Beamed Power

>
> Yeah? And? These power stations aren't THAT expensive. Few tens of
> millions or so. Maybe one hundred million.
>

And then some. They come in about $1 billion per gigawatt.

>
> Why do I have to do all your numbers for you? Shouldn't you
> do that bearing in mind you're making the claim that it makes
> sense?
>

Some references would suffice.

Also, I am not familiar with the strip antenna technology you described,
and am asking for some source data.

> Oh, well, lets assume an arbitrary 1kg/m^2. Sounds in the ballpark

I would rather have some real numbers. Anybody got any references ?

1 kg / m^2 for something only 1mm thick sounds high to me.
What material is it made from ? Aluminum ?

> (that would make it less than 1mm thick, but in space that's probably
> not totally out of the question.) Cost to GEO is about ~$10000 per kg.
>

Sure, could it be even less than 1 mm thick ?

> You need atleast 1km^2, that's 1 million m^2.
>
> Therefore one GEO transmitter would cost atleast 10 billion.
>

Good, that is one data point.

Now, let us look at the assumptions.

What is the thickness for the antenna material ?
If it were thinner, let us say like kitchen aluminum Foil.
I just measured some, it weighs in at 0.0475 kg per square metre,
thickness is unspecified,
looks like less than 0.1 mm

1 km^2 would be 10e6 m^2 = 47,500 kg

Cost to GEO from Earth surface about $ 475 million US.

Also, does it need to be solid Aluminum ? Can we use aluminized mylar
or Kapton ? A lot lighter.

Does it need to be solid surface ? Would a mesh be OK ?

===

If we get a bit more ambitious, 50 tons of Aluminum, well, we could
recover that from surplus rocket stages and Shuttle external tanks, and
avoid launch costs. We would need a space factory to process the
Aluminium and turn it into foil. That is starting to get more
expensive in capital cost, probably not what we would do for the first
one or two.

> You may need two in fact, one for receive, one for transmit. That

Yes, we need two at least.

> makes 20 billion. On top of that you need to stick some equipment

$ 1 billion US might suffice. For the space segment.

Ground segment would be a lot less.

> on the ground to receive the microwaves and distribute it. On top
> of that are the development costs.
>

How much for development ?

Some phased array analysis.
Materials research to figure how thin a material we can use.
Then we need to research the method of deployment/construction.
Other ?

Add another billion for the ground segment and R&D, actually it would
probably be less than half that.

> This for about a megawatt. i.e. not very much power
>

The O'Neil designs were for about 1 Gigawatt per square kilometre of
antenna.

So my numbers give about $ 1 billion or two per gigawatt.
In the same ball park as terrestrial power systems.

> >>For most normal sitations, the antennas are 10s or hundred of meters
> >>
> >
> > Please define "normal" situation, I am not surwe what you are referring
> > to.
>
> Like when you need to transmit more than tens of kilometers. Try looking
> at the equations sometime.
>

I am quite familiar with the equations, no need to labor that point.

Microwave telecom systems routinely go tens of kilometres, so that is a
good experience base.

>
> > So we agree that the safety risk from SPS sized microwave beams is
> > non-existent.
>
> No.
>

Now I am really confused.

You stated that SPS beams would be less intense than cell phones, ergo
less hazardous.

Or did you mean that cell phones may yet turn out to be hazardous ?

>
> > Do you think we can sell this as safe to the genral public ?
>
> Yes.
>

Well that is hopeful at least.

Cheers,

CR.