joehol@microsoft.UUCP (Joseph HOLMAN) (11/06/90)
I'm looking for a supplier of Solar Cells, other than Radio Shack. (i've got their price already...) Can somebody out there give me a telephone # ??? Joe Holman uunet!uw-beaver!microsoft!joehol joehol@microsoft.uucp 206-936-8921.
ssave@caen.engin.umich.edu (Shailendra Anant Save) (12/18/90)
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: ssave@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)
ICBM: 42 33'W 83 71'N Fax: 313-747-1781
Eagles may soar, but weasels don't get sucked into jet engines.
(For those who don't know, a weasel is a wolverine)henry@zoo.toronto.edu (Henry Spencer) (12/29/90)
In article <1990Dec17.190857.16559@engin.umich.edu> ssave@caen.engin.umich.edu (Shailendra Anant Save) writes: > 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| henry@zoo.toronto.edu utzoo!henry
ries@venice.SEDD.TRW.COM (Marc Ries) (12/29/90)
In article <1990Dec28.210436.10601@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:
->(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 Rieshenry@zoo.toronto.edu (Henry Spencer) (12/29/90)
In article <939@venice.SEDD.TRW.COM> ries@venice.sedd.trw.com (Marc Ries) writes: > 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. "Very high" amounts of energy are needed if we want a major fraction of our total energy supply to come from solar. -- "The average pointer, statistically, |Henry Spencer at U of Toronto Zoology points somewhere in X." -Hugh Redelmeier| henry@zoo.toronto.edu utzoo!henry
stevek@blenny.UUCP (Stephen Kogge) (12/30/90)
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
dll@teda.UUCP (Dan Liddell) (12/30/90)
In this followup, I have uppercased Harry Spencer's comments to make him look like a crude, boorish, shouting fellow. :) NOT REALLY. I did it just to separate his text from my text, for readability. He is not really shouting, and the tone of his posting was polite. My sources for information are Encyclopaedia Britannica, Nasa Tech Briefs, the CRC Handbook of Chemistry and Physics, Farrington Daniels' "Direct use of the Sun's Energy", and a little personal research (the stuff on the albedo of a solar cell, and its effective albedo). Opinions and recollections are clearly marked. In article <1990Dec28.210436.10601@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >(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.) 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? Dead solar cells can be found in a panel by photographing it with infrared film. The cells that have died show up "brighter" in the photo, because they are hotter,because they are not converting light to electricity, and that difference shows up as heat. OPINION:Silicon solar cells do not represent much of a disposal problem, at least not because of the silicon. They are probably good candidates for recycling. Imagine how bad things would be with selenium photocells. >(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. OPINION:This a criticism more appropriate to small installations, that are away from the power grid. The power grid would have a moderating influence on local storage needs. A "large" power grid could also have some portions of the grid illuminated while others were dark (the USA don't stretch across enough time zones to make this one work). RECOLLECTION:Frequently, it is cheaper to set up a solar/lead-acid system than it is to run power to places that are not already on the grid. I couldn't find anything (in the time that I alloted to research this posting) about the cost of lead-acid batters, which I guess to be the most economical storage system. >(3) SOLAR ENERGY IS THINLY SPREAD AND VERY LARGE COLLECTING AREAS ARE NEEDED. 1.920 calories/square centimeter/minute, which is 22 watt-hours/square meter/minute. These are calculations for a typical house (mine), which used 587 kwh in november. I assume a 12 hour day, no degradation of the solar constant during the morning and evening hours, and 16 percent conversion efficiency. I come up with about 8 square meters of silicon solar cell to satisfy my rather inefficient energy needs. >(4) LARGE-SCALE SOLAR POWER SERIOUSLY CHANGES THE HEAT BALANCE OF THE > SURROUNDING AREA, SO IT IS NOT COMPLETELY CLEAN. Life systems are open systems. Nothing is 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. By "most" sunlight I assume that you mean more than 50%. Here are some reflectivities of some common things: percentage reflectivity -------------------------------- EARTH (the planet) 36 concrete: 17 to 27 green forests: 5 to 10 moist plowed fields: 14 to 17 dark soil: 5 to 15 DESERT SOIL: 25 to 30 snow: 45 to 90 clouds: 5 to 85 silicon solar cell: about 6 Two thirds of the reflected light from the earth is caused by reflection from cloud cover. The low albedo of silicon solar cells is mitigated somewhat by the fact that they convert about 16% of the sunlight that falls on them to electricity. In this fashion, they display an "effective" albedo of about 22% (6 + 16 percent). Looks like they would blend in well with concrete. Decide for yourself. OPINION: Solar energy is a niche player now, but the niches are getting larger. >"THE AVERAGE POINTER, STATISTICALLY, |HENRY SPENCER AT U OF TORONTO ZOOLOGY >POINTS SOMEWHERE IN X." -HUGH REDELMEIER| HENRY@ZOO.TORONTO.EDU UTZOO!HENRY -- Dan Liddell UUCP decwrl!teda!dll TELEPHONE 4089805200 USA curb your dogma. The opinions and views expressed are Dan's.
