Top solar manufacturers are making progress on greening their supply chains and recycling efforts, but a key European Union decision on cadmium could redefine what it means to be good for the environment
The EU’s decision on whether to exempt solar makers from regulations on hazardous chemicals, such as cadmium and lead, could come as soon as next month.
Its repercussions could be profound, particularly on market leader First Solar, which makes a cadmium-telluride thin-film cell. But First Solar is not alone in feeling the pain. General Electric and its partner PrimeStar Solar also work with cadmium, as does Abound Solar.
The EU could decide whether to exempt the solar industry from hazardous chemical regulations in June, including those on cadmium, a component of many cells.
Industry sources say the EU review may not be finalized until the fall, but the exemption should be decided by the end of June. If it is not granted, chemicals such as cadmium could eventually be banned from use.
Already this year seems to be a big one for solar’s efforts to manage its supply chain, improve manufacturing and scale-up recycling. In Europe, a voluntary recycling program created to take back spent solar panels is ready to begin, and the number of companies participating has almost doubled to more than 25.
“This is a key year for PV recycling,” says Ben Santarris, public affairs manager at crystalline silicon cell maker SolarWorld. The program calls on companies to aside money ahead of time to process the panels they sell, a step Sheila Davis, executive director of the Silicon Valley Toxics Coalition, considers critical for the industry.
For companies such as SolarWorld, which has had a panel-recycling program at a factory in Germany since 2003, the new efforts don’t represent a big change. For others, the change is more significant.
However big changes do confront SolarWorld – specifically the removal of lead from its cells and panels. “We are committed to beginning to remove lead from our production facilities this year,” says Santarris.
The effort is a challenge both chemically and financially, and without an exemption from EU hazardous chemical regulations, could be mandated. The company uses lead during metallization, to coat silicon wafers with circuitry, and then to connect cells inside modules. A substitute is hard to find.
While the amount of lead is small enough not to violate California’s strict regulations, says Santarris, the pressures on the industry are considerable.
These pressures may weigh heaviest on cadmium telluride companies. First Solar defends its use of cadmium and has stepped up efforts to monitor the material in its supply chain.
Cadmium is a byproduct of zinc refining and purification, and would go to waste if not used, says Lisa Krueger, vice president of sustainable development. More so, by the time it ends up in the cadmium telluride compound First Solar uses, it is very stable and insoluble to water, so it doesn’t run off with the rain.
The compound is then placed between two pieces of glass, insulating it from exposure to the environment. “There is very little opportunity for the cadmium to be exposed to people or the environment,” says Krueger. “We’ve done a lot third-party validation.”
She also points out that a cadmium-telluride cell takes less energy to manufacture than a crystalline-silicon one. This means the CO2 output is lower, 14 to 15 grams per kWh of product compared with 28 to 29 for crystalline silicon, she says.
The company is nonetheless stepping up its efforts to monitor its supply chain. “There are things we can do to improve (our) supply chain,” acknowledges Krueger. One thing is to peer deeper, all the way back to the refiners and purifiers who handle raw materials. It is an effort now underway.
That means getting more information and validating the information suppliers do release, Krueger says. The company already audits some of companies. It will decide whether to audit more.
Still, long term, it doesn’t seem possible Europe will leave the industry unregulated. “Solar has an impact,” says Davis. “If it wants to be green, it needs to proactively address those impacts.”
The compounds of cadmium even at a small percentage are proven containing toxic which may cause bioaccumulate, we should be aware of the danger that this element brings.
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