Power From Space
It’s Raining Energy Out There
By John D. Turner

I have been a space enthusiast for years. I remember back in 1966 when I was in grade school, getting in trouble for “borrowing” the family television, a 13" “portable” Philco black and white set, to watch the first rendezvous and docking in space. Having secured my mom’s permission by calling home, I then proceeded to have the school superintendent drive me to my house to pick it up.

Unfortunately, I hadn’t really received permission; my mom wasn’t home, so I faked the phone call, let myself in with my key, and took the set. Of course when my mom returned home, the set was gone and she thought it had been stolen. My actions made our school superintendent an accessory to theft. It was all straightened out in the end (and I and my class did get to see the rendezvous and docking since it happened before mom found the set to be missing), but needless to say, I was in considerable hot water for quite some time, both at home and at school.

Space has always fascinated me.

In the early 80’s I read a book called “The High Frontier” by Gerard K. O’Neill. In it he proposed building large orbiting space colonies which would, among other things, be used to build large orbiting solar power satellites (SPS, aka powersats) which would be used to send power from space where the sun always shines, down to Earth via microwave beam where it would be collected by a large receiving antenna or “rectenna” and distributed through the existing electric power grid. The book came out of a question he had posed to a freshman physics class at Princeton University in 1969; “Is the surface of a planet really the right place for an expanding technological civilization?”

O’Neill proposed building large manned colonies at the L4 and L5 Earth-Moon Lagrange Points. These colonies would be cylindrical in shape. By spinning them on their longitudinal axis, “gravity” could be simulated via centrifugal force on the inside surface of the cylinder. Since centrifugal force always acts perpendicular to the axis of rotation, “up” would be towards the center of the cylinder, no matter where on the inside surface of the cylinder you were standing.

The amount of “gravity” experienced at the surface would depend on the size of the cylinder and the amount of spin it had. Thus, you could design colonies with Earth-normal “gravity”, or more or less, as required. As you move inward from the surface of the cylinder, the apparent gravity would decrease. For example, if you built a three-storey building, the apparent gravity on the first floor would be greater than the apparent gravity on the roof. At the center of the cylinder, the apparent gravity would be zero.

The size of the colonies depended on how big you wanted to make them. O’Neill postulated the initial colony as being of sufficient size to hold 10,000 people, with a self-sufficient biosphere. A colony capable of holding 10 million was not considered out of the question. For a good idea of what an O’Neill colony would look like, check out the Science Fiction TV series Babylon 5.

Obviously, building such a structure would require launching an enormous amount of mass into orbit. And not just low Earth orbit (LEO); the Earth-Moon L4 and L5 points are located about the same distance from the Earth as is the Moon. The current International Space Station, when complete, will weigh in at about 453.6 metric tones (roughly 1 million pounds), and has taken many shuttle missions to build. Even a 10,000 person habitat would comprise many times that much mass, in orbit 1000 times further out than is the ISS. But O’Neill did not postulate building it the same way that the ISS was constructed.

Realizing that boosting the materials from Earth would be prohibitively expensive, he and his students at Princeton, whose aid he enlisted in developing the project, set about finding another way. Instead of sending pre-fabricated parts into space from the Earth, why not manufacture them in orbit? And instead of sending raw materials from Earth, why not get them from the Moon? This lead into investigations into lunar and asteroid mining, mass drivers for raw material delivery and spacecraft propulsion, as well as research and design concepts for the colonies themselves.

And as a reason to build the colonies in the first place and ultimately to pay for them, the construction of the aforementioned solar power satellites. In his book, O’Neill laid out the entire project. His research is echoed and expanded on by planetary scientist T.A. Heppenheimer in his book, “Colonies in Space”, also first published in 1977. Heppenheimer saw space power satellites as being the key to overcoming the problems envisioned in the book “Limits to Growth”, published in 1972, which is often cited by environmental activists and population control advocates.

In “Colonies”, Heppenheimer cites work done by J. Peter Vajk concerning construction of solar power satellites. In Vajk’s model, construction of the first space colony begins in 1982. It is completed in 1988. Using lunar resources at that time, the colony is capable of building another colony, a duplicate of itself in two years, or building two 5 Giga-watt (GW) power satellites in one year. By 1998, there are 16 colonies, each containing 10,000 people, and they are turning out 32 power satellites each year. By 2007, 25 years after the start of the project, the initial investment is repaid, and all revenues are plowed back into building more colonies and satellites. The model does not allow the colonies to go into debt to provide a more rapid economic return and revenues are only obtained from the sale of electricity from the powersats, not from any other manufacturing processes or patents that may be realized from low or zero-gravity environments.

The cost of the project? $178 billion in 1975 dollars. The cost to the consumer for the generated electricity? Initially 1.5 cents per KWh, falling to 1.0 cents per KWh over time; also in constant 1975 dollars. In October 1978, Vajk published a paper entitled “Satellite Power System (SPS) Financial/Management Scenarios” for the Department of Energy detailing how this could come about.

Another researcher, Mark Hopkins, carried out similar studies for NASA in the summer of 1975. Like Vajik, his model called for a lunar mining base and orbital construction shack, with a start date in 1982. By 1987, the first lunar material is delivered to the orbital construction shack and the work crews build the first powersat, which is transported to the L1 point to provide additional power for the lunar base. In 1989, the first commercial powersat is built, and by 1999, all new and replacement power plants in the United States use space-generated power. Meanwhile, the first space colony is completed in 1998, additional construction facilities are completed, and the second colony comes on line by 2011.

Total costs? $106 billion from program start through completion of the first colony, with a net cost of $26 billion for production of all powersats produced through 1999. As they are produced, the powersats begin offsetting construction cost by sale of electricity, providing an ever increasing stream of revenue estimated to be around $80 billion per year by 2008.

