solar cells
Shailendra Anant Save
I am intrigued by solar methods of generating power. What I
would like to know, is what is keeping this method from becoming
the cleanest power generating method available?
0> How does a solar cell work? How do they work in arrays?
Are they high current/low voltage sources or vice-versa?
1> How good is the regulation of a cell over a variable load?
Meaning, if there was no regulation circuitry after the cell
output, what will happen?
2> What are these cells made of? How is this different from the
photo-voltaic effect? Is it any different?
2a>Do these cells work on light energy? Or is it heat? Infra red?
3> Typically, what is the efficiency of such a cell?
4> Where can I get a solar array? What are the different prices
that I would expect to pay?
5> Is any company active in this research? What kind of results
are they having?
I'd appreciate anyone helping me to find the answer to these
questions and more. It all started when I read that all that is
required is that about 2% of the energy incident on the earth (from
the sun) is sufficient to meet all human power needs for the next
century. How realistic is this? We do have a lot of sun in the
Sahara, you know.....
--Shailendra
--
Physical: Shailendra Save, Logical: ss...@caen.engin.umich.edu
2303 Conger Baits II, UUCP: ...!umix!caen.engin.umich.edu!ssave
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Eagles may soar, but weasels don't get sucked into jet engines.
(For those who don't know, a weasel is a wolverine)
Peter Brooks
> 0> How does a solar cell work? How do they work in arrays?
> Are they high current/low voltage sources or vice-versa?
A solar cell is a diode that is connected to a load. When sunlight
shines on the diode it generates electron-hole pairs, and with the
built-in field, current flows through the load. (I know, this is
vastly oversimplified for those who know device physics and
probably too complex to those who don't.)
You can put them in an array in series, parallel, or series-parallel
to get your voltage and current requirements.
> 1> How good is the regulation of a cell over a variable load?
Your load voltage/current will probably go all over the place. You
would probably need a power supply or have the cells run a charger
into a battery pack, then draw power from the batteries.
> 2> What are these cells made of? How is this different from the
> photo-voltaic effect? Is it any different?
Silicon, Gallium Arsenide. (The photo-electric effect, you mean?
That has to do with the energy required to knock an electron off
a piece of metal. this is a distant cousin.)
> 2a>Do these cells work on light energy? Or is it heat? Infra red?
You need light of a certain frequency, but visible light works
fine. It depends on the physics of the material you use, but for
silicon, near infrared or better is desired. GaAs will probably use
higher frequencies.)
> 3> Typically, what is the efficiency of such a cell?
For Si, maybe 10%. Amorphous Si, 4%. I have heard of greater values for
GaAs, but am not sure of the state of the art.
> 4> Where can I get a solar array? What are the different prices
Try a marine supply. they sell small arrays for sailboats. Lots of
$$. Maybe 300 or so for a boat array. Try Edmund Scientific for small
wafer type cells.
> 5> Is any company active in this research? What kind of results
Arco solar, exxon (I think). some success, but the cost has to come
down. That's one of the major areas to tackle. This may be an urban
legend, but I have heard that for the average Si array, it costs more
in energy to produce it than it may be expected to generate in its
lifetime.
>
> --Shailendra
There are lots of books on solar cellsand photovoltaics. I used to have
an old one from the IEEE press, but it's long gone. Try a decent
library, particularly the engineering library of your friendly
university for more information.
Pete Brooks p...@hpocia.sj.hp.com
Disclaimer: Do you think HP would authorize me to say this? I didn't
think so.
Roy Smith
>> 4> Where can I get a solar array? What are the different prices
> Try a marine supply. they sell small arrays for sailboats. Lots of
> $$. Maybe 300 or so for a boat array.
Just happen to have some catalogs, so I'll fill in some details for
Peter. Try Defender Industries in New Rochelle, NY (914-632-6544) or West
Marine Products in Watsonville, CA (800-538-0775). Most of the panels sold
by either are made by Sovonics or Arco. All ratings are at 14V output. Some
samples from the West catalog (Defender's is similar):
33W, up to 2.5A, 12-17 A*Hr/day, 50" x 25-3/4", $399
21W, up to 1.7A, 8.5-13.6 A*Hr/day, 54" x 15-3/4, $299
55W, up to 3.17A, 17-28 A*Hr/day, 50.9" x 13" x 1.4", 12.6 lbs, $449
The A-Hr/day ratings are averages, factoring in number of daylight
hours, typical cloud cover, etc, and will obviously vary from place to place.
I don't understand how the 55W panel gets roughly 50% more power out of
roughly half the surface area, but I'm just typing what's in the catalog.
There is an interesting note which says that you get less output voltage in
hotter weather. Seems counter-intuitive to me, but I never was very good at
semiconductor physics. Supposedly the above ratings are all for 1,000W/m^2
and 25C. That makes the 33W panel 33/831 = 4% efficient and the 55W one
would be 55/427 = 13%. Come to think of it, that fits very well with Peter's
estimate of:
> For Si, maybe 10%. Amorphous Si, 4%.
The 33W and 21W panels are flexible Sovonics units while the 55W one
is a rigid Arco job. I guess the flexible ones are the Amorphous Si. Not
only is the rigid more efficient in terms of power/area, but it's a better
buy in terms of power/dollar too. On the other hand, I think sailors like
the flexible because you can beat on it a lot more without breaking it.
In all cases, the output from the panels is so variable, that the
only rational thing to do is to use it to charge a battery, which you then
draw down from. West says that if the max amperage rating of the panel is
greater than 1% of the A*Hr rating of your battery (ignoring the units
mismatch; they mean 2.5A panel and a 250 A*Hr battery), you need a regulator
or you risk over-charging the battery.
--
Roy Smith, Public Health Research Institute
455 First Avenue, New York, NY 10016
r...@alanine.phri.nyu.edu -OR- {att,cmcl2,rutgers,hombre}!phri!roy
"Arcane? Did you say arcane? It wouldn't be Unix if it wasn't arcane!"
Paul Dietz
>down. That's one of the major areas to tackle. This may be an urban
>legend, but I have heard that for the average Si array, it costs more
>in energy to produce it than it may be expected to generate in its
>lifetime.
The number I have seen is that for polycrystalline silicon arrays,
the "energy payback time" is 10 years. For thin films like a-Si,
1 year (but energy is only a small part of their cost of fabrication).
Paul F. Dietz
di...@cs.rochester.edu
anmar mirza
The bottom is fairly accurate. It is something less than 10 years
at the national average of about 4.5 hour mean peak solar radiation..
Since polycrystalline cells were first made in the early fifties
they have shown little degradation in the roughly 40 years. This is
for the cells, when exposed to weathering, the interconnections will
corrode, but modern packaging has reduced this. Current panels have
10-12 year warranties, and an expected life of over 25 years!
If the interconnections corrode, many times they can be repaired,
further extending the life.
Amorphous cells usually degrade to about 2-3 percent efficiency from
6 percent when new. As I said before, polycrystalline cells are rated
at around 14% efficiency, and they don't degrade. The more exotic
cells such as GaAs have efficiencies around 30% with little
degradation, but they are horrendously expensive.
--
Anmar Mirza # If a product is good, # I speak only my # Space, humans next
EMT-A # they will stop making # opinions on these # goal in the race
N9ISY (tech) # it. Unless it is # subjects, IU has # for immortality.
Networks Tech.# designed to kill. # it's own. # --- me
Shailendra Anant Save
Shailendra
--
Physical: Shailendra Save, Logical: ss...@caen.engin.umich.edu
2303 Conger Baits II, UUCP: ...!umix!caen.engin.umich.edu!ssave
Ann Arbor. MI 48109. Audible: 313-763-1627(H) 313-764-8033(O)
anmar mirza
Yes, GaAs cells typically run about 20%-23% efficiency, and they have
hit a peak of 30% for those used in satelites, and the record
efficiency for any photovoltaic cell is 39% using two cells sanwiched.
The top cell absorbs the higher end of the sprectrum, while the bottom
cell absorbs in the lower end. As I said, the high efficiency ones
are horrendously expensive, but if you are powering a 100 million
dollar satelite, what is 1 or 2 million for high efficiency, light
weight cells? Definately not cost effective for home use. My set up
is not dollar for dollar cost effective compared to the utility, but
it makes use of a power source that otherwise would have been wasted,
and once the panels are made there will be no more pollution from
them over their lifetime, and they are very recycleable. If my entire
roof were covered I would be able to sell power to my neighbors, as I
could produce about 14 kWh times 4.5 mean peak average hours of daily
sunlight, meaning I would be producing a yearly average of almost
1900 kWh per month. Since I currently buy about 125 kWh per month
from PSI, down from 300 since I have started installing my system,
I would have plenty of power from space that was otherwise wasted.
More in the summer, and less in the winter, but that is ok, I like
to air condition my house in the summer, and that would do it nicely.
with an expected panel life of over 25 years, that ain't bad at all!
But, I digress, and it is getting near quitten time.
Henry Spencer
> I am intrigued by solar methods of generating power. What I
>would like to know, is what is keeping this method from becoming
>the cleanest power generating method available?
(1) Solar cells are expensive to make and don't last forever. (Also, the
production processes are not particularly "clean" and the more
advanced cells are often hazardous wastes when they are retired.)
(2) Extensive energy storage or extensive long-range power transmission --
difficult and expensive either way -- is needed to cope with
outages due to night and cloud.
(3) Solar energy is thinly spread and very large collecting areas are needed.
(4) Large-scale solar power seriously changes the heat balance of the
surrounding area, so it is not completely clean. In particular,
desert areas normally reflect most sunlight back out into space,
but when paved with solar cells, most of the energy is released
as heat into the biosphere instead.
--
"The average pointer, statistically, |Henry Spencer at U of Toronto Zoology
points somewhere in X." -Hugh Redelmeier| he...@zoo.toronto.edu utzoo!henry
Marc Ries
->(1) Solar cells are expensive to make and don't last forever. (Also, the
-> production processes are not particularly "clean" and the more
-> advanced cells are often hazardous wastes when they are retired.)
Yet, the prices are falling as we speak. There is no reason why the pure
silicon-based PVs can not last "forever" -- there is nothing to break
down within the cell itself. It's true that creating PVs are not
100% "clean", but then neither is any power generation source, from
"hydro to nuclear." It takes alot of "dirty" manufacturing to make
computers -- will you stop using them?
->
->(2) Extensive energy storage or extensive long-range power transmission --
-> difficult and expensive either way -- is needed to cope with
-> outages due to night and cloud.
New battery storage technologies are being made, along with other methods
holding energy over time -- underground storage, etc. There are even
experimental "reverse" PVs that store energy during daylight and release
it at night.
->
->(3) Solar energy is thinly spread and very large collecting areas are needed.
->
PVs work in Alaska... Very large collecting surfaces are only needed for
the production of very high amounts of energy. A typical home could be
powered by PVs covering the roof area alone.
->(4) Large-scale solar power seriously changes the heat balance of the
-> surrounding area, so it is not completely clean. In particular,
-> desert areas normally reflect most sunlight back out into space,
-> but when paved with solar cells, most of the energy is released
-> as heat into the biosphere instead.
I would guess that there are very few deserts in the world *today* which
are being threatened by reverse-desertification. Beside, you don't
have to cover the *whole* desert to power America: the stats have been
hashed in this group previously.
The real question is that the sun provides the earth, via sun-light and
invisible energy, many more times the amount of energy then the earth's
population uses: what is the most benign, inherently-sane, way to process
this incredible "free" energy? Solar power in general is one of the
"cleanest" ways to do that. A passive solar house is a good example:
No PV's, no Solar hot water, just sun-light....
- Marc Ries
Henry Spencer
> Yet, the prices are falling as we speak...
They have been falling for a long time, actually, but they still have a
way to go before solar cells are very useful in the absence of constraints
that rule out other forms of power.
> There is no reason why the pure
> silicon-based PVs can not last "forever" -- there is nothing to break
> down within the cell itself...
Oh yes there is: the cell. There is a common misconception that
semiconductor devices ought to be eternal; it is not true. There are
a variety of failure mechanisms, including diffusion of the doping
elements within the silicon -- yes, diffusion happens in solids too,
it's just slow -- migration under electric fields, and infiltration
of contaminants from the outside. These effects are not completely
insignificant for any semiconductor and are quite noticeable in those
that are being pushed hard under a severe cost constraint. (A particularly
severe example is the laser diode in a CD player, whose lifetime is
measured in months if you run it 24 hours a day.)
> It's true that creating PVs are not
> 100% "clean", but then neither is any power generation source, from
> "hydro to nuclear." ...
Agreed; the point is that solar cells are not exempt from cost-benefit
calculations for environmental impact. They are not the magic solution,
free of any environmental price, that some people think.
> New battery storage technologies are being made, along with other methods
> holding energy over time -- underground storage, etc...
At the moment, all are fearfully inefficient and tremendously costly if
used in bulk, barring extremely favorable circumstances. The state of
battery technology in particular is a disgrace.
> PVs work in Alaska...
When the sun is shining. I spent the last ten days at home on holiday in
central Saskatchewan; we saw the sun on maybe four of those days, tops.
> Very large collecting surfaces are only needed for
> the production of very high amounts of energy. A typical home could be
> powered by PVs covering the roof area alone.
Numbers, please. And state whether you assume massive redesign of the home
for minimum electrical use, including what alternate form of heating you
propose. There is no prospect of redesigning any large fraction of the
homes in North America any time soon.
Stephen Kogge
One point on the curve. I have a 30W (18" X 30") array. It charges
a car battery that I keep outside. Here in Maryland it cannot produce enough
total charge to keep 1 2.4W 12 volt fan running all the time.
My meters show ~2 Amps (24W) in full sunlight. The array does
not track the sun and from about 3pm on the charge drops off to a few
milliamps. During the winter I have to watch the voltage on the battery and
let it charge with no load for a few days. In the summer I end up putting
a car battery charger on the battery a couple of times.
Steve Kogge
Larry Setlow
At the moment, all are fearfully inefficient and tremendously costly if
used in bulk, barring extremely favorable circumstances. The state of
battery technology in particular is a disgrace.
How promising are those new (and how new, for that matter) plastic
batteries that were reported in the PC mags a few months back? The
(second- and third-hand) reports I heard made them sound like sliced
bread for portable computers and cars, even. I haven't heard any
figures for storage capacity or whether they like deep-cycle
operation, though.
anmar mirza
>->(1) Solar cells are expensive to make and don't last forever. (Also, the
>-> production processes are not particularly "clean" and the more
>-> advanced cells are often hazardous wastes when they are retired.)
> Yet, the prices are falling as we speak. There is no reason why the pure
> silicon-based PVs can not last "forever" -- there is nothing to break
> down within the cell itself. It's true that creating PVs are not
it has been almost 40 years since they were first made. The amorphous
cells will degrade over time, but their manufacturing process is so
much simpler and cheaper to replace them every 10-20 years. Depends on
what you are trying to power. Also, amorphous cells are a lot less
energy intensive, and less polluting to make than polycrystalline
cells.
Coal burning plants, nuclear, wind, hydro, oil, none of our power
sources last forever, or even more than a generation, without some
type of overhaul.
>->(2) Extensive energy storage or extensive long-range power transmission --
>-> difficult and expensive either way -- is needed to cope with
>-> outages due to night and cloud.
These can all be overcome, there is no new technology needed to do
this, and with improvements on existing technologies efficiency goes
up. If a new technology comes along that is better, great.
>->(3) Solar energy is thinly spread and very large collecting areas
are needed
Well, since most areas on earth get at least 500 watts per meter
squared during peak, and we can easily tap 14% of that with photovoltaics,
and much much more (the exact percentage of efficiency of the La Luz
plants escapes me), I would say there is a flaw with your reasoning.
What is great about solar energy is that *everyone* can get some,
even if only to a limited degree, and don't knock it bub, you are
powered by energy from the sun, where do you think your food comes
from?
> PVs work in Alaska... Very large collecting surfaces are only needed for
> the production of very high amounts of energy. A typical home could be
> powered by PVs covering the roof area alone.
As is true of most of the world.
>->(4) Large-scale solar power seriously changes the heat balance of the
>-> surrounding area, so it is not completely clean. In particular,
>-> desert areas normally reflect most sunlight back out into space,
>-> but when paved with solar cells, most of the energy is released
>-> as heat into the biosphere instead.
Where does the energy from your rooftop go? I would wager that should
solar become a very well utilized form of power, it would disrupt the
total biosphere less than any other form of energy, where do you think
your oil came from? The problem is not with the power source, but the
number of consumers of that power. Even nuclear would be safe if we
only had to have one small plant to satisfy the energy demands of the
entire world.
I like Marc's response to your post, he is saying that he is willing to
try this seemingly less harmful source of power before trying others that
are known to have deletarious effects.
Your post is common of the attitude many of the peoples of this
country. You already having it fail even before you have tried to make
it work. I am glad that there are some people who are working with it,
and having success.
anmar mirza
>They have been falling for a long time, actually, but they still have a
>way to go before solar cells are very useful in the absence of constraints
>that rule out other forms of power.
Never ever rule out other reasonable forms of power. We do not want to
get into the trap of relying on one source again.
>> There is no reason why the pure
>> silicon-based PVs can not last "forever" -- there is nothing to break
>> down within the cell itself...
>Oh yes there is: the cell. There is a common misconception that
>semiconductor devices ought to be eternal; it is not true. There are
>a variety of failure mechanisms, including diffusion of the doping
>elements within the silicon -- yes, diffusion happens in solids too,
>it's just slow -- migration under electric fields, and infiltration
>of contaminants from the outside. These effects are not completely
>insignificant for any semiconductor and are quite noticeable in those
I have said it before, and I'll say it again, polycrystalline cells,
made in the early 50's, have shown no significant deterioration in
power output. Amorphous cells degrade comparatively quickly.
