🚀 go-pugleaf

Sheridan Mayo <scmayo@rsc.anu.edu.au> wrote in article
<6054uj$ni7$1@clarion.carno.net.au>...
> In article <01bcc70c$bd572070$0400a8c0@BAHN>,
> William L. Bahn <bahn@pcisys.net> wrote:
<snip>
> >None-the-less, let's not forget a few things:
> >(1) That rate falls off as the cosine of the latitude.
> >(2) That rate falls off as the cosine of the sun's angle from zenith.
> >(3) The insolation that reaches the surface falls off with theta due to
> >greater atmospheric absorption and reflection.
> >(4) A generating plant must produce electricity 24 hours a day.
> >(5) Efficiencies of large area modules is significantly lower than
single
> >cells.
> >(6) One square kilometer may not be a lot of land when it's mostly bare.
> >But try to cover it with something and it's a very big hunk of real
estate.
> >
> [snip lots of interesting stuff about practicalities and problems
> of solar power.]
>
 
> The value of 400W/meter square was actually for the UK so that
> included a latitude factor but didn't include the other factors.
> I was actually thinking about the idea of solar power in Australia but
> didn't have any figures available.

The Siemens map I spoke of shows that western Australia (just a rather
small section) is one of only a few places in the world with a scale factor
of six (i.e., 6kW-hrs/day per kW rating at zenith). 

> 
> Anyway I agree that there are problems & limitations with solar power
> (chiefly that it is only there in the day!) but consider the
practicalities
> that were involved with nuclear power when it was first getting off the
> ground. They were enormous and it was sheer political will (and the
> defence connection) that made it happen. Look at the massive cost of
> fusion experiements - yet they still go ahead. I think this really puts
> the problems of solar power (which are largely down to
> fabrication costs) in perspective. Solar power has possibilities but
> by and large there isn't a fraction of the political will behind it.
> 
> For what it's worth I suspect that the future for solar power lies not
> so much in large scale plants but in providing power on a small scale
local
> basis as it is much more scalable than other forms of power generation.
> I did see something a while back about developing solar cell windows - 
> i.e. they are largely transparent but absorb about 15% of the light for
> power generation - the idea being that by covering a building in the
> things it could generate some of it's own power (it was suggested this
> be used for buildings like offices which are mostly used in the day).

I also think that solar power's promise lies primarily in distributed
point-of-use production. And I agree that the development of solar power
and other alternative energy sources lacks the political will to push it. I
have often wondered if nuclear energy would have become much more palatable
and accepted if we had not pushed the commercial development of light water
reactors that had allowed quick development of naval nuclear powered ships.
A lot of other things could have tipped the balance as well - such as
focusing on more numerous but smaller plants located well away from
populated areas. With a small enough plant you can rely on total
containment as your final defense instead of trusting engineered safety all
the way. As it is, nuclear power has gotten such a political and public
opinion black eye that newer, intrinsically safe reactor designs are lumped
in the same bag as Chernobyl.

One other thing to keep in mind with solar energy - the amount of silicon
we are talking about as a fraction of the total industrial capacity. For
the 400MW plant we were discussing, I estimated between 5 and 30 square
kilometers of panel area and that the steady state panel replacement would
be on the order of perhaps 500 m^2 per day and more likely it would
actually be along the lines 6000 m^2 per day. We have a semiconductor fab
nearby that just made a HUGE expansion from 3000 wafer starts a month to
30,000 wafer starts a month - if these are six inch wafers that's a total
wafer area capacity of 18 m^2 per day. So if a solar cell fab turned out
100 times this volume of production it would still take the total
production of two or three of them just to supply this one plant with
enough modules to replace the ones that fail on a daily basis. Not to
mention the fifty years total production output to supply the initial
panels to construct the plant. And let's keep in mind that this is for a
small plant.

One calculation I would like to do is to estimate how much of the current
semiconductor industry's fab capacity would be required to supply enough
solar modules to satisfy the electrical production needs of the state of
California - both initially and the steady state replacement requirements.
I'm hoping to get some actual information regarding the aggregate capacity
of the silicon processing industry later this week.