Solar panels start to die, leaving toxic waste behind

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In a typical e-waste facility, this high-tech sandwich will be treated roughly. Recyclers often remove the panel frame and its junction box to recover the aluminum and copper, then shred the rest of the module, including the glass, polymers and silicon cells, which are covered with a plastic electrode. silver and soldered with tin and lead. (Since the vast majority of this mixture by weight is glass, the resulting product is considered impure, ground glass.) Tao and colleagues estimate that a recycler who dismantles a standard 60-cell silicon panel can achieve about $ 3 for salvaged aluminum. , copper and glass. Vanderhoof, meanwhile, says the cost of recycling this panel in the United States is between $ 12 and $ 25, after freight charges, which “often equal the cost of recycling.” At the same time, in states that allow it, it typically costs less than a dollar to throw a solar panel into a solid waste landfill.

“We think the big blind spot in the United States for recycling is that the cost far exceeds the revenue,” Meng said. “It’s on the order of a 10 to 1 ratio.”

If the most valuable components of a solar panel, namely silicon and silver, could be separated and purified efficiently, it could improve that cost / income ratio. A small number of dedicated solar photovoltaic recyclers attempt to do so. Veolia, which operates the world’s only commercial-scale PV silicon recycling plant in France, shreds and grinds the panels, then uses an optical technique to recover the low-purity silicon. According to Vanderhoof, Recycle PV Solar initially used a “thermal process and ball mill process” that could recover over 90% of the materials in a panel, including silver and low purity silicon. But the company recently received new equipment from its European partners capable of “recovering more than 95%,” he said, while separating the recovered materials much better.

Some PV researchers want to do even better than that. In other recent review article, a team led by scientists from the National Renewable Energy Laboratory is calling for the development of new recycling processes in which all metals and minerals are recovered at high purity, with the goal of making recycling as economically viable and also beneficial for the environment as possible. As lead study author Garvin Heath explains, these processes could include the use of heat or chemical treatments to separate the glass from the silicon cells, followed by the application of other chemical or electrical techniques to separate and purify silicon and various trace metals.

“What we’re asking for is what we call a high-value integrated recycling system,” Heath told Grist. “The high value means we want to recover all the constituent materials that have value from these modules. Integrated refers to a recycling process that can go after all of these materials, without having to go from one recycler to another. “

In addition to developing better recycling methods, the solar industry should think about how to reuse the panels whenever possible, as used solar panels are likely to cost more than the metals and minerals they contain ( and since their reuse usually requires less energy than recycling.). As is the case with recycling, the EU leads on this point: thanks to Circular business models for the solar energy industry program, the European Commission is funding a range of demonstration projects showing how solar panels from rooftops and solar farms can be reused, notably to power electric bicycle charging stations in Berlin and residential complexes in Belgium.

Recycle PV Solar also recertifies and resells the undamaged panels it receives, which Vanderhoof says helps offset the cost of recycling. However, he and Tao are concerned that various American recyclers are selling second-hand solar panels with low quality control overseas to developing countries. “And these countries generally don’t have regulations for e-waste,” Tao said. “So ultimately you throw your problem on a poor country.”

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