What are rare earth elements – and what do they have to do with the environment?

Rare Earths: Green or not-too-green?

It's great to shrink our high-tech toys through the use of rare earths, but they have other important uses, especially in regard to the environment. The metals are used in the creation of numerous "green" items, including hybrid cars, air pollution controls, LED light bulbs and wind turbines.

Specifically, magnets made from rare earths are used in wind turbines and related items like generators, making them strong and powerful, yet light and efficient. Rechargeable batteries, which power everything from tiny e-readers to the heavy hybrid vehicles mentioned above, also use these elements, lanthanum in particular. Every Toyota Prius, for example, carries 10 pounds (4.5 kilograms) of lanthanum in its "nickel-metal hydride" battery. (Guess what the "metal" part of the name refers to? Lanthanum, of course [source: Popular Mechanics].)

Of course, rare earths aren't perfect. All rare earth ores contain uranium and thorium -- radioactive elements that become waste products when mined, and must be carefully disposed of. It also takes more chemicals to separate uranium and thorium than it does to separate base metals such as copper, zinc and lead, which isn't great for the environment [source: Think Global Green].

In China and elsewhere, lax regulations and illegal mining of rare earth metals have resulted in polluted land and water and even poisoned local inhabitants, which is obviously a major issue [source: Houses of Parliament]. The mining process uses a lot of energy, too, and can cause topsoil degradation and erosion. And finally, many high-tech gadgets made with rare earths are chucked into landfills when they're no longer useful, and researchers don't know yet if, over time, the rare earths will be released back into the environment -- and if so, what that may mean for our planet [source: Houses of Parliament, Smith].

Ultimately, though, production of rare earths continues to ramp up, suggesting that, at least for now, their innumerable environmental and societal benefits outweigh the costs. So it looks like these elements are here to stay -- at least until the next best thing is discovered.

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