[ExI] Fwd: [Extropolis] Solar Power Satellites

[Keith Henson]

---------- Forwarded message ---------
From: Keith Henson <hkeithhenson at gmail.com>
Date: Thu, Jun 15, 2023 at 8:41 AM
Subject: Re: [Extropolis] Solar Power Satellites
To: <extropolis at googlegroups.com>


On Thu, Jun 15, 2023 at 4:53 AM John Clark <johnkclark at gmail.com> wrote:
>
> On Wed, Jun 14, 2023 at 11:00 PM Keith Henson <hkeithhenson at gmail.com> wrote:
>
>> > It takes 64 days for a power satellite to repay the fuel needed to put it in orbit.
>>
>>
>> https://groups.google.com/g/power-satellite-economics/c/sL1zfrmHVqU
>
>
> Yes but the principal reason it costs so much to put something into geosynchronous orbit is not due to the high cost of rocket fuel, so I don't think that's the correct question to ask. I want to know something else.  By selling its electricity, how many centuries will it take to repay the bill for building and maintaining something larger than a supertanker and launching it into geosynchronous orbit?

That's not the way you do the accounting, but it takes about ten years.

I spent years working out the economics.

You can't charge much more than 3 cents per kWh to be competitive.
>From LCOE, the ratio between the cost of the power satellite and the
cost of the power is ~80,000 to one.  So the cost can't exceed
$2400/kW.  At 6.5 kg/kW, and $200/kg to GEO, the lift cost is

1300 transport to GEO
 900 parts
 200 rectenna
2400/kW total cost

It takes about ten years to repay the cost but the satellites should
last 20 to 50 years, maybe longer.

That's not really the problem with doing them.  If you want to replace
1/3 of the current energy and do it over 20 years, that takes around
25,000 starship flights a year.  At that flight range, damage to the
ozone needs to be considered.

I had NOAA work this out for the hydrogen-burning Skylon, but it needs
to be done again for LNG/LOX.

Keith

PS Details on construction and transport.

https://www.youtube.com/watch?v=VEkZkINrJaA


Keith

  I don't have a good answer to that question and I don't think
anybody else does either. When building something several thousand
times larger than anybody has before I don't think anybody can even
guess how much it will cost that will turn out to have been accurate
to within an order of magnitude.  But as I said, I'd love it if my
skepticism of Solar Power Satellites proved to be unfounded.
>
>   John K Clark
>>
>>
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