What's wrong with this idea?

Hi Tango,
Just a few comments, I hope that at least one or two will be helpful....

spacesettlers@yahoogroups.com wrote:

> 1. What's wrong with this idea?
> From: "victoriatangoman"
>
>Message: 1
> Date: Sat, 14 Sep 2002 23:26:05 -0000
> From: "victoriatangoman"
>Subject: What's wrong with this idea?
>
>Usually, when we read of the SPS scenario, there is a SPS and a
>dedicated rectenna farm.
>
>To me, such a scenario negates two of the advantages of GSO, namely
>the wide footprint into which a SPS can beam power and the never
>varying power output of the SPS.
>

I am afraid that I don't really understand your concerns here; of
course a rectenna will be required to receive the microwaves the SPS
produces - are you concerned about the initial costs of the rectennas?
Or worried about some aspect of the feasibilty of a dedicated rectenna
facility? Also is GSO Geo-Synchronous Orbit (also called GEO
Geostationary Earth Orbit)? If so, how is the unvarying output of the
SPS a problem? Is it scheduling of power delivery that you are
concerned with - what do you do with the excess power? As I said, I am
just a little confused, please be more explicit.

>To me these limations present three different scenarios for
>increased efficiency. What are the flaws of logic or engineering
>that I may be overlooking in the descriptions below?
>
>1.) A SPS for a city is designed for below peak power rating, and
>the neighboring SPS, which would be offset by perhaps a few
>timezones, can supplement with additional power to meet the peak
>power rating. Necessary premise: Peak power demand will ebb in the
>city providing supplemental power while it is rising in the city in
>need of the power. I also, realize that the microwaves coming in
>from the SPS a few time zones away will be coming in at an acute
>angle, and thus not be as concentrated. And this might also cause
>havoc with issues like restricted airspace.
>
Using one SPS to take up the slack where another fails to deliver
enough power is a very real possibility; in fact I think there is
already a power transmission satellite in orbit - reflecting microwaves
transmitted from Earth to other points on Earth. On a related note, my
own (admittedly inexpert) understanding of SPS systems is that there are
two schools of thought on beam reception: a narrow and high energy
density beam, or a wider beam with lower energy density.
The high density option allows there to be small dedicated
facilities where the energy is converted into electricity, and put onto
a distribution grid like any other powerplant. This has some advantages
- very little of your energy is wasted 'off target', the existing grids
and billing systems can be used, and the receiving facility can be made
small (and so perhaps cheaper, at least in so far as the materials
required to BUILD the rectennas) and located in a remote area if so
desired. The down sides of the high density beam have to do with its
detrimental effects on those things which are not rectennas - what about
birds, or just missing the target? What could you do to prevent the use
of the SPS as a doomsday space weapon?
The low power density option does away with many safety concerns by
making basking in the beam harmless; sure you get warm, but microwaves
are NOT ionizing radiation - and generally contain less energy than
infra-red light. The low density beam has its own problems though; the
beam has a large footprint, and so requires a large (potentially
expensive) area of rectennas; plus losses to water vapor in the
atmosphere may be higher. If the rectennas are simply built into the
roofing materials of the customer area, then perhaps they could be made
available cheaper, and eventually the whole area could be brought
on-line piecemeal for lower cost than a huge dedicated facility - but
how do you charge for the power? Or distribute it to clients with high
requirements? Also, doing this wastes some (potentially much) of the
energy in the beam by sending it off target - if you are blanketing the
entire San Francisco (for example) area with your transmission, some of
your signal is going to hit the ground.
My personal vision here sees some hope in those schemes where the
utility companies buy the excess electricity from the building owner -
they still maintain their own grid, and sell fuel generated power to
high requirement or peak time customers, but they are spared
considerable stress on the grid by the distributed delivery of power by
the SPS. Needless to say, the arrangement between building (rectenna)
owner and the SPS owner need work.

>2.) A super-sized SPS, with multiple transmitter arrays, serving
>multiple rectenna farms in a narrow longitudinal band. This could
>provide power balancing between different utilities. Also by
>extending this concept to a larger scale, could a Super-Size SPS
>serve multiple utilities across the hemispherical line, thus
>providing power to summer peak loads while the other hemispehre is
>experiencing winter?
>
Again, rectenna 'farms' (large, dedicated facilities) may or may not
exist; but I don't believe there is a technical barrier to serving
multiple areas sequentially (or even simultaneously, provided they are
few and large enough). About serving opposite hemispheres though, your
earlier point about a highly acute beam angle (with respect to the
ground) being a problem (which is true enough) may factor in; at some
point it may be easier just to put another SPS or even a constellation
of 'relay' satellites.

>3.) A transfer of microwave power to and from multiple orbiting SPS
>in order to take power where it is needed. This prevents designing
>SPS capacity for peak power load. Thus, a SPS orbiting above a
>longitude in the night, can beam a portion of its power across
>space, perhaps relayed by other SPSs, to a SPS above a daylight
>longitude. This SPS would receive the microwaves, phase them into
>its own transmission and beam them down to the rectenna. What effect
>would the microwaves have on the communication satellites KU band
>signals? Such a lateral transfer of microwaves would cut a swath
>through all of the uplink-downlink paths.
>
Relaying energy from one SPS to another should present few
difficulties; and the idea of using one SPS to cover for another is
appealing. Hmm... actually - wouldn't the transfer between SPSs use
high density beams? Wouldn't this create some of the same safety
concerns as transmitting a high density beam to Earth? Also, I am not
sure that it would be practical to design the SPS to deliver energy to
satisfy peak demand - you've got to pay for every gram of the SPS, and
the extra (up-to-peak) capacity which (by definition) cannot sell its
energy off-peak may not be worth the extra cost. On the optimistic
side, an SPS might make sufficient money without meeting peak demand...
The effects on the Ku (and other) band(s) should be minimal; while
the microwave beam from an SPS could probably fry an average
communications satellite very quickly, this shouldn't be a problem
because the SPS isn't being pointed at them. Remember -
electro-magnetic radiation doesn't interfere with itself casually; just
crossing beams won't do it.

>Thanks for your help in troubleshooting this idea.
>
You're welcome - I just hope some of it was useful.

Joe.