Proposal: Power Generation Teams

[dragoon500ly]

Power, can’t live without it!

One of the staples of science fiction is the Solar Power Satellite (SPS) that orbits the earth, absorbing power from the sun and then beaming to receivers on Earth. It’s an interesting concept for the Project as there would be a need for energy at levels beyond what the fusion power packs can provide. So here is a little background…

In 1968, a Czech-born physicist/engineer named Peter Glaser posted a brief article on this topic in the November 1968 issue of the journal Science. He would later be awarded a patent in 1973 for this concept. NASA and the Department of Energy (DOE) would later begin a four-year, $19.6 million study of the concept of a Solar Power Satellite.

Glaser had noticed that a satellite in geosynchronous Earth orbit, 35,786 kilometers above the equator, would pass through Earth's shadow for only a few minutes each year. In this orbit, the satellite would move at the same speed as the Earth’s rotation (1,690 kph). This would result in that for a person on the Earth’s surface, the satellite would appear to remain in the same spot over the equator. Allowing for the possibility of electricity to be ‘beamed’ from the satellite to a ground-based receiver.

Glaser’s theory was that the electricity would be converted into microwaves and be beamed to a receiving antenna (rectenna) on Earth where it would be converted back into electricity and then distributed to the power utility grid.
With the satellite positioned over the equator and moving at the same speed as the planet’s rotation, it would generate power for roughly half the day and then sit dormant during the night period.

But there is just one problem, for the SPS to contribute a meaningful amount of power. It has to be big, as in colossal. In order to generate five gigawatts of power, with modern technology, a SPS would measure 10.5 kilometers long by 5.2 kilometers wide and would mass over 50,000 metric tons.

The rectenna would measure in the area of two kilometers or so across. To meet just the electrical needs of the U.S. at current levels, would require 60 SPS generating some 300 gigawatts of power.

There is also the problem of building the SPS. Due to their size, they have to be constructed in orbit and this requires transport.

To give an idea of the scale, considered this, the largest single-launch U.S. payload ever put into low earth orbit (LEO) was the 77 tons of the Skylab Orbital Workshop, which was launched using a two stage, Saturn V rocket. To reach GEO would require a three stage Saturn V rocket, with a gross liftoff weight of 3,000 metric tons. The Space Shuttle has a gross liftoff weight of 2,040 metric tons. In order to achieve the necessary cargo space, a vehicle (Space Freighter) would have to be designed with a gross liftoff weight of 11,000 metric tons.

Ouch!

Another construction method is to build a ‘dockyard’ in LEO and then tow the completed SPS into GEO. The best NASA estimates would see two SPS being lifted into LEO each year. EACH SPS would require about 200 Space Freighter launches as well as hundreds of OTV transfers between the dockyard and GEO. The additional propellants for each would demand even more Space Freighter launches.

Despite extensive reliance on automation, NASA/DOE estimated that at least 1,000 astronauts would have to be in space at all times. Then there is the support staff, which could, conservatively outnumber the astronauts by at least 10 to one.

Now this material is pulled from the original study, but based on what I’m seeing so far, SPS are a non-starter as far as the Project goes, after all we are talking a major space project just to get several fairly large satellites into orbit, stating that security would be impossible would be an understatement!
This leaves us with two possibilities for a Power Generation Team, multi-fuel generators, coupled with an almost impossible logistical chain (the large generators can average a fuel usage of 5,000 gallons per day!). Or extensive use of fusion power plants.

Another problem would be the MASSIVE scale of hardware to support a Power Team, think of the tens of thousands of feet of cable, transformers, etc to power a small town.


Thoughts?