cover over the poles, that would help a lot.

The problem with virtually all sides in the energy debate is that they're looking at most 2 to 25 years into the future. I don't know about you guys, but I really do plan to live longer than that; and I'm even concerned with how our country and the world will fare even after I die, assuming I ever do. My short-term view is currently up to about 2250... but I'm thinking I may still be too precipitate.

Hatched by Dafydd on this day, August 6, 2008, at the time of 5:23 PM

Trackback Pings

TrackBack URL for this hissing:


The following hissed in response by: Geoman


1) My preferred solution to this problem would be a space fountain.
3)Why have people on the moon - why not just have teleoperated robots?
4)Cake again.
5)Yep - but once 1 to 4 are in place, how hard will it be to replace the whole system every 10 years or so when the solar cells are too damaged? In fact 1 to 4 make the construction of anything (colny ships to Mars, habitats) feasable and cheap.
6) Microwaves?

Of course, my prefered soltuion is what I'd call "ubiquitous solar". Every avalible sruface - roads, buildings, sidewalks, etc is coated with a material that generates electricity. Think of it as solar paint. Since all these items are dual purpose, efficiency of the collection could be low. And yet massive amounts of power would be generated. Best of all the power generation and usage could occur at the same spot.

2250? It pays to think positive my friend.

The above hissed in response by: Geoman [TypeKey Profile Page] at August 6, 2008 6:34 PM

The following hissed in response by: k2aggie07

The problem with solar is that it requires a colossal amount of silicon as well as other rare earth elements to dope it. And even so, the really fancy ones are only at 20-30% efficiency.

There are all sorts of theoretical alternatives -- thermoelectics being one, piezoelectrics being another. The question, though, always comes back to an as-yet-unnamed technological breakthrough.

I have more faith in the ability to really manipulate atomic particles. If you actually figure out mass-energy conversion on a controllable scale, your problems are solved...for another few millenia, at least.

The above hissed in response by: k2aggie07 [TypeKey Profile Page] at August 6, 2008 7:04 PM

The following hissed in response by: SlimGuy

There was a major story in Scientific American on a full solar project and what it would take out in the desert southwest just to power up the USA.

It was very inefficient in that it used so much of its generated power to store compressed air for 'dark hours power'.

The above hissed in response by: SlimGuy [TypeKey Profile Page] at August 6, 2008 8:39 PM

The following hissed in response by: SlimGuy

There has also been a lot of discussion in the EU countries of making a massive solar installation in northern Africa and then transmitting the power back to the EU.

The above hissed in response by: SlimGuy [TypeKey Profile Page] at August 6, 2008 8:47 PM

The following hissed in response by: SteveC

Your info on space elevators is old. Carbon nanotubes have the necessary strength for the cable though many engineering problems still need solved.

The above hissed in response by: SteveC [TypeKey Profile Page] at August 6, 2008 9:13 PM

The following hissed in response by: AMR

A disadvantage and big one. If the satellite shifts orbit even by a very small percentage, due to the long distance involved, the power beam becomes a death ray. Or an eeevil country could turn it into one.

The above hissed in response by: AMR [TypeKey Profile Page] at August 6, 2008 10:06 PM

The following hissed in response by: LarryD

Space Based Solar Power (SBSP) Assessment, by the National Security Space Office.

Cheap orbital capacity is an absolute must, for this to be economical. The microwave beam would be too diffuse to be a weapon, but this also means that the ground receiving antenna won't be small. One advantage not mentioned yet, is that the solar influx in orbit is about four times what reaches the ground.

Orbital solar power can avoid the storage requirement that ground based solar power has, by proper placement of the satellites.

I think we're more likely to have IEC fusion before we can meet the engineering requirements for SBSP, though.

The above hissed in response by: LarryD [TypeKey Profile Page] at August 7, 2008 6:13 AM

The following hissed in response by: MikeR

Indeed, Dafydd, Jerry Pournelle has been posting about this on his site, for a long time. (You have to poke around there; things are hidden in lots of places.)
I think that the cheap access to low orbit is the one requirement that would (a) provide immediacy to all the others, and (b) provide zillions of other benefits anyhow. Our whole space program is currently bottlenecked behind the Shuttle. (See again Pournelle on SSTO (single stage to orbit), but of course that's only one of many approaches.)

