Solar panels may look bright and shiny, but they have a dark underbelly: production of polysilicon for panels gives off a highly toxic byproduct called silicon tetrachloride. In China, where factories are rushing to alleviate a polysilicon shortage that’s cramping the global solar-panel industry, the bubbly white liquid is often just dumped in nearby villages. “The land where you dump or bury [silicon tetrachloride] will be infertile. No grass or trees will grow in the place,” says a material-sciences expert at Hebei Industrial University. “It is poisonous, it is polluting. Human beings can never touch it.” While silicon tetrachloride can be recycled — with significant investment cost, time, and energy consumption — many Chinese factories are cutting corners, and environmental agencies seem to largely be looking the other way.

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