Researchers at Rutgers University have found a way to replace rare-earth elements in light-emitting diodes with much cheaper and more abundant materials. The cost of the new phosphor materials may be only 10% of the cost of rare-earth phosphors, according to a report published at Inside Climate News.
LED lamps use 10% to 20% of the energy of incandescent bulbs, and between 50% and 85% of the energy of compact fluorescent lamps. But LEDs also are more expensive because of the rare-earth elements used to manufacture them.
Over the past decade, rare-earth elements have increased in cost by as much as 1600% because of increased demand and fewer exports from China, which produces more than 90% of the world’s supply.
So researchers at Rutgers looked for alternatives. According to the report, they developed new combinations of materials to create new classes of phosphors which not only are free of rare-earth elements but also free of toxic materials such as cadmium and selenium.
“The prices of these rare earth elements have gone through the roof,” Zhichao Hu of Rutgers University told Inside Climate News. “That makes us think, ‘Is there a way we can bypass these rare-earth elements? Is there a way that we can use earth abundant elements to make phosphors that have the same properties, emit the same light, but are cheaper?’”
The findings were presented at the American Chemical Society’s annual conference in Boston last month.
The American Chemical Society said in a press release that LEDs produce the soft, white light consumers favor in a roundabout way. LEDs typically have a single semiconductor chip that produces light (usually blue) that must be shifted to white with the help of a yellow-emitting phosphor coating. That phosphor is now made with rare-earth elements, and that’s the problem the Rutgers team has been working on.
Huge drop in power use, or maybe not
A switch to LED lighting could cut the amount of electricity used for lighting in the U.S. by 50% by 2030, according to the U.S. Department of Energy.
But the report suggests that’s unlikely because of the “rebound effect”: As the cost of lighting falls, people use more of it.
The report, for example, cites a 2010 study by researchers at Sandia National Laboratories who found a direct connection between lower cost and higher consumption. Another study, this one published earlier this year, said that energy used for residential lighting will probably fall in the short term but energy savings will decline, or even be eliminated, as the amount of lighting increases over time.
“The multifunctionality of LED lighting may cause consumers to use significantly more light, creating the potential for both rebound and backfire to occur,” the study in the Journal of Industrial Ecology said. “The results indicate that the adoption of CFL and LED lighting will decrease residential energy consumption if consumers continue to use the same amount or slightly more light; however, when an expansion of lit spaces is included or a large increase in lighting usage occurs, energy consumption will increase and, over time, reduce or completely erode energy savings.”
And even with a projected 90% drop in the cost of phosphor materials, Inside Climate News suggested retail prices of LEDs wouldn’t automatically follow suit.
Ram Sephardi of the University of California Santa Barbara said that the new technology looks promising, but the “proof of the pudding” would be whether manufacturers adopt it.
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