The Case For Space Based Solar Power Development

Energy policy is in the news again, with debates in Congress, statements from presidential candidates, consternation over our dependence on the Middle East for oil, and a California recall election traceable in part to energy supply problems for that state. Use of energy, whether fuel for transportation, electrical energy running the internet, or the destructive energy released in weapons, is central to our economy and security.

It is with good reason that the technical term for energy use per unit time, "power", suggests control in the human world as well. Three actions taken now - working to reserve radio spectrum for power transmission, focusing on reductions in costs for space launch, and investing in space solar power system research - hold the promise of opening up vast new sources of power within the next 10-15 years.

Space is big - there is an awful lot of energy out there, and the crumbs we fight about here on Earth are laughably tiny in comparison. Zettawatts from the Sun pass just through the region between Earth and Moon - that's enough energy for each man, woman and child in the US to sustainably power an entire US economy all to themselves. Even our terrestrial energy choices, fossil or renewable, fission or wind, almost all derive from the energy profligacy of our Sun and other stars before it.

Gathering power in space and transmitting it to Earth should not be a mystery to us in this 21st century. Communications satellites already do it routinely. One significant obstacle to power applications, however, is regulatory: there is no spectrum allocated to power transmission, as there is for communications. Since frequency of operation has a significant impact on transmitter design which may alter the design of the overall solar power system, the earlier we have a frequency allocation decision, the better. The Federal Communications Commission and the International Telecommunications Union should be prodded to start work on this issue now.

The potential for power from space has been recognized for over thirty years (1). Studies in the late 1970's by NASA and the Department of Energy produced a reference design for solar power satellites using then-current technology that showed technical feasibility, but also high cost. NASA returned to the subject with an exploratory study from 1999 to 2001.

A review by the National Research Council (2) found the program to have a credible plan which required significant funding increases. Rather than strengthening the program, however, all funding for the space solar power group ceased after September 2001, and essentially no R&D work on power from space is now being done in the US. Worldwide over a trillion dollars a year goes to the energy industry, and utilities routinely construct multi-billion-dollar power plants. The energy industry has a bigger wallet than the entire US federal discretionary budget.

Money is not directly the problem here; profitability is. The two essential factors in the cost equation are the cost per delivered Watt of the solar power components, and the cost per delivered Watt of getting those components to their final destination in space. Current costs put the capital investment needed for a space solar power system well above the $2/Watt of competitive terrestrial options such as fission plants and wind turbines. R&D work is needed to bring these costs to where the vast energy resources of space are within reach of a large utility project. The cost of components is the first problem here. Current prices for solar electric power systems are about $2.50 per peak Watt, a price that has been declining about 7% per year for the last few decades. The day/night cycle, non-ideal sun angles, weathering, and cloud cover reduce power output enough to make the final cost per average Watt $10 or more. Terrestrial solar power is still too expensive for wholesale utility use, but it is now competitive for home owner installation in many areas.

In space you can get peak power almost all the time. The $2.50/Watt homeowner systems are not space-rated, but the space market is still small; with a larger market suitable photovoltaic elements could be produced at comparable cost. Transmitting power from space will have somewhat higher losses than transmitting from a terrestrial power plant. Nevertheless, component costs are potentially much closer to wholesale utility requirements for space solar power than they are for terrestrial solar, and with continued improvement in prices, in another 10 to 15 years component costs should not be an obstacle to large-scale installation.

The other cost of concern is delivery to orbit. Typical communications satellite solar panels have a mass per kW of about 20 kg, so with current launch costs of $10,000/kg that comes to $200/Watt, or a hundred times too large to be competitive at the utility level. Bringing that number down requires both improvements in mass per kW, and cheaper access to space. Mass per kW is sensitive to solar power system design (3). The NASA/DOE reference design came to 10 kg/kW; more recent studies of light-weight design options have suggested mass could be as low as 1 kg/kW (4).

Significantly more R&D effort to validate these designs and settle on a few cost-effective approaches would be extremely helpful here. The lower the mass requirement, the less we need to bring down launch costs to break the $2/Watt barrier. Lower launch costs is a major goal of all space advocates. The X Prize contenders, Musk's Space-X, even the major aerospace "EELV" program all have the intention of significantly reducing launch costs.

Whether any rocket based system will succeed remains to be seen - perhaps we will have to wait for space elevators to see much reduction in cost to orbit. But there are some indicators that we could see a factor of 3-5 improvement, and perhaps more, over the next decade with a sufficiently large and competitive launch market.

