Thursday, November 15, 2007

Saving on Silicon

IBM is tapping on solar's door again (see previous story about IBM's flirtations with entering the solar industry). This time, IBM has devised a way to recycle slicon from discarded semiconductor wafers for ultimate utilization in solar cells. From IBM's website:
The new wafer reclamation process produces monitor wafers from scrap product wafers - generating an overall energy savings of up to 90% because repurposing scrap means that IBM no longer has to procure the usual volume of net new wafers to meet manufacturing needs. When monitors wafers reach end of life they are sold to the solar industry. Depending on how a specific solar cell manufacturer chooses to process a batch of reclaimed wafers - they could save between 30 - 90% of the energy that they would have needed if they'd used a new silicon material source. These estimated energy savings translate into an overall reduction of the carbon footprint -- the measure of the total amount of carbon dioxide (CO2) and other greenhouse gases emitted over the full life cycle of a product or service -- for both the Semiconductor and Solar industries.
Separately, MIT Technology Review reports that Clean Venture 21, a Kyoto, Japan-based has developed a novel way of making solar cells that cuts production costs by as much as 50 percent by reducing the amount of silicon needed. The photovoltaic (PV) cells are made up of arrays of thousands of tiny silicon spheres surrounded by hexagonal reflectors. These spheres work like car headlights but in reverse, ensuring that any light hitting the reflector is directed toward the sphere--essentially acting as mini-concentrators. The hexagonal shape of the reflectors allows them to be slotted together without dead space between them.

Of course, the whole basis of the thin-film solar boom is the avoidance of silicon as a raw material. This piece by Popular Science (it has a cool slide show and animation too!) talks about Silicon Valley-based Nanosolar's silicon-free thin film technology.

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