WC Archive

The 400x concentrators only work if all the sunlight actually makes it to the cells; if you have haze or thin cloud which diffuses the light, the output of the concentrator will fall off much faster than a flat plate panel's.  That would probably affect the payback in some areas; if the times when power is most valuable have significant periods of haze, the concentrators would be impaired when they are most needed.

On the power-hungry band from central Texas to SoCal, I bet they're right at home.  I hope these folks can turn this into product pronto.

A foot is 0.3048 meters. so 23 feet is about 7 meters. A circle that size has an area of 38 square meters. Sunlight in San Diego at high noon on a clear day carries about 1kW per square meter of thermal energy. So this thing has an overall efficiency of 6.6 divided by 38 or 17%. That's pretty good. But then you have to multiply that by all the chain of efficiencies of things like DC to AC power converters, and keep in mind their considerable costs.

And so on and on. The usual story.

It also might be relevant to note that there seems to be a lot of metal in the mount and tracker, and fresnel lenses get dirty.

I do not wish to sound like a johnny-one-note, but the solar stirling engines tested by Cummins during the 80"s had what looks to me to be a less complex design and higher overall conversion efficiency. They put out clean 60 Hz AC that could go right on a power grid without any electronic hokus pokus.

What we need to sort out all these gee-whiz claims is a challenge to the technical community. A straightup money prize of say $10 million to the winner of a shoot-out on such and such a day and place. Whoever can turn sun into AC juice with the most practical device wins the pot. A totally impartial panel of experts to make the call.

My entry would be a big soupy pond of sewage-fed algae, sun dried and stuffed into the burner of a free piston stirling engiine. Night or day, rain or shine, dust or haze.

Wimbi, I like your idea very much, but with a twist: I'd enlarge the pot of money, and offer at least 3 "first-place" prizes. That's because I don't think there will be "one right answer" to the problem. The "most practical" way to turn sunlight into electricity may vary with climate, latitude, cost, whether the source is best for an existing grid or for rural, off-grid places, technical skill required, availability of spare parts, and so on. There may be one smart system for the southwestern United States and another for villages in Nepal.

You're pointing out something very important: this is a promising way to generate electricity, but it's not yet a useable system for delivering energy services. And it's the services we want, not the fuel per se.

Wow. I like the stirling engine idea a lot! The pyron solar approach is ok but I wonder about the practicality of pools of water in the desert and cleaning the lenses at night. Dust storms?

It looks like this outfit has got the cost down, has support from big players and may have a couple of orders in the pipeline.

Very good ideas, folks. Sure, there is no universal solution to solar power. Maybe prizes for sunny places, for high places, for places like mine that have lots of biomass and little bright sun. I have always been amazed at the fanatical efforts people will put out to win a prize, even a relatively worthless one. We should try to harness that insane passion to noble ends, eh?

As for SES solar stirling project. I wish somebody could get out of them their data on mean time to failure. My own efforts have come up with nothing but fuzz, and obique hints from the sponsor that they are trying for (not yet got) a very modest life before major repairs.

The crank stirling engine has had the advantage of many hundreds of millions of dollars of R& D, and still cannot boast of a reasonable life (years). The free piston stirlings, that use gas bearings instead of conventional lubrication, have good life, but relatively speaking, almost no funding except for exotic NASA space applications with near impossible requirements that drive their unit costs out of sight.

We have several 1000 sun concentrators with high-intensity pv and have talked $2/Watt for years, but who cares? We are also ignored by the ignorant. Who is the audience for these demonstrations in the USA?

pictures at http://www.harbornet.com/sunflower/pvdish.html

One audience is CEO's and CFO's and the lingua franca is ROI.

Make the kind of case these people are making.