>Agreed; the point is that solar cells are not exempt from cost-benefit
>calculations for environmental impact. They are not the magic solution,
>free of any environmental price, that some people think.
This is a problom that some of the people who I deal with share.
What I have a problem with is people who refuse to consider building
passive solar heating or cooling systems into their house, when it
costs little or no extra, and the long term payoffs are significant.
Right now though, solar cells offer an easy way for people to generate
power on a small scale, a way for them to be independant. It is
also a good way to make use of space that is wasted (rooftops).
>
>Numbers, please. And state whether you assume massive redesign of the home
>for minimum electrical use, including what alternate form of heating you
>propose. There is no prospect of redesigning any large fraction of the
>homes in North America any time soon.
Pardon me, but on the average, when I do a site survey for
photovoltaics in a retrofit installation, I can usually reduce a
households power consumption by 30% without major redesign, or loss of
comfort. I can usually drop it 50% by redesigning lighting schemes and
refrigeration and the like. This is assuming they do not heat with
electric. If they do, and they switch to a combination
geothermal/passive or active solar, the savings can be even greater.
What is really good about passive solar heating and geothermal systems
is that they *will* pay for themselves in savings compared to the old
system. The turn around time can be as little as 10 years.
If the house is being built, then the extra cost is minimal.
anmar mirza
since even in Maryland you get around 3 hours peak sunlight average,
that would give you around 6 Ah average daily (more in summer, less
in winter). Sounds like even a worst case summer scenario (cloudy for
a week) shouldn't deplete your battery from full charge. Maybe the
battery is old? Car batteries really aren't good for that application,
they don't like the cycle rate. Try a marine style deep cycle battery,
that should give better performance. If you don't want to run right
out and buy a new battery, test your battery by seeing how long it'll
run your fan from a full charge, till the voltage drops to around 11
volts, then calculate how much capacity your battery has. If it has
less than 20-30 Ah, then that may be your problem.
Paul Dietz
[ about the cost of solar cells ]
>About a dollar a watt, for large installations. Five dollars a watt
>for smaller installations. I wonder what the "real costs" of conventional
>power are?
I find the $1/watt figure very hard to believe. Reality check: why
should the cost/cell when buying a small number of cells be FIVE TIMES
that of buying a large number? I suspect the $1 figure refers to some
(rather optimistic) projections about what the cost might come down
to, given a decade or so of development and improvement in the
manufacturing processes. Sandia (a few years back) projected that
flat plate cells would have to drop to $1/W at 15% efficiency before
they had major grid-connected market penetration, even in the desert
southwest; maybe that study was where this number comes from.
The balance of plant cost (power conversion electronics, supports,
labor, etc.) is also considerable, and has to drop to $1/W (1986(?)
dollars) for major grid-connected applications to be competitive.
The noncompetitive nature of current PV systems for on-grid
applications is illustrated by the market dominance (in solar
electrical generation) of solar-thermal systems by Luz. Their units
generate at least 90% of the world's grid-connected solar electricity.
They currently produce electricity at a levelized cost 1/2 - 1/3 that
of PV systems, are more efficient (at least in areas with large
amounts of direct sunlight, such as deserts), and offer the prospect
of energy storage in molten salt phase change systems (for example,
using alkali carbonate eutectics), which are cheaper (and more
efficient, I believe) than electrical batteries, at least on a large
scale.
There's a lot of money flowing for Luz to improve its system, and they
project the cost will drop further, to maybe $.06/kWh. So PV faces a
moving target, and may remain confined to off-grid niche markets. I
wonder if even the off-grid stationary market might fall if very low-E
selective surfaces could be made that could provide high temperatures
in nontracking collectors.
Paul F. Dietz
di...@cs.rochester.edu
John Berryhill
>> down within the cell itself...
>
>Oh yes there is: the cell. There is a common misconception that
>semiconductor devices ought to be eternal; it is not true. There are
Of all of your points, I least understand the significance of this one.
Name a single part in a diesel turbine that will last as long as a
single-crystal Si solar cell. Heck, nuclear plants last roughly
30 years.
Comparing solar cells to laser diodes in terms of reliability is
stretching things quite a bit. Of almost any semiconductor device
you could pick, laser diodes operate under the highest power
densities and thermal stress. And, no, at the temperatures and electric
field strengths encountered in solar cells, diffusion of dopants is
not at all significant.
There are plenty of barriers to large-scale use of PV power. Reliability
is not one of them.
--
John Berryhill
143 King William
Newark, DE 19711
Wm Randolph Franklin
>
>What is really good about passive solar heating and geothermal systems
>is that they *will* pay for themselves in savings compared to the old
>system. The turn around time can be as little as 10 years.
What interest rate does this assume? Does it take advantage of any tax
breaks (if there are any left)? Thanks.
The reason I ask is that many "efficient" devices make no sense in my
home when interest is included. E.g., I take years to burn out a $1
100W power 1700 lumen 1000 hour bulb. Some haven't burnt out since we
bought the house 8 years ago. A $10 fluorescent bulb would have to
contain a nuclear power source and provide the light free to be as
cheap if money costs 12%.
Really, I'm in favor of conservation, but it has to honestly be cheaper.
--
Wm. Randolph Franklin
Internet: w...@ecse.rpi.edu (or @cs.rpi.edu) Bitnet: Wrfrankl@Rpitsmts
Telephone: (518) 276-6077; Telex: 6716050 RPI TROU; Fax: (518) 276-6261
Paper: ECSE Dept., 6026 JEC, Rensselaer Polytechnic Inst, Troy NY, 12180
Henry Spencer
>try this seemingly less harmful source of power before trying others that
>are known to have deletarious effects.
Better the devil we don't know than the one we do? Sorry, I do not agree.
We need to take a careful and rational look at the *costs* of both approaches
before deciding. We know enough about the economics and side effects of
solar power, including *its* deleterious effects, to make rational decisions
about it... and right now, the answer tends to be "uneconomical except in
special circumstances", although it is showing steady improvement and is
worth watching for the future.
>Your post is common of the attitude many of the peoples of this
>country. You already having it fail even before you have tried to make
>it work...
The post I was responding to was typical of the attitudes of many of the
"true believers", who enthusiastically promote their cherished beliefs
while ignoring known costs and problems. Choices this important should
be based on rational calculation, not "gee, this sounds nifty".
Charles K Hughes
A lot of people having been talking about the cost of solar power versus
alternatives...those opposed to solar power as uneconomical are, perhaps,
not looking at the complete picture. Solar power is probably bext compared
to Nuclear power in terms of "manufacture" of the energy output.
Nuclear power: fuel is dug from the ground, processed (slag is put aside
to be buried), used to generate energy, remains of fuel are buried.
Solar power: no digging, no processing, energy is converted from
sunlight, no remains.
Under the absolute worst case scenario a solar cell will last forever as
its own waste product. Presumably it won't contain harmful substances
that can get into water supplies, the air, etc. Now, if it does contain
some harmful substance, then we should recycle it.
Under the absolute best case scenario nuclear waste is with us for
thousands of years. Nuclear waste gives off radiation while it decays,
sufficient radiation to kill things nearby, and enough to poison the
air/water/earth/etc nearby.
Am I missing something here? Sure, producing nuclear energy is cheap,
but what are the hidden costs incurred in disposal? In accidents?
Compare the *TRUE* total costs and Solar energy looks like it is free.
The comparison is not identical when fossil fuels are substituted for
Nuclear but there are still hidden costs - global warming, acid rain,
oil spills, etc.
The only technologies that compare favorably (in economic terms) are
dams, energy plants on water, wind, and solar. These all have hidden costs
in regard to the environment, but they are (effectively) unlimited sources
of energy that create no "unnatural" pollution. Carbon monoxide, dioxide,
and the sulfur compounds are "natural" pollution, but not when we are
measuring our "natural" pollution in terms of TONS. Nuclear waste is not
a natural pollution.
In addition, Solar (and theoretically Solar-Wind :) power can be generated
off-planet. Now, we were talking about the economical aspects of oil
& nuclear? The biggest cost in alternative energy is the startup cost.
The biggest cost in oil is the continuing requirement for it. And the
biggest cost for nuclear is the disposal (regardless of what the cost of
transportation of the waste is, we will, eventually, pay the full cost).
Stephen Kogge
>>
>> One point on the curve. I have a 30W (18" X 30") array. It charges
>>a car battery that I keep outside. Here in Maryland it cannot produce enough
>>total charge to keep 1 2.4W 12 volt fan running all the time.
>>
>That sounds strange, each day your fan will only draw 4.8 Ah, and
>since even in Maryland you get around 3 hours peak sunlight average,
>that would give you around 6 Ah average daily (more in summer, less
>in winter). Sounds like even a worst case summer scenario (cloudy for
>a week) shouldn't deplete your battery from full charge. Maybe the
>battery is old? Car batteries really aren't good for that application,
>they don't like the cycle rate. Try a marine style deep cycle battery,
>that should give better performance.
>
trying various wet cell NiCd and gell cells I decided to put a fresh
battery in the system. My assumption was that the 34 Amp hour NiCd cells were
old or damaged, the gell cells I tried next were used and followed
the same poor charge characteristics. I hesitated using a car battery since
it had to go outside. A friend of mine runs an electronics surplus store
(Electronics Plus in College Park Md) and warned me that the acid fumes
from the batteries he had for his emergency radio transmitter ate holes
in his plumbing and I really ought to put the lead acid battery outside.
I replaced all the blocking diodes at one point and saw an increase
in charge current. I have considered using a trick I read about using power
FETs instead of diodes. (I think it was FETs, I will have to check my notes).
In order to find our what is really happening I need to get
the device driver finished for the ADCs I have connected via SCSI and
MULTIBUS to this Sun 3/50. I could then have a cron driven process
watch the battery voltage and charge/discharge currents. For all I know
the reverse leakage into the array at night through the blocking diodes
is as large as my load.
One guess is that I am being hit by the less than the 100% charge/use
effeciency of batteries.
A second possible problem is that since the array is fixed on the
roof in one position I do not get a full days charge time. But since I
cannot move the house/roof it has become a valid part of this experiment.
The question I am trying to answer is "can anyone get enough power from
solar to make the expense worth it". This implies the most simple setup
and almost no maintenance.
Like I said this is one point on the curve. With several more
arrays and switches to drop the array off line when there is no charge
and drop the load off line when the voltage drops too far I would probably
see more available power and fewer times when I need to put the battery
charger on the system.
It's such an neat concept I continue to work with it.
Steve Kogge
Vance Morrison
>The reason I ask is that many "efficient" devices make no sense in my
>home when interest is included. E.g., I take years to burn out a $1
>100W power 1700 lumen 1000 hour bulb. Some haven't burnt out since we
>bought the house 8 years ago. A $10 fluorescent bulb would have to
>contain a nuclear power source and provide the light free to be as
>cheap if money costs 12%.
I agree that in gerneral the cost of money is NOT taken into account
for many concervation systems. On the other hand, in the case of
fluorescent bulbs, I think they DO in fact pay for themselves even when
the cost of money is taken into account.
Lets take your example. Lets also assume that both bulbs have a 10 year
lifetime (if anything this makes my analysis concervative). Lets also
assume that interest is 12% and that the light is used 3 hours a day
(conservative for a living room light), and that electricity costs
$.07/Kw-hr (thats what I pay, your rates may vary.).
Lets assume that I have $10 to spend. I could
1) By a flourescent bulb and use it for 10 years.
2) By a incandecent for $1 and save $9 in the bank at %12 interest
compounded daily for an effective rate of 12.7% for 10 years.
In both cases I have used the bulb for 10950 hours over 10 years.
The incandecent uses 75W and the flourecent uses 18W.
In the first case I must pay (10950*18/1000)*.07 = $13.80 of electricity
In the second case I must pay (10950*75/1000)*.07 = $57.49 of electricity
But I also have the money I made in the bank 9*.127*10+9 = $20.43 Thus
my 'true' cost is 57.49-20.43 = $37.06.
Thus I have still saved (made) $23.26 by using the flourescent, even
with interest taken into account.
This analysis does not take into account the fact the value of the money
(interest) for the electricity payments, however, adding this correction
will only help the case of using flourescents.
--------------------------------------------------
Now in this analysis I used the original number, I would have used
different numbers. I can buy flourecent adapters for $12 not $10 (but
replacements for just the bulb for $8). Also, since I don't take out
loans for things under $100, the real choice is between saving that
money or 'investing' it in a flourescent. Thus I would have used
%8 interest (since thats what I can get in a CD). It really doesn't
matter because the results point the same way.
The only 'dubious' assumption I have made is assuming 3 hour use.
Certainly not every light in your house sees this much use, but certainly
some do, so those are the ones you should replace.
Vance
Paul Dietz
>In article <1990Dec31.1...@bronze.ucs.indiana.edu> ami...@silver.ucs.indiana.edu (anmar mirza) writes:
>>What is really good about passive solar heating and geothermal systems
>>is that they *will* pay for themselves in savings compared to the old
>>system. The turn around time can be as little as 10 years.
>What interest rate does this assume? Does it take advantage of any tax
>breaks (if there are any left)? Thanks.
>
>The reason I ask is that many "efficient" devices make no sense in my
>home when interest is included. E.g., I take years to burn out a $1
>100W power 1700 lumen 1000 hour bulb. Some haven't burnt out since we
>bought the house 8 years ago. A $10 fluorescent bulb would have to
>contain a nuclear power source and provide the light free to be as
>cheap if money costs 12%.
You have to be really careful here. I suspect the *effective*
interest rate you would pay is much, much less than 12%. Why? Two
reasons: taxes and inflation. Unless you are careful, these effects
might actually give you a negative effective interest rate.
In contrast, the savings from personal capital investments like
increased efficiency are tax-free (unless they increase your assessed
property value), and are also inflation resistant, since energy prices
will likely tend to rise with inflation, at least roughly.
Paul F. Dietz
di...@cs.rochester.edu
anmar mirza
>In article <1990Dec31.1...@bronze.ucs.indiana.edu> ami...@silver.ucs.indiana.edu (anmar mirza) writes:
>Better the devil we don't know than the one we do? Sorry, I do not agree.
>We need to take a careful and rational look at the *costs* of both approaches
>before deciding. We know enough about the economics and side effects of
>solar power, including *its* deleterious effects, to make rational decisions
>about it... and right now, the answer tends to be "uneconomical except in
>special circumstances", although it is showing steady improvement and is
>worth watching for the future.
It's kinda interesting that passive solar systems have been with us
for many millenia, the first thing you do when you build a dwelling if
you don't have central heat is to build it so that it makes full use
of available sun. I don't think that photovoltaics will ever become
viable on a large scale, but it is *very* good for small scale
installations. Solar steam generation, such as the La Luz plants, make
very efficient use of solar, and is a fast growing technology. It does
need to be backed up with a fossil fuel, as does most solar
installations need to have a back up for when the sun don't shine for
long periods, but at least you have taken a significant percent out of
the total hydrocarbons needed, just as a passive solar collector on
your house can take a chunk out of your heating bill. As far as I
know, the bad effects of solar steam generation plants are small
compared to those of a coal fired plant, or a nuclear plant, or even
those of a hydroelectric plant. What is more, we can act to counteract
the effects of a solar steam generation station than we can with a
coal fired plant. I live in an area where we burn a lot of coal, and
we mine a lot of our own, and I think I would rather see the area used
for a strip mine and power plant used for a solar plant. It is very
area intensive, but so is strip mining. It changes the amount of
sunlight reflected, but so does the strip mine, and the exhaust of a
coal fired plant. It changes the local ecology of the area used, but
again, so does a strip mine, and the coal plant. The solar steam
plant, however, if we find that there is a global warming or cooling
problem due to reflected or absorbed sunlight, we can counteract that
by having our reflectors reradiate more, or absorb more, a lot easier
than we can scrub CO2 out of the atmosphere. If we find that the plant
is interferring with global CO2 by limiting available sunlight for
plants and trees, we can counteract easier than we can when we
liberate carbon that has been locked up for several million years.
And finally, barring a major increase in population over the next 1000
years, our solar plant will keep working long after the coal and oil
is used up. Maybe it'll teach us to live within a solar economy.
What I find really important about photovoltaics is that *I* can do
it. Me. One person. I don't even have to lay out a huge amount of
cash, or be very rich to do it. I can tell our utility where they can
put their lines, or in the case of my property where it'll cost a
little under 10,000 to run power out to it, I can buy a lot of panels
for that ten thou. *I* don't have to depend on a utility to provide me
with electricity. *I* can do it. And unlike wind or water, I can even
do it in town on my rooftop. Imagine that! I can live in the middle of
a town and not have to buy power from the utility.
*That* is where photovoltaics comes into importance.
Dollar for dollar photovoltaics are *not* now cost effective when you
add in batteries, inverters, control circuitry, and maintenance, but
they give me freedom. And they *are* cost effective when the utility
wants ten thousand to run power lines out to my property, then will
charge me a higher rate than you get in the city.
>The post I was responding to was typical of the attitudes of many of the
>"true believers", who enthusiastically promote their cherished beliefs
>while ignoring known costs and problems. Choices this important should
>be based on rational calculation, not "gee, this sounds nifty".
Ok, I can buy that. I hope I don't come across as one of those types.
All my opinions of it are formed by my working with it and others that
I interact with who work with it. I get tired of listening to the
'experts' who have never even done any work with it who condemn it to
death. I don't think that right now it is cost effective on a straight
dollar to dollar basis, but when you factor in social costs I believe
it comes out ahead. Unfortunately, I lack the resources to do in depth
studies on the subject of social costs. I do think that barring a
discovery of some cheap form of power, solar will be our cheapest
alternative in our future, on a dollar to dollar basis. I also am
willing to be one of those many people who work to make any new
technology feasable on an economic scale. If it fizzles, then it
fizzled, but not because I didn't try.
One final note on this long post.