Competition in the commercial launch market already has some providers such as Sea Launch offering $4000-$5000 per kg prices to low earth orbit. Use of solar electric propulsion allows higher orbits at only slightly higher cost. Given the multi-trillion-dollar potential market for space-based power, increased funding for launch systems development to accelerate these improvements would also be a worthy investment. There is another way to reduce launch costs. In David Criswell's Lunar Solar Power proposal (5), instead of launching the final components from Earth, manufacturing facilities are sent from Earth to the Moon to build the solar power system components there. And to save even further on launch costs, the solar components stay on the Moon and transmit power directly from there. The initial capital investment is higher than for an Earth-launched system primarily due to the much larger antennas needed to transmit power efficiently from Moon to Earth, but overall costs per delivered Watt should be much lower, and the costs for such an approach are less dependent on reducing launch costs from Earth.

Component and launch will not be the only costs - for example we need to learn how to cost-effectively put together very large (kilometer-scale) objects in space. Improved robotics and computational capabilities should make this much less expensive now than was true for the 1970's era designs, but it is another area where we need some experience to be confident in cost estimation. Further R&D in robotics may also be needed.

Looking at the major cost areas again, for the wholesale utility market space solar power is currently about a factor of 2 too expensive with regard to cost of materials and components, and at least a factor of 10 on the launch cost side. Both cost barriers have realistic chances of being overcome in the next decade.

The prospects for space-based solar power are at least as bright as for fusion power; these two options were identified as the only long-term sustainable energy sources in a report published in Science magazine last year (6). While space solar power has received essentially no government funding for two decades, fusion gets close to $1 billion/year. The ITER fusion project scheduled for completion in 2014 will cost $5 billion for a research reactor that produces only thermal power - in contrast the 1995 "Fresh look" (7) study for space solar power found some systems with an estimated cost of $6 to $8 billion, producing 250 MW electric available for commercial sale, readily expandable to several GW and a profitable return on investment. With some further research those numbers can likely be improved upon, but the funding has been terminated rather than increased.

We already have an immense fusion reactor working for us in our solar system, ultimately responsible for almost all our energy choices. All we really need to do is make better use of it by tapping into it more directly.

Any rational energy policy for the United States must support the steps needed to make that happen: increased investment in reducing launch costs, reserving radio frequency spectrum for power transmission, and moving towards a billion dollars per year in a robust and diverse program of R&D on space solar power.

This is nuts for several reasons. I once saw an estimate that--to build orbiting solar stations, it would take 50 shuttle flights per year. Add that to the cost.

If it rains where the receiver is, the amount of radiation reaching the antenna is reduced.

The animal rights nuts will go ballistic whenever a goose flys through the beam and dinner is delivered--pre-cooked--out of the sky.

Not to mention the NIMBYs opposing siting of the antennas, Earth Firsters sabotaging them, airplanes flying through the beams and having various systems roasted, etc, etc.

An idea whose time is went.

--Boris

Here's the plan:

Instead of doing the blatently obvious and beaming power down to the ground so we can recharge our Makitas, we will do something just slightly non-obvious.

We will use the power in space.

The heavy industry use of power will be removed from the power grid. It is about 1/3 of the power use. Heavy industry will be moved into outer space. No more pollution, no more acid runoff from strip mines, it's an environmentalist's dream and he'll have to go to school to learn about something else to whine about.

Actually, it's NOT nuts: the engineering is quite straightforward. And originally, the shuttle system was SUPPOSED to be capable of several hundred flights a year. Of course, we were supposed to be flying a second-generation shuttle 5 years ago, and finishing development of a third-generation shuttle by now.

The economic payback for setting up the infrastructure to build SPS's is also straight-forward, and has the added benefit of once you've got the the infrastructure in place in GEO and Lunar orbit, as well as on the Moon, then from that point, you can build as many more as you want for O&M costs. . . .

As for the animal-rights activists and treehuggers, if they object morally to the power, let them. . . .in the dark, with no electricity. Rectennas are a bit hard to sabotage with anything less than a squadron of bombers, and for the most part, the loss due to clouds or rain isn't terribly significant. I've been following the issue since the late 1970s. . .