amirza@silver.ucs.indiana.edu (anmar mirza) (01/01/91)
In article <939@venice.SEDD.TRW.COM> ries@venice.sedd.trw.com (Marc Ries) writes: >In article <1990Dec28.210436.10601@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >->(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 This is true, the polycrystalline cells themselves do not degrade, and 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 # 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
amirza@silver.ucs.indiana.edu (anmar mirza) (01/01/91)
In article <1990Dec29.063939.20478@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >In article <939@venice.SEDD.TRW.COM> ries@venice.sedd.trw.com (Marc Ries) writes: >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 # 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
amirza@silver.ucs.indiana.edu (anmar mirza) (01/01/91)
In article <1146@blenny.UUCP> stevek@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 >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. > 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. 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. -- 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
berryh@udel.edu (John Berryhill) (01/01/91)
In article <1990Dec29.063939.20478@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >> 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... 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
wrf@mab.ecse.rpi.edu (Wm Randolph Franklin) (01/01/91)
In article <1990Dec31.173248.24523@bronze.ucs.indiana.edu> amirza@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%. Really, I'm in favor of conservation, but it has to honestly be cheaper. -- Wm. Randolph Franklin Internet: wrf@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@zoo.toronto.edu (Henry Spencer) (01/01/91)
In article <40313@nigel.ee.udel.edu> berryh@udel.edu (John Berryhill) writes: >>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... > >Of all of your points, I least understand the significance of this one. The significance is simply that the cell lifetime, replacement cost, and disposal must be figured into the costs, instead of being quietly ignored. -- "The average pointer, statistically, |Henry Spencer at U of Toronto Zoology points somewhere in X." -Hugh Redelmeier| henry@zoo.toronto.edu utzoo!henry
henry@zoo.toronto.edu (Henry Spencer) (01/01/91)
In article <1990Dec31.171413.18138@bronze.ucs.indiana.edu> amirza@silver.ucs.indiana.edu (anmar mirza) writes: >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. 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". -- "The average pointer, statistically, |Henry Spencer at U of Toronto Zoology points somewhere in X." -Hugh Redelmeier| henry@zoo.toronto.edu utzoo!henry
Ordania-DM@cup.portal.com (Charles K Hughes) (01/01/91)
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). Charles_K_Hughes@cup.portal.com
stevek@blenny.UUCP (Stephen Kogge) (01/02/91)
In article <1990Dec31.174455.25630@bronze.ucs.indiana.edu> amirza@silver.ucs.indiana.edu (anmar mirza) writes: >In article <1146@blenny.UUCP> stevek@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 >>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. > The battery I have now is a new car battery. After about 3 years of 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
morrison@cs.uiuc.edu (Vance Morrison) (01/02/91)
wrf@mab.ecse.rpi.edu (Wm Randolph Franklin) writes: >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
dietz@cs.rochester.edu (Paul Dietz) (01/02/91)
In article <-BS^0H*@rpi.edu> wrf@mab.ecse.rpi.edu (Wm Randolph Franklin) writes: >In article <1990Dec31.173248.24523@bronze.ucs.indiana.edu> amirza@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 dietz@cs.rochester.edu
amirza@silver.ucs.indiana.edu (anmar mirza) (01/02/91)
In article <1990Dec31.220520.27738@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >In article <1990Dec31.171413.18138@bronze.ucs.indiana.edu> amirza@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'. -- 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
phil@brahms.amd.com (Phil Ngai) (01/02/91)
In article <18584@teda.UUCP> dll@teda.UUCP (Dan Liddell) writes: |>(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.) | |OPINION:Silicon solar cells do not represent much of a disposal |problem, at least not because of the silicon. They are probably good Henry was probably thinking of Galium Arsenide. Arsenic is generally considered a haz mat. |>(4) LARGE-SCALE SOLAR POWER SERIOUSLY CHANGES THE HEAT BALANCE OF THE |> SURROUNDING AREA, SO IT IS NOT COMPLETELY CLEAN. | |Life systems are open systems. Nothing is completely clean. Spoken like a person who's scared of math, and doesn't accept that often, a large enough quantitative change is a qualitative change. Not the kind I want running national policy. -- Whatever happened to Global Warming? Could we have some Local Warming?
