Hello All!:) Dr. Bunsen Honeydew here, with another breakthrough!:laugh3:

I'm an earth-friendly nut, so naturally, I'm always searching for the answer to a better way - so that nobody needs to be harmed making the stuff we all enjoy, and so the general environment is healthier, and things like Polar Bears, even if we have to give them man-made ice cubes to stroll around on, manage to survive without the mercury and toxic chemicals in their systems.

 

So, in my wanderings, I've always been perplex by a contradiction: Those of us who are eco-geeks like the super-efficient homes and appliances, and like the solar panels, batteries, and attendant hardware for all this nifty eco-home stuff to work, and make our carbon footprint go down (and save us some dough in the long run as well). But, unfortunately you can't just yet have your sun and keep it neatly bottled in an eco-friendly way. Until now.

 

Since silicon solar cells are the mainstay, and since they're made from one virtually inexaustible supply of silica (quartz, sand, quartzite, etc.), containing the earth-friendly plentiful element Si, they look like they'll be here to stay. But how are they made?? Magic? Well, almost. They're made by using relatively pure silica as the base ingredient, and carbon, which is reacted to yield impure elemental silicon. Then, this 'metallurgical grade' silicon in reacted with halogens (chlorine, for example) to form one of several compounds which can be distilled ultra-pure, and then reduced back to silicon. Melted and crystalized, sliced thin, polished, bonbarded with ions in a vacuum, bombarded with nitrogen atoms, and to make a long story short, the modern silicon solar cell is produced.

 

What's not earth-friendly about the process? Well, for one, it takes a lot of carbon, and generates greenhouse gases. Then the refining requires the production, transport, and consumption of vast quantities of chlorine gas, and some toxic intermediates in the purification. So, the search is on for a better method - one that's less risky, less demanding of carbon, and less energy intense (for better payback).

 

Lo and behold, some enterprising chemical investigators discovered that molten salt baths can be used to electrolytically separate all sorts of things, from Calcium metal to Titanium to Silicon, and at a reasonable purity! All it takes is some of the right basic salts, some carbon electrodes, and lots of electricity (but maybe less than the other methods).

The FFC Cambridge process is what this relatively new process is termed, and it's quite promising, if not already in production, perhaps it should be! Here's a bit on it:New silicon production method with no carbon reductant

 

But is it really the answer, or are there some bugs? Can it yield the purity required of silicon to meet the solar cell's requirements? These are still questions to be answered.

 

Basically, for eco-homes that are solar-electric or wind-electric, the intermittancy of the energy requires storage devices, and the low voltages require lots of heavy wire and inverters.

 

What that means in terms of the materials is currently unacceptable to be feasable for more citizens, and to be free of the environmentally risky mining and refining methods for these elements.

 

Consider this: A solar/wind powered home might require 800# of lead, 300# of copper, .01 oz. gold, .1 oz tantalum, and will have required vast amounts of chlorine gas to be produced, many pounds of carbon for the silicon, in addition to hundreds of pounds of iron, aluminum, zinc coatings, plastics, etc. to make it all work.

 

A similar non-eco home may require almost no lead, 150# copper, and almost no gold or tantalum for the initial power supply, and much less iron, aluminum, zinc coatings, and plastics, but does require a power plant, a share of which uses other resources attribitable to this house's needs.

One could argue that the coal being burned to power the home gives up it's load of lead and mercury (and other metals), and the fly-ash/scrubber wastes contain in a matter of years just as much lead, plus the mercury. And one could also argue that the detriment to the envrionment is much less for the solar/wind powered home in that the carbon foorprint is so much less as to make up for the rest.

 

This might be the case, but even so, is it a destination, or just a beginning? My way of thinking is that we need to complete the circle, and minimize risky rare materials. We want the hot pizza and the cold beverage, not the copper wire! So I began to approach things from a broad perspective, and discovered that we can have the best of both worlds. Instead of nickel or lead in batteries, choose lithium or carbon nanotubes. Instead of copper conductors, use aluminum conductors where applicable. Eco-friendly plastics can substitute for much of the zinc-coated conduit, and gold can be recycled from the waste electronics, and minimized wherever else it is needed. Even tantalum has replacements in carbon film capacitors and the like. In short, a better path is there, if we should so choose it. It is the better way forward.

thanks for that chuck. It was a really interesting read.