NYT writes solar concentrator developer Bill Gross (re: Wired CEO CFO above) spent $800M in 8 months, must be quite a ride... is this entertainment or is this the energy news that a democracy can respond to? There seems to be a news disconnect concerning high-intensity photovoltaic cells. This is big news, good news, and hard news. Where is the news media?

taking the fact that Sanyo has decided to stake their future on developing renewable energy sources etc. anyone with a decent concentrator might consider contacting them. After all solar installation on rooftops in Japan isn't terribly uncommon.

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A while back I sent a tip to WC on a modified Stirling engine, flat-packing solar dish (of flat concentric polished stainless steel rings for greater surface area & durability) & a salt fuel cell battery – being trialled in sunny Australia.

Extracts:

a ‘phase change’ heat cell containing salt and graphite (as a heat conductor) can store 9.5 times more energy than the same sized lead-acid battery used in photovoltaic systems. It can also store 100% of the solar energy directed into it, compared to only 15% for photovoltaics. Salt cells last in excess of 25 years

salt melts as 900°C, then you can take it to 1500°C - it just holds the heat. air heated by the salt cell drives power piston, to provide a stable 240 V into a house.

AU$15k for a 5m dish, Stirling engine & salt cell, can produce up to 5 kW hours of electricity and 20 kW hours of hot water (at 50°C), on an intermittent basis and at a combined heat and power efficiency of more than 80%. This is enough to cover domestic electrical (5 kW/h) and hot water (3 kW/h) needs and an absorption chiller for air conditioning (12 kW/h) – with energy storage for approximately four days without sunshine.

a single unit will repay its CO2 footprint (the amount of CO2 generated in its production) within 18month

a AU$1,000 desalination unit uses a vacuum to reduce the boiling point of salt water to 40–50°C. The unit can supply 300 litres of distilled water per hour, 24 hours a day, and produces ‘latent’ heat which can be used to make the unit as efficient as a reverse osmosis system, minus the CO2.

http://downloads.publish.csiro.au/ecos/ecos_download.cfm?article_id=EC124p28.pdf&issue_id=124&issue_year=2005

It also has a hybrid arrangment with wind turbine. I like the fact that it's a fresh application of 200 yr & 100 yr old technology (with adaptable functionality & long-term reliability in mind). This type of 'bush innovation' can really be WC. Interestd to hear yr opinions.

Janelle,

It certainly seems like a reasonable approach. I hope Mssrs. Glynn and Slade push a successful product out the door and it gets a great reception.

People here in America are sleep-walking into the future and we need folks in other countries to shake us up a bit.

Janelle, it's considered courteous to give a heads-up for a pdf download of indefinite size.  Dial-up users might want to pass on it.

Fresnel reflectors are clever, molten-salt heat storage is slick, and 16% electric efficiency is pretty darn good.  The system wouldn't work very well with diffuse sunlight, but many parts of the world have little cloud and would be perfect for this.

When will they be on the market, and at what price?

EP, pt taken. I nrly warned pdf but assumed that words like download, publish & pdf in a url would be sufficient. Never assume, right?

est. cost approx AUD$17k (approx USD 13k these days, although would have been more like USD9k not long ago). + AUD$1k desalination.

Solar co-generation is coming soon..to a collector near you! Stayed tuned to this channel..

http://amazngdrx.myblogsite.com/blog/_archives/2005/7/2/990726.html

Ran across a link to a German TV program talking about this a couple weeks ago (wish I could find that link). They interviewed the couple and showed more details about the equipment. Minimum of hype, plenty of details.

