Environmental Goods & Services (EGS) News

Waste wafers give solar power a silicon boost - 15 November 2007

A simple method of recycling waste silicon from microchips that could help ease the shortage of refined silicon for solar energy panels has been developed by IBM.

The company has devised a simple way to remove the integrated circuit patterns from discarded scrap semiconductor wafers made out of silicon. These can then be sold to the solar panel industry for use in photovoltaic cells that generate electricity on rooftops.

The process involves coating the surface of a silicon wafer with water and scraping it with an abrasive pad. The primary goal is removing the proprietary circuit patterns from the surface of the wafer.

Every day about 250,000 wafers are produced globally to make chips for products from cellphones to computers, and to monitor and control manufacturing, according to an industry group.

IBM estimates that 3.3% of these wafers are normally scrapped before they reach the market, which adds up to nearly 3 million discarded wafers per year. It reckons the silicon from these discarded wafers could make solar panels capable of generating 13.5 megawatts of energy. Rapid growth

That is a small amount of the overall solar market, however. The world's largest solar panel maker, Sharp, makes about 710 megawatts' worth of solar cells per year. But Eric White, an IBM semiconductor engineer who helped develop the recycling process, says that, as the semiconductor industry grows, more of the wafers could become available for the solar industry.