[ExI] SpaceX Super Heavy and Space Solar

[Adrian Tymes]

On Sun, Oct 20, 2024 at 5:00 PM Keith Henson via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

> On Sun, Oct 20, 2024 at 1:28 PM Kelly Anderson via extropy-chat
> <extropy-chat at lists.extropy.org> wrote:
> >
> > Has anyone run the numbers on whether space based solar makes sense yet
> if the Super Heavy keeps some of its economic promises?
>
> Yes.
>
> 100 tons is 100,000 kg. If a flight gets down to even $10 million,
> that's $100/kg to LEO, double that to GEO with electric propulsion.
> 6.5 kg/kW is a reasonable number, so $1300/kW for transport, $900/kW
> for parts and labor, plus $200/kW for the rectenna.  That adds up to
> $2400/kW.  Divide by 80,000 to get 3 cents per kWh.
>
> Looks good from energy return time, takes about 66 days to pay back
> the fuel energy used to lift it to orbit.
>
> The problem is that it takes 500 flights to build one.  A reasonable
> construction rate of 50 a year would take 20 years to replace 1/3rd of
> current consumption. I don't know if the atmospheric damage of 25,000
> flights per year would be acceptable, but NOAA could answer that
> question if asked.
>
> The money through this program is $600 B/year.
>

Needing that much money up front, 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, even at significantly lower economic efficiency ($0.10-0.50
per kWh, perhaps).

You may see such a prototype as "wasteful" or "wasted", and in the long run
it would become obsolete.  It is a necessary expendable, in a sense, to get
the program started.

In that light, what are the numbers for a prototype that could be built
with just one Super Heavy?  The $/kWh will be worse, but you have an
absolute maximum to LEO of 100 tons.
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