Solar power sats without colonies...

What of the cost of the ground based receiving station?

The operation and maintanence staffing of that facility also is part of the equation...

Now as for the LEO orbit, I've given this a little thought (stress LITTLE). LEO orbit for SPS is, basically, useless.

We now have thin film photoelectic materials. From what I have read we will soon have spray on (few microns thick) materials that would serve the same purpose as our solar panels. Now, if these materials were able to withstand the environment of space, I can concieve of a way that this would make economic sense for LEO launching....

Instead of a large SPS, how about a fleet of large, though wispy thin ones? If we launch a mass to LEO and it unfolds itself, we could design a device that has two surfaces, one with highly reflective properties and one that can convert solar to eletricity. This large semicircular wings would unfold around a very small central satellite. Being really thin, orient the reflective surfaces to the sun and utilize the wings / solar cells as a solar sail. In this orientation the satellite could ascend, slowly, to a higher orbit, even GEO. At the desired orbit, the satellite can turn and have the solar-electric conversion side of the wings facing the sun.

There would then be a small SPS in a desired orbit, launched only to GEO.

Complicating factor is no very large solar sail has been used yet. That and the unfolding mechanism could be complex. On the plus side, this would, for a rather small weight, yield a lot of surface area.

I wouldn't see this as benefiting a city. A small SPS is best for remote industrial activities or remote communities.

If this is viable, then after a lot of these are in orbit... someone might develop a viable business model for space maintanence. At that point a lot of other interesting things might develop.

Dan Wylie-Sears wrote:
Panels costing $500/kg after the economies of scale kick in? Sounds
kind of steep. What interest rate did you assume in order to come
up with the price of power?

Note that groundbound solar can also be thermal, either convective
or steam-turbine. Either one takes care of the nighttime issue by
just having some thermal mass to store the heat. Convective thermal
solar probably works better at night, because of the lower
temperature at the outflow.

How do you figure the part about "more reliable"? If a system on
the ground gets a glitch, you drive around in a truck to find it and
fix it. If a bit of space junk hits the wrong wire, what do you
do? And how much did you budget for maintenance, in order to get
higher reliability than can be achieved with maintenance and repair
workers commuting on wheels?

Matt Gallimore makes a good point about the orbit. Launch costs are
usually quoted to LEO, but LEO puts you in the dark part of the
time, plus satellites in LEO catch a few stray air molecules and
occasionally need to reboost a little. But if you go to a higher
delta V orbit, you need to pay the rocket equation.

--- In spacesettlers@yahoogroups.com, Ian Woollard
wrote:
>
> I found when I did the arithmetic, the projected costs of the
panels
> and the launch costs worked out very roughly the same. So the costs
> seem lower than terrestial *and* more reliable.
>
> In addition, the economies of scale that you inevitably get on the
> panels is good too.
>
> On 11/3/05, Dan Wylie-Sears wrote:
> > I haven't checked out the details at all, but relatively small-
scale
> > SPS without colonies sounds plausible at first glance. (By
> > relatively small scale, I mean compared to the terawatts of
global
> > demand.)
> >
> > But first SPS has to beat ground-based solar. I'm dubious that
the
> > factor of four gained from full-strength sunlight 24-7 is enough
to
> > outweigh launch costs, unless we can get by with launching only a
> > small fraction of the mass and using space resources for the
rest.
> > The amount of area on the ground isn't a real problem in the
medium
> > term: it's less than we already have paved.
> >
> > --- In spacesettlers@yahoogroups.com, Ian Woollard
> > wrote:
> > >
> > > I did some maths a few months back. I got some answers that
> > surprised
> > > me. I then checked out the Fresh Look study for SPS, and there
were
> > > some notes that agreed with my analysis.
> > >
> > > It looks like Solar Power Sats are actually economic, with no
need
> > for
> > > lunar launch infrastructure.
> > >
> > > Basically, I took a Falcon I, and asked- how often could I
launch
> > it?
> > > Then I did the maths, and extrapolated the economies of scale
on
> > the
> > > hardware and launch infrastructure of the Falcon I.
> > >
> > > The launch costs fell below about $500/kg which is reckoned to
be
> > the
> > > breakeven cost for SPS to be viable.
> > >
> > > I then did a similar thing for solar panels.
> > >
> > > Result: Energy costs of about $0.05/kWh for 4 4GW SPS; dropping
> > lower
> > > if you build multiple stations.
> > >
> > > This assumes very high launch rates however- dozens of
launches per
> > > day. Analysis of the Falcon I suggests that it may be possible
> > (it's
> > > not dissimilar to a V2 in size, and the Germans managed quite a
> > lot of
> > > launches per day; so it's not totally without precedent and it
> > seems
> > > likely the same techniques would work for the Falcon I.)
> > >
> > > The economics get even better if you use Russian launchers or
> > > something (Chinese :-) or Indian labour); because the cost of
> > labour
> > > is much lower...
> > >
> > > The downside is that it doesn't involve launching any people at
> > all.
> > > The upside is that it would cause the launch costs to plummet
and
> > that
> > > in itself can open space.
> > >
> > > --
> > > -Ian Woollard
> > >
> > > "People are brilliantly stupid, and stupidly brilliant"-Robin
> > Abrahams
> > >
> --
> -Ian Woollard
>
> "People are brilliantly stupid, and stupidly brilliant"-Robin
Abrahams