Digest Number 550

>
>Message: 2
> Date: Wed, 18 Sep 2002 20:25:41 -0000
> From: "victoriatangoman"
>Subject: Re: What's wrong with this idea?
>
>Just a small point: the electricity markets do exist, it's just that
>the SPS production capacity doesn't exist. Right now, today, if you
>could deliver electricity at the wholesale cost of 2-3 cents/kWh
>you'd find buyers. In some locations, Europe, and most especially
>Japan, you could probably charge even more.
>
>Using your figures below, if you had a 5 GW SPS, then it could
>deliver a revenue stream of (at $.03/kWh) $1,314,000,000 per year.
>If you capitalized that revenue stream in order to determine a value
>for the sale of the entire SPS, well I'm preparing a very detailed
>financial analysis for a later posting, but let's just say, that you
>could probably realize a lot more than typical earth powerplants,
>which go for about $1/watt. But these plants also incur fuel costs
>in order to meet the 2-3 cents/kWh price target. So, a worst case
>price scenario would be $5 billion.
>
>Don't ask me how much to build the damn thing. Probably much more
>than you could sell it for! According to O'Neill's estimates, 5 GW
>of capacity in orbit, would require a mass of 5,000,000 kg. WE're
>not going to launch that!
>
>But I digress.
>
Good points though - I've never seen figures for Earth-based powerplants
before, but if US$1.00 per watt is accurate then perhaps the SPS
scenario is rosier than I had imagined. Also, I think I am paying
US$0.06 per kilowatt hour currently (no pun intended).

>>but lets take a stab at estimating the size of an SPS....
>>
[Snip]

>>This works out to a square of about 1494 meters to a
>>side, and a 5 gigawatt facility to a square of about 3340 meters to a
>>side. As you have pointed out, with sufficient focussing technology the
>>beams between SPSs could experience little beam spreading - how big a
>>rectenna would we really need to recieve an incoming beam from another SPS
>>120,000 km away?
>>
>I don't claim to have the answers, but I sure like to ask the
>questions. I thought that there would be no beam spreading due to
>atmospheric conditions.
>
Not due to atmospheric conditions, but our focusing tech isn't perfect -
the beam will have a larger cross section when it arrives at its
destination than when it was initially transmitted. Just to pull a
rough (and hearsay) and not terribly parallel example out of my ass
here... we monitor the Terra - Luna distance regularly with sets of
special (I think the actual term is 'Retrograde') reflectors left on the
surface of Luna during the Apollo missions. The laser from Terra, when
it arrives, is tens of meters across.

> Further, energy density could be increased. Further still, if laser was used, the beam could be tighter, and
>perhaps more energy dense. But in the end, I can't answer your question.
>
I understand, I am just a little frustrated that we seem to be the
entirety of Space-Settlers interested expertise. I don't feel
comfortable with even the solutions I have advanced - I don't feel they
have been examined rigourously enough - and my expertise in this area
(especially the physics, though I did get a pretty good grade in the
optics section of the university physics class I had in 1993) is
completely inadequate to my mind. Ideally, I'd like someone with a few
years of experience in broadcasting tech, or a phD in physics, or
Electrical Engineering expertise, to weigh in on some of the numbers we
have bandied about; or to provide a more thorough analysis than I can do.

And as an aside, if you wish to confine yourself to 10 watts per square
meter then the minimum size of a receiving rectenna on another SPS
should be calculable. For a 5 GW beam, 500 million square meters of
rectenna would be necessary - this works out to a square about 22361
meters to a side. This is considerably larger than the proposed solar
array, but it could be made much smaller if you decided to go with a
higher density beam; a beam sending 1600 watts per meter (about as
intense as sunlight) would cut the size to just 3.125 million square
meters (1768 m per side) which is smaller than the solar arrays; though
perhaps a reflector would be superior (avoids the convert - store -
reconvert - transmit inefficiencies).

>>>No, I'm not concerned about the cost of rectennas. In the greater
>>>scheme of things, they'll probably be the least expensive
>>>component of the SPS system.
>>>
>> Maybe - rectennas seem pretty cheap to build; but remember any
>>Terran facility requires maintenance. And a dedicated rectenna
>>farm (emphasis added to highlight the idea that perhaps the rectenna
>>facility could be built to be multi-purpose, or simply added to an existing
>>facility) has to be built on land somewhere - and land can be
>>expensive, as can permits to use the land.
>>
>Many of the suggestions to date have focused on leasing rectenna
>space from farmers, who could still do their thing under the mesh. I
>can't think of a more ideal solution to this issue. Better and
>cheaper than trying to lease rooftops in a city. Farms can be 100%
>covered, while cities will always have streets that can't be
>covered.
>
True enough, but sending the power directly to the city cuts
transmission inefficiencies associated with high tension lines. The
only other issue I would worry about is idiot lobbyists trying to get
'Irradiated' meat labelled, or seperated, or marked unsafe for human
consumption, or some other such thinly veilled protectionist shit. In
such cases it may be more economic to just some power to the wires and
bring the energy in from the surrounding countryside. I do like the
farm idea though, quite a bit.