phil@brahms.amd.com (Phil Ngai) (01/02/91)
In article <37448@cup.portal.com> Ordania-DM@cup.portal.com (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. | 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?
Ordania-DM@cup.portal.com (Charles K Hughes) (01/02/91)
>In article <37448@cup.portal.com> Ordania-DM@cup.portal.com (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? Charles_K_Hughes@cup.portal.com
greg@sce.carleton.ca (Greg Franks) (01/02/91)
In article <37487@cup.portal.com> Ordania-DM@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. -- 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 greg@sce.carleton.ca ...!cunews!sce!greg | the installed base" -- Enzo Torresi
cramer@optilink.UUCP (Clayton Cramer) (01/03/91)
In article <37448@cup.portal.com>, Ordania-DM@cup.portal.com (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. 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. > Charles_K_Hughes@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. You must be kidding! No company would hold opinions like mine!
north@manta.NOSC.MIL (Mark H. North) (01/03/91)
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 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
cage@fmeed1.UUCP (Russ Cage) (01/03/91)
In article <37487@cup.portal.com> Ordania-DM@cup.portal.com (Charles K Hughes) writes: > 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: russ@m-net.ann-arbor.mi.us (All non-business mail) Member: HASA, "S" division.
loren@dweasel.llnl.gov (Loren Petrich) (01/03/91)
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: loren@sunlight.llnl.gov Since this nodename is not widely known, you may have to try: loren%sunlight.llnl.gov@star.stanford.edu
Ordania-DM@cup.portal.com (Charles K Hughes) (01/03/91)
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 Charles_K_Hughes@cup.portal.com
whit@milton.u.washington.edu (John Whitmore) (01/03/91)
... 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
keithl@loop.uucp (Keith Lofstrom;;;628-3645) (01/03/91)
>| Solar power: no digging, no processing, energy is converted from >|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 keithl@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
leland@cbnewse.att.com (leland.m.kornhaus) (01/04/91)
In article <1148@blenny.UUCP>, stevek@blenny.UUCP (Stephen Kogge) writes: > In article <1990Dec31.174455.25630@bronze.ucs.indiana.edu> amirza@silver.ucs.indiana.edu (anmar mirza) writes: > >In article <1146@blenny.UUCP> stevek@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 > 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). > effeciency of batteries. > 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
amirza@silver.ucs.indiana.edu (anmar mirza) (01/04/91)
In article <1991Jan3.072059.20842@loop.uucp> keithl@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. >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 # 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
amirza@silver.ucs.indiana.edu (anmar mirza) (01/04/91)
In article <1569@manta.NOSC.MIL> north@manta.nosc.mil.UUCP (Mark H. North) writes: >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. -- 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
berryh@udel.edu (John Berryhill) (01/04/91)
In article <1990Dec31.215646.27617@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >In article <40313@nigel.ee.udel.edu> berryh@udel.edu (John Berryhill) writes: >>>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... >> >>Of all of your points, I least understand the significance of this one. > >The significance is simply that the cell lifetime, replacement cost, and >disposal must be figured into the costs, instead of being quietly ignored. I have never seen these figures for nuclear (or more appropriate to the current area of application, small diesel). If this exercise was intended to be a economic comparison between technologies, why not keep the rules consistent. As has been pointed out, lifetimes for cells other than amorphous Si are longer than just about any technology with moving parts that you would like to name. BTW, just who is it that ever said that any energy technology was eternal? -- John Berryhill 143 King William Newark, DE 19711
berryh@udel.edu (John Berryhill) (01/04/91)
In article <1991Jan2.015717.23554@amd.com> phil@brahms.amd.com (Phil Ngai) writes: > >So you must think that solar cells grow on trees. Actually, in a manner of speaking, they do. -- John Berryhill 143 King William Newark, DE 19711
phil@brahms.amd.com (Phil Ngai) (01/04/91)
In article <37487@cup.portal.com> Ordania-DM@cup.portal.com (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? |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? -- Whatever happened to Global Warming? Could we have some Local Warming?