Basically, it's an array of smaller, discrete units. Each unit is water/weather-tight, and has a freshnel lens on top focusing on a small high-flux PV cell in the bottom. The entire group of individual units sits/floats in a water bath (gotta actively cool the high-flux PV). Since most of the weight is supported by water:

• you don't have to have a very strong framework supporting everything


• the hottest part of each unit (the small, high-flux PV cell), sitting on a water-tight heat-sink, gets maximal cooling


• the weight of the units pushes the lower side down a few inches under the surface of the water (the fresnel lens stays a few inches above the surface, so no flodding), so heat is very effectively carried away from that high-flux PV


• minimal effort is required to aim the units (they still have to be harnessed together, and you do need some kind of active tracker); they are relatively stable, but have little resistance to movement

• you get economies of scale through mass-production


• you can pretty easily scale a small installation up to something larger


• if one of them fails, you can easily replace it without needing to take the whole array off-line

As a guy who has spent his life (so far) working on all sorts of things to change sunlight into electricity, and as a one-time farm kid whose fate it was to fix busted hardware all day, I shrink to see a system as complex as a lot of little lenses focusing sunlight on bits of glass floating on a puddle of water.

What happens when a goat decides to jump on the thing? What happens when the water gets full of sand? What happens when it gets all wavy and evaporates in a wind storm? and so on.

So I keep coming back to the brute force solution- a field or pond of weeds of any kind that insist on growing despite hell or high water, and a thing you can stuff the weeds into to burn to make electricity. My favorite is an air charged free piston stirling engine- big, ugly rugged simple and lasts forever. I have tried crank stirlings many times, and neither I nor anybody I have heard about can claim much life out of them before some kid like I once was has to take them apart and replace the rings and seals and wash the oil out of the regenerator..

Unfortunately, the article is incoherent.  Author Pyper uses the meaningless (but all too common) term "kW/h" (page 3), and talks about peak production rates in "kW hours" (page 1).  This is nonsense, and it's impossible to determine what it is supposed to mean.  It also makes it impossible to properly compare it to photovoltaic on an even basis.

Don't get me started on that funky venetian-blind windmill.  Nobody uses such things for electric generation, and for very good reason.  Just look at the size of the tower compared to the area of the thing!  And why would anyone convert electricity to heat in a salt bank just to convert maybe 20% of it back to electricity?

I'm not sure if any of you guys have come across this Christchurch NZ company which has developed a "wobble yoke" for the Stirling engine and is having quite a bit of interest from energy providors. Field trials underway in the UK at the moment I believe:

http://www.whispertech.co.nz/main/wobbleyoke/

Thought the info might be pertinent to the discussion.

Engineer poet its simple kw/h is how fast your gona make/spend money and kilowatt hours is how much money your gona make/spend.

Its not actauly about the electricity its all about the money.

Okay, wintermane, if you're presuming to lecture me on this subject you should be able to expand "kW/h" into its fundamental SI units and explain what it means in physics terms.

Go ahead, I'll wait.

You guys are overlooking the important part of this, overpowrering solar energy focused on a water cooled PV cell works.

Maybe not as well as it could given a simpler design, but still this proves you can overpower a solar cell.

Now how about a rotary mirror system that allows the solar cells to produce synchronous AC current for the grid. This could provide greater efficiency from the cells as it would temper the heating effect.

The whole floating thing is kind of strange, and the use of a lense means it can only work in direct sunlight, not diffuse cloud light.

Plus the heat from the cooling water is not collected.

Combined with algae growth systems that use the excess photosynthetic light, and provide rapid evaporation to distill water and collect heat, and biofuel systems to process the algae using solar power, this system could produce maximum hours of peak electric power from expensive PV cells, while providing waste water recycling, biofuel (hydrogen,biodiesel, ethanol, and methane), organic fertilizer, and heat for either heating or cooling (adsorption cycle)buildings.

Solar cogeneration, the next wave in renewable energy, hang 10!

I dont have to engineer because all that matters to everyone in the real world is how much money is involved and kw/h tells you how much you make per hour and kw hours tells you how much you made per month.

Or spent if your consuming them.

In other words, you can't.  You lack the knowledge to explain the terms you're using.

I'll stay this straight out:  the term "kilowatts per hour", regardless of how it is expressed or abbreviated, is meaningless.  It is never used by anyone with knowledge of what they are talking about except to explain that it is erroneous.