>See my message #1999 for other interesting tidbits. Selected quotes
>follow.
>
>BILL WOULD BAN SPACE-BASED MIND CONTROL WEAPONS
>
[Snip]

>http://www.fas.org/sgp/congress/2001/hr2977.html
>The Kucinich bill was hailed by Citizens Against Human Rights Abuse,
>one of a number of organizations of people who say they are victims
>of government experimentation involving electromagnetic and other
>psychotronic weapons. See their web site here:
>
>http://www.dcn.davis.ca.us/~welsh/
>The bill has been referred to three House Committees.
>
Not to sound paranoid, but the latest fad in weapons research here in
the US is 'Non-Lethal' weaponry - and it is amazing what sorts of odd
effects you can get - with oh, sound, for instance. The members of
congress (or at least a significant subset of them) are privy to some of
the data from the DoD research programs - if some of them are concerned
with regulating mind-influencing 'weapons', then perhaps there is more
going on than we can see from here. The CAHRA concerns sound a bit like
the drivel you get from the inevitable raving loonies.

>Now imagine if you told this group that you were going to beam
>microwaves down onto their heads. Wasn't there a movie a few
>decades ago called scanners, where some guys with ESP would blow up
>your head? I could just see the pandemonium that would ensue. No,
>better to deal with the cows and chickens and wheat. Heck, we could
>even tell people that they'll get roasted beef and chicken in the
>supermarkets. No more having to cook their food, it's done by
>microwaves from space
>
Ok, we can laugh at the kooks; but remember those masses who might be
enthusiastic about cheap (SPS) energy and smile at the 'roast beef' bit
are the same ones who'll be coming after you with torches and pitchforks
if the propaganda spins against you. This is one of the reasons that a
decent economic and safety model needs to be practically bulletproof
here in the US; if the vested energy interests get their money behind an
anti-SPS mis-information campaign the project (regardless of merit) is
finished. It's not enough to find an economic way to build it, or a
cheap, safe way to down-port the energy - the idea also has to go to one
of the major energy 'big-boys'. If you fail to sell one (or several) of
them on the idea, they may decide to squash it like a bug, just to keep
any competitors from taking advantage of it. Enter the lobbyists.

>>Here in the US, (God Bless America,
>>
>>Land of the Lawsuit!) and California especially, getting
>>permission to put up a rectenna facility may meet considerable - and expensive -
>>resistance.
>>
>Expensive compared to what? The regulatory process can't be avoided.
>Rectenna's will probably be a whole lot cheaper to permit than a
>polluting power plant.
>
Expensive in comparison to existing Terra-based energy producing
technologies; you yourself admitted that the cost to construct a 5 GW
SPS would be considerably more than its potential sale price of US$5
Billion. If the project is big-ticket already, it could be made
completely uneconomical by just one or two carefully crafted class
action lawsuits - imagine being liable for all of the cancer related
medical expenses of the customer population.... No company in their
investors right minds would consider building an SPS under such
circumstances, but even something that extreme is unnecessary - if
legislation makes an SPS more expensive per watt than Terra-based
powerplants, then the project is dead.

>>Oh yeah - if the rectenna farms are considered a hazard to
>>
>>people and wildlife, and have to be located in remote locations
>>where mishaps with improperly targetted beams will be least damaging,
>>then add the cost of building roads to the new location, improving the land
>>to a usable state, and then patching the facility into the grid - with
>>attendant transmission losses for sending the power through the
>>extra kilometers of wire.
>>
>Yes, but all within the economics of the project, especially
>considering the cost incurred in orbit. Look at what they did in
>Brazil www.itaipu.gov.br (thanks for the site, Lucio) to get some
>power and it made economic sense.
>
Did it? What is the price per kilowatt hour in those markets? How much
did the Itaipu dam cost? Is it paid for yet? What sort of interest did
they pay on the loans they used to build it? Or is it subsidized by
governmental spending? It IS a great mega-engineering project, but was
it really penny-wise - or was it a international prestige / foreign
relations victory?

[Snip]

>>>My first concerns were about the constant, never ceasing exposure
>>>of humans to the microwaves. What health issues may derive from such
>>>exposure?
>>>
>> Surprisingly few. I feel a little more confident here because
>>I did a little graduate level research in molecular biology, and the lab
>>I was in handlesd a few radioisotopes. The three criteria to concern
>>yourself with where ratiation damage to biological systems is involved are:
>>Ionizing radiation, which Penetrates the body, above a critical
>>Threshold level. First. microwaves are not ionizing radiation -
>>an individual microwave contains less energy than even far infra-red
>>radiation, which itself has much (orders of magnitude?) less than
>>UV light, which has less than X-rays, etc. A quick look at a chart
>>of the Electro-magnetic spectrum should put your mind at ease. Secondly -
>>
>>penetration is a bit of problem, but not much of one; microwaves
>>are absorbed by water molecules, so microwaves may penetrate a few
>>centimeters into the body, but most of them will expend their
>>energy in the outermost cm or two of the body. Lastly, the threshold level -
>>10 watts / meter is certainly less radiation than you get from solar
>>radiation every day; it certainly seems reasonable to postulate
>>that the human bodys' tolerance for non-ionizing EM radiation is much
>>higher than 10 w/m.
>>
>Terrific. That's good information to have. Thanks.
>
You are most welcome. Actually let me retract the second point - I am
uncomfortable with it, and it is unnecessary to the safety issues in any
event.

[Snip]

More later,

Joe.