I don't think *any* form of power we come up with is going to be
effective unless we stop our population growth. Just think, if there
were only a billion people on this planet, we all could live the
lifestyle of the 'rich American'.
Paul Dietz
>, the first thing you do when you build a dwelling if
>you don't have central heat is to build it so that it makes full use
>of available sun.
Wrong! The first thing you do is make the thing *damn* well
insulated. After that, maybe you use solar for the small heat input
required, or maybe (because this required heat input is so small) you
just stick a small electric resistive heater in each room. The
source of the heat is secondary to the its efficient use.
Paul F. Dietz
di...@cs.rochester.edu
Phil Ngai
| Solar power: no digging, no processing, energy is converted from
|sunlight, no remains.
So you must think that solar cells grow on trees.
| Under the absolute worst case scenario a solar cell will last forever as
|its own waste product. Presumably it won't contain harmful substances
|that can get into water supplies, the air, etc. Now, if it does contain
|some harmful substance, then we should recycle it.
Aside from the fact that you keep ignoring the cost of making solar cells,
why are chemical poisons, which last forever, more acceptable than
nuclear ones, which decay away? They are both invisible. They have both
been used to kill people.
--
Whatever happened to Global Warming? Could we have some Local Warming?
Charles K Hughes
>writes:
>| Solar power: no digging, no processing, energy is converted from
>|sunlight, no remains.
>
>So you must think that solar cells grow on trees.
Yes, as a matter of fact, I do...what do you think leaves are? However,
you took the statement out of context. In comparison to Nuclear Energy,
the solar cells are the Nuclear power plant, *NOT* the fuel that runs the
power plant.
>
>| Under the absolute worst case scenario a solar cell will last forever as
>|its own waste product. Presumably it won't contain harmful substances
>|that can get into water supplies, the air, etc. Now, if it does contain
>|some harmful substance, then we should recycle it.
>
>Aside from the fact that you keep ignoring the cost of making solar cells,
I'm not ignoring the cost of making the solar cells, you are simply
espousing the view that the cost of creation is the only cost. It isn't.
All the costs must be added in in order to find the actual price per unit
of energy delivered by any source.
>why are chemical poisons, which last forever, more acceptable than
Chemical "poisons" can be broken down using current technology.
>nuclear ones, which decay away? They are both invisible. They have both
>been used to kill people.
Nuclear poisons can't be broken down by us. They will decay over time,
but since we can break down chemical poisons it makes no sense whatsoever
to create nuclear ones.
>
>
>--
>Whatever happened to Global Warming? Could we have some Local Warming?
anmar mirza
not modern ones. I have built a number of such and the first thing you
look for is a well drained site where you can catch the morning sun,
and then you orient the doorway to do just that. In other words, a
place where you can't just stick a resistive heater. Many 'primitive'
peoples kept the same thoughts in mind when building shelter.
By no means was I trying to infer that modern man was that intelligent.
:)
Greg Franks
Yes we can. We only do it at the present time with the more
interesting elements for power generation and weapons. I have long
since forgotten what the fission products of U238 and Pu239 are.
--
Greg Franks, (613) 788-5726 | "The reason that God was able to
Systems Engineering, Carleton University, | create the world in seven days is
Ottawa, Ontario, Canada K1S 5B6. | that he didn't have to worry about
gr...@sce.carleton.ca ...!cunews!sce!greg | the installed base" -- Enzo Torresi
Paul Dietz
>In article <37...@cup.portal.com> Ordan...@cup.portal.com (Charles K Hughes) writes:
>> Nuclear poisons can't be broken down by us. They will decay over time,
>>but since we can break down chemical poisons it makes no sense whatsoever
>>to create nuclear ones.
>Yes we can. We only do it at the present time with the more
>interesting elements for power generation and weapons. I have long
>since forgotten what the fission products of U238 and Pu239 are.
In particular...
The chemicals being discussed (from advanced PV cells) are toxic
*elements*, not compounds, and so cannot be destroyed by chemical
processing. Such elements might include arsenic (from GaAs), selenium
(from CuInSe2) or cadmium (CdTe). The amounts wouldn't be very large.
They could probably be mostly recycled.
The "nuclear poisons" of long-term interest are mostly actinides,
not fission products (with some exceptions, such as some technetium
and iodine isotopes). Transuranic isotopes are all fissionable
by fast neutrons, I believe, and many can also be used as fuel in
thermal reactors (plutonium, for example, in mixed oxide fuel).
The GE PRISM reactor, a molten sodium fast reactor with on-site
electrochemical fuel reprocessing, burns its own actinides (which
never are in a form "cool" enough for clandestine diversion). Now,
the history of molten sodium cooled reactors is not exactly rosy, but
the design does serve as an existence proof.
Final comment (about the lifespan of a PV system): degradation of the
PV cell itself is only one thing to worry about. The metal and
concrete supports for the cells, electrical connections to the modules
and the plastic or glass encapsulating the cells may all degrade or
corrode when exposed to sun, rain and wind. Power conditioning
electronics and sun tracking systems (if present) can fail. Corrosion
due to faulty encapsulation has been a problem in some varieties of
modules, I understand.
Paul F. Dietz
di...@cs.rochester.edu
Roy Smith
> The chemicals being discussed (from advanced PV cells) are toxic
> *elements*, not compounds, and so cannot be destroyed by chemical
> processing. Such elements might include arsenic (from GaAs), selenium
> (from CuInSe2) or cadmium (CdTe).
I'll admit to not knowing much about heavy metal chemistry but I
think Paul's statement in somewhat misleading. True, you can't destroy
elements by chemical processing, but the real point is not so much whether
you can destroy them, but if you can render them harmless. The classic
example is taking chlorine and sodium, both elements, and both substances
which are not nice to children and other living things, and turning them
into plain old table salt.
I havn't the foggiest idea if there are analagous ways to render
arsenic, selenium, or cadmium harmless.
--
Roy Smith, Public Health Research Institute
455 First Avenue, New York, NY 10016
r...@alanine.phri.nyu.edu -OR- {att,cmcl2,rutgers,hombre}!phri!roy
"Arcane? Did you say arcane? It wouldn't be Unix if it wasn't arcane!"
Mark H. North
back and found --
Using commercially available solar cells we could produce all the energy
we (USA) now consume with about 10000 sq mi of 10 watt panels. The cost
would be on the order of 100 trillion dollars (yes, that's a T). That's a
big number but my question is this: Presumably such a project would take
tens of years to complete so the cost would be amortized over many years.
How can we determine if we can afford it based on GNP and all that. I've
done the calculation for my energy use and my house and found that it
would double the cost of my house (I have a fairly expensive house). If it's
possible for me as an individual (though painful) it should be possible for
a country as a whole, no? Particularly when amortized over a hundred years
or so.
BTW, if anyone has serious heartburn over my figures I can post them
it's only 10 or 12 lines.
Mark
Clayton Cramer
>
> A lot of people having been talking about the cost of solar power versus
> alternatives...those opposed to solar power as uneconomical are, perhaps,
> not looking at the complete picture. Solar power is probably bext compared
> to Nuclear power in terms of "manufacture" of the energy output.
> Nuclear power: fuel is dug from the ground, processed (slag is put aside
> to be buried), used to generate energy, remains of fuel are buried.
> Solar power: no digging, no processing, energy is converted from
> sunlight, no remains.
WRONG! Production of solar cells requires significant energy inputs
for refining and production. The ONLY use of solar power that can be
considered to be "free" is proper building design to take advantage
of differing summer/winter sun angles. Everything else involves
some manufacturing costs. When you find montrosities like Solar One
near Daggett, CA, with acres of aluminized mirrors focussing sunlight,
while being degraded by sandstorms, you have clear evidence that some-
one hasn't looked at the total energy input required. (Hint:
aluminizing mirrors is VERY energy intensive).
There's a place for solar power -- but most of the reason for
subsidies to it is because it is NOT cost-effective for most
situations.
--
Clayton E. Cramer {pyramid,pixar,tekbspa}!optilink!cramer
Gun Control: The belief that the government, with its great wisdom and
moral superiority, can be trusted with a monopoly on deadly force.
You must be kidding! No company would hold opinions like mine!
Loren Petrich
The issue of chemical vs. nuclear poisons was brought up yet
again. I feel that this anti-nuclear allergy that too many people have
will someday be remembered as one of the irrational phenomena of our
time. But I doubt that it is worse that the turn-of-the-century
enthusiasm for patent medicines made from radium and other radioactive
materials.
As to chemical poisons being decomposable, that depends on
what kind of chemical poison. Heavy metals cannot be chemically
decomposed. And some chemical poisons are difficult to decompose, such
as chlorinated hydrocarbons. The persistence of certain pesticides
like DDT should be well known. True, DDT and other such
non-biodegradable substances can be burned at high temperature, but
burning at high temperature is just that.
I remember some years back that the EPA was hoping to burn
some toxic wastes in a ship at sea, but some environmentalists didn't
like that idea very much.
I keep on being amazed by the anti-RTG movement. They complain
that those who send up RTG's on spacecraft have not done comprehensive
studies of possible alternatives. Yet I wonder if the anti-RTG people
have done anything similar. Consider the difficulties of doing
maintenance on a spacecraft, which usually cannot be brought back to
its designers. Millions of dollars and months of work go into
designing some spacecraft, so it is important that they be likely to
keep on working. One should try to use components that need as little
maintenance as possible, and RTG's fit the bill very well. They are
continuously "on" and have no moving parts. Solar cells are one common
alternative, but they tend to degrade over time and they cannot be
used in the outer Solar System, due to the extreme dilution of
sunlight there. A focused-sunlight system would have several problems.
A mirror would have to be kept pointing at the Sun, and the generating
system has an abundance of moving parts, which are an all-too-familiar
maintenance headache. There is also the problem of replenishing leaked
working fluid. And I am not aware of any focused-sunlight system that
has ever been used in a spacecraft.
Chemical reactions are out of the question. Buth fuel and
oxidizer would have to be taken along, which would add a serious
amount of weight for a months-long mission. The power sources usually
have an abundance of moving parts, and would have to be made redundant
for the sake of safety (if one breaks down, the others could keep on
moving). Batteries have a minimum of moving parts, but they usually
have a very low available power to mass ratio (ask any designer of a
battery-powered car). Fuel cells are relatively efficient, but even
they have moving-part problems, and they require liquid hydrogen and
oxygen, which must be kept away from heat. Systems using combustion
can use fuels and oxidizers that are liquid at room temperature, but
they also suffer from problems with moving parts -- consider typical
turbines and piston engines.
So either solar cells or RTG's are the way to go for
spacecraft. I presume that this is the standard argument.
In fairness to opponents of nuclear energy, I think that there
is a sociological question to be considered. Most nuclear energy has
been handled as large-scale projects. Simply consider how big a
typical nuclear reactor is and how long it takes to build one. Big
organizations have to justify their policies, and they often make
excuses for keeping on doing what they have been doing. And they
sometimes seem insensitive and arrogant. It's just what computers have
seemed like in their early years, before personal computers became
common.
And on the issue of safety, one should ask what kinds of
critical tests are possible. It is much easier to perform really tough
tests on an RTG than on a nuclear reactor, so one may feel more
confidence in their safety.
And another possible difficulty with solar cells -- how much
energy does it take to make them? They would not be too good if the
amount of energy needed to make them was only equal to their output
for several years of running. Has that question ever been addressed?
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
Loren Petrich, the Master Blaster: lo...@sunlight.llnl.gov
Since this nodename is not widely known, you may have to try:
Charles K Hughes
First a question: Why is this thread posted to three groups?
Now for the real reason for my post:
Mark writes:
>This subject has always intrigued me. I did a little research some time
>back and found --
>
>Using commercially available solar cells we could produce all the energy
>we (USA) now consume with about 10000 sq mi of 10 watt panels. The cost
>would be on the order of 100 trillion dollars (yes, that's a T). That's a
>big number but my question is this: Presumably such a project would take
>tens of years to complete so the cost would be amortized over many years.
>How can we determine if we can afford it based on GNP and all that. I've
Based on GNP I don't think you can. However, I think you are neglecting
the savings benefit - you need to subtract the current cost of fuel &
maintenance and add the new cost of maintenance to get the real cost.
Also, there are other factors that would have to be added in (as someone
pointed out in an earlier post) - the cost of money, climatic alterations,
startup costs [somebody has to make those 10000 sq miles of panels :) ],
etc, etc.
>done the calculation for my energy use and my house and found that it
>would double the cost of my house (I have a fairly expensive house). If it's
It might double the cost of your house, but you won't be worried about
losing power, power lines falling, heating or electricity bills, etc.
If we remained on a power grid the cost of electricity shouldn't increase
much, and it shouldn't do anything to the cost of your home.
>possible for me as an individual (though painful) it should be possible for
>a country as a whole, no? Particularly when amortized over a hundred years
No. A lot of people don't have homes. :)
>or so.
Banks don't do 100 year mortgages. :)
>
>BTW, if anyone has serious heartburn over my figures I can post them
>it's only 10 or 12 lines.
Please do, I don't have serious heartburn but there is a little pain
from that 100T figure, and the doubling of the cost of a home.
>
>Mark
John Whitmore
... in response to discussion of toxicity of solar cells
>>why are chemical poisons, which last forever, more acceptable than
>
> Chemical "poisons" can be broken down using current technology.
Not true; the poisons in semiconductor manufacture, at least,
are As and other heavy metals. These can be stored, but only
storage is possible. Of course, these metals were toxic before
they were mined from the ground...
>>nuclear ones, which decay away? They are both invisible. They have both
>>been used to kill people.
>
> Nuclear poisons can't be broken down by us. They will decay over time,
>but since we can break down chemical poisons it makes no sense whatsoever
>to create nuclear ones.
This is false assurance; in any case, nuclear byproducts are
shorter-lived toxins than simple chemically toxic heavy metals (they
break down in times of a few hours to days to months, and even the
worst of the wastes will die down in 200k years). Also, the fuel
for the nuclear plants had a half life of some millions of years when
it was in the ground; burning it DID dispose of the U-235, though
at the expense of a lot of radioactive daughter products.
Solar cells, by the way, are 100% silicon, and are NOT toxic.
Small amounts of aluminum for wire, and infinitesimal amounts of
phosphorous, boron, or other dopants, are not in any sense toxins
in the concentration that is used in semiconductor devices.
John Whitmore
Edward Fitzgerald
Thought the readers might be interested that the recent edition of J.C. Whitney
auto parts mailorder catalog advertises several battery chargers that are
solar cell technology. Prices range from $24.44 to $79.99 and all carry the
caveat "will not charge a "dead" battery", but hey, at least they are finally
good enough that three different manufacturers are offering them through this
one catalog... :)
leland.m.kornhaus
> In article <1990Dec31.1...@bronze.ucs.indiana.edu> ami...@silver.ucs.indiana.edu (anmar mirza) writes:
> >In article <11...@blenny.UUCP> ste...@blenny.UUCP (Stephen Kogge) writes:
> >>
> >> One point on the curve. I have a 30W (18" X 30") array. It charges
> >>a car battery that I keep outside. Here in Maryland it cannot produce enough
> battery in the system. My assumption was that the 34 Amp hour NiCd cells were
> old or damaged, the gell cells I tried next were used and followed
> the same poor charge characteristics. I hesitated using a car battery since
> it had to go outside. A friend of mine runs an electronics surplus store
> (Electronics Plus in College Park Md) and warned me that the acid fumes
> from the batteries he had for his emergency radio transmitter ate holes
> in his plumbing and I really ought to put the lead acid battery outside.
> I replaced all the blocking diodes at one point and saw an increase
> in charge current. I have considered using a trick I read about using power
> FETs instead of diodes. (I think it was FETs, I will have to check my notes).
> It's such an neat concept I continue to work with it.
>
> Steve Kogge
When you make your power calculations consider this rule of the thumb:
It takes 120% of the power a lead acid cell can hold to charge it 100%
It takes 140% of the power a nicad cell can hold to charge it 100%
These are rough figures but may explain why your results with the
nicads were so poor. I am assuming 6Ah of charge into a nicad yields
about 4.5 Ah of stored energy. The rest is dissipated as heat. Also,
a very cold lead acid cell (Probably - I'm guessing) has a higher
internal resistance which may result in losses. Im basing this guess
on the fact that at -20 F a car battery can only produce 15-20%
of it's rated Cold Cranking Amps. This may be due to the "slower"
chemical reaction within it
Keith Lofstrom;;;628-3645
>|sunlight, no remains.
Most solar cells are made with processes that are similar to those used to
make integrated circuits. A big IC fab turns out on the order of a million
wafers a year, and turns out tens of thousands of gallons of liquid toxic waste
and hundreds of thousands of cubic feet of gaseous waste in the process.
A million 6 inch wafers is about 20,000 square meters.
Assume an average insolation of 400 cal/cm2-day -- or about 180 watts/m2
average, for a flat plate collector without tracking. Given a collection and
storage efficiency of 14%, that's about 25 watts per square meter. So, this
million wafer plant is turning out about 500 Kw of generating potential a year.
If the cells last 20 years, that's 10 Mw-year of power per those thousands of
gallons of toxic waste. Scaled to nuclear plant size, that's millions of
gallons of waste per year for the same amount of power. I'd rather take a few
cubic meters of high-level radwaste any day.
Safety? Ever see the results of a fab fire? A co-worker had a wall clock
that had barely survived a silane fire. Interesting Salvadore Dali effect.
When I was with my former employer, we had building evacuations about twice
a year. Rule of thumb: safety costs money. As prices go down, safety may
go down, too. Imagine hundreds of fab fires a year...
That same silicon area could be turned into about 100 GW of power controller.
Some friends are working on controllers that will save about half the motor
power use on the New York subway. Other folks are working on reprogrammable
motors for the Detroit's assembly lines - smart controllers could save about
30% of power use. I saw a paper once on a smart power controller for the
off-hook detection for telephones; this circuit saves about 3 watts per
phone. There's a lot of phones out there. So why waste all that silicon
processing capability on such trivial power savers as solar photovoltaics?
