[ExI] SpaceX Super Heavy and Space Solar

[Keith Henson]

On Mon, Oct 21, 2024 at 1:25 PM Adrian Tymes via extropy-chat
<extropy-chat at lists.extropy.org> wrote:
>
> On Mon, Oct 21, 2024 at 3:44 PM Keith Henson <hkeithhenson at gmail.com> wrote:
>>
>> On Sun, Oct 20, 2024 at 4:12 PM Adrian Tymes via extropy-chat
>> <extropy-chat at lists.extropy.org> wrote:
>>
>> > before the program is generating revenue, makes it economically infeasible.  No one with the requisite finances will believe that heavily in the revenue until after a small scale prototype is demonstrating,
>>
>> You can't scale a power satellite down for beans.  It is a feature of
>> microwave optics (diffraction).
>
>
> You can.  It may be substantially less efficient, but it does work - at all - at smaller volumes.

Adrian, if you can beat this problem, you will get nothing but praise
from me. I worked on power satellites for ten years and made no
progress on the scale-down problem whatsoever.

>> > even at significantly lower economic efficiency ($0.10-0.50 per kWh, perhaps).
>>
>> That would just kill the idea.
>
> How does the existence of limited markets that can pay higher amounts for the same service kill the idea?

Let's put numbers on this.  What power level is a limited market?

  "Not being able to deploy the same rate to the general market" is
not an answer: at most, you just ignore those limited markets, but I'm
saying there is a way for a beginning, not-yet-as-efficient service to
take advantage of these markets.
>
>>
>> The rectenna is going to cost the same, a billion
>>
>> bucks.
>
>
> I can build a rectenna for less than $100.  Not $100B, but $100.
>
> It's a tiny little thing that might not even handle a kW.  But it would handle 1 W, and cost less than a billion bucks.

I have held such things, Paul Jaffe made them maybe ten years ago.
But a one km power beam from GEO at 2.45 GHz spreads out to 10 by 14
km.  The center beam power density for 5 GW is 230 W/m^2,  Our
imaginary one rocket power sat would supply about .46 W/m^2.  How much
power do you propose to supply?

> Likewise, ordinary satellite antennas receive far-smaller-than-power grade "beamed power" from orbit all the time, and very few if any cost a billion dollars.
>
> Your assertion that any rectenna, regardless of the power level involved, will cost a billion bucks is blatantly false.

It's $200/kW.  I worked this out 10-15 years ago. It is fine if you
don't like my number. What do you calculate as a rectenna cost?

> Likewise, your assertion that it is impossible to scale down a power satellite because of physics is questionable at best.  They don't scale down very well, but "not for beans" and "literally impossible" are quite distinct.

I agree.  We get power, a miniscule amount, from the communication
satellites.  Great for communication, useless for power.

> You would be well served to toss out these notions of "impossible" and "can never under any possible circumstances be economical", and instead to actually present numbers.

I know the numbers.  What do you want to know?  Of course, you need to
ask what purpose a power satellite s for.

> For instance, https://www.electricchoice.com/electricity-prices-by-state/ shows that current electricity rates in Hawaii is above $0.30/kWh and has been for over a year.

Consider the spread between generation cost and retail.  Most of what
we pay in CA is for distribution.

> That is to say: a system that could serve all of Hawaii's needs and charge $0.30/kWh would, right now, be commercially competitive.  Other sources say that Hawaii's electricity consumption is a few TWh/year.
>
> So, downsize a rectenna to just Hawaii's needs.  This is not the exact same billion dollar rectenna that would be used for larger projects.  (It very much wouldn't, unless Hawaii's power grid gets grid-tied to anywhere else.  That it isn't is part of why electricity costs so much there.)

I have seen an analysis.  Don't remember the details, but we could
regenerate them right here.
https://en.wikipedia.org/wiki/List_of_power_stations_in_Hawaii

Installed capacity is right at 3 GW and an average of around 1.07 GW.
So whatever cost you get from the capital cost will only be generating
revenue about 1/3rd of the time unless you can generate another
market.  Fairly soon you need to ask where do you put the rectenna.

Continue?

Keith

> Unless you still maintain that the mere existence of a market that would pay $0.30/kWh would kill all solar power satellites forever?  Because if so - and a literal reading of your words says that you are in fact making that claim - then the existence of Hawaii's power market says solar power satellites can never work, according to your logic.  We can assume, with good enough probability, that Hawaii will continue to be inhabited and continue to need power for many decades to come, and with only slightly lower probability that its power rates will continue to be substantially higher than most of the continental US's.
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