Republication of Postings from the U.S. Department of Energy (DOE) Solid-State Lighting Program by Jim Brodrick, SSL Program Manager, U.S. Department of Energy
Although I recently spent a week at the beach, there was no sand, surf, or bathing suit in sight. That’s because I was in Long Beach, CA, at DOE’s 14th annual Solid-State Lighting R&D Workshop. And instead of hanging 10 on a breaking wave, I rolled up my sleeves along with the other 250 folks in attendance, as we dove headfirst into the toughest technological issues facing SSL today.
The speakers were truly amazing, and kept the audience riveted to their seats right up until the very end of the third day. The father of LED lighting, Shuji Nakamura, who won the 2014 Nobel Prize in physics for inventing the energy-efficient blue LED, set the tone by focusing on SSL’s cutting edge, wowing the crowd with his discussion of such innovations as tunnel-junction blue/green LEDs, violet LEDs, microLEDs, patterned sapphire substrates, high-power semipolar laser diodes (LDs), and Li-fi using LEDs and LDs.
One recurrent theme in Long Beach was that, thanks to the advent of SSL, lighting is no longer “just lighting” and offers many new possibilities. Bruce Bugbee of Utah State University discussed the science as well as the practical economics of using LED lighting in indoor farms to turn photons into food, explaining that selectively tuning the spectrum can not only increase crop yield, but can also change such characteristics as nutritional content, disease resistance, appearance, and taste.
In a panel discussion on creating value from human physiological responses to light, Windy Boyd of the National Institute of Environmental Health Sciences explained that by affecting our circadian rhythm, exposure to light at night may have the potential to increase our risk of common diseases. Jamie Zeitzer of Stanford University reviewed key studies on how light affects the sleep-wake cycle as well as alertness; while Michael Herf discussed f.lux, a software program he created that’s used by more than 10 million people to adjust the CCT of their computer screens in support of their circadian rhythms and biology, and how he’s worked to model the effects on sleep and health of the screens and light people are exposed to. NASA flight surgeon Smith Johnston III discussed the role of lighting in his treatment of the astronauts under his care.
Another panel explored the use of engineered light to accommodate various applications. Wouter Soer of Lumileds concluded that we need more application-based metrics for spectral design, while Konica Minolta’s Po-Chieh Hung cautioned that although spectral optimization is possible for virtually any application, the “spiky” spectra that result may distort color perception both visually and photographically. Scott Rosenfeld of the Smithsonian American Art Museum looked at minimizing light-caused damage to art objects, while Rensselaer Polytechnic Institute botanist Tessa Pocock considered the action spectrum from a plant’s point of view. In a separate talk, Susanne Seitinger of Philips Lighting described how connected lighting can play a key role in creating smart cities by leveraging the existing infrastructure to provide valuable information on the environment, traffic, noise, and the network itself.
A panel on the future of SSL manufacturing in the U.S. — which featured representatives from Cree, Acuity Brands, Hubbell Lighting, and Finelite — emphasized the opportunity that exists to add jobs domestically, as well as the gains that have already been made. The panelists cited cutting-edge R&D, a high degree of product complexity, offering large numbers of SKUs, right-sizing production facilities, and instituting lean manufacturing practices as among the keys to helping the country maintain its leadership in the technology.
There were many other topics covered at the Long Beach workshop — from the challenges facing the luminaire industry, to the synergy between lighting and display technology, to the integration of lighting into buildings, to an Asian LED manufacturer’s perspective on the lighting market. And the LED and OLED breakout sessions and topic tables literally crackled with energy as they came to grips with the remaining technological hurdles (see DOE’s short videos about the challenges still facing LEDs and OLEDs). The networking reception, which featured 60 posters showcasing cutting-edge SSL research projects, buzzed like a beehive for hours.
With all of the progress that’s been made over the past decade, it’s important to keep in mind that it’s still very early in the game, and that we’re a long way from achieving SSL’s full potential in terms of lighting performance, efficiency, adoption, and energy savings. In fact, we’re just at the beginning, which is why DOE continues to support SSL R&D in a variety of ways, including holding this workshop. The input we got in Long Beach will help us update our SSL R&D Plan, which is widely consulted by industry and government and charts a roadmap to propel SSL forward, breaking one technological barrier after another and securing a recognized leadership role for the United States in this transformative technology.
DOE forecasts that SSL has the potential to slash energy consumption for lighting by 75% by the year 2035, lowering U.S. electricity bills by $50 billion annually. But this will only happen if we keep our feet on the accelerator so that the present barriers are overcome. That’s why we gathered in Long Beach. The workshop presentations are posted on the DOE website, and will soon be followed by the highlights.
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