From: Eugene Leitl (eugene.leitl@lrz.uni-muenchen.de)
Date: Fri Nov 06 1998 - 09:32:43 MST
Michael Lorrey writes:
> Solar power generating stations suffer from one serious fault: peak
> demand incompatibility. being able to store power from this intermittent
> source for supply to the grid at periods of peak demand (when the power
> is also worth the most) is of utmost importance.
Peak demand is during daytime, where -- nice coincidence --
photovoltaics performs best. Local spikes can be averaged
out if power is dumped into the grid. So basically all you
need is to provide a basal PV/electrolyzers/hydride or
(buckytube) pressure storage/fuel cells capability to make
it through the worst-case nighttime. Seasonal variations
should be taken care by fossil/nuke power plants
(fine-grain decentralized, to limit thermal lossage for power/thermal
coupling) for now, but PV and photosynthetics (both
biorenewables and future engineered/de novo processes)
is really the only viable long-term option.
> As for the amount of power it generates, the area of Arizona should see
> a solar flux level equivalent to over 250 terawatts. Given that the only
1) Centralizing PV is pointless, especially in the U.S. with its low
(both local and global) building density
2) How do you arrive at that number? Assuming a day-average insolation
flux of, say, 500 W/m^2, and a conversion efficiency of, say, 10%,
you arrive at a conservative 50 W/m^2 (with 1 kW/m^2 and 20% about four
times that much). If you need 5 kW/human during daytime (an
overkill in private sector, if a minimum of husbandry is
applied, let the industry look after itself), that's
100 m^2, or a square of 10x10 m (5x5 m in best case).
Inconspicous, if integrated into roof and facade,
having an additional benefit of reducing building
renovation costs.
3) By utilizing terrestrial rectenna arrays/PV satellites from lunar
and NEA material processed in situ and EM-driver put into Earth
orbit, you can get 100% clean power essentially 24/24 without
consuming ground (which is not a real problem anyway).
> solar technology currently available which has any kind of near-market
Maybe thin-film amorphous Si would be not the only technology
available if the field has been properly funded for a decade
or so (but, oh, no market demand, since energy is very cheap,
particularly in the US. After 4 weeks of near-L.A. smog, one cannot
fail to notice that people will adapt to any conditions for absolutely
irrational reasons). Novel materials like CuInSe and polymer
('last all summer long') are in theory perfectly possible and
economical once we need them. Of course people would have to
pay a lot for chemical feedstock once easily accessible
fossils are depleted, being restricted to fixed atmospheric
carbons and hydrocarbon imports from space, unless the Singularity
intervenes.
> cost effectiveness is thin film amorphous, which has a conversion
> efficiency of around 10%, we are talking about 25 terawatts of generated
> power. Accounting for DC to AC inveting and distribution losses, we are
> talking about 20 terawatts of power. This is a significant amount, but
> not a significant percentage of the world power demand.
DC/AC inverting is not a problem, you can synthesize such power
directly by dynamically combining individual cells (controllers
demostrated), distribution lossage nonexistant if produced in situ,
which also takes care of centralism/landscape optical pollution.
I suggest you revise your assumptions, as they are unnecessary
pessimistic.
ciao,
'gene
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