Lighting Up Yale in New Ways
by Patrick Lee:
This past holiday season, the legendary Rockefeller Center Christmas tree embodied a lighting revolution: instead of incandescent bulbs, 30,000 light-emitting diodes (L.E.D.s) covered the spruce and, in the process, saved New York City about $380 a day, cutting the tree’s expected electricity consumption by more than half.
L.E.D.s’ increasing prominence in everyday applications, from holiday lights to traffic signals and large-screen TVs, is not new. The science behind the technology is over 40 years old. But Yale scientists have found a unique way to apply research in the field of quantum dots to white-light L.E.D.s, a form of solid-state lighting. Experts predict that with these recent advances, L.E.D.s will soon overtake old-school technologies like incandescent and fluorescent bulbs.
It will most likely be another decade before L.E.D.s penetrate the market as a viable and cheap lighting alternative. But, given the monstrous electricity demands that keep the University running, the potential for energy savings in L.E.D.s is especially relevant to Yalies, many of whom burn the midnight oil daily.
Quantum dots, small nanoparticles with easily manipulated properties, efficiently absorb energy and re-emit visible light of a specific wavelength. Their small size reduces light scattering in L.E.D.s, thus increasing light output.
“If you use quantum dots in white light L.E.D.s, you have all sorts of ability to create whatever colors with the right mixtures and different sizes,” said Mark Reed, Associate Director of the Yale Institute for Nanoscience and Quantum Engineering. “Quantum dots are more efficient in generating white light.” Even though the basic principles behind both quantum dots and L.E.D.s are known, researchers are still exploring where the two technologies intersect.
The potential savings from L.E.D. technology are undeniable: L.E.D.s could more than double the average efficiency of current lighting systems. Given the L.E.D. penetration of the U.S. lighting market, Americans could realize savings in electricity consumption amounting to billions of dollars per year.
Jeff Tsao, a principal member of the technical team at Sandia National Laboratories, has analyzed potential scenarios for the impact of L.E.D.s on a national and global scale. Tsao projects that it will take five to seven years for L.E.D.s to outrank fluorescents in efficiency. After that, he said, everything is in the hands of supply and demand. “In the lab, solid-state lighting is already getting very close: the question is when the commercial production will ramp up,” Tsao said. “One could imagine that in 15 years, solidstate lighting will be pretty common.”
If L.E.D. technology proves as successful as Tsao suggests, L.E.D.s could significantly impact energy use and efficiency on Yale’s campus. In one sense, Yale is a perfect testing ground for new approaches to energy conservation: the University is like a self-contained Petri dish, ripe for the implementation and observation of up-and-coming technologies. But Tom Weil, a business consultant and investor in L.E.D. technology, suggested that Yale might not actually be the ideal place for an L.E.D. revolution. Weil teaches the college seminar, “Global Energy Sources, Uses and Issues,” and his class focuses on patterns of energy consumption at Yale.
“In a place of the commons, where people share and where different people have access to the same switches, it’s not an easy job for the people who are trying to track consumption,” he said. “You have the whole problem of people in suites: who’s responsible for leaving the light on?”
But even if Yale does not prove conducive to scientific experimentation, it can still contribute to the revolution by exposing its students to L.E.D.’s potential and increasing awareness of energy usage. “You can take all of the alternative electricity generation that we’re looking at these days—all taken together, they won’t replace coal. While some major league things haven’t been shown to be practical, there are things—and L.E.D.s are a great example—that we know are really practical and economic,” Weil said.
Whether or not L.E.D.s meet expected deadlines in maximizing efficiency and minimizing cost, the fact remains that Yale—as a campus concerned with sustainability—has the potential to take the lead in exploring this technology by fostering a culture of global awareness and local action.