Ordania-DM@cup.portal.com (Charles K Hughes) (01/04/91)
>In article <37448@cup.portal.com>, Ordania-DM@cup.portal.com (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_K_Hughes@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. :)
Ordania-DM@cup.portal.com (Charles K Hughes) (01/04/91)
> > 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: loren@sunlight.llnl.gov > >Since this nodename is not widely known, you may have to try: > >loren%sunlight.llnl.gov@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. Charles_K_Hughes@cup.portal.com
markb@agora.rain.com (Mark Biggar) (01/04/91)
In article <37487@cup.portal.com> Ordania-DM@cup.portal.com (Charles K Hughes) writes: >>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. 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
andrewt@cs.su.oz (Andrew Taylor) (01/04/91)
In article <5119@optilink.UUCP> cramer@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? 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"
grayt@Software.Mitel.COM (Tom Gray) (01/04/91)
In article <1991Jan3.072059.20842@loop.uucp> keithl@loop.uucp (Keith Lofstrom;;;628-3645) writes: >>| Solar power: no digging, no processing, energy is converted from >>|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. > >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. . . . . . . . . .
meier@Software.Mitel.COM (Rolf Meier) (01/04/91)
In article <1991Jan3.072059.20842@loop.uucp> keithl@loop.uucp (Keith Lofstrom;;;628-3645) writes: >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 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
jdnicoll@watyew.uwaterloo.ca (Brian or James) (01/04/91)
In article <37550@cup.portal.com> Ordania-DM@cup.portal.com (Charles K Hughes) writes: (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
lindsay@gandalf.cs.cmu.edu (Donald Lindsay) (01/05/91)
In article <1991Jan3.072059.20842@loop.uucp> keithl@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. 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
dietz@cs.rochester.edu (Paul Dietz) (01/05/91)
In article <11515@pt.cs.cmu.edu> lindsay@gandalf.cs.cmu.edu (Donald Lindsay) writes: >In article <1991Jan3.072059.20842@loop.uucp> keithl@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 dietz@cs.rochester.edu
Ordania-DM@cup.portal.com (Charles K Hughes) (01/05/91)
>In article <37487@cup.portal.com> Ordania-DM@cup.portal.com (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? Charles_K_Hughes@cup.portal.com
gary@ke4zv.UUCP (Gary Coffman) (01/05/91)
In article <37550@cup.portal.com> Ordania-DM@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. >> 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_K_Hughes@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
cage@fmeed1.UUCP (Russ Cage) (01/05/91)
In article <37550@cup.portal.com> Ordania-DM@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 >carelessly spewn across the ocean floor (& associated tales of using rifles >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?) -- Russ Cage Ford Powertrain Engineering Development Department Work: itivax.iti.org!cfctech!fmeed1!cage (CHATTY MAIL NOT ANSWERED HERE) Home: russ@m-net.ann-arbor.mi.us (All non-business mail) Member: HASA, "S" division.
