Adrian Tymes wingcat at pacbell.net
Fri Jul 9 16:45:10 UTC 2010

Actually, check

Current US price for electricity is around 11 cents/kWh.
Granted, that's including taxes et al - but it's not
much better (and often worse) elsewhere, where that
isn't included.

If you could accept 10 cents/kWh - merely competitive
with today's prices (and better than rising prices - an
insulator against current trends, which may be enough
for a 10 year payback), that's an additional $6400/kW,
or almost $1300/kg given your numbers.  $1400/kg to GEO
is still a bit of an improvement on today's numbers,
but not quite as far as $100/kg.

--- On Thu, 7/8/10, Keith Henson <hkeithhenson at gmail.com> wrote:
> From: Keith Henson <hkeithhenson at gmail.com>
> > 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).
> Though people have been more optimistic, the general
> consensus is that
> 5kg/kWh is reasonable.  so if parts and ground
> rectenna cost $1100/kW,
> then the transport cost can't be more than $100/kg. 
> 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.
> > 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.

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