Conclusion: Solar cells are an expensive joke for residential and bulk
industrial power. They are O.K. for satellites, mountaintops, toys,
calculators, and other niches.
*H*O*W*E*V*E*R* - they do have one saving grace, and one that I think makes
the whole thing worthwhile: the folks that DO install residential solar power
systems will find themselves with a trickle of power and not much money left.
So, if they want to survive, they will have to be fiendishly clever about
efficient and cost-effective power use. And the rest of us will benefit from
the hard-won knowledge here, even if those gaining that knowledge suffer
greatly for it.
Nothing succeeds at keeping a determined person at a task as effectively
as telling them how ridiculous they are. So for all of you solar folks
that I have made RAGING MAD, please take that emotional energy and make
something impressive with it. You are free to flame at me, but you will
bring about an energy revolution faster by building inexpensive and
attractive energy-saving products, rather than sounding off about evil
power companies and energy company conspiracies like a paranoid flake.
And if any of those products require efficient, cost-effective use of
silicon, give me a call ;-)
--
Keith Lofstrom kei...@loop.uucp ...!sun!nosun!loop!keithl (503)628-3645
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Power ICs
anmar mirza
>Most solar cells are made with processes that are similar to those used to
>make integrated circuits. A big IC fab turns out on the order of a million
>wafers a year, and turns out tens of thousands of gallons of liquid toxic waste
>and hundreds of thousands of cubic feet of gaseous waste in the process.
>A million 6 inch wafers is about 20,000 square meters.
Except for the amorphous panels. Though I prefer polycrystalline ones
myself.
>
>Conclusion: Solar cells are an expensive joke for residential and bulk
>industrial power. They are O.K. for satellites, mountaintops, toys,
>calculators, and other niches.
Well, I don't know about being a joke, but they are ideally suited for
those smaller installations.
>*H*O*W*E*V*E*R* - they do have one saving grace, and one that I think makes
>the whole thing worthwhile: the folks that DO install residential solar power
>systems will find themselves with a trickle of power and not much money left.
>So, if they want to survive, they will have to be fiendishly clever about
>efficient and cost-effective power use. And the rest of us will benefit from
>the hard-won knowledge here, even if those gaining that knowledge suffer
>greatly for it.
Actually, in some instances in design I have found times when it *is*
cost effective. It never works that way out in practicality. And I
*never* figure in inflation of cost for power when I have done cost
analysis. Like I have said before, you *don't* have to make any
sacrifices to do this, it just makes it a bit cheaper. And the cost to
someone who is buying a half a million dollar house is comparitively
small.
>Nothing succeeds at keeping a determined person at a task as effectively
>as telling them how ridiculous they are. So for all of you solar folks
>that I have made RAGING MAD, please take that emotional energy and make
>something impressive with it. You are free to flame at me, but you will
>bring about an energy revolution faster by building inexpensive and
>attractive energy-saving products, rather than sounding off about evil
>power companies and energy company conspiracies like a paranoid flake.
Actually, I am not raging mad at you, I get the feeling you are
baiting us. And personally I have never said that solar is the only
way to go. All along I have been saying that it will take a
combination of things to make it work. The biggest of all is a reduced
population level. Besides, if we have these attractive energy saving
products, we don't have to buy as many solar panels.
And I am not paranoid. You all are just out to get me :). If you want
to put your trust in a public utility, that is fine by me, I just want
people to have an alternative if they want it, and from the interest I
have found, people want it.
>And if any of those products require efficient, cost-effective use of
>silicon, give me a call ;-)
Ok, I would like 30 arco M75 48 watt panels 8-).
anmar mirza
>done the calculation for my energy use and my house and found that it
>would double the cost of my house (I have a fairly expensive house). If it's
>possible for me as an individual (though painful) it should be possible for
>a country as a whole, no? Particularly when amortized over a hundred years
>or so.
Really? Wow! You must use a *huge* amount of power.
For a *total* system, panels, inverters, batteries, control circuitry,
trackers, wiring and distribution panels (appliances are
not figured in due to the rather variable nature of them) I estimate
an *average* cost of around $60 a kWh/month. So if your home uses
1000 kWh a month it will cost around $60,000 for a total system,
amortized over 30 years. I figure after about another $20,000 (not
inflation adjusted) to overhual the system. Of course, the overhual
can be done in stages, so the cost isn't all at once, rather spread
out over 10 years or so. The $60 a kWh/month figure is an average. The
most expensive is when people are in the 500 kWh per month range, then
the cost is near $90 a kWh/month. The cheapest is for people who use
under 150 kWh/month, then the cost goes down to around $50 a
kWh/month. These are all for my area, with 4.5 hours peak average
sunlight. Areas farther north will be more expensive, and areas with
more sun will be cheaper.
There is an interesting curve on the prices, as the inverters,
batteries, panels, and wiring/distribution panels all interact
differently at different levels.
The cheapest is a hybrid system. a wind/solar or hydro/solar work very
well together, or even a wind/hydro/solar system. Hydro and solar work
very well for my area because in the late fall, winter and spring,
when the sun is least, there is usually more water. Hybrid systems can
bring the cost down to as low as $25 a kWh/month.
Also keep in mind, there is no absolute price, each system has it's
own costs, and can vary widely for the same monthly power consumption.
I am working on designing a system that will power a small community,
(around 1000 people). As soon as I get cost estimates I'll post them.
John Berryhill
>
>So you must think that solar cells grow on trees.
Actually, in a manner of speaking, they do.
anmar mirza
>
>auto parts mailorder catalog advertises several battery chargers that are
>solar cell technology. Prices range from $24.44 to $79.99 and all carry the
>caveat "will not charge a "dead" battery", but hey, at least they are finally
>good enough that three different manufacturers are offering them through this
>one catalog... :)
Yeah, they are good for keeping your car battery topped off when you
aren't driving your car. They usually put out in the range of
100-300mA. They can extend the life of your car battery by a year or
two. I personally wouldn't buy or use one, but if you have the spare
bucks sitting around they are ok. If you don't want to buy one, but
are interested in extending your car battery life, one thing you can
do is to plug it into a trickle charger at night. This will really
help in the winter.
Phil Ngai
|you took the statement out of context. In comparison to Nuclear Energy,
|the solar cells are the Nuclear power plant, *NOT* the fuel that runs the
|power plant.
I don't care if the poison comes from the construction of the physical
plant or the burning of the fuel, why do you?
|All the costs must be added in in order to find the actual price per unit
|of energy delivered by any source.
So how come you keep ignoring the manufacture of solar cells?
| Chemical "poisons" can be broken down using current technology.
Explain to me how you plan to break down elemental poisons like
Arsenic and Lead?
Charles K Hughes
> The issue of chemical vs. nuclear poisons was brought up yet
>again. I feel that this anti-nuclear allergy that too many people have
>will someday be remembered as one of the irrational phenomena of our
>time. But I doubt that it is worse that the turn-of-the-century
>enthusiasm for patent medicines made from radium and other radioactive
>materials.
I don't think the "allergy" is irrational given 3-mile island,
Chernobyl, lists of missing nuclear fuel, 55 gallon drums of nuclear waste
carelessly spewn across the ocean floor (& associated tales of using rifles
to shoot holes in drums that wouldn't sink), etc.
Radioactive materials are dangerous to complex organisms, and the more
RM that is around, the more dangerous it is (the probability of an
accident increases).
>
> As to chemical poisons being decomposable, that depends on
>what kind of chemical poison. Heavy metals cannot be chemically
>decomposed. And some chemical poisons are difficult to decompose, such
Heavy metals don't need to be decomposed - they can be refined and reused.
>as chlorinated hydrocarbons. The persistence of certain pesticides
>like DDT should be well known. True, DDT and other such
>non-biodegradable substances can be burned at high temperature, but
>burning at high temperature is just that.
What we can make, we can unmake. I don't think the environment should be
responsible for decomposing the unnatural chemical compounds that we
introduce into it.
The cost of "unmaking" is very high, mainly because it is cheaper in the
short run to just discard the waste byproducts. In the long run, these
byproducts will come back to haunt us - cf. Lovecanal, DDT, etc.
>
> I remember some years back that the EPA was hoping to burn
>some toxic wastes in a ship at sea, but some environmentalists didn't
>like that idea very much.
I can't imagine why.
>
> I keep on being amazed by the anti-RTG movement. They complain
What is RTG?
>that those who send up RTG's on spacecraft have not done comprehensive
A nuclear power plant?
>studies of possible alternatives. Yet I wonder if the anti-RTG people
>have done anything similar. Consider the difficulties of doing
>maintenance on a spacecraft, which usually cannot be brought back to
>its designers. Millions of dollars and months of work go into
>designing some spacecraft, so it is important that they be likely to
>keep on working. One should try to use components that need as little
>maintenance as possible, and RTG's fit the bill very well. They are
>continuously "on" and have no moving parts. Solar cells are one common
> [solar cells degrade]
> [focused sunlight systems require lots of moving parts]
> Chemical reactions are out of the question. Buth fuel and
>[good reasons deleted]
>moving). Batteries have a minimum of moving parts, but they usually
>have a very low available power to mass ratio (ask any designer of a
>battery-powered car). Fuel cells are relatively efficient, but even
>they have moving-part problems, and they require liquid hydrogen and
>oxygen, which must be kept away from heat. Systems using combustion
>can use fuels and oxidizers that are liquid at room temperature, but
>they also suffer from problems with moving parts -- consider typical
>turbines and piston engines.
>
> So either solar cells or RTG's are the way to go for
>spacecraft. I presume that this is the standard argument.
Hmmm...why not ground or space power generation for those satellites
that orbit the earth & moon? Deep space satellites are of little concern
here because once they leave, they're gone for good.
RTGs (assuming they are small nuclear plants) are dangerous in any orbit
that decays before the nuclear fuel becomes non-radioactive.
>
> In fairness to opponents of nuclear energy, I think that there
This is war buddy....you know the saying... :)
>
> And on the issue of safety, one should ask what kinds of
>critical tests are possible. It is much easier to perform really tough
>tests on an RTG than on a nuclear reactor, so one may feel more
>confidence in their safety.
I still don't like the idea of a blob of nuclear goop falling from the
sky into my living room. :)
>
> And another possible difficulty with solar cells -- how much
>energy does it take to make them? They would not be too good if the
>amount of energy needed to make them was only equal to their output
>for several years of running. Has that question ever been addressed?
If the energy is free, who cares how much it took to make them?
>
>
>$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
>Loren Petrich, the Master Blaster: lo...@sunlight.llnl.gov
>
>Since this nodename is not widely known, you may have to try:
>
>loren%sunlight...@star.stanford.edu
The real question (as I see it) is the *TRUE* cost. Burning fossil fuels
is cheaper than solar, nuclear is cheaper then solar, almost everything
is cheaper than solar if only the current fuel costs are looked at. If the
total cost of burning fossil fuels, using nuclear energy, etc is
totalled, solar will come out the clear winner.
Andrew Taylor
> When you find montrosities like Solar One
> near Daggett, CA, with acres of aluminized mirrors focussing sunlight,
> while being degraded by sandstorms, you have clear evidence that some-
> one hasn't looked at the total energy input required. (Hint:
> aluminizing mirrors is VERY energy intensive).
The latest LUZ plants (by Solar One you presumably mean their first) seem
close to economically competitive without tax credits. Certainly the LUZ people
believe they will be able to be able to build unsubsidised, commercially
competitive plants.
Given this, your claim that there is no net energy production is very
implausible even if energy was a large fraction of their costs.
Have you numbers to back up your claim?
Nothing about mirror degradation by sandstorms is mentioned in [1]. It does
mention the importance of mirror-washing and the cost-effective techniques
they have developed do this.
At the very least, the Luz plants are not "monstrosities" but
valuable tests of the engineering issues in building solar-thermal plants.
Andrew Taylor
[1] Power Engineering Review August 1989 "Solar Electric Generating Stations"
Charles K Hughes
> writes:
>>
>> A lot of people having been talking about the cost of solar power versus
>> alternatives...those opposed to solar power as uneconomical are, perhaps,
>> not looking at the complete picture. Solar power is probably bext compared
>> to Nuclear power in terms of "manufacture" of the energy output.
>> Nuclear power: fuel is dug from the ground, processed (slag is put aside
>> to be buried), used to generate energy, remains of fuel are buried.
>> Solar power: no digging, no processing, energy is converted from
>> sunlight, no remains.
>
>WRONG! Production of solar cells requires significant energy inputs
>for refining and production. The ONLY use of solar power that can be
>considered to be "free" is proper building design to take advantage
>of differing summer/winter sun angles. Everything else involves
>some manufacturing costs.
No, the energy requires no production costs. Solar energy is free. The
"power plant" or "engine" that converts solar energy into electricity
is where the manufacturing costs come into play. Since we have those costs
already (nuclear plants, coal/oil plants, power dams, etc) it is reasonable
to lump the cost of solar plants into that same group. "Light" requires
no refining in order to use it.
>When you find montrosities like Solar One
>near Daggett, CA, with acres of aluminized mirrors focussing sunlight,
>while being degraded by sandstorms, you have clear evidence that some-
>one hasn't looked at the total energy input required. (Hint:
No, you get clear evidence that some twit didn't take into account
the sandstorms.
>aluminizing mirrors is VERY energy intensive).
I believe you, I think flat glass with a silver coating, or even stainless
steel would be cheaper.
>
>There's a place for solar power -- but most of the reason for
>subsidies to it is because it is NOT cost-effective for most
>situations.
This is dependent on how you define "cost-effective". We are always going
to need energy, and our current mass-production is not truly cost effective.
Fossil fuel usage has a hidden cost. The oil we burn could bubble forth
from the ground like salt water, and be absolutely free, but we're going
to pay for burning it. I define cost-effective as startup, maintenance,
*AND* disposal costs. Disposal costs are whatever it takes to prevent the
byproducts from polluting the planet. We can ship nuclear wastes to the sun,
and/or capture all the emission from our engines, but neither of these
alternatives is as cheap as converting to solar. In general, everyone
likes to look at & cite the easily seen costs, but nobody talks about
the hidden costs, and those are the greatest of all.
>
>> Charles_...@cup.portal.com
>
>
>--
>Clayton E. Cramer {pyramid,pixar,tekbspa}!optilink!cramer
>Gun Control: The belief that the government, with its great wisdom and
>moral superiority, can be trusted with a monopoly on deadly force.
Aw, c'mon...the U.S. could probably use a good tyranny! :)
>You must be kidding! No company would hold opinions like mine!
.address above. :)
Brian or James
(tons of RTG and nuclear power stuff deleted)
>> And another possible difficulty with solar cells -- how much
>>energy does it take to make them? They would not be too good if the
>>amount of energy needed to make them was only equal to their output
>>for several years of running. Has that question ever been addressed?
>
> If the energy is free, who cares how much it took to make them?
*Sigh* Let's say that a solar cell takes 10 arbitrary energy
units to make. Let's say it produces 9 AEU during its life. That means
every time you install one, the net cost to the power production system
is one AEU. Things that use up more of a resource than they produce do
not, on the whole, make good sources for that resource.
It's reasoning like Mr. Hughes' that gives the anti-nuclear
folks a bad name.
James Nicoll
Donald Lindsay
(Keith Lofstrom;;;628-3645) writes:
>used to make integrated circuits. A big IC fab turns out on the
>order of a million wafers a year, and turns out tens of thousands of
>gallons of liquid toxic waste and hundreds of thousands of cubic feet
>of gaseous waste in the process.
>Scaled to nuclear plant size, that's millions of
>gallons of waste per year for the same amount of power.
I detect a humongous assumption, namely, that cell fab and chip fab
use the same amount of processing per area.
Some ICs are built with more than 20 processing steps (ie layers). I
can't imagine how a mass-market solar cell could be that intricate or
various. Chips also have about three orders of magnitude more
pins/area. Chips also require the highest purity of materials, and
their yield depends on very stringent definitions of "working". Even
a reject solar cell is likely to worth using.
You are also making the big, fat assumption that those "most" solar
cells have anything to do with the way we will make things in the
future. Glad to hear you have such faith in technological progress.
The US government agreed with you: that's why they axed the solar R&D
funding, a decade-odd ago. I can't express politely what I think of
their foresight. Am I to think better of yours?
--
Don D.C.Lindsay .. temporarily at Carnegie Mellon Robotics
Paul Dietz
>In article <1991Jan3.0...@loop.uucp> kei...@loop.uucp
> (Keith Lofstrom;;;628-3645) writes:
>>Most solar cells are made with processes that are similar to those
>>used to make integrated circuits. A big IC fab turns out on the
>>order of a million wafers a year, and turns out tens of thousands of
>>gallons of liquid toxic waste and hundreds of thousands of cubic feet
>>of gaseous waste in the process.
>
>>Scaled to nuclear plant size, that's millions of
>>gallons of waste per year for the same amount of power.
>
>I detect a humongous assumption, namely, that cell fab and chip fab
>use the same amount of processing per area.
Another assumption: that the area of the cells = the area of the
collector.
In fact, if sophisticated, expensive single crystal Si, GaAs or high
performance tandem cells are ever used on earth on a large scale, they
will be used with lens/mirror concentrators at concentration ratios of
100 or greater. This only works in areas with lots of direct sunlight,
like the southwest, but that's the sunniest part of the country anyway.
Flat plates, if they are to have large grid-connected market penetration,
have to be very cheap, which means using thin layers of more crude
materials deposited by cheap techniques (for example, electroplated
CdTe). These polycrystalline or amorphous materials are of much
lower quality (and cost) than the materials used in IC manufacture.