The entire cost of the project, principle and interest, is paid back by 2019, with the maximum expenditure in any given year being under $8 billion which is comparable to the peak cost of the Apollo program, corrected for inflation. Electrical costs to the consumer in this model begin at 0.8 cents per KWh, and drop over time to 0.35 cents per KWh. (All numbers in constant 1975 dollars).

As might be expected, there were skeptics. In 1976, Dr Gerald Driggers of the Southern Research Institute undertook his own independent analysis. It was his belief that it would be more difficult and much more expensive than either Vajk or Hopkins estimated. To his surprise, he found that the first powersat could be built in 1992, with the total cost for building a lunar base, space construction facility, a colony for 6000 workers and producing the first 20 10-GW powersats to be $102.5 billion; less than the other two! At a subsequent press conference, he stated “I thought we would shoot down these earlier estimates, but they were right.”

Please note: the technology to do this already exists. It existed in 1975. The timelines from start to completion are probably pretty much the same. If we were to start in 2009, when the next president takes office, we could potentially have the first powersat online sometime around 2018, with a total conversion to space solar by 2020 or so.

Obviously, this would require a much more ambitious schedule than President Bush’s planned return to the moon by 2020.

Of course, today $178 billion won’t buy what it did in 1975; inflation over 30 years alone will drive actual dollar outlays up considerably. But then again, electricity costs are higher as well; you won’t be selling the power for 1.5 cents/Kwh. And the market is world-wide, not just in the U.S. A 10 GW powersat, using current designs, will generate 87.5 terawatt-hours (TWh) of electricity per year, or 1750 TWh over its 20 year design life. At $0.22 per kWh (cost for electricity, UK, January 2006) a 10 GW powersat would generate $19.3 billion per year, or $386 billion over its lifetime, assuming no increase in the amount charged for electricity.

With all activity taking place off planet, environmental impact in the form of greenhouse gas emissions is minimal. There are no nuclear fuel issues to deal with. No unsightly windmills to mar the view or chop birds into tiny bits. No dams to impede the path of spawning salmon. The rectenna are quite large, to be sure, but they can be tucked away in desert areas where they don’t bother anyone. Even if located in more populated areas, they can be sited such that crops can be grown or cattle grazed beneath.
And sunlight is a “renewable” resource estimated to last for several billion years more at the very least.

For these reasons, and because $90/barrel oil is driving up the cost of energy significantly, space power satellites are once again being looked at seriously as a possible fix to the many energy and environmental problems facing us in the future. A proposal has been floated for setting up a small, demonstration project using a 1 MW powersat in a 300 mile orbit beaming power down to a 260 foot rectenna located on Helen Island, an uninhabited island belonging to the western Pacific nation of Palau.

Headed up by American entrepreneur Kevin Reed, the project is a long way from the grandiose visions of O’Neill and Heppenheimer. The amount of electricity generated would be enough to power 1,000 homes, and with a 300 mile orbit, the satellite would only be overhead for 5 minutes once every 90 minutes or so, necessitating some sort of long-term battery storage. And, being only 300 miles up instead of at geosynch, it will be in Earth’s shadow for half its orbit at which time it will generate no power. Still, as a proof of concept demonstrator, it would be groundbreaking, potentially heralding a whole new industry. And there is no reason why additional rectennas can’t be built along its flight path.

Reed’s joint U.S.-Swiss-German consortium to begin manufacturing the necessary solar components within two years, and hopes to attract financial support from manufacturers of the other necessary components – launch vehicles, satellites, transmission technology – eager to demonstrate how their technologies can support such a project. The estimated cost for the project is $800 million, with completion, if all goes well, as early as 2012.

Considering the potential profits to be made, one would think that there would be some venture capitalists somewhere who might be interested in backing the project. Perhaps some dot com millionaires who grew up with this stuff and might be interested in an investment in the future. Perhaps someone like Dennis Tito or Mark Shuttleworth, both who ponied up as much as $20 million to spend a week in space courtesy of the Russian space agency.

Or perhaps Elon Musk, who has worked in the past with Robert Zubrin on the Mars Direct project. Musk, a cofounder of PayPal, is also the CEO and CTO of SpaceX, a company that develops and manufactures space launch vehicles, which he also founded. He is also the principal owner and Chairman of the Board of Tesla Motors, a company which is attempting to build cost-effective electric automobiles for the mass market, as well as the primary investor and Chairman of the Board of SolarCity, a photovoltaics products and services startup company. His stated goal? To help combat global warming. Space solar applications would dovetail nicely with his goals and previous investments.

There are people who are interested in making all this happen. For more information, visit the websites of the National Space Society and the Space Studies Institute. They will get you started.

It’s raining soup out there; all we need is a bowl and a spoon! And the will to start, and complete the project.

Further information:

• Lagrange Points
• “Whatever happened to Solar Power Satellites?”, The Space Review, 30 Aug 2004
• “Bright Future for Solar Power Satellites”, Space.com, 17 Oct 2001
• “Solar Satellites Will Power Earth, Scientists Say”, Space.com, 8 Sep 2000

NOTES:
1 KiloWatt (KW) = 1000 Watts of power, or about enough energy to power a small home.
1 MegaWatt (MW) = 1000 KiloWatts of power
1 GigaWatt (GW) = 1000 MegaWatts of power
1 TeraWatt (TW) = 1000 GigaWatts of power, which is 1,000,000,000,000 watts - a very large number!
1 KWh = one KiloWatt of power expended for one hour of time.
1 TWh = one TeraWatt of power expended for one hour of time. 

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