Thin-Film Toxicity, Expense Will Plummet With Magnesium Chloride
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We’re seeing bath salts in the news again. This time, the alternative use of the product has a benign purpose, unlike a couple of years ago, when people associated it with designer drugs. In fact, according to an article last week in the journal Nature, a chemical typically found in bath salts—magnesium chloride—appears to have the potential to bring down both the cost and the negative environmental effects of newer solar panels that use thin-film technology (about 7% of the total PV panels sold).
Magnesium chloride sourced from the ancient Zechstein Sea (Photo: ancient-minerals.com).
Most solar cells are made from silicon. However, cadmium telluride has been favored off and on because the cells made with it are thinner, lighter, and often cheaper than silicon cells. But the material has several drawbacks: the cadmium chloride used to make it is both expensive and poisonous. Here’s what a reviewer from the Institute of Electrical and Electronics Engineers has to say about it:
“Cadmium chloride is filthy stuff. Its cadmium ions are extremely toxic, causing heart disease, kidney disorders, and a host of other health problems. One accidental spill of the water-soluble compound can wipe out fish from a river.”
To work with cadmium chloride, you have to protect skin and maintain a fume cupboard in the lab, as well as carefully monitor your disposal of wastes.
Researchers at the University of Liverpool in the United Kingdom have found a new way to create thin-film solar that promises relief from the expense and current dangers of the cadmium chloride method. They have just demonstrated that the efficiency of PV cells made from cadmium telluride and magnesium chloride is equivalent to that of commercial cadmium telluride cells activated with toxic cadmium chloride. Using magnesium chloride for PV manufacture would be 300 times cheaper than using cadmium chloride.
“If this new process succeeds, that will help drive the search to find substitutes for tellurium as well.”
That’s an exceptionally good idea, too, because with an abundance of about 1 µg/kg, tellurium is as rare on earth as platinum, and DOE anticipates a supply shortfall by 2025.
Both substitutions would help cut the cost and environmental impacts of thin-film photovoltaics.
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