Paul F. Dietz
di...@cs.rochester.edu
Charles K Hughes
>writes:
>|you took the statement out of context. In comparison to Nuclear Energy,
>|the solar cells are the Nuclear power plant, *NOT* the fuel that runs the
>|power plant.
>
>I don't care if the poison comes from the construction of the physical
>plant or the burning of the fuel, why do you?
Because you aren't taking into account the poison that comes from the
physical plant. If you want to take that into account, then that just adds
similar amounts of poison to each side of the argument. In addition, I'm not
talking solely about photovoltaic cells - there are other ways to convert
the suns energy.
>
>|All the costs must be added in in order to find the actual price per unit
>|of energy delivered by any source.
>
>So how come you keep ignoring the manufacture of solar cells?
I don't. Those are startup costs like the building of a nuclear plant.
>
>| Chemical "poisons" can be broken down using current technology.
>
>Explain to me how you plan to break down elemental poisons like
>Arsenic and Lead?
I don't, and never said so. I said "chemical" and you are talking about
"elemental". Elemental poisons are not broken down, they are recycled into
the system.
>
>--
>Whatever happened to Global Warming? Could we have some Local Warming?
Gary Coffman
>Chernobyl, lists of missing nuclear fuel, 55 gallon drums of nuclear waste
Actually Three Mile Island showed that primary confinement works even in
an induced loss of cooling accident. Chernobyl showed that even the worst
scenario put up by the anti-nukes, core meltdown, *no* confinement,
and a core fire for God's sake, didn't result in the fearmongers predicted
mega-deaths.
>> As to chemical poisons being decomposable, that depends on
>>what kind of chemical poison. Heavy metals cannot be chemically
>>decomposed. And some chemical poisons are difficult to decompose, such
>
> Heavy metals don't need to be decomposed - they can be refined and reused.
So can nuclear fuels, but we're soooo scared we don't.
>> I keep on being amazed by the anti-RTG movement. They complain
>
> What is RTG?
Radioisotope Thermoelectric Generator. A completely sealed, no moving
parts, no active control system, lump of radioactive material that
gives off enough heat through natural radioactive decay to heat a
thermopile enough to generate useful amounts of electrical power.
>> So either solar cells or RTG's are the way to go for
>>spacecraft. I presume that this is the standard argument.
>
> Hmmm...why not ground or space power generation for those satellites
>that orbit the earth & moon? Deep space satellites are of little concern
>here because once they leave, they're gone for good.
Beamed power has been very strongly opposed by the enviornmentalists because
of the supposed danger of the microwave power beam used to transmit the
energy. Or were you planning to use a *really* long extension cord.
>
> RTGs (assuming they are small nuclear plants) are dangerous in any orbit
>that decays before the nuclear fuel becomes non-radioactive.
RTGs are designed to survive rentry without breaching their sealed shielding.
The designs used have been exhaustively tested by actually sending
dummy units up and causing them to renter. They work.
>> And on the issue of safety, one should ask what kinds of
>>critical tests are possible. It is much easier to perform really tough
>>tests on an RTG than on a nuclear reactor, so one may feel more
>>confidence in their safety.
>
> I still don't like the idea of a blob of nuclear goop falling from the
>sky into my living room. :)
Hook a couple of leads to it and run your computer off of it for a few
years. Now that's a UPS!
>> And another possible difficulty with solar cells -- how much
>>energy does it take to make them? They would not be too good if the
>>amount of energy needed to make them was only equal to their output
>>for several years of running. Has that question ever been addressed?
>
> If the energy is free, who cares how much it took to make them?
If it takes more fossil fuel to manufacture them than they will produce
over their operating lifetime you care. And it does take more energy
to manufacture them than they produce over their lifetime. They are
net energy losers. Also the manufacture of solar cells requires some
very nasty chemicals that must be disposed of after manufacture.
> The real question (as I see it) is the *TRUE* cost. Burning fossil fuels
>is cheaper than solar, nuclear is cheaper then solar, almost everything
>is cheaper than solar if only the current fuel costs are looked at. If the
>total cost of burning fossil fuels, using nuclear energy, etc is
>totalled, solar will come out the clear winner.
>
>Charles_...@cup.portal.com
For solar cells the answer is a clear no on an energy basis and an
enviornmental basis. For solar boilers driving freon turbines the
energy cost is a net win. But the enviornmental costs are bad considering
what the inevitable freon leaks will do to the ozone layer. Maintence
costs in general are high since efficiency is very low and you need a
lot of them to produce useful power. Perhaps the worst effect of using
large scale solar energy to replace fossil fuels or nuclear plants is the
effect on the climate. By placing large arrays of solar cells or solar
turbines on the surface of the earth, you dramatically change the reflectivity
of the earth in that area. A good solar collector absorbs almost all of the
solar energy striking it and reradiates very little thus creating a
hotspot in the local enviornment. The effects on the weather of the several
hundred square miles of solar collectors needed to replace one nuclear
plant should be spectacular.
Gary
Richard Foulk
>>|sunlight, no remains.
>
>Most solar cells are made with processes that are similar to those used to
>make integrated circuits. A big IC fab turns out on the order of a million
>wafers a year, and turns out tens of thousands of gallons of liquid toxic waste
>and hundreds of thousands of cubic feet of gaseous waste in the process.
>A million 6 inch wafers is about 20,000 square meters.
>
I'm certainly not an expert, but the similarity between solar cell production
and IC manufacture might easily be out-weighted by their differences.
IC production requires a number of additional processes that don't seem
applicable to solar cells. Does anyone have real information to add?
--
Richard Foulk ric...@pegasus.com
Lucius Chiaraviglio
writes:
>In <37...@cup.portal.com> Ordan...@cup.portal.com (Charles K Hughes) writes:
>> A lot of people having been talking about the cost of solar power versus
>>alternatives..
> why can't you do this with nuclear? (you can, it is currently
> politicaly incoirrect to try, or even talk about it)
Can you think of a way to recycle all of the various radioisotopes
generated by fission and its associated side-reactions? Sure, some of them
are potentially useful (not necessarily safely usable, but that is another
issue), but I doubt that you are really going to be able to find a use for all
of the other moderate- to long- lived radioisotopes. If you can come up with
such high-demand uses, I am looking forward to hearing them.
>> Under the absolute best case scenario nuclear waste is with us for
>>thousands of years.
> Wrong. Worst case is 50 years before the total toxicity is
>below other types of waste produced by "natual" fired power plants.
Could you provide references for this? This runs counter to most of
what I have read.
>Ask the Canadians, they have been storing rad waste so long it has become
>safe to dig up and do tests on.
Safe after taking what precautions? With enough precautions, digging
into the rubble of Chernobyl would be "safe," but with enormous cost, and
requiring that everyone involved is superhumanly careful.
>> Am I missing something here? Sure, producing nuclear energy is cheap,
>>but what are the hidden costs incurred in disposal? In accidents?
>>Compare the *TRUE* total costs and Solar energy looks like it is free.
> What are the hidden costs of Solar? Solar thermal produces
> oxygen-nitrogen compounds by the 10s of tons per day,
Why do you say this? I suppose solar thermal could be arranged to
produce fair quantities of nitrogen oxides if one really wanted to, but I see
no way that the solar thermal schemes I have heard of which actually have
produced useful amounts of energy could produce any nitrogen oxides at all.
> Solar
> photovoltaic (after you dispose of the toxic wases from it's
> construction) has an ENORMOUS continuous labor maintenence cost.
> You figure it: How many square miles of solar collector can
> you dust off once a day?
This is not necessary in all locations. In some places, the rain will
do most of this for you.
> There would have to be hundreds of square
> miles to replace one coal/oil/nuclear generation plant. You want
> decentralized? No thank you, I'll hire the utilities to wipe
> the dust off, and do it in a central location where costs can
> be kept down.
For areas of high population density, this is true, but as others have
posted already decentralization (not necessarily solar, even) is actually the
most economical thing for some people in sparsely-populated areas.
> Besides, personal solar photovoltaic is DANGEROUS
> around the house: Your kids will burn their fingers in the basement
> full of lead acid batteries you would have to have for cloudy
> days, the occasional hidrogen-oxygen gas explosions from the
> batteries charging would get your house insurance canceled.
It is the owner's responsibility (which could be regulated by building
codes, etc.) that the batteries be stored safely. This is not too hard to do.
(Although I must say that I would rather not increase the amount of lead that
has to be kept track of in scattered places. We need better, safer
batteries.) I have heard of batteries exploding occasionally, but never
heard of anyone's house insurance being canceled on this account.
And
> at least once a week, you would have to risk life and limb
> climbing up on the roof to wipe the dust, leaves, snow etc off
> the collectors (efficiency goes way down with only a fine coating
> of dust).
As I said, in some areas the need to do this would be less frequent.
(And in some areas I have been in, it would be more frequent. Blortf.) In
some cases, like on many one-story houses, one could easily install the solar
cells where they could be hosed down from the ground, and maybe a squeegee on
a long pole used to wipe them off (I'm not sure about this last part -- they
may be too fragile for this -- putting them under a layer of glass would solve
that, but would reduce their efficiency).
> Do you know that 10's of THOUSANDS of americans loose
> their lives climbing up on the roof just to clean their gutters
> a couple of times a year? If we all climbed up on our roofs
> once a week, it would decimate our population.
I don't like climbing up to clean gutters either. (-: I would
probably just let them get stopped up. :-) If I have to put solar cells on
an area of my house (if I ever get one) where I can't hose them down from the
ground, I will also install a catwalk and railing up their so that even if I
trip on untied shoelaces while standing on wet ice coated with banana peels I
won't go off the roof. I would recommend the same for other roof
installations requiring periodic or frequent maintainance.
> [. . .] Rad wastes have the
> ADVANTAGE of having a half life! This means we know how long
> before they disapear into the NATURAL background radiaion.
Exactly. In the case of nuclear power plant waste, this is
inconveniently long.
> Here's a piece of misinformation you seem to subscribe to:
> rad wastes are highly radioactive and last for thousands of years?
> Wrong. Anything that is highly radioactive has a short half life
> by definition (more of the nuclei going per second). Anything that
> lasts for thousands of years has a long half life by deffinition,
> so it is not very radioactive an can safely be handled, eaten, etc.
> You cannot have it both ways, but this myth continues to be used
> by people who do not know or think about the concequences.
Okay, here's a counterexample: the combination of radium and its
daughter nuclei (actually, the radium may be bad enough by itself, but I can't
remember enough of the details of which of the radionuclides emit what types
of radiation). Radium is considered highly dangerous radioactively (as well
as chemically), yet it has a half-life in the few thousands of years.
For safety purposes, "highly radioactive" means any one or more of three
things: the number of disintegrations per second per unit of matter, the
energy in the radiation, and the penetrance of the type of radiation. I am
sure other people here can think of plenty of other counterexamples. Also, I
find your statements about what is "not very radioactive" and "can safely be
handled, eaten, etc." rather suprising, but I welcome your willingness to eat
radium -- okay, that's not quite fair due to the chemical toxicity -- how
about a nice slice of bread made from wheat grown on (weakly radioactive at
that) carbon-14 dioxide? :-)
> I would
> hope that the general education level on the net would tend to
> result in people who CAN reason, but I dispair...
As you can see, some of us have reasoned about fission power, and thus
remain skeptical and suspicious.
--
| Lucius Chiaraviglio | Internet: ch...@midway.uchicago.edu
Lucius Chiaraviglio
(Paul Dietz) writes:
>In fact, if sophisticated, expensive single crystal Si, GaAs or high
>performance tandem cells are ever used on earth on a large scale, they
>will be used with lens/mirror concentrators at concentration ratios of
>100 or greater. This only works in areas with lots of direct sunlight,
>like the southwest, but that's the sunniest part of the country anyway.
Uh -- won't the resulting overheating kill the solar cells, or at
least inactivate them for the duration of exposure to concentrated direct
sunlight? My information on this may be out of date, but I thought that even
a very hot day without concentration of sunlight was enough to lower the
efficiency of photovoltaic cells. Also, using concentrators takes away most
of the advantages that solar cells have in not absolutely requiring unclouded
sunlight in order to produce a significant amount of electrical energy.
Lucius Chiaraviglio
>In article <37...@cup.portal.com> Ordan...@cup.portal.com (Charles K
>Hughes) writes:
>>
>> I don't think the "allergy" is irrational given 3-mile island,
>>Chernobyl, lists of missing nuclear fuel, 55 gallon drums of nuclear waste
>
>Actually Three Mile Island showed that primary confinement works even in
>an induced loss of cooling accident. Chernobyl showed that even the worst
>scenario put up by the anti-nukes, core meltdown, *no* confinement,
>and a core fire for God's sake, didn't result in the fearmongers predicted
>mega-deaths.
Chernobyl did result in a lot of casualties, and we probably have a
lot of delayed casualties in store, considering what radiation exposure from
nuclear weapons testing has done to many of its victims. Sounds pretty bad to
me. In areas where the pollution that could be eliminated by installation of
nuclear power is worse than having a Chernobyl disaster every once in a while
(any claims that our reactors are immune to a disaster that bad must be taken
with several grains of sodium-22 chloride :-) ), arguably the installation of
nuclear power is worthwhile, IF no better alternatives are available. Claims
that I have seen that no better alternatives to nuclear power and fossil fuels
are available have been less than entirely convincing.
>>> As to chemical poisons being decomposable, that depends on
>>>what kind of chemical poison. Heavy metals cannot be chemically
>>>decomposed. And some chemical poisons are difficult to decompose, such
>>
>> Heavy metals don't need to be decomposed - they can be refined and reused.
>
>So can nuclear fuels, but we're soooo scared we don't.
Some of the radioisotopes from them can be reused, but all of them?
Doesn't seem likely.
>>> And another possible difficulty with solar cells -- how much
>>>energy does it take to make them? They would not be too good if the
>>>amount of energy needed to make them was only equal to their output
>>>for several years of running. Has that question ever been addressed?
>>
>> If the energy is free, who cares how much it took to make them?
>
>If it takes more fossil fuel to manufacture them than they will produce
>over their operating lifetime you care. And it does take more energy
>to manufacture them than they produce over their lifetime. They are
>net energy losers.
That's what I thought too, but somebody posted here a couple of years
ago that some solar cell plant in the United States was running entirely on
the power generated by solar cells it had manufactured. Anyone know about
this? Or is this solar cell plant cheating by offloading some procedure
requiring lots of electrical energy onto its suppliers?
> [. . .] For solar boilers driving freon turbines the
>energy cost is a net win. But the enviornmental costs are bad considering
>what the inevitable freon leaks will do to the ozone layer.
The solar thermal schemes I have heard of do not use freon, although
that would work. The schemes I have heard of either heat the water directly
with the concentrated sunlight, or else heat oil which then transfers its heat
to water by means of a heat exchanger. I think the Luz collectors use the
latter method, but I am not sure.
> Maintence
>costs in general are high since efficiency is very low and you need a
>lot of them to produce useful power.
These factors don't necessarily connect.
Last time I heard, the Luz installation was VERY CLOSE to being cost-
competitive with conventional power generation methods, although it does stack
the deck in its favor by using conventional burners (I forgot whether oil or
gas) to run the steam turbines at night and on cloudy days (of which Arizona
doesn't have much).
> Perhaps the worst effect of using
>large scale solar energy to replace fossil fuels or nuclear plants is the
>effect on the climate. By placing large arrays of solar cells or solar
>turbines on the surface of the earth, you dramatically change the reflectivity
>of the earth in that area.
This is true. However, the effect would not be enormously greater
than that of all of the waste heat generated by a conventional (including
nuclear) power plant, which converts no more than 45% of its generated heat
into electrical energy.
> A good solar collector absorbs almost all of the
>solar energy striking it and reradiates very little thus creating a
>hotspot in the local enviornment.
If we had solar collectors that good, solar energy would already be
competitive with overkill.
> The effects on the weather of the several
>hundred square miles of solar collectors needed to replace one nuclear
>plant should be spectacular.
See above about waste heat from the nuclear power plant. Also, when a
nuclear plant blows real bad, it will eclipse the climactic effects generated
by a solar installation of equivalent power output.
Paul Dietz
>In article <19...@ke4zv.UUCP> ga...@ke4zv.UUCP (Gary Coffman) writes:
>>> Heavy metals don't need to be decomposed - they can be refined and reused.
>>
>>So can nuclear fuels, but we're soooo scared we don't.
>
> Some of the radioisotopes from them can be reused, but all of them?
>Doesn't seem likely.
Actually, all the actinides (which comprise most of the long term
waste hazard) can be reused as fuel, at least in fast reactors.
> That's what I thought too, but somebody posted here a couple of years
>ago that some solar cell plant in the United States was running entirely on
>the power generated by solar cells it had manufactured. Anyone know about
>this? Or is this solar cell plant cheating by offloading some procedure
>requiring lots of electrical energy onto its suppliers?
Cheated, I bet; production of elemental silicon is an energy-intensive
process. Purification by conversion to chlorosilanes is also very
energy intensive.
>that would work. The schemes I have heard of either heat the water directly
>with the concentrated sunlight, or else heat oil which then transfers its heat
>to water by means of a heat exchanger. I think the Luz collectors use the
>latter method, but I am not sure.
Right, although they want to switch to direct heating of steam in the
collectors. This would simplify the plants considerably, but steam is
corrosive, and the collector pipes would have to be stronger. They
are trying it in a plant being built in Spain. If this works it could
reduce their cost to $.06/kWh (utilities buy baseload power for
$.02-.03/kWh, more for peaking power).
> Last time I heard, the Luz installation was VERY CLOSE to being cost-
>competitive with conventional power generation methods, although it does stack
>the deck in its favor by using conventional burners (I forgot whether oil or
>gas) to run the steam turbines at night and on cloudy days (of which Arizona
>doesn't have much).
