How 'green' is the production of silicon for PV solar panels?
Question:
My question actually has 3 parts: 1) How is it mined and refined? 2) What countries have the majority of it? 3) Will there be negative environmental and sociopolitical impacts on the mining of this material? (As with "blood diamonds" and strip-mining?)
Answer:
There is a bit of a spiel on this link about the manufacture of silicon semiconductors and how they work.
http://www.phys.unsw.edu.au/courses/firs...
To try and simplify this a bit.
Silicon is one of the most commonly occurring substances on earth. For pv cells it is refined to be virtually 100% pure. (Plenty of heat). Dopents are added to create either a surplus of electrons or a shortage of electrons. Making the final ingot produced either n type or p type respectively.
Slices of p and n type ingots are placed together and electrical connections are made to each side. (Diodes and transistors are made the same way with much smaller surface areas.) In the presence of light an electrical current flows from one contact to the other = electricity.
There are basically two types of silicon cells multicrystaline and monocrystaline. The later is more efficient and require more power to produce because they are manufactured from single crystals.
Not all solar panels are made from silicon. Gallium Arsenide cells are even more efficient and expensive
http://www.mdatechnology.net/techsearch.
There is a company called dyesol that claims to have produced a solar cell that utilises Artificial Photosynthesis.
http://www.dyesol.com/index.php?page=how...
Most countries have sand that can be refined into high purity silicon. If it is lower silica sand it takes more energy. The white sands usually contain the highest levels of silicon and are usually the preferred source. Countries with large sandy coastlines are the best sources of this sand.
As with anything if there is a buck in it, someone is going to get ripped off. If performed responsibly sand mining can have minimal environmental impact. It disturbs quite a small area which can be revegitated as the activity moves on. When driven by a quick buck it can be a disaster.
In short pv producition can be done in quite a green but not always.
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silicon = melted sand.
sand mines itself and is found nearly everywhere.
you are on the right track though:
how about this question:
how many manufacturers of PV panels run their operations on PV energy?
Hahaha!
Silicon is made out of sand.
All countries have enough of it.
It takes huge amounts of energy to purify it. So factories are found where cheap energy is available.
The production will be as green as the available energy.
all that i know is that it works great...
DOE did a lifecycle analysis on the energy used to make PV vs. their overall energy production and concluded that when put into service the panels make up the difference within a couple years.
As a roundabout answer to your question, I would guess that the leading countries in silicon wafer production (US, Japan, China) would also lead in PV production capacity.
The amount of energy you get out of a panel is three fold or more to the amount of energy needed to manufacture it. It's the closest thing you will get to getting something for nothing.
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