We should also be allowing the building of nuclear power plants as fast as we can. "The China Syndrome" represents one of the biggest wrong turns in recent American history.

The above hissed in response by: MikeR [TypeKey Profile Page] at August 7, 2008 9:27 AM

The following hissed in response by: MikeR

By the way, you probably meant "a factor of 1000" or "several orders of magnitude" in your post, instead of "a factor of 2".

The above hissed in response by: MikeR [TypeKey Profile Page] at August 7, 2008 9:29 AM

The following hissed in response by: Dafydd ab Hugh


By the way, you probably meant "a factor of 1000" or "several orders of magnitude" in your post, instead of "a factor of 2".

It looked funny when I wrote it; but this was one of the posts here that I write quickly, as opposed to those that take hours... and I forgot to look it up.

I meant "three orders of magnitude," and I've changed the post accordingly. Thanks!


The above hissed in response by: Dafydd ab Hugh [TypeKey Profile Page] at August 7, 2008 1:32 PM

The following hissed in response by: Cain

I believe SteveC is correct on the space elevator solution. I remember reading that a Japanese led break-through in nanotube technology had effectively solved the tether strength issue, which was indeed a huge hurdle. I think this technology has the best near-term potential. I've seen estimates of payload cost coming down to the range of $10 to $100 a pound once this is in production. Hang onto your hats once that's in place. It will have a revolutionary impact in multiple areas of science and commercial interests.

The above hissed in response by: Cain [TypeKey Profile Page] at August 7, 2008 2:00 PM

The following hissed in response by: Dafydd ab Hugh

Cain, SteveG:

I don't know enough materials science to really have an opinion, but this article on Wikipedia says it's good but not good enough yet.

Is your information more recent? Can you link to something that's readable by ordinary humans (or lizards)?


The above hissed in response by: Dafydd ab Hugh [TypeKey Profile Page] at August 7, 2008 5:02 PM

The following hissed in response by: hunter

I hate to be an uber-nerd on this, but oil is solar energy, combined with geological pressure.
But seriously, for a small fraction of the cost, we could develop thorium fission, and have clean, unlimited power.
I love space. I am re-reading an old classic "The Man Who Wanted Stars", right now.
But until we achieve a vastly cheaper way to space, forget about giant power grids.
And if you think enviro-extremists are going a bit far over the wasteland/holy ground of ANWR, just think of sending gigawatts of microwaves down here from GSO.
If you think they are worrisome with their mutterings about political trials for daring to dispute AGW, try and see the lynch mobs that develop over multi-hundreds of sq. km. diode receiving grids.
Thorium would be orders of magnitude cheaper, and we cannot run out. And it would be safe.

The above hissed in response by: hunter [TypeKey Profile Page] at August 7, 2008 8:17 PM

The following hissed in response by: AMR

While I am for nuclear power and was a reactor operator in the Navy and a operator and shift supervisor civilian life, I have a serious mistrust of the management of said civilian facilities. With the pitting of profit against safety some may fear making decisions that may be right from a split second decision making standpoint but if the safety first decision was wrong, the costs can be in millions because of lost production and grid fines. I sincerely believe that the control room operators and supervisors should be NRC employees to counter that concern and buffer the control room operations staff from management retribution; similar to the FAA employing airport flight controllers. There are downsides to this idea, but having been there, done that, I have seen the intimidation factor at work.

The above hissed in response by: AMR [TypeKey Profile Page] at August 7, 2008 8:50 PM

The following hissed in response by: Bart Johnson

From the viewpoint of failure analysis, every single component of a system increases the probability of failure. KISS works.
Converting sunlight to electricity to convert that to microwaves to send that to Earth to convert that to heat or to electricity is asking for failure.
IF you insist on Earth orbit solar energy collection, just use lenses to focus light to Earth to make steam or something to make electricity.
Just be careful where you walk when its operating.