California, around Daggett and Boron, not in AZ. Note that they would
like to burn more gas, but they currently get some sort of favorable
regulatory treatment that would go away if they got more than 25% of
their energy from gas. Natural gas is really cheap now, especially in
the summer when Luz's plants operate most. At 38% efficiency (about
that of Luz's plants) and at the summer spot market price for natural
gas, the fuel cost of electricity would be less than $.02/kWh.
Most of the planned new generating capacity in the US is gas fired.
>than that of all of the waste heat generated by a conventional (including
>nuclear) power plant, which converts no more than 45% of its generated heat
>into electrical energy.
The most efficient generator on-line is a natural gas fired combined
cycle plant in Europe with an efficiency of 52%. Efficiencies should
continue to rise; MCFC/steam turbine combined cycle plants may exceed
70% efficiency, if and when they come into use, and should also
have far lower NOx emissions.
Paul F. Dietz
di...@cs.rochester.edu
Doug Mohney
>In article <37...@cup.portal.com> Ordan...@cup.portal.com (Charles K Hughes) writes:
>>
>> I don't think the "allergy" is irrational given 3-mile island,
>>Chernobyl, lists of missing nuclear fuel, 55 gallon drums of nuclear waste
>
>Actually Three Mile Island showed that primary confinement works even in
>an induced loss of cooling accident. Chernobyl showed that even the worst
>scenario put up by the anti-nukes, core meltdown, *no* confinement,
>and a core fire for God's sake, didn't result in the fearmongers predicted
>mega-deaths.
Well, actually, you're wrong as hell on Chernobyl for several reasons:
The core did not pull a full meltdown. The initial explosion helped to
vent heat (yes, as perverse as that sounds) and distribute some of the
fissionables. The Soviets rushed like hell to re-enforce the bottom of the
core and to cool down the fire, but it wasn't like tiddly-winks to
fix things.
Had the fires cut the wrong way, you would have involved anywhere from another
1 to 3 reactors and had a massive radiation release.
Both TMI and Chernobyl demonstrated that s**t happens. Neither accident
followed the "predicted scheme."
Finally, you cannot tally up the cancer deaths over the next 20 years. Nor,
given the chaos which occured in and around the countryside, the exact number
of directly related deaths due to direct radiation exposure & the cleanup
efforts.
Would you like to live next to Chernobyl? I'm sure there are plenty of people
who would sell you their farms real cheap...oops..most of them have already
been relocated away from the site because the background levels are too
hazardous for exposure over any length of time.
Doug Mohney, Operations Manager, CAD Lab/ME, Univ. of Maryland College Park
* Ray Kaplan was right *
Paul Dietz
Heating would be a problem (at least for silicon; GaAs cells are more
heat tolerant), so the cells would be mounted in actively cooled
fixtures, probably with some liquid coolant loop.
The ability to use diffuse sunlight is an advantage, but high
concentration is also nice -- silicon solar cells (at least) become
more efficient at high concentration ratios (at constant temperature).
I'm not sure why this is. Also, concentration schemes should have
a higher overall efficiency than flat plate schemes, since one can
use more sophisticated cells that would be absurdly expensive
with unconcentrated light. This would become important in the
long run if the area covered by collectors becomes significant.
It is possible to achieve low concentration ratios, even for diffuse
light, by means of involute mirrors or fluorescent concentrators.
Paul F. Dietz
di...@cs.rochester.edu
Phil Ngai
|>I don't care if the poison comes from the construction of the physical
|>plant or the burning of the fuel, why do you?
|
| Because you aren't taking into account the poison that comes from the
|physical plant. If you want to take that into account, then that just adds
|similar amounts of poison to each side of the argument. In addition, I'm not
"Similar" amounts of poison? You just make this up and expect us to believe.
|>So how come you keep ignoring the manufacture of solar cells?
|
| I don't. Those are startup costs like the building of a nuclear plant.
"Like". I love the way you non-technical people "analyze" things. But
I suppose when you don't know what you're talking about, that's what
you have to resort to.
| I don't, and never said so. I said "chemical" and you are talking about
|"elemental". Elemental poisons are not broken down, they are recycled into
|the system.
(we are supposed to believe that elements are not chemicals)
Ok, then we'll recycle radioactive material as nuclear fuel. This makes
nuclear power perfectly clean and non-polluting.
--
As long as a woman is weaker than men, she will fear
violence at their hands.
Mark Biggar
>>been used to kill people.
> Nuclear poisons can't be broken down by us. They will decay over time,
>but since we can break down chemical poisons it makes no sense whatsoever
>to create nuclear ones.
But, where does the energy to break down those poisons come from. I wouldn't
be supprised if the energy to break down the toxins produced by solar cell
manufacture to completely safe stuff (remember CO2 and Methane are both
greehouse gases) is some large precent of the total lifetime power output
of the solar cells.
--
Mark Biggar
John G. DeArmond
>In article <19...@ke4zv.UUCP> ga...@ke4zv.UUCP (Gary Coffman) writes:
>>In article <37...@cup.portal.com> Ordan...@cup.portal.com (Charles K
>>Hughes) writes:
>>>
>>> I don't think the "allergy" is irrational given 3-mile island,
>>>Chernobyl, lists of missing nuclear fuel, 55 gallon drums of nuclear waste
>>
>>Actually Three Mile Island showed that primary confinement works even in
>>an induced loss of cooling accident. Chernobyl showed that even the worst
>>scenario put up by the anti-nukes, core meltdown, *no* confinement,
>>and a core fire for God's sake, didn't result in the fearmongers predicted
>>mega-deaths.
Three Mile Island showed us even more than Gary states. As a person who
spent over 3 years at TMI after the accident, designed their Post-Accident
radiation monitoring system, qualified their diesel generator system, ad
nausium, I speak with a bit more authority than simply having an education
via the 6 o'clock news.
What TMI demonstrated is that under the worst case scenario, that is, a
scenario in which there is bulk melting of the core, the systems work
and there is no danger presented to the public. In point of fact, TMI
WAS a WORST CASE LOCA. The core was allowed to remain uncovered
long enough for the bulk of it to melt. But instead of burning through
the reactor vessel, evaporating 2 million gallons of water in the sump,
burning through 35 feet of concrete in the building foundation and killing
millions as it enters the water table, the liquid core simply ran to the
bottom of the vessel and was quenched by the residual water contained
therein. What remained was what you'd expect of a ceramic material
after being quenched while white hot. A mass of fractured rubble.
The authorities on the subject that I've discussed (I'm not a
core dynamics expert, my speciality is radiation measurement systems)
pretty much agree that TMI represents the worst case accident.
The perceived hazards stemed from the medias' hysteria, the govenor's
hysteria and the plant staff's self-admitted mishandling of the
public relations. The last part is somewhat understandable since this
was the first time to have to deal with this kind of event. Plus, of
course, the country was still suffering from the "malaise of the spirit"
induced by the Georgia White Trash, um, I mean Jimmy Carter.
Though I've never seen any numbers published, I wonder how many people
were hurt by the hysteria-induced evacuations? I wonder how many people
suffered stress problems or were in car wrecks while leaving? There
were casualties from TMI but none related to the accident.
> Chernobyl did result in a lot of casualties, and we probably have a
>lot of delayed casualties in store, considering what radiation exposure from
>nuclear weapons testing has done to many of its victims. Sounds pretty bad to
>me.
Chernobyl sounds like a minor incident to me. The prompt casulties numbered
perhaps a few hundred. Not unlike that from a flood or airline accident.
Regrettable but not earth shattering. The delayed casulties must be
evaluated statistically. From that perspective, they must be considered in
the same class as other statistically measured deaths. Similiarly,
the risk must be compared with competing technologies. If one compares the
estimated few thousand excess cancers from Chernobyl over the next
50 years to the estimated few hundred thousand deaths due to the coal
cycle, Chernobyl looks like a pretty safe place to be. By any rational
evaluation, Chernobyl was a rather minor event as disasters go.
>In areas where the pollution that could be eliminated by installation of
>nuclear power is worse than having a Chernobyl disaster every once in a while
>(any claims that our reactors are immune to a disaster that bad must be taken
>with several grains of sodium-22 chloride :-) ),
I know that it is impolite to confuse this argument with facts but I must
do so. You are flat wrong. A Chernobyl-style event is physically impossible
with America's reactor designs. For a Chernobyl to happen, the following
events would ALL have to take place:
* All reactor safeguards would have to be bypassed. Not impossible but
highly improbable and technically very difficult.
* The reactor core would have to have a positive temperature coefficient
of reactivity. American reactors are designed with a large NEGATIVE
temco not only for safety but because it makes them much easier to
regulate. There is sufficient negative reactivity designed in that
most cores will start shutting down with a 50 degree rise in temperature.
* The reactor would have to be capable of running dry. This is impossible
since water is also the moderator in American designs. In fact, the
power is controlled over a fairly wide range in BWR reactors by
controling the steam void fraction.
* The containment would have to be breeched or left open. Short of a
military assault on the reactor, this is pretty much an impossibility.
* Several chemical and physical laws would have to be broken. Example:
The big killers at Chernobyl were the most abundant long lived
fission products, Cs-137 and the iodines, primarily I-131. In an
aqueous environment such as in a reactor coolant system, the Cs and
I combine to form a chemically inert and non-volatile compount
cesium iodide. This is exactly what happend at TMI. The Cs and I
concentrations in the containment atmosphere were orders of magnitude
less than the models predicted because most of the stuff was in
solution or plated out on the containment surfaces.
An extreme demonstation of the intrinsic safety of American reactors was
the BORAX experiments conducted in the desert in the late 60s. In this
experiment, a small scale model but functioning reactor was constructed
in the desert. As the final experiment, the control rods were forcibly
and rapidly ejected from the core by explosives. The core went prompt
critical but shut down within milliseconds as the water boiled from the
massive heat generation. The vessel exploded from the steam pressure
but the fuel elements retained their structural soundness and no melting
occured.
>arguably the installation of
>nuclear power is worthwhile, IF no better alternatives are available. Claims
>that I have seen that no better alternatives to nuclear power and fossil fuels
>are available have been less than entirely convincing.
That sir, is simply because you've not looked any further than the newspapers
for your education. If you had given even a cursory review to the literature,
you would not need convincing. Of course it is easy to simply dismiss all
the world's experts as self-serving but if you do that, then who ARE the
experts? Dan Rather? Hardly.
The fact of the matter is that there is no energy source proposed or
in production that is better than nuclear power. Especially when the
entire fuel cycle impact on the environment is rationally assessed,
nuclear is the big winner. With a fully closed loop fuel cycle, little
new raw uranium would be required and the quantity of concentrated high level
waste would be miniscule. There have been several designs proposed and
some tested for "waste burner" reactors. These are specially designed
nuclear reactors designed to transmute reactor waste into either inert
isotopes or into radioactive isotopes with short half-lives. The little
that remains is easily contained using technology now in common use in
the rest of the world.
The problem is that the public has chosen to ignore the experts and
instead believe what the media and the vested interests have told them
to believe. As a result, we've given up on the nuclear option for this
century. And when we finally wake up and realize that we must again
go back to nuclear, we'll have given the market over to the Japanese
and the French who will gladly sell us reactors that they've perfected
in the meantime.
So Lucius, you CANNOT say that you've examined the facts and have decided
that nuclear is dangerous. AT most, you've formed an uninformed opinion
based on non-facts as presented in the media and the pop-science press.
Take the time, read the literature, maybe attend some conferences
and then come back with an INFORMED opinion.
John
--
John De Armond, WD4OQC | "Purveyors of speed to the Trade" (tm)
Rapid Deployment System, Inc. | Home of the Nidgets (tm)
Marietta, Ga | "To be engaged in opposing wrong offers but
{emory,uunet}!rsiatl!jgd | a slender guarantee of being right."
Greg Kuperberg
>"Similar" amounts of poison? You just make this up and expect us to believe.
Please take this discussion elsewhere. It doesn't belong in sci.physics.
Thank you.
----
Greg Kuperberg
gr...@math.berkeley.edu
Clayton Cramer
> >In article <37...@cup.portal.com>, Ordan...@cup.portal.com (Charles K Hughes)
# ## Solar power: no digging, no processing, energy is converted from
# ## sunlight, no remains.
# #
# #WRONG! Production of solar cells requires significant energy inputs
# #for refining and production. The ONLY use of solar power that can be
# #considered to be "free" is proper building design to take advantage
# #of differing summer/winter sun angles. Everything else involves
# #some manufacturing costs.
#
# No, the energy requires no production costs. Solar energy is free. The
# "power plant" or "engine" that converts solar energy into electricity
# is where the manufacturing costs come into play. Since we have those costs
# already (nuclear plants, coal/oil plants, power dams, etc) it is reasonable
# to lump the cost of solar plants into that same group. "Light" requires
# no refining in order to use it.
This is a semantic game. There are no ongoing costs to use solar
power (at least in solar cells), but there are substantial
manufacturing costs. Also, the batteries required to make solar
power useful other than during the peak hours of sunlight don't
have the lifetime of the solar cells.
# #When you find montrosities like Solar One
# #near Daggett, CA, with acres of aluminized mirrors focussing sunlight,
# #while being degraded by sandstorms, you have clear evidence that some-
# #one hasn't looked at the total energy input required. (Hint:
#
# No, you get clear evidence that some twit didn't take into account
# the sandstorms.
Sorry, but I left a written question at Solar One asking them what
sort of energy analysis they had done to make sure that they were
actually a net producer energy of energy -- and the response said
that they didn't know if it was a net producer or not.
# #aluminizing mirrors is VERY energy intensive).
#
# I believe you, I think flat glass with a silver coating, or even stainless
# steel would be cheaper.
Silver isn't as an energy intensive -- except that it tarnishes
quickly, and rapidly loses reflectivity.
Stainless steel might be a good choice, but it also has problems
with abrasion reducing reflectivity also.
Unfortunately, places with lots of sunlight are also frequently
places with duststorms. (Hint: this is causal, not correlation).
# #There's a place for solar power -- but most of the reason for
# #subsidies to it is because it is NOT cost-effective for most
# #situations.
#
# This is dependent on how you define "cost-effective". We are always going
# to need energy, and our current mass-production is not truly cost effective.
# Fossil fuel usage has a hidden cost. The oil we burn could bubble forth
# from the ground like salt water, and be absolutely free, but we're going
# to pay for burning it. I define cost-effective as startup, maintenance,
# *AND* disposal costs. Disposal costs are whatever it takes to prevent the
# byproducts from polluting the planet. We can ship nuclear wastes to the sun,
# and/or capture all the emission from our engines, but neither of these
# alternatives is as cheap as converting to solar. In general, everyone
# likes to look at & cite the easily seen costs, but nobody talks about
# the hidden costs, and those are the greatest of all.
#
# ## Charles_...@cup.portal.com
# #--
# #Clayton E. Cramer {pyramid,pixar,tekbspa}!optilink!cramer
I'm willing to talk about them, but the postings on this subject
show a lack of willingness to really understand that solar power
isn't a freebie. There is much the same irrational enthusiasm
for the wonders of solar power that used to be present in the
pro-nuclear literature.
--
Clayton E. Cramer {pyramid,pixar,tekbspa}!optilink!cramer
Gun Control: The belief that the government, with its great wisdom and
moral superiority, can be trusted with a monopoly on deadly force.
Clayton Cramer
> In article <51...@optilink.UUCP> cra...@optilink.UUCP (Clayton Cramer) writes:
> > When you find montrosities like Solar One
> > near Daggett, CA, with acres of aluminized mirrors focussing sunlight,
> > while being degraded by sandstorms, you have clear evidence that some-
> > one hasn't looked at the total energy input required. (Hint:
> > aluminizing mirrors is VERY energy intensive).
>
> The latest LUZ plants (by Solar One you presumably mean their first) seem
> close to economically competitive without tax credits. Certainly the LUZ people
> believe they will be able to be able to build unsubsidised, commercially
> competitive plants.
>
> Given this, your claim that there is no net energy production is very
> implausible even if energy was a large fraction of their costs.
> Have you numbers to back up your claim?
I didn't say that I knew for sure that there was no net energy
production -- but read the other posting I made discussing what
happened when I submitted a written request for information on
this subject.
I'm suspicious that the tax credits have unintentionally hidden
net energy loss, because energy is expensive.
> Nothing about mirror degradation by sandstorms is mentioned in [1]. It does
> mention the importance of mirror-washing and the cost-effective techniques
> they have developed do this.
It used to mentioned as a problem on tours of Solar One. During
duststorms, they turn all the mirrors parallel to the ground --
of course, there's not much of a loss of power, because the
dust reduces light significantly.
Also, they have lots of electric motors moving those mirrors
to track the Sun. How much electricity? I was told while I
was there in the early 1980s that they FINALLY were producing
more electricity than they were using.
> At the very least, the Luz plants are not "monstrosities" but
> valuable tests of the engineering issues in building solar-thermal plants.
>
> Andrew Taylor
>
> [1] Power Engineering Review August 1989 "Solar Electric Generating Stations"
I'm sure they can be valuable tests -- I'm suspicious that these
projects may be inappropriate uses of solar power. (There are
some very appropriate uses, by the way -- but it's much harder
to figure out how to turn them into boondoggle engineering
welfare projects like Solar One).
anmar mirza
>
>least inactivate them for the duration of exposure to concentrated direct
>sunlight? My information on this may be out of date, but I thought that even
>a very hot day without concentration of sunlight was enough to lower the
>efficiency of photovoltaic cells. Also, using concentrators takes away most
>of the advantages that solar cells have in not absolutely requiring unclouded
>sunlight in order to produce a significant amount of electrical energy.
October/Novemeber 1990 Home Power Magazine. Seems that a new company,
Midway Labs has come out with concentrator panels that require no
active cooling. "The economic advantage of concentration is more
effective use of expensive highly refined silicon. The PowerSource
module uses about 20 times LESS PV material than a conventional
unconcentrated module. It also makes about 50% MORE power. The
combined area of all the silicon cells in a single PowerSource module
is about 30 square inches and it generates 75 watts. The combined cell
area in a conventional PV panel is about 575 square inches of
hyperpure silicon to produce about 50 watts of power."