There are two terms you should keep in mind:
Watts (with the SI prefixes micro, milli, kilo, mega, giga, etc).  Watts are units of power.
Watt-hours (with the same SI prefixes).  Watt-hours are units of energy (power=energy/time, energy=power*time).

"watts per hour" would be power/time, which is meaningless.  Purge it from your thinking, because it will only lead you astray and make you look foolish.

You know this prolly isnt the topic to talk about it its prolly best to talk about this tendancy of engineers to try fruitlessly to make to world use the "proper" terms for power in the mass social change topic but what the heck why not.

Actauly I can tell you a kw/h is in fact a kilowatt as is funny enough a kilowatt hour.

But kw/h and kilowatt hour are terms created by common people because they are what they wana use.

You are in fact no different then the 1000s of english teachers railing against aint and aint got nothing and so on.. we dont care what you think because you aint us.
Thus the social masses steal from the little social groups aka engineers the terms they wana use and use em as they wana use em and dont care how you feel about" your" terms;/

Alot like environmentalists railing against "clean coal" and green blah blah blah and whatever. The masses do not care they do not listen they do not notice and they just see what they like and use it as they like.

So be upset all you like rail against the "stupidity" of a word or label all you want... we dont care never did and never will and if anything we will always enjoy watching you suffer.. thats what we do best.

If it werent for little groups railing about this and that the world would be alot less fun to watch and being a clueless barbarian or a dudnerheaded american or a souless tasteless unwashed mass would be no where near as entertaining.

Okay, play Humpty Dumpty all you want.  Try to re-define the meaning of the terms of physics to suit your popular slang.

Now take the understanding you've prevented with your careless obfuscation and try to calculate how much it's going to cost you to run the air conditioner you're thinking of buying.  That's a trivial problem compared to the scientific heavy lifting out there, and guess what?  You've made yourself unfit for doing any of it.

Terms in physics, chemistry, engineering and many other practices are precise for a reason.  If you don't know those reasons, you are claiming that ignorance is as authoritative as hard facts.

My contempt for this attitude knows no bounds.

You know you just demonstrated why solar has and will have such a hard time in the energy production industry.. why this design for solar energy will face stiff problems EVEN if it works.

Because as you put it

Okay, play Humpty Dumpty all you want. Try to re-define the meaning of the terms of physics to suit your popular slang.

This is how many people whom you are trying to convince right now look at what your saying. They dont care if it works...

You are clearly encroaching on what they concider THIER turf and you are doing it in a way that is just as humpty dumpty to them as what I was telling you was to you.

That is what worldchanging faces. That is the force that pushes against the changes we hope to make in this world.

Wintermane, what do you mean by "they don't care if it works"?

People DO care if these things work.  They don't want their money wasted.

Gross errors in terminology which obscure the physical meaning behind the terms helps to hide errors which will prevent things from working.

Worse, this nonsense helps scam artists to take the public for a ride because the public (confused by nonsense in print and even in classrooms) lacks the proper understanding to see through it.

Jamais im litteraly saying they dont care if solar works or not they feel its just plain WRONG. I cant describe how or why they feel this way because I personaly dont feel that way but I do know they act exactly like engineer here does whenever I talked to them about solar. Even if it "works" its just not THE WAY to be doing things.

Hell look at him foam at the mouth over such a silly thing as adding a useless /h to the term kilowatt. Now imagine 1000s of engineers / managers in the power industry looking at most solar setups and foaming away exactly in the same way again for something that doesnt realy matter....

Humans are just plain touchy buggers.

Let me get this straight.  You

• Use blatantly wrong and misleading terminology, then
• Waste time and words defending these errors instead of just correcting your usage,

See what I mean Jamais?

EP...I'm not understanding why concentration systems are more vulnerable to haze, etc than ordinary flat PV systems. Surely there isn't enough haze in the few feet between the reflector and the cells to make a material difference?