Re: SPSs and the candidates

From: Bill Bogen (wbogen_at_visteon.com)
Date: 11/04/04 

Date: 4 Nov 2004 11:54:40 -0800

"Christopher M. Jones" <christopher.m.jones@gmail.com> wrote in message news:<S4SdnU3Sea1qIRTcRVn-iw@comcast.com>...
> Bill Bogen wrote:
> > "Christopher M. Jones" <christopher.m.jones@gmail.com> wrote in message news:<AfWdnbdneMrCZhncRVn-ow@comcast.com>...
> >>Current energy usage world-wide runs at around 400 EtaJoules
> >>per year, or an average of roughly 13 teraWatts continuously.
> >>Even at 100% conversion efficiency of the ~1400 W/m^2 of
> >>insolation at Earth this corresponds to over 9,000 km^2 of
> >>area in solar power systems. This is a lower bound, a more
> >>realistic estimate would be at least a factor of 4 larger
> >>due to inefficiencies in each step of the process.
> >
> > So, using a factor of 4, we need 36,000 km^2 of solar panels or of
> > mirrors reflecting into heat engines.

Actually, the requirements are even greater. Let's assume we start
on-orbit testing of SPS soon, build mines and factories on the Moon,
and provide all the Earth's energy requirements by 2050 (when the
population will have reached 9.31 billion). Further, let's assume
that the world has gotten free and rich by then and that everyone
consumes as much as Americans will in 2050.

So world power consumption will be 1.815 x 10^14 W or 181 Terawatt.
Whooweebaby.

If provided by solar panels or mirrors & generators with a
to-the-customer capacity of 100W/m^2, this will require 1,815,068 km^2
of SPS, somewhat more than the land area of Alaska. Comes to about
200 m^2 per person.

> > By an amazing coincidence, this
> > is almost exactly the amount of aluminum foil made in Europe in 2003.
> > So if we can make 4% as much as that in space (as well as heat engine
> > parts, microwave components, etc) using lunar materials, then in 25
> > years we could provide all the Earth's current energy needs.
>
> This is not an encouraging statistic. It indicates how
> far we have to go not how easy it will be.

Nobody said it was going to be easy.

> It indicates
> that we need to be able to make solar panels and related
> systems nearly as abundantly as we make aluminum foil
> today in order for SPS to be feasible with today's, let
> alone tomorrow's, energy needs. Worse yet, according to
> some we need to make factories in space or on the Moon
> which can process local materials and make PV arrays as
> cheap and abundantly as we make foil. The last time I
> checked PV arrays were just slightly more complex and
> costly to manufacture than foil.

So don't use PV arrays, use foil mirrors and heat engines. What we'll
be selling is 200 m^2 of SPS-output to each person. Put on an
individual basis, that doesn't seem so outrageously large.
 
>snip<>
>
> >>This ain't gonna happen overnight.
> >
> > True. What source of power would?
>
> None. That's the point. SPS is not an instant panacea.
> Nothing is an instant panacea for power production.

Um, what's the point of that point? Who has proposed SPS as an
instant panacea? Don't take a few lines in a discussion as an actual,
full-blown business plan for an instant, world-wide energy system. A
real SPS system will require real research. Let's start now. Or
rather, let's encourage our respective governments to fund modest,
on-orbit tests of SPS. Soon.