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Re: starship-design: Fuel costs

>>At 2:40 PM 9/2/96, Timothy van der Linden wrote:
>>>Kelly wrote:
>>>>Electricity costs about 4-10 cents per kilowatt hour.  If you could
>>>>the energy directly into antimatter.  Antimater would (at $0.05 a KwHour)
>>>>cost $1.25 E9 per kilogram.  Thats one and a quarter billion dollars a
>>>>kilo!  Given that an Explorer class ship has a mass of 500,000 tons.
>>>>comes to a fuel mass of 210,000 tons.  Half of which is anti-matter.
>>>>105,000,000 kg of anti-matter for a cost of roughly $130 E15  or about
>>>>thousand trillion dollars, or a bit under 100,000 times the federal
>>>>For comparison a Li-6 fueled fusion craft would take 4,570 times its dry
>>>>weight in fuel to get to half light speed.  For an Explorer class thats
>>>>2.23 E9 tons of lithium-6.  (Which is about 8% of the mass of a given
>>>>of mined Lithium.  Maybe we can seel back the other isotopes of lithium
>>>>after we remove the isotope we want?)  At current comercial rates (
>>>>at about $300/lb.  Or $660/Kg) for Lithium (ignoring procesing fees) that
>>>>tonage would cost about $1,470 Trillion dollars, or 1 thousand times the
>>>>federal budget.  Nearly a hundred fold improvement.  8(
>>>This is still "raw" energy, the processing costs needed for normal
>>>electrical energy are now inside the design of the starship. I think your
>>>comparison should include the power plants (and the maintaining of them)
>>>inside the starship.
>>But the power plants arn't in the starship, or to be carried with it.  They
>>will be at the supposed anti-mater production platform (way out in the
>>outer solar system).

> I meant this for the Explorer design that uses the fusion fuel and thus may
> need a kind of powerplant. I understand that any (non-beamed) starship is
> some powerplant, however some fuels are easier to "ignite" than others (and
> have lighter engines).

> What you should have mentioned in the previous letter is that for fusion
> powered ships one needs only one powerplant (the one in the ship) while for
> anti-matter powered ships one needs two powerplants (one in the ship and
> "on the ground").

> What I am not so sure about is the difference in design, fusing fuel may
> need much more heavy equipment than "burning" anti-matter. However maybe it
> is the otherway around, only the future will tell. Therefore making
> comparisons like the above have little or no value.

> Timothy

Well with the explorer class I did make some estimates about the engines
thrust and weight (if we aren't going to try to do that, were not trying to
figure out starships), as to the relative weight of an Antimater drive vrs a
fusion on (and the unidentified weight of the antimater tanks!!) I can't
realy guess, though for the purpose of the post I assumed (for no good
reason) that they might be about the same.