[ExI] EP and Peak oil.

[hkhenson]

At 09:29 AM 4/7/2008, John K Clark wrote:
>"hkhenson" <hkhenson at rogers.com>
>
> > It [the magnetic force between wires] would
> > be .2 N/m for 1000 amps
>
>Perhaps I'm missing something but I don't understand your point.

You did.  This was for a highly optimistic voltage and *one* GW.  The 
force I noted goes up as the square of the current.  Plug in 1000 GW 
which is the production of about 3 years of power sats and try 
again.  You can also reduce the voltage to a more reasonable number.

There is an additional problem.  If a space elevator/tether is cut it 
falls along the equator.  Not a hazard on the ground since the 
terminal velocity of the cables is no higher than rope of a similar 
low density.  But it's a major problem in space because it whacks at 
high speed into other elevators/tethers if there are any.  Bringing 
down hundreds of power leads from GEO is just inviting a catastrophe.

Still another problem, high vacuum and air good insulators, but low 
pressure gas is not, and these wires transit a lot of low pressure 
gas.  Any ideas for really lightweight solution?  If you *really* 
have something against microwaves, bringing power down 
mechanically  like the elevator sends it up might be the best solution.

>One Newton is the force of earth's gravity on an object with a mass
>of 102 g, so we're talking about a force of 20 grams per meter.
>A meter long toothpick wade of WOOD inserted ever meter to act as
>a spacer to keep the wires the proper distance apart would be far
>stronger than necessary.

You also missed that the force is in tension.  Shut off the power and 
the wires are going to move toward each other.  Unless you do have 
close spacers that also work in compression to keep them apart, the 
conductors are going to hit and stick in the vacuum.  Be an 
interesting task to bring them back into service.

> > about 7.14 million N going to GEO.
>
>That's tiny!

It's 1/5 the lift off thrust of a Saturn 5, and it's applied in a way 
which is massively multiplied into tension on the conductors.

Keith