Wind turbines, electric vehicles, light-emitting diodes, flat-screen displays, and solar panels all rely on elements that are mined and refined in just a few countries and traded in small quantities. Demand for many of these elements is expected to grow rapidly as these technologies become more commonly used, and impending supply constraints could hold back their growth.

As the wind-power industry expands, for example, demand for the rare-earth element neodymium, a crucial ingredient in the high-strength magnets used in wind turbines, is projected to outstrip supply by 16 percent in 2014. (China controls 97 percent of global production of rare-earth elements.)