Re: beanstalks (was Re: Metallic hydrogen ...)

From: Henry Spencer (henry_at_spsystems.net)
Date: 06/10/04 

Date: Thu, 10 Jun 2004 04:03:27 GMT

In article <ca8hkc$gd1$1@panix2.panix.com>,
James Nicoll <jdnicoll@panix.com> wrote:
>>...The only fundamental limit is that you need $3-4 worth of LOX
>>plus a cheap hydrocarbon (kerosene, propane, whatever) to get a kilogram
>>of dry mass into orbit...
>
> I was looking at Ultimate Rockets (Rockets so advanced that
>the main cost is fuel) last year. As far as I could tell, LOX is
>cheap ($0.10/kg)...

Even that number is rather too high; it would be more like $0.02/kg if you
were using it in sufficient bulk to justify your own LOX plant. The raw
material, after all, is air...

>...and H is expensive ($3.60/kg). In a lot of the
>systems the H2 was -the- cost-defining expendible material used.

Yes, liquid hydrogen is fairly costly, not least because it's made from
petroleum... (And the manufacturing process releases quite a bit of CO2
into the air, too.)

> For some reason I never got around to pricing standard fuels
>like kerosene.

Yes, that makes a big difference.

> In any case, I don't think you will use up $3-4 worth of LOX
>per kg of dry mass. Maybe of payload...

Even with hydrocarbons, the fuel pretty much dominates the cost. LOX in
bulk is almost free by comparison. 

-- 
"Think outside the box -- the box isn't our friend."    |   Henry Spencer
                                -- George Herbert       | henry@spsystems.net

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