[ExI] Could Thorium solve our energy problem?

[samantha]

Keith Henson wrote:
> On Thu, Jul 8, 2010 at 6:02 PM,  samantha <sjatkins at mac.com> wrote:
>
> [sorry for not fixing the subject on the previous reply]
>
>   
>> I agree that this is a much more immediate energy solution than space
>> based solar, at least SBSP of any design I am familiar with.  The first
>> problem with SBSP is the huge mass all the mirrors and collectors
>> represent and the high cost of launch.
>>     
>
> To put numbers on it, for two cent power and a ten year payback, the
> cost limit is around $1600/kW  (80,000 hr at 2 cents per kWh).
>   
What do you mean by "two cent power"?  
> Though people have been more optimistic, the general consensus is that
> 5kg/kWh is reasonable.
Can you point me to the work?  Does it add in a precentage of all 
components? 

>   so if parts and ground rectenna cost $1100/kW,
> then the transport cost can't be more than $100/kg.
Ah, thanks.

>   That's a 200 to
> one reduction from current cost.  It's doable (I think) with something
> like a Skylon to the point you run out of atmosphere and laser heated
> hydrogen from there on up to LEO and a second stage also using laser
> heated hydrogen from LEO to GEO.  It does take some $60 B of lasers.
>   

Or perhaps using on of the other non-rocket space launch methods.   Are 
the $60B of lasers amortized into the cost?
>   
>> The second is that you have no
>> way to do all the assembly and maintenance required at GEO.  Doing it
>> with astronauts is a non-starter.  We would need a lot better space
>> robotics than we have.
>>     
>
> Not actually.  Supporting 1000 people at GEO to do assembly takes
> around 1% of the mass flow to build power satellites.  But it doesn't
> matter.
>   
Why doesn't it matter?  It cost a lot more than mere mass to support 
astronauts working at GEO.  We don't do much of that now.   Not to 
mention I doubt we have 1000 suitably trained astronauts.

- samantha

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