richard@pegasus.com (Richard Foulk) (01/05/91)
>>| Solar power: no digging, no processing, energy is converted from >>|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. > > [... lots of wild guesses based on a pretty shaking premise elided] 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 richard@pegasus.com
chi9@quads.uchicago.edu (Lucius Chiaraviglio) (01/05/91)
In article <1991Jan4.173128.26484@cs.rochester.edu> dietz@cs.rochester.edu (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 | Internet: chi9@midway.uchicago.edu
phil@brahms.amd.com (Phil Ngai) (01/05/91)
In article <37572@cup.portal.com> Ordania-DM@cup.portal.com (Charles K Hughes) writes: |>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.
dietz@cs.rochester.edu (Paul Dietz) (01/05/91)
In article <1991Jan5.011526.15425@midway.uchicago.edu> chi9@quads.uchicago.edu (Lucius Chiaraviglio) writes: >In article <1991Jan4.173128.26484@cs.rochester.edu> dietz@cs.rochester.edu >(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. 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 dietz@cs.rochester.edu
greg@garnet.berkeley.edu (Greg Kuperberg) (01/06/91)
In article <1991Jan5.023803.4201@amd.com> phil@brahms.amd.com (Phil Ngai) writes: >"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 greg@math.berkeley.edu
cramer@optilink.UUCP (Clayton Cramer) (01/06/91)
In article <37547@cup.portal.com>, Ordania-DM@cup.portal.com (Charles K Hughes) writes: > >In article <37448@cup.portal.com>, Ordania-DM@cup.portal.com (Charles K Hughes) # # writes: # ## 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_K_Hughes@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. You must be kidding! No company would hold opinions like mine!
cramer@optilink.UUCP (Clayton Cramer) (01/06/91)
In article <1755@cluster.cs.su.oz.au>, andrewt@cs.su.oz (Andrew Taylor) writes: > In article <5119@optilink.UUCP> cramer@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). -- 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!
amirza@silver.ucs.indiana.edu (anmar mirza) (01/06/91)
In article <1991Jan5.011526.15425@midway.uchicago.edu> chi9@quads.uchicago.edu (Lucius Chiaraviglio) writes: > > 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. There is a good article on concentrator panels in the 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 # 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
amirza@silver.ucs.indiana.edu (anmar mirza) (01/06/91)
In article <1991Jan5.025526.9284@cs.rochester.edu> dietz@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 It is actually very simple, more photons in=more electrons out. 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. -- 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
dietz@cs.rochester.edu (Paul Dietz) (01/06/91)
I wrote: >>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 <1991Jan5.222423.14844@bronze.ucs.indiana.edu> amirza@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 dietz@cs.rochester.edu
johnsson@cs.chalmers.se (Thomas Johnsson) (01/07/91)
In article <1991Jan5.025526.9284@cs.rochester.edu> dietz@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 >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 (johnsson@cs.chalmers.se) Dept. of CS, Chalmers University of Technology, S-412 96 Goteborg, Sweden phone: dept: +46 (0)31 721088.
josef@nixpbe.nixdorf.de (josef Moellers) (01/07/91)
In <40564@nigel.ee.udel.edu> berryh@udel.edu (John Berryhill) writes: [ stuff deleted ] >As has been pointed out, lifetimes for cells other than amorphous Si >are longer than just about any technology with moving parts that you >would like to name. As I am considering getting into the solar panel hype, could You give me some more information on the lifetime of a-Si panels? They look so cost-effective to me! PS Please use the network address below. Sending a "Response" will not reach me B-{( -- | Josef Moellers | c/o Siemens Nixdorf Informationssysteme AG | | USA: mollers.pad@nixdorf.com | Abt. STO-XS 113 | | !USA: mollers.pad@nixdorf.de | Heinz-Nixdorf-Ring | | Phone: (+49) 5251 104662 | D-4790 Paderborn |
meier@Software.Mitel.COM (Rolf Meier) (01/07/91)
In article <5173@optilink.UUCP> cramer@optilink.UUCP (Clayton Cramer) writes: > >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
jws@thumper.mlb.semi.harris.com (James W. Swonger) (01/08/91)
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.