---Reprinted without permission from Home Power Magazine, Oct/Nov 1990
Article by Richard Perez
A ten module system, including tracker is about $4,500. This produces
about 750 Wh.
10 of my Arco M75's will run about $3000 and produce about 480 Wh.
Trackers is about another $700
I would need about 16 M75's To compete power output wise with the
Midway Labs units, at a cost of $4800, plus another $800 if I wanted
trackers.
Without the trackers on the Midway Labs modules, the cost is a little
more than $5 a watt, with trackers is is around $6 a watt.
I am probably going to stick with my Arco's to keep my system
consistant, but I am going to mention it to customers when they ask me
to put together a system for them.
anmar mirza
>
>ago that some solar cell plant in the United States was running entirely on
>the power generated by solar cells it had manufactured. Anyone know about
>this? Or is this solar cell plant cheating by offloading some procedure
>requiring lots of electrical energy onto its suppliers?
the issue) was less than 10 years at 5 hours PMSRAD (Peak Mean Solar
Radiation Average Daily). I get about 4.5 PMSRAD where I live it will
take only a little while longer. Panels have an industry expected life
of over 25 years for polycrystalline panels. Amorphous panels with a
life of around 10 years take about 2 to pay for themselves in cost to
make energywise.
> These factors don't necessarily connect.
>
> Last time I heard, the Luz installation was VERY CLOSE to being cost-
>competitive with conventional power generation methods, although it does stack
>the deck in its favor by using conventional burners (I forgot whether oil or
>gas) to run the steam turbines at night and on cloudy days (of which Arizona
>doesn't have much).
Gas I think. I think they were down to 12 cents a kWh for the solar
production, which is the lowest in the industry. They were also saying
they could easily drop it further with the next plant.
Nationwide average is 6 cents a kWh, and in my area it is about 8
cents. So far wind has come the closest to the nationwide average with
8 cents a kWh. Talk with Tom Gray about wind power, and the American
Wind Energy Association. tg...@well.sf.ca.us.
anmar mirza
di...@cs.rochester.edu (Paul Dietz) writes:
>The ability to use diffuse sunlight is an advantage, but high
>concentration is also nice -- silicon solar cells (at least) become
>more efficient at high concentration ratios (at constant temperature).
>I'm not sure why this is. Also, concentration schemes should have
Efficiency suffers as the heat goes up, but there are various ways
around that. The Midway panels I mentioned a few posts ago use no
active cooling, and they use monocrystalline silicon cells.
Paul Dietz
>>The ability to use diffuse sunlight is an advantage, but high
>>concentration is also nice -- silicon solar cells (at least) become
>>more efficient at high concentration ratios (at constant temperature).
>>I'm not sure why this is. Also, concentration schemes should have
In article <1991Jan5.2...@bronze.ucs.indiana.edu> ami...@silver.ucs.indiana.edu (anmar mirza) writes:
>It is actually very simple, more photons in=more electrons out.
No, you misunderstand: I was talking about *efficiency*, not power
output. The fraction of the light falling on the cell that is
converted to electrical energy is higher at high intensity, so actual
power output (at constant cell temperature) increases superlinearly
with concentration ratio (considering only direct sunlight). I don't
understand why this is.
Paul F. Dietz
di...@cs.rochester.edu
Donald Lindsay
>scenario put up by the anti-nukes, core meltdown, *no* confinement,
>and a core fire for God's sake, didn't result in the fearmongers predicted
>mega-deaths.
Just a nit: yes, there weren't mega-deaths. However, the cost of the
cleanup is projected to be higher than the _total_ profit made by the
entire Russian nuclear power industry in its entire history. I guess
leaving off the containment vessels was a long-term false economy.
>For solar cells the answer is a clear no on an energy basis and an
>enviornmental basis. For solar boilers driving freon turbines the
>energy cost is a net win. But the enviornmental costs are bad considering
>what the inevitable freon leaks will do to the ozone layer.
Solar/One didn't use Freon, and no one is proposing turbines in
household units. I'm not sure just what you are attacking here.
>Perhaps the worst effect of using
>large scale solar energy to replace fossil fuels or nuclear plants is the
>effect on the climate.
I doubt this. In terms of absorption, planting the prairies with
wheat probably had a bigger effect. Not to mention all those nice
black parking lots: are you aware of the "micro climate" caused
by cities?
The low-tech approach to solar power is farming biomass and
fermenting it to alcohol. Gosh, those evil hazards and climate
consequences!
The high-tech approach is solar cells. I am unimpressed by people who
(a) assume that they are intinsically hard to make, and (b) assume
that research can never overcome this hypothesized drawback. I am
also unimpressed by people who dismiss rooftop solar cells because
the battery banks will leak fumes, or explode. Gosh: such concern
about householders who already have flammable gases piped into their
houses!
I will admit that the world desperately needs better battery
technology, but that relates to money, not safety.
Glenn A. Serre
flamed in this thread?
i.e.,
In a typical nuclear electric generation plant, what reaction products are
produced, and how much is produced per kilowatt-hour?
What are the half-lives of those reaction products?
What pollutants are produced by coal- (or oil- or gas-) fired generating plants
and how much of each per kilowatt-hour?
What pollutants are produced by extraction and transport of these fuels? (Same
question applies for nuclear).
What pollutants are produced by the manufacturing process for solar cells?
etc., etc.
If y'all are going to discuss the merits of solar power versus nuclear power
(or fossil fuels) then you probably ought to start out with some facts and
numbers. I've been reading a lot of "I think" and "It seems", but have seen
littl, if any, quantitive data.
If anyone out there has numerical answers to the questions I pose above,
please email them to me and I will post a summary (If there are any responses).
Also, please cite sources.
Thanks in advance.
--
--Glenn Serre | kicked off CU's computer 'cause I'm not taking
gas...@nyx.cs.du.edu | a night class this term :-)
Rolf Meier
>off-hook detection for telephones; this circuit saves about 3 watts per
>phone. There's a lot of phones out there. So why waste all that silicon
I hate to be picky in an otherwise good posting, but phones use much less
power than that. In the on hook state, there is of course no power being
supplied. Off hook, the average loop draws about 40 mA, with the CO
voltage of about 50 V, so the CO supplies about 2 W. Most of that is
dissipated in the CO and the loop; a phone requires about 1/4 W to
function, but typically dissipates about 1 W since most loops are short.
Proprietory digital phones (and tomorrow's ISDN phones) may actually
use more power, because the digital circuitry needs to be continuously
active in order to sense signaling information. For highly functional
digital sets, an ac adapter is often required because you can't
guarantee supplying more than 1 W to the end of the loop.
___________________________________________________________________
Rolf Meier Mitel Corporation
Tom Gray
>
>Most solar cells are made with processes that are similar to those used to
>make integrated circuits. A big IC fab turns out on the order of a million
>wafers a year, and turns out tens of thousands of gallons of liquid toxic waste
>and hundreds of thousands of cubic feet of gaseous waste in the process.
>A million 6 inch wafers is about 20,000 square meters.
>
>Safety? Ever see the results of a fab fire? A co-worker had a wall clock
>that had barely survived a silane fire. Interesting Salvadore Dali effect.
>When I was with my former employer, we had building evacuations about twice
>a year. Rule of thumb: safety costs money. As prices go down, safety may
>go down, too. Imagine hundreds of fab fires a year...
>
I once walked into a colourless odourless cloud of poison gas while in a
hallway at the fab plant of a former employer. There was an interesting
Salvadore Dali effect on my lungs as I walked 10 feet into it and
stumbled 10 feet out of it. It was colourless and odourless the only
indication I had was that I couldn't breathe. Anyway the afternoon spent
outsde on the lawn with the other 1000 workers in the building were
interesting.
Strange but if this had happened with a nuclear material the newspapers
and electronic media would have been full of warnings of calamity.
The residential area next to the facility would have been evacuated.
But since it was only a cloud of poisonous gas the incident passed without
comment.
.
.
.
.
.
.
.
.
.
Russ Cage
> Chemical "poisons" can be broken down using current technology.
Oh, really? Arsenic, lead and cadmium are chemical poisons. They
cannot be broken down by anything other than NUCLEAR processes.
They are used in solar-cell systems, in the cells themselves
and in batteries.
Widespread use of solar-electric power puts large amounts of all
of these substances into small packages widely spread. Some will
inevitably leak.
> Nuclear poisons can't be broken down by us. They will decay over time,
>but since we can break down chemical poisons it makes no sense whatsoever
>to create nuclear ones.
The more long-lived nuclear poisons are themselves valuable nuclear
fuels (plutonium). When used as fuels, they are broken down into
short-lived isotopes with half-lives of years to decades. Inside
a century, they are largely gone, replaced by stable isotopes.
--
Russ Cage Ford Powertrain Engineering Development Department
Work: itivax.iti.org!cfctech!fmeed1!cage (CHATTY MAIL NOT ANSWERED HERE)
Home: ru...@m-net.ann-arbor.mi.us (All non-business mail)
Member: HASA, "S" division.
David Feustel
is used to refine uranium 235. Does this sound like a net energy
gain?
--
David Feustel, 1930 Curdes Ave, Fort Wayne, IN 46805, (219) 482-9631
EMAIL: netcom.uucp
Lucius Chiaraviglio
>ch...@quads.uchicago.edu (Lucius Chiaraviglio) writes:
>>than that of all of the waste heat generated by a conventional (including
>>nuclear) power plant, which converts no more than 45% of its generated heat
>>into electrical energy.
>
>The most efficient generator on-line is a natural gas fired combined
>cycle plant in Europe with an efficiency of 52%.
Okay, my info is a little out of date. When did this plant come on
line?
> Efficiencies should
>continue to rise; MCFC/steam turbine combined cycle plants may exceed
>70% efficiency, if and when they come into use, and should also
>have far lower NOx emissions.
For all of us who don't know all our alphabet soup: what's MCFC?
(Alphabet soup isn't bad, but this is a new one on me.)
Of course, higher efficiency heat engine cycles (unless they use
something combustion-specific like MHD (magneto-hydrodynamic) generators)
could also be applied to solar thermal installations.
Robert McArthur
>I know that it is impolite to confuse this argument with facts but I must
>do so. You are flat wrong. A Chernobyl-style event is physically impossible
>with America's reactor designs. For a Chernobyl to happen, the following
>events would ALL have to take place:
Impossible is a long word. By the time you have said it, its happened.
The only valid use of the word impossible is with "not".
--
Robert McArthur Centre for Resource and Environment Studies
Australian National University
ACSNet r...@arp.anu.oz.au ACT Australia 2601
Pegasus|PeaceNet|EcoNet peg:robert (06) 249 4760
Thomas Johnsson
>The ability to use diffuse sunlight is an advantage, but high
>concentration is also nice -- silicon solar cells (at least) become
>more efficient at high concentration ratios (at constant temperature).
>I'm not sure why this is. Also, concentration schemes should have
>a higher overall efficiency than flat plate schemes, since one can
>use more sophisticated cells that would be absurdly expensive
>with unconcentrated light. This would become important in the
>long run if the area covered by collectors becomes significant.
How much more efficient? How much concentration, i.e., what power
densities can solar collectors stand? Presumably, such cells also
degrade more quickly?
Thomas Johnsson (john...@cs.chalmers.se)
Dept. of CS, Chalmers University of Technology, S-412 96 Goteborg, Sweden
phone: dept: +46 (0)31 721088.
Rauno-Petri Luoma
>j...@Dixie.Com (John G. DeArmond) writes:
>
>>I know that it is impolite to confuse this argument with facts but I must
>>do so. You are flat wrong. A Chernobyl-style event is physically impossible
>>with America's reactor designs. For a Chernobyl to happen, the following
>>events would ALL have to take place:
>
>Impossible is a long word. By the time you have said it, its happened.
>
>The only valid use of the word impossible is with "not".
What are you trying to say ?
Why can't word impossible be used alone.
For example: If you don't have legs it is impossible for you
to broke your leg, or isn't it.
Paul Dietz
>>The most efficient generator on-line is a natural gas fired combined
>>cycle plant in Europe with an efficiency of 52%.
>
> Okay, my info is a little out of date. When did this plant come on
>line?
Fairly recently, I believe.
>> Efficiencies should
>>continue to rise; MCFC/steam turbine combined cycle plants may exceed
>>70% efficiency, if and when they come into use, and should also
>>have far lower NOx emissions.
>
> For all of us who don't know all our alphabet soup: what's MCFC?
>(Alphabet soup isn't bad, but this is a new one on me.)
>
> Of course, higher efficiency heat engine cycles (unless they use
>something combustion-specific like MHD (magneto-hydrodynamic) generators)
>could also be applied to solar thermal installations.
MCFC = molten carbonate fuel cell. These fuel cells use a molten
carbonate electrolyte, and operate at 600 deg C. They are capable
operating on natural gas with no external reforming, or on
desulfurized coal gas. A pilot plant may be in operation within
the decade.
Paul F. Dietz
di...@cs.rochester.edu
Russ Cage
>Chernobyl, lists of missing nuclear fuel, 55 gallon drums of nuclear waste
>to shoot holes in drums that wouldn't sink), etc.
Three-Mile Island neither killed nor harmed anyone. It was
also about the worst possible accident for that reactor type.
Chernobyl was a bad design, and thus a special case. Just
because an airplane built by an idiot is likely to crash and
kill him does not mean all airplanes are dangerous.
Lists of "missing" nuclear fuel can mean nothing more than
bookkeeping errors. They do not imply hazard except to
the hysterical; nuclear fuel != nuclear bombs.
Said drums sound like an apocryphal horror story. However, a
steel drum would not last long in the sea, and would be crushed
by ocean-floor pressure anyway. If it contained, say, machine
parts with enough air space to float it, shooting holes in it
to sink it is perfectly reasonable. (A barrel full of heavy
sludge wouldn't float.)
> Radioactive materials are dangerous to complex organisms, and the more
>RM that is around, the more dangerous it is (the probability of an
>accident increases).
Really? Then tell me why there have been far more medical
disasters (Minimata (sp?) syndrome) caused by chemical poisons
than by nuclear ones?
> Heavy metals don't need to be decomposed - they can be refined and reused.
How are you going to refine the 5 ppm of lead in your drinking
water into metallic lead for re-use? Do you have any concept
of the thermodynamic property of ENTROPY, and the ENERGY input
required to reduce it? I thought not.
> What we can make, we can unmake. I don't think the environment should be
>responsible for decomposing the unnatural chemical compounds that we
>introduce into it.
The nice thing about short-lived radionuclides is that they
un-make themselves, and many of them have useful properties
while so doing. (Iodine for radio-immuno-assays and treatment
of thyroid disorders. Cobalt for radiation therapy and food
preservation. Krypton for lights which require no power, for
safer roads in remote places.)
> The cost of "unmaking" is very high, mainly because it is cheaper in the
>short run to just discard the waste byproducts. In the long run, these
>byproducts will come back to haunt us - cf. Lovecanal, DDT, etc.
Yet another reason why nuclear power is a good idea. For a few
tons of material per year (which is EASY to track, comparatively),
you can avoid using millions of tons of something else which is
likely to yield chemical poisons like Love Canal's sometime
during its production or use.
> What is RTG?
> A nuclear power plant?
RTG = Radioisotope Thermal Generator. They are not "reactors";
they generate power using the heat given off by certain isotopes,
which are refined from spent nuclear fuel. These are ideal for
powering space probes which go far from the sun, and are yet
another useful byproduct of nuclear power.
> Hmmm...why not ground or space power generation for those satellites
>that orbit the earth & moon? Deep space satellites are of little concern
>here because once they leave, they're gone for good.
Satellites built for trips inside Mars orbit typically use solar
cells. Galileo (bound for Jupiter) and Ulysses (heading for the
south pole of the Sun via Jupiter), plus the Pioneer and Voyager
probes (remember the Voyager-Saturn encounter on TV?) are all
powered by RTG's. Lander probes (such as the lunar ALSEP packages
and the Viking Mars landers) use RTG's to get through the night.
> RTGs (assuming they are small nuclear plants) are dangerous in any orbit
>that decays before the nuclear fuel becomes non-radioactive.
Wrong. They are sufficiently well-encapsulated to survive re-entry
and impact without loss of fuel, unless they strike rock. The RTG's
on board the Apollo 13 LEM re-entered and hit the Pacific somewhere.
No trace of radioactive material was found.
> This is war buddy....you know the saying... :)
A war on truth, perhaps?
> I still don't like the idea of a blob of nuclear goop falling from the
>sky into my living room. :)
You won't see one from us. The chances of seeing one from the
Soviets goes down steadily.
> If the energy is free, who cares how much it took to make them?
If you have to put energy in to make something, is it "free"?
(Is this the best thinking you can present?)
Blair P. Houghton
[..much cogent discussion of nuclear safety re RTG power deleted...]
>Russ Cage Ford Powertrain Engineering Development Department
So, uh, Russ, when're we going to see an atomic Taurus for under $10grand?
:-)
--Blair
"Some questions simply have to be asked."
James W. Swonger
You don't necessarily have to use Arsenic. There are other N dopants, like
Phosphorus.
Even if you do use Arsenic, the As in the silicon is going to stay put. The
concentration of As/Si is about 100ppm @ Nd=1E19. The only way to release it
is to eat away the silicon with which it is mixed. In oxygen Si quickly forms a
passivating oxide layer. HF is not commonly found in nature, so the oxide is
not going anywhere. Relax. Quit yipping.
Since solar cells require fewer masking steps they use fewer chemicals and
produce less waste. (Each mask uses a given amount of photoresist, etchant,
stripper, etc).