Thanks Bryce! Just my odd world view, if ever this world were to make sense.. How do you manage in the countryside down yonder?

My view of the world? I dont really know what I think. There were reports on our news today that global warming is irreversible for the next 1000years. I dont really know what to think. I do know though, that when the time comes, im going to do something to make the world a better place. I want to do that with every fibre in my body. Something big too. If its stopping global warming, then so be it. If its becoming the prime minister of australia, then ill do all in my power to achieve that as well. In the meantime though, i think i next to get a supportive girl, and take amazing photography.

Go with the supportive girl - feels better than either the global warming or the Prime Minister's position!;)

Global Warming is irreversible for the next 1000 years? Hmm.. Well, that assumes we can't do something about it. There's everything from adding mineral supplements to the ocean, to cloud forming technologies, and other changes we could make (reforesting areas, i.e.) as well. But it's one complex set of simultaneous equations, and I'm guessing that given the nature of chaotic tipping points, we might not quite have it down to a perfectly predicable level. But I could be wrong - it's amazing what we already do know. Looking at -33C this morning, I would very much appreciate a little local "global warming" for a change!:laugh3:

ill get you the article. http://bigpondnews.com/articles/Environment/2009/01/28/Climate_change_is_irreversible_298352.html

Thanks Bryce! But that's assuming we pass current levels and reach some 'peak'; which is probably inevitable at this point in time, the way things go. But, there are ideas! Water the deserts with desalinated ocean water. Bring sand and crushed rock to raise the levels of those island nations. Build giant dikes to save coastal cities. Tow the icebergs to Australia, blast them into small pieces, and haul them to the dry interior! Do the same for all the world's deserts.

I still think it's early claims that are being made. Maybe if we use enough ground limestone, we can help neutralize the oceans, and add mineral nutrients to stimulate phytoplankton, etc. Reforest more areas, and grow crops that hold more carbon, like prairie grasses and plants. With enough solar power, we could even remove CO2 from the atmosphere, convert it to stored carbon, and put it back into the ground.

Or, more likely, some of the easier things will be done (ocean neutralizing and fertilizing, first on a test basis), and watering the deserts. The rest we'll have to adapt to - we're actually amazing at doing that, but the real loss will be the diversity of life.

Still, have hope in humankind's ingenuity. Maybe that and really huge parks with lots of sprinklers..

An estimate on how much gold is really in your computer: From a table of High Extractable Metals, the typical PC contains .001% gold. Since this old one here weighs about 23 pounds, running the calculations means that it contains approximately .0034 ounces of pure gold. That's .1 Gram of gold. To put this into some visual realm, think about it this way: A small paperclip weighs approximately .5 grams, so if you "clip off" about a fifth of a paperclip, this would roughly equal the mass of gold in your computer. While it's not much gold (roughly $3.00 worth on the market), the millions of PC's, cell phones, laptops, digital cameras, stereos, and countless other electronic gadgets create a huge demand for gold, and we have yet to recycle appreciable amounts of these things.

How rare is gold? Well, typical gold ore contains so little of the metal, that it would take a mass of ore in a room 15 foot x 30 foot (roughly 5 meters X 10 meters), floor to ceiling filled with ore, just to get one ounce of the metal. By contrast, it would take approximately 300 computers to yield the same amount of gold. The computers also contain 9X that amount of silver, plus palladium and other precious elements, making it essential that we recycle them.Metallurgical recycling of electronic scrap.pdf (application/pdf Object)

Back to Silicon: I've been doing some searching, and ran across the price for Solar Cell grade silicon. It's fluctuating quite a bit, with the futures markets, but for 2008 ran around $165 per Kilogram. (This works out to around $75/lb.). It's set to drop in response to both other thin-film technologies, and it's own supply improvements, possibly down to $113/Kg. (~$51/lb.). Silicon of this purity requires quite a lot of processing, and leads to a price roughly half that of silver on the open market, but the quantity of 'ore' is inexhaustible, it's 'green', and the ability to refine it is getting less and less expensive with newer methods.

Improved availability may drop the price per watt of solar power from the current $4.00/watt down to $2.60/watt. Currently, it takes about 5-7 years for a set of panels mounted on a rooftop to pay back their cost in savings of electricity (all externalities aside); this drop could knock down the payback period to 3-5 years, and adding more government incentives to go solar could dramatically increase the number of installed panels.

