Thursday, April 16, 2009

Recommendation: Do a cost benefit analysis

There is going to be some EM waste energy dumped in the area of the receiving station for the Solaren's space based power generator. The antennas typically receive about 95% of the energy transmitted and they have a conversion efficiency of about 85%. The receiving station will be connected to PG&E's electrical grid* and its service area ranges from Eureka to Bakersfield in California. So it is possible that a portion of Fresno County will end up as a dump for the waste energy that will be used by the Fresno Metropolitan Area and/or other regions of the state. The major question is how the energy will be distributed? And will the benefits outweigh the costs?

*Edit: The power lines in west Fresno County run north-south along the I-5 corridor connecting to the Los Angeles and San Francisco areas and the rest of the electrical grid.

Problems with Space Based Power

Solaren which recently signed an agreement with PG&E to purchase power in 2017 is an upstart company with an address in Manhattan Beach, California. Their plans for space based power generation are certainly not finalized and they are still looking for a site for their facility.

The power levels that they are looking at are 200 megawatts with a receiving station covering a few square miles. Let's say 4 square miles or 10 million square meters. This would imply an energy density of about 20 watt per square meter of surface area. It will be a little higher perpendicular to the direction of the beam since it strikes the surface at an angle. By comparison the solar constant is 1,366 watts per square meter. They will probably claim that the power transfer is point to point rather than being broadcast but can they guarantee confinement of the beam to their property and not expose the public to risk on nearby highways and byways?

That raises the question of the right of free passage and who has the right of way. Will the facility create a hazard to navigation? Not just in the air but also in space? A space based facility may need international approval. It is not just the company's decision or California's decision. International boundaries are crossed and so the federal government will have to be involved.

With respect to geosynchronous orbit there may be no construction code in effect but the launches need to be approved. And there are concerns about geosynchronous orbit becoming overcrowded. So it is still a waiting game to see what happens.

Wednesday, April 15, 2009

Space Based Energy - Good Idea?

Space based power generation may have its advantages but the chief obstacle is getting the energy down to Earth safely. There is a trade-off between lowering the energy density of the beam and the size of the antenna structure needed to receive it. One also has to ask if the high power levels will produce unwanted electromagnetic "polution"? Will the power beam interfere with communications or the operation of electronics? Medical equipment and devices like pacemakers are particularly sensitive and require special attention. This is the sort of question that the US Federal Communications Commission considers before granting broadcast stations a license. It is one of the reasons for limiting the power of transmitters. The problems involved are the subject of international agreements. More than just the permission of the California Public Utilities Commission would probably be needed.

Monday, April 13, 2009

A Trivial Exchange

SCENE: A museum containing the persona of historical figures about 100 years in the future.

Fourier: "Mathematicians rule. My particular claim to fame is the discovery that periodic functions can be represented by a sum of sinusoidal functions."

Ptolemy: "Sire, I claim priority with epicycles."

Kepler: "I proved you wrong with my ellipses for the orbital motion of the planets."

Ptolemy: "Did you ever figure out the librations?"

Aristotle: "Don't I get credit for uniform circular motion?"

Archimedes: "Are not epicycles an assembly of cycloids?"

Riesz: "What Fourier did lacks rigor. If one compares the Fourier Transform of a continuous function with that of a similar function which differs only by the value at a particular point one will find that the two transforms are exactly identical."

Nyquist: "That's a rather trivial example. From the perspective of Sampling Theory the transform of the signal with noise should differ at the sampling frequency."

Armstrong: "Suppose you made the frequency of the noise signal a function of time as in FM modulation. The energy of the noise would be distributed over many frequencies and less noticable. So the transforms could be made practically indistinguishable."

Sire: "You scientists never fail to amuse me. Was not all this foreseen and communicated through the Laws of Nature?