A solar cell's life will be a tradeoff between efficiency (minimum metal
coverage of Si) and interconnect life. A well encapsulated cell will escape
corrosion problems. A cell with adequate current density margin on its
metallization will not be subject to catastrophic failure; its lifetime
would be limited by the creep of its junctions.
Andy Wilcox
|> In article <37...@cup.portal.com> Ordan...@cup.portal.com (Charles
K Hughes) writes:
|> >
|> > I don't think the "allergy" is irrational given 3-mile island,
|> >Chernobyl, lists of missing nuclear fuel, 55 gallon drums of nuclear
waste
|>
in
|> an induced loss of cooling accident.
Containment Worked?
"There were some rather large releases of radioactive materials [at
TMI],
but unfortunately, there were so few detectors out in the field that
it
was very difficult to tell what happened to those radioactive
materials,
whether they did impact on people, or whether they simply blew off
and
became sufficiently diluted... "
-Dr. Chauncey Kepford before the Subcommittee on Natural
Resources and Environment of the Committe on Science and
Technology of US House of Rep. _Three Mile Island Nuclear
Plant Accident_, US Gov't Printing Office, pp 3-4.
Hal Lillywhite
>Three-Mile Island neither killed nor harmed anyone.
Not quite true. Statistically we could probably attribute the
deaths of a few coal miners and the illness of several more to the
coal they had to dig to replace the electricity previously generated
by TMI.
Hal Lillywhite
>Three-Mile Island neither killed nor harmed anyone.
Not quite true. Statistically we can probably attribute the death
of a few miners and the illnesses of several more to the coal they
had to dig out of the ground to replace the electricity previously
generated by TMI.
James W Bales
>>> -- silicon solar cells (at least) become
>>>more efficient at high concentration ratios (at constant temperature).
>>>I'm not sure why this is.
> di...@cs.rochester.edu
If I may hazard a guess it is because Si is an "indirect-gap"
semiconductor.
All semiconductors have bandgaps, and to first order photons
whose energies are less than the bandgap don't get absorbed (remember
that a photon's energy is proportional to it's frequency, equivalently
the energy is inversely proportional to it's wavelength. Blue is high
energy, red is low, and infrared even lower). This is because of
conservation of energy. However, momentum must also be conserved.
Photons have very little momentum. For our purposes we can assume
photons have NO momentum. This is the basis for distinguishing
between direct-bandgap and indirect-bandgap semiconductors.
In a direct-bandgap semiconductor an electon changes only its energy,
not momentum, when it absorbs a photon. In an indirect-bandgap
semiconductor an electron MUST change BOTH energy and momentum
when it absorbs a photon (solid-state physicists may flame me
for glossing over a lot of things here). But, since a photon has
no momentum, this means the electron has to get momentum from
somewhere else. Usually this momentum comes from vibrations
of the atoms composing the crystal. The more the atoms are vibrating,
the higher the probability of a given photon being absorbed.
As you increase the photon flux, you increase the current,
which means there are more electrons moving through the active
region of the device (the junction). But, as the electrons flow they
bang into the atoms of the crystal (both the Si atoms and more so
the As and P dopant atoms). This increases the number of lattice
vibrations (aka phonons) available, which means a given photon
is more likely to be absorbed. Viola! Increased efficiency.
Caveat. The temperature of the cell is a measure of the number
of phonons present. So, this process will tend to increase the
temperature of the cell in the active region. When you stated that
this was observed at constant temperature, I assume you mean the
ambient tmperature was kept constant, not the temperature at the
junction.
Incidently, if the temperature of the junction does go up, the bandgap
decreases, which means that a larger fraction of the spectrum can be
absorbed. I don't know enough about Si to say how important this is,
but it could be more important than what I described above, given
a big enough delta T.
Another possibility involves "two-photon absorption" which
would allow the absorption of two photons whose energy,
when summed, is greater than the bandgap energy. We won't go into
that, this is already long enough :-)
Hope this was more than you wanted to hear! I should point out
that my experience is with GaAs, a direct-bandgap material. Has anyone
out there done much with indirect materials who can shed some light
on this?
Jim Bales ba...@athena.mit.edu
John Whitmore
> Chernobyl showed that even the worst
>scenario put up by the anti-nukes, core meltdown, *no* confinement,
>and a core fire for God's sake, didn't result in the fearmongers predicted
>mega-deaths.
A few words of amplification, about Chernobyl:
A fission reaction requires a moderator (usually graphite)
for operation, and 'core meltdown' refers to destruction of the
graphite core. So, 'core meltdown' is the absolute worst-case
for American nuclear plants, BECAUSE meltdown stops the reactor.
Unhappily, while reactor cores on this side of the ocean
are all 'under-moderated', the soviet design is 'over-moderated',
so that DESTROYING THE CORE SPEEDS UP THE REACTOR. Only for
a brief time, of course, but that's enough to make a VERY dirty
explosion. Chernobyl's accident was very simply a nuclear explosion
(yes, just like in a bomb); it is NOT a scenario that could conceivably
occur on any power plant in this country (or western Europe, for
that matter).
It is axiomatic that a worst-case analysis is a bad analysis;
the old Rasmussen report did a more conventional risk analysis , and
there is no reason to doubt its conclusions (nukes are safe). The Three
Mile Island design, and the Chernobyl design, were NOT included in that
study. TMI was studied after the accident, of course (look in the
EPRI Journal for a complete analysis), and many changes were made
in consequence. Chernobyl-style plants, on the other hand, are
still in operation. Damn, that's scary.
John Whitmore
John Berryhill
>Widespread use of solar-electric power puts large amounts of all
>of these substances into small packages widely spread. Some will
>inevitably leak.
This is my candidate for nuttiest post so far in the thread. Arsenic
doped silicon is in the ppm range and is a constituent of the resulting
crystal lattice. It's not going anywhere.
Likewise it stays put in GaAs, a chunk of which is sitting on my desk where
it's been for months now. At 800C, it will begin to dissociate.
I suppose that Russ avoids table salt since it contains Chlorine which
we all know is a poisonous gas, because that is exactly analogous to the
"leaking" problem that he's crying about. Typical Luddite reaction.
As far as the fab processes go, the production of solar cells is not at all
comparable to microelectronic circuit fabrication. The toxic organic
solvents associated with IC fab arise mainly out of the necessity of the
several photolithographic steps needed to define all of the components. A
solar cell is a single diode. One diffusion step and then you screen-print
the contact. And if you are really worried about the possible release of
the gaseous source used for the diffusion (I generally use a 1000 ppm PH3
in He), you can use solid sources which are as safe to handle as the
wafers.
--
John Berryhill
143 King William
Newark, DE 19711
Christoph Splittgerber
>
>Three-Mile Island neither killed nor harmed anyone. It was
>also about the worst possible accident for that reactor type.
^^^^^^^^
Come on you kidding me don't you ? It was very close to a major disaster
and I don't understand what makes you think, that the way it finally went,
was the worst possible accident. I hope we never have to see the real
worst case.
>Chernobyl was a bad design, and thus a special case. Just
>because an airplane built by an idiot is likely to crash and
>kill him does not mean all airplanes are dangerous.
This one is really amusing. So, do you assume that all the airplanes
crashed were build by idiots ?
>Lists of "missing" nuclear fuel can mean nothing more than
>bookkeeping errors. []
**JESUS CHRIST**
>Really? Then tell me why there have been far more medical
>disasters (Minimata (sp?) syndrome) caused by chemical poisons
>than by nuclear ones?
Because they are not handled in a proper way either. The real bad thing
is not the nuclear/chemical stuff itself; it's us and the way we deal
with it. Anyway, pointing out something bad doesn't justify anything.
>[]
>A war on truth, perhaps?
For sure !
Take care, Chris
----------------------------------------------------------------------
Nothing left to do but :-) :-) :-)
--
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Replies-To: ch...@alderan.uucp UUCP: uunet!mcsun!unido!alderan!chris
Phone: +49 711 344375 Fax: +49 711 3460684
Neal Dalton
In article <92...@fmeed1.UUCP> ru...@m-net.ann-arbor.mi.us (Russ Cage) writes:
>Three-Mile Island neither killed nor harmed anyone.
This is not true. The incidents of cancer surrounding the TMI site is
very significant.
I forget the stats, but they where many times that of the average and/or
surronding area.
Neal /\ / _ / \|||/ Neal Dalton
/ \ / _ _\ / / \ Cray Research, inc
/ \/_</_(_/\_/ ( o o ) _________ 655-F Lone Oak Dr.
\ ^ / / \ Eagan, MN 55121
\ 0 / < OH NO, )
Internet: n...@cray.com \_/ \ not him!/ Fax: (612) 683-5599
uucp: uunet!cray!nrd \_______/ Phone: (612) 683-5607
Cameron Randale Bass
>In article <92...@fmeed1.UUCP> ru...@m-net.ann-arbor.mi.us (Russ Cage) writes:
>
>>Three-Mile Island neither killed nor harmed anyone.
>
>This is not true. The incidents of cancer surrounding the TMI site is
>very significant.
>
>I forget the stats, but they where many times that of the average and/or
>surronding area.
>
Gee whiz. Didn't it occur to you that if you forgot the statistics,
you could be plain wrong? Also, even if such statistics exist (which
is extremely doubtful considering the long latency of most radiation-
induced cancers), how were they compiled? What is the sample size?
Whose axe was being ground?
I have seen this type of garbage many times from anti-nuclear
people and it stinks. Just because you wish it to be the
case, doesn't make it necessarily so. Radiation (both natural
and man-made) is just another risk factor. Radation is not
the anti-christ whose mere hint causes cancer in surrounding
time-zones.
Oh and by the way, that is 'incidence'.
dale bass
--
C. R. Bass cr...@virginia.edu
Department of Mechanical and Aerospace Engineering
University of Virginia
Charlottesville, Virginia (804) 924-7926
Mike Van Pelt
>>You are flat wrong. A Chernobyl-style event is physically impossible
>>with America's reactor designs.
>
>
>The only valid use of the word impossible is with "not".
When talking about the [im]possibility of a Chernobyl-style event
in a US-style reactor, you're talking about something very much of
the same order of magnitude as the possibility of Robert McArthur
tripping over a roller skate on the steps of the Centre for Resource
and Environment Studies building, zipping out-of-control across
Australia, and smacking into Ayers Rock with enough force to sink
the entire continent.
Is this awful disaster scenario impossible, or not impossible?
--
Don't forget that the media is wallpapered with idiots; | Mike Van Pelt
no matter how stentorian their voices or smooth their | Headland Technology
writing style, they're mostly just trying to make sure _| (Was: Video Seven)
you don't change the channel. - Barry Shein | ...ames!vsi1!headland!mvp
Steve Emmerson
writes:
>In article <92...@fmeed1.UUCP> ru...@m-net.ann-arbor.mi.us (Russ Cage)
writes:
>>Three-Mile Island neither killed nor harmed anyone.
>This is not true. The incidents of cancer surrounding the TMI site is
>very significant.
References please.
Steve Emmerson st...@unidata.ucar.edu ...!ncar!unidata!steve
Mike Smith
>I am
>also unimpressed by people who dismiss rooftop solar cells because
>the battery banks will leak fumes, or explode. Gosh: such concern
>about householders who already have flammable gases piped into their
>houses!
Not to mention the couple of gallons of gasoline for the lawn mower.
And the car in the garage ... lead/acid battery, fuel tank, and all.
I can remember my dad teaching me about battery safety when I was
about 6 years old and 'helping' him work on the car ...
I doubt if an insurance company would like the idea of a large
battery bank uncovered in the garage. I also doubt that it would
be very hard to make a safe installation that would meet building
codes and insurance requirments. See your local Big Computer Shop
with an UPS for an example ...
Battery safety is an issue, but one rather low on the list ...
Battery efficiency is far more of a 'show stopper'.
--
E. Michael Smith e...@apple.COM
We all agreed that reducing the deficit was important.
Unfortunately the Republican congress critters thought this meant
'Soak the Middle Class' and the Democrats thought it meant to
'Soak the Rich' while what the people wanted was less spending ...
John G. DeArmond
>This is not true. The incidents of cancer surrounding the TMI site is
>very significant.
>I forget the stats, but they where many times that of the average and/or
>surronding area.
This is simply flat wrong. Even if there were to be radiation-induced
cancers, they would only NOW be showing up. The latency for leukemia,
the only known radiogenic cancer, (lung cancer is has only been linked to
radiation only when the irradiation is from ingested radioactive
particulate. No particulate exposure was ever postulated since the only
releases were controlled ventings of noble gas.) is estimated to be at
least 10 years and more likely 20 years. Even if 10 years is the case,
there would have to be several more years before the victims progressed
through the disease to either cures or death and more time before the
cases are reported and collected for statistical analysis.
Allegations of excess cancer from TMI has been refuted by scientists from
both sides of the debate. The only one I know that claimed otherwise
was from the self-styled epidemiological husband-and-wife team from the
local area. The only problem was that neither had any scientific training
and as a result, almost every experimental parameter and technique was
flawed. They carefully chose the sample area to maximize the apparent
cancers and then used faulty analysis techniques. Some called it fraud;
I'll be more generous. Peer review was via the 6 o'clock news.
There is other data that will be published shortly that will lay this
sham to rest once and for all. For now, I must respect the researchers'
confidentiality but we'll have more than enough discussion after
the peer-reviewed publication.
Before spouting this kind of stuff, why don't you do some homework first?
You'll appear much more informed.
John
--
John De Armond, WD4OQC | "Purveyors of speed to the Trade" (tm)
Rapid Deployment System, Inc. | Home of the Nidgets (tm)
Marietta, Ga | "To be engaged in opposing wrong offers but
{emory,uunet}!rsiatl!jgd | a slender guarantee of being right."
anmar mirza
>
>Battery safety is an issue, but one rather low on the list ...
>Battery efficiency is far more of a 'show stopper'.
Yeah, it's a big issue. Here are some tips for those poor slobs who
have to live with a lead-acid battery bank.
1. Buy some catalyst vent caps. These recombine the hydrogen and oxygen
into water and return it to your cell. This can cut the watering time
down to once a year or less. They are expensive, but they pay off in
less maintenance and increased safety as there is less free hydrogen
floating around. Besides, they give your batteries that neat high-tech
look.
2. Build a wooden building for your batteries outside. Have a fan push
air into the bottom and have a vent on top. It can be a small fan,
brushless is best.
3. If you don't like the catalyst vent caps, use rubber stoppers and
oxygen or aquarium tubing to vent your explosive gasses outside.
4. Think of buying gell cells. These do not require any watering and
are more resistant to sulfation. They do not give off any gasses
except under unusual circumstances.
5. I am going to leave the obvious ones such as fusing at the battery
and no smoking near the batteries and spark proof switches nearby and
the like up to the common sense of the user.
6. And my final recommendation, buy Ni-Cd's. They last a lot longer,
they deep cycle a lot better, they rarely require any watering, and
they pay for themselves compared to the best lead acids.
There, I hope that this helps someone who is putting together a
battery bank. Using any of these will drastically increase the safety
of your bank. Of course, this probably won't reach those who are of
the type that is inclined to keep dangerous chemicals such as drain
cleaner or oven cleaner in the house, and it probably won't affect
those who keep gasoline in their garage without proper safety
precautions, all of which is more dangerous than batteries if the
proper safety precautions aren't observed.
--
Anmar Mirza # If a product is good, # I speak only my # Space, humans next
EMT-A # they will stop making # opinions on these # goal in the race
N9ISY (tech) # it. Unless it is # subjects, IU has # for immortality.
Networks Tech.# designed to kill. # it's own. # --- me
Dave Sill
>
>I suppose that Russ avoids table salt since it contains Chlorine which
>we all know is a poisonous gas, because that is exactly analogous to the
>"leaking" problem that he's crying about. Typical Luddite reaction.
Hah! Russ Cage a Luddite? That's rich!
The original Luddites opposed technology/mechanization because they
thought automation would put them out of work.
Neoluddites, on the other hand, oppose technology because of it's
negative effects.
To generalize either movement as scientifically ignorant is to
demonstrate one's own ignorance.
--
Dave Sill (d...@ornl.gov) It will be a great day when our schools have
Martin Marietta Energy Systems all the money they need and the Air Force
Workstation Support has to hold a bake sale to buy a new bomber.
Doug Mohney
>
> Gee whiz. Didn't it occur to you that if you forgot the statistics,
> you could be plain wrong? Also, even if such statistics exist (which
> is extremely doubtful considering the long latency of most radiation-
> induced cancers), how were they compiled? What is the sample size?
> Whose axe was being ground?
>
> I have seen this type of garbage many times from anti-nuclear
> people and it stinks. Just because you wish it to be the
> case, doesn't make it necessarily so. Radiation (both natural
> and man-made) is just another risk factor. Radation is not
> the anti-christ whose mere hint causes cancer in surrounding
> time-zones.
It's very easy to be skeptical of statistics. It took the Department of Energy
close to 30 years to admit they have severe environmental problems at
bomb-making plants. Studies have shown that living near places like Hanford
Nuclear Reservation (where national security took precidence over environmental
concerns) and Rocky Flats, CO, is bad for you, due to the amounts and types of
radioactives released during their operation.
Would you want to live near Hanford or Rocky Flats? Would you want to have
children there? Current estimates of cleanup are, oh, $400-500 billion.
Doug
Doug Mohney, Operations Manager, CAD Lab/ME, Univ. of Maryland College Park
* Ray Kaplan was right *
Rolf Meier
>
>Also, they have lots of electric motors moving those mirrors
>to track the Sun. How much electricity? I was told while I
>was there in the early 1980s that they FINALLY were producing
>more electricity than they were using.
>
What garbage.
If the mirrors are properly balanced, it would take miniscule amounts
of power to track the sun.
The mirrors are racing around at 1 revolution per day.
___________________________________________________________________________
Rolf Meier Mitel Corporation