The above hissed in response by: Bart Johnson [TypeKey Profile Page] at August 7, 2008 11:03 PM

The following hissed in response by: agimarc

Space Solar Power is enjoying a bit of a comeback led - interestingly enough - by the DoD Advanced Programs folks. They have a need to inject large combat teams anywhere in the world within hours. When you go to fight, you also need utilities. The concept is to put SPS capable of several tens to hundreds of megawatts into GeoSynch orbits, and use them as primary energy sources for combat forces. The military hits the ground, unfurls a rectenna (microwave antenna), plugs it in and they are up and running.

Over the last 30 years, photvoltaic energy conversion efficiencies have gone from the 12-13% range to the 27-28% range. This means that requred masses for large power stations in orbit have fallen significantly.

Gerard O'Neill (colonies), Peter Glaser (SPS) and Bill Brown (microwave transmission) did a lot of the baseline work 30 years ago. It appears that technology has caught up a bit with the idea.

With a push from DoD and a follow-up from the free market, we may see something after all.

For more information, you can look around at Space Studies Institute of Princeton and the Space Frontier Foundation (free market space guys). URL for SFF:

The above hissed in response by: agimarc [TypeKey Profile Page] at August 8, 2008 7:32 AM

The following hissed in response by: SteveC

I do not read the Wikipedia article as being that grim. As it points out in the section on tapered cables, it is theoretically possible to make the cable from steel, just not practical. Carbon nanotubes should be strong enough once manufacturing problems are solved. So the material has gone from Unobtainium to Realhardtogetium. A couple of problems intrinsic to properties of the material is that carbon nanotubes conduct electricity and they burn. Thunderstorms will be a problem.

The above hissed in response by: SteveC [TypeKey Profile Page] at August 11, 2008 6:07 PM

The following hissed in response by: Cain


I'm forced to retract what I posted earlier. It's been well over a year since I had looked into this particular topic and it seems your information is accurate. Nanotube technology has not advanced as quickly as previously predicted and there remain significant hurdles in this area. The company I've watched off and on over the past few years is It's pretty clear from browsing their website that the tether breakthrough has yet to be realized. If only wishing for something to be true were enough. A working and secure space elevator would be such an incredible advance but alas, it remains several years away at best.

The above hissed in response by: Cain [TypeKey Profile Page] at August 13, 2008 11:15 PM

The following hissed in response by: Dafydd ab Hugh


If the space elevator can be made to work -- and I believe I will live to see it -- then that would unquestionably be the best solution: We could have, say, ten of them around the equator (or wherever is best); and each could probably accomodate fifty or maybe a hundred vehicles/payloads going up simultaneously... so we might be able to launch a thousand payloads every day or two, however long it takes to traverse the entire elevator.

Heck, we could be flinging stuff into GEO so fast, coupled with linear accelerators shooting valuable mass off of the Moon, that we could build an O'Neill colony every year!


The above hissed in response by: Dafydd ab Hugh [TypeKey Profile Page] at August 14, 2008 12:34 AM

The following hissed in response by: Cain

It will indeed be great to see. I always thought it would help address the problem of nuclear waste from power plants too. This seems to be one of the main objections now (given that reactor meltdown risks have fallen significantly) from the enviro-crowd; how to safely dispose of waste. How simple and safe would it be to gently lift the stuff slowly to orbit, attach a cheap thrust device to it and send it happily off towards the sun? Problem solved.

The above hissed in response by: Cain [TypeKey Profile Page] at August 14, 2008 12:56 PM

Post a comment

Thanks for hissing in, . Now you can slither in with a comment, o wise. (sign out)

(If you haven't hissed a comment here before, you may need to be approved by the site owner before your comment will appear. Until then, it won't appear on the entry. Hang loose; don't shed your skin!)

Remember me unto the end of days?

© 2005-2009 by Dafydd ab Hugh - All Rights Reserved