A link, alread in the green thread, but here it is again if anyone's interested: PV Costs Set to Plunge for 2009/10 - Renewable Energy World

Also, if you're interested in a general synopsis of silicon solar cell manufacture, here's a link ( a bit dated, but a good overview):How solar cell is made - Background, Raw materials, The manufacturing process of solar cell, Quality control

Images for Silicon:Facts, pictures, stories about the element Silicon in the Periodic Table

BUMP

PV cell - they do require plating for a conductive surface. Actually, sputter coating; the cells I had were plated with silver, but copper has been used as well - it requires very little copper (super thin), which is a relief.

Perhaps in the future aluminum can be sputter coated onto the surface, and perhaps soldered with aluminum solder, though this would be less reliable. Anyhow, just searching for eco-friendly ways..

Lithium Iron Phosphate cells should come down in price as well, given time.. they're more eco-friendly than anything else, outside of carbon nanotube cells. Flywheels may be competitive too, but the composites use some wicked chemicals to manufacture, so I'm hoping for better here too.

Spamela Anderson is an expert on this.:rolleyes:

Hey, I'm just trying to promote the answer to Life, the Universe, and Everything!:P Silicone, that's what Pamela's jugs have in them, not Silicon! If they were silicon, they'd clink when they bounce!:laugh3:

Check this out!!

Silicon 42 is the magic isotope!"Magic" numbers remain magic - physicsworld.com

Its a pyramid scheme I tells ya!

Pyramids, hmm.. speaking of geometric forms, I began a search for that all-essential industrial element, Fluorine. Fluorine can be hard to find on earth, usually being mined from regions of unique geology, where rare fluorospar crystals are available in mineable quantities. The rarity of the resource and sometimes risky mining and refining, put me on a search for a better source of Fluorine. And here's where Silica minerals comes in! It turns out that Biotite mica (the black flecks in granite) offer an excellent source of Fluorine! Biotite Mineral Data

While not extremely concentrated (at a little over 1 % Fluorine), the availability of biotite is inehaustible, and the byproducts of mining common granite pegmatites can be silicon dioxide, useful for producing pure silicon.

Flourine is essential in various processes. In the chemical Hydrofluric Acid, it can be used to clean surfaces, and to etch glass. As a salt (sodium fluoride) is has uses for the electrolysis of molten salt baths to produce aluminum metal and other metals. While risks are very significant, it has yet to find replacement materials or methods in many applications associated with solar cell manufacturing and silicon processing, as well as many other industrial applications. So while reducing it's necessity & recycling are wise goals, it may never be possible to entirely phase out our modern need for Fluorine, and reducing one area of concern (its source) helps ensure a bright future.

Thanks for that! Im concentrating the silica as we speak.

 

If that makes sense. Ionno.

Confusion on that last post.. Anyhow, it's everywhere, and without it, we wouldn't have these nifty computers to play with! (or, they'd be using germanium chips instead..). Silicon - abundant, natural, beautiful, and it makes great paperweights too!:P

**Bumps pet thread**:P

Silicon - Abundant, clean, natural, beautiful. :daisy:

Today's Topic: Solar Cell Manufacturing.

Here's a good place to look@:Solar Cell Manufacturing Plants

The future is sparking in the sun!!:sunny:

Carbon Challenges Silicon: Valley in California may change name to carbon valley.:P

Carbon nanotubes' next target: solar cells - Ars Technica

Silicon solar cell payback here:Solar Power

Chuck, have you considered the political implications of decentralized power production? It could be interesting...

Yes, that's part of our secret plan to break up the centralized control of the economy..:wink:

I've considered it Jay, although I'm not sure it would ever amount to more than a percent or two of the total population. Perhaps in time though, this could change. Anything to beak up massive blocks of power would help keep us freer, that's for sure!!

I've thought of it also as a better way forward for people in the Middle East as well - they have ample solar for energy production, and lots of sand - they could be producing a great deal of the solar cells for the global demand, and providing a greater increase in income to citizens there.. It would be quite nice to see them use solar to pump and desalinate much more sea water, irrigate large areas, and be net food exporters, all with systems built using solar power - a great way to ensure long term economic stability, and reduce the threat of extremist violence through much improved standards of living..