[ExI] The L5 Society ( was: EP and Peak oil.)

Keith Henson hkeithhenson at gmail.com
Thu Apr 10 06:43:03 UTC 2008

On Wed, Apr 9, 2008 at 10:37 AM, John K Clark <jonkc at att.net> wrote:
> "hkhenson" <hkhenson at rogers.com>

>  OK, so forget rubber, let's try something that can do a little bit better
>  than 500 volts/mil, something like Fused Quartz, it can do
>  5 x 107 volts/mil. Yes Quartz is about twice as dense as rubber,
>  but even so that should reduce the weight by a factor of 50,000 or so.

Can you cite the source for this remarkable number?

>  And I'm not saying a space elevator will ever be built, I'm just saying
>  that if one can be made then there is no reason not to use it to carry
>  power lines.

Long as you need power near the equator and the loses in 22,000 miles
of wires are not more than microwave transmission.

>  > He  might have been willing to consider Peter's fantastic vision
>  >[power satellites] , but Gerry [O'Neill] had shown that another
> > fantasy, lunar industrialization, was a  prerequisite.
>  It currently costs about $20,000 to put one kilogram into geosynchronous
>  orbit, and no I can't give you a number, I don't know how much a power
>  satellite would weigh except that it would be many many kilograms.

Easy to look up.  I am using 2kg/kW which works out to 10,000 metric
tons for 5 GW.

>  It
>  seems to me that for the idea to be practical a dramatically cheaper way
>  needs to be found to put massive things in that orbit, and the only two
>  ways I know of are space elevators or lunar industrialization. If neither
>  of those can work then power satellites are Dead On Arrival.

I just finished working out the numbers for using 200 times reusable
rockets about twice the size of a Saturn V.  To my surprise the energy
payback works out to 15 days and it takes 3 power sats to provide the
propellants.  Now if we can get the cost of the rockets down to a
reasonable number that might work.  Incidentally, the best guess for
the space elevator is only a dollar a kg for lift energy, but a
hundred dollars a kg for capital cost.

I have not yet worked out the numbers for laser launch.

>  You would know better than me but I was under the (perhaps incorrect)
>  impression that the L5 society was set up to promote ideas like O'Neill's.

You are exactly correct.

>  And by the way you never should have changed the name, the L5 society
>  sounded cool.

It wasn't my idea.

Keith Henson

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