Your first objection is the most constraining. NOTHING will happen in space until we send the shuttle to the scrapheap of history. It is a horrendously expensive, overly complicated, terribly fragile, one-size fits all craft which has in no regard fulfilled the promises made back when it was originally funded. While we're at it, we can stop pouring money into the space station. The old sci-fi vision of a wheel in space is where we need to go. Humans do not tolerate null G well for long periods. Unless someone comes up with field generated gravity, long term work in space will require a wheel design.

Using the power in space is a good idea, but most of the products would still be designed to be used on earth, which doesn't get around the transportation problem. A space elevator would be necessary for this to work.

Here's an idea that might work:

Take a load of Nitrogen-14 into space, and let radiation from the sun hit it, turning it into carbon-14, a radioactive isotope. This is what happens naturally in the atmosphere, we would just be doing it in a much more concentrated bundle. Take the Carbon-14 down to Earth, and make a nuclear battery out of the material. The battery would have a half life of 5700 years.

"Actually, it's NOT nuts: the engineering is quite straightforward. And originally, the shuttle system was SUPPOSED to be capable of several hundred flights a year. Of course, we were supposed to be flying a second-generation shuttle 5 years ago, and finishing development of a third-generation shuttle by now."

There is no rocket technology that can reduce the cost to where it has to be to launch thousands of metric tons into orbit economically. I say this as a 28-year rocket propulsion specialist. Therefore such concepts are science fiction--unless and until a space elevator is developed.

--Boris

"The proposals I've seen for SPS call for 99.5% of material to be of LUNAR origin, not Terran. You launch it using a mass-driver, not a rocket, and refine in orbit.

And since NASA's been studying the concept since 1972, I'd call it less science fiction than a Space Elevator, which requires mass production of materials which we cannot currently produce in sufficient quantity to make. . ."

You and I will be long dead before any of this happens.

I was part of a major study on using (possible) lunar ice deposits (at the South Pole) as a propellant source.

It would be melted, electrolyzed, and shipped to an in-space depot for use by Mars missions.

The problem is that emplacement of the infrastructure (nuclear reactors, vacuum-tolerant digging equipment, supplies, spares, shops, mechanics, doctors, infirmaries, et al) make the payoff a distant (if ever) eventuality.

The same problem faces any scheme that purports to use Lunar materials for space-based construction: there is no infrastructure in place, and the costs of emplacing it kill you. The way I put it, "If God were to put the stuff there for us--for free--it might begin to make economic sense."

Better to work on a space elevator, which has a nearer-term likilhood of becoming real.

See:

http://www.liftport.com/
http://www.spacedaily.com/news/future-00n.html
http://news.bbc.co.uk/2/hi/technology/2188107.stm
http://www.space.com/businesstechnology/technology/elevator_update_020819.html
http://www.wired.com/wired/archive/11.04/nanotech_pr.html
http://www.sciencenews.org/20021005/bob9.asp
http://www.elevator-world.com/magazine/archive01/0211-002.html
http://www.americanantigravity.com/highlift.html

I have been doing psychic transmitting of designs from one of the beloved Saints of India!! Sri Sattya Sai Baba from Bangalore India. I was shown the effects of transmitting solar power from way up there all the way down to earth and you have to really be sure where the beam of sunlight is going to hit because it will be very hot and probably be very damaging to the earths atmosphere. I would think maby the Moonlight might be a safer way of making energy that way. Even if you could make the wire go 100 miles up to where the atmosphere changes, it would probably be impossible to stabilize. Elninio effects could be serious.

I see more earthly and artistic designs that fit the geological and environmental and historic and patriotic or silliness of whatever state the huge sculptures or towers or panels or structures are and they are all high tech with ability to open and close and fit in with us. They are not all the same, because all over the world is not the same and therefore some need protection from earthquake's and others from hurricanes. Some have gullies for snow to melt off them like water flowing down the rice patties of India during the monsoons. Much Fun!!!!! Many shapes, many designs many artists using mathematical reflective art, and the Photo-voltaic medium can make this a really great and beautiful country. Of course, Safety is very important and we really don't need all the engineering disasters. Why not just do it right and get it good. We just dont have the money to waste on experimenting with dangerous stuff.
Were not getting any richer either. I think it is important to get it done ASAP. We don't want to have to go back and fix them either. We don't want them to take up too much land. We want them to generate as much electricity as possible. We don't want to fry from them.
Americans are Married to Electricity and cant really live without it. What if we didn't have any like in the North East last year. We would have breezed through a disaster if we had our Solar receivers working right here on earth.

I have some drawings of many receivers that came to me through channeling from Sai Baba if you are interested.

from sunshineus

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