cage@fmeed1.UUCP (Russ Cage) (01/08/91)
In article <5173@optilink.UUCP> cramer@optilink.UUCP (Clayton Cramer) writes: >It used to mentioned as a problem on tours of Solar One. [....] >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. Even working against wind loads, the amount of power needed to track the sun is minuscule. 1/10 HP is overkill for all but the biggest arrays. Rapid tracking to stow mirrors in sandstorms would take more power, of course, but that is a transient and infrequent requirement. If the array catches 700 W/m^w and the system turns 20% of that into electricity, each square meter produces 140 watts, or about twice what the tracking motor needs. If each part of the array has 100 m^2 of area, then tracking takes about .005 of the energy output; not negligible, but far from a killer. -- Russ Cage Ford Powertrain Engineering Development Department Work: itivax.iti.org!cfctech!fmeed1!cage (CHATTY MAIL NOT ANSWERED HERE) Home: russ@m-net.ann-arbor.mi.us (All non-business mail) Member: HASA, "S" division.
berryh@udel.edu (John Berryhill) (01/08/91)
In article <9231@fmeed1.UUCP> russ@m-net.ann-arbor.mi.us (Russ Cage) writes: >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
bales@athena.mit.edu (James W Bales) (01/08/91)
In article <1991Jan5.225316.12934@cs.rochester.edu> dietz@cs.rochester.edu (Paul Dietz) writes: >>> -- silicon solar cells (at least) become >>>more efficient at high concentration ratios (at constant temperature). >>>I'm not sure why this is. > Paul F. Dietz > dietz@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 bales@athena.mit.edu
kehler@ensub.Wichita.NCR.COM (Kyle Ehler) (01/15/91)
With all the talk about solar cells, my lament is why are these cells still
so expensive?? When I was in third grade I got a kit to build solar cells
the kit came from bell labs. It was complete including wafer, chemicals
and instructions. I never built them because I had no money for the electric
furnace needed to bake the cells. In the 25 or so years since, the kit has
been lost... anyone else out there had one of these??
I remember much of the instruction book, making cells was not difficult
and purity didnt seem to be a concern. Today, with the treknological leaps
and bounds in processing, is there such a thing as buying the wafers and
doping/baking your own cells???
I'm cheap, in the quest for inexpensive power I might be willing to trade
labor for long-term investment in the purchase/fabrication of a PV array.
(even if it is inefficient)
One more drivel; a while back I messed around with Fresnel lenses and PV
cells, I used a 12" fresnel on a 4" cell. Positioned the lense just right
will really multiply the output of the cell, only problem is the heat has
shattered a couple of my test jigs. Liquid cooling of the cell helps, but
the heat gain is just short of tremendous, remember roasting fire ants with
a magnifier (try it with a 12" fresnel..poof*). Perhaps the use of a UV
or IR filter would help?. -kejwoodard@nmsu.edu (Jeff Woodard) (01/22/91)
I'm sorry if this breaks into a current thread, or rehashes anything
already discussed, 'cause I just caught up and haven't read recent
postings.
Anyway, I've seen a couple of postings that gave addresses
where solar cells could be purchased, namely 'Real Goods', and one
other that I can't remember now. I received catalogs from those folks,
but they don't carry the individual cells, only large panels. I'm
looking for a 'cheap' source where I can get some cells that are
comperable to those sold by Radio Shack (Arrrgggg!!!). I'm trying to
construct a small airplane that will be solar powered, and would like
to keep the cost of the cells down.
I purchased some from 'All Electronics', but they were pretty
worthless, and were basically unsolderable. I'm in the Las Cruces,
El Paso (Urggg!) area, and can't seem to find any among local
suppliers (even though there is supposed to be a manufacturing plant
here).
Thanks in advance, and if I get enough response, I'll post a
summary to the net.
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When I grow up I wanna be the guy that thinks of all the really neato stuff
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I don't know why they call me woody, I just smile and wonder.
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