Blue LED creators receive Nobel Prize in Physics for 2014
The Royal Swedish Academy of Sciences has awarded the 2014 Nobel Prize for Physics to the team of researchers that created the first blue LEDs in the early 1990s and ultimately enabled functional white light output from LED sources. Isamu Akasaki (Meijo University, Nagoya, Japan and Nagoya University, Japan), Hiroshi Amano (Nagoya University, Japan), and Shuji Nakamura (University of California, Santa Barbara) have been honored "for the invention of efficient blue light-emitting diodes which has enabled bright and energy-saving white light sources."
The trio of scientists will formally receive their Nobel awards in December at a ceremony in Stockholm. The three innovators will also share a monetary prize of SEK 8 million ($1.1 million). The Academy noted that the blue emitter was instrumental in creating white light by combining with existing red and green LEDs. More recently, the white light is most often generated by a blue LED along with a mix of yellow, red, and/or green phosphors in a phosphor- converted white LED device.
The Academy released the infographic depicted nearby, which demonstrates the impact that LED sources can have on energy consumption. Indeed, LED sources have reached 300 lm/W in efficacy in the laboratory. At the system level, shipping solid-state lighting (SSL) products regularly achieve efficacy in the 150-lm/W level.
"With 20% of the world's electricity used for lighting, it's been calculated that optimal use of LED lighting could reduce this to 4%," said Frances Saunders, president of the Institute of Physics, in response to the Nobel announcement. "Akasaki, Amano, and Nakamura's research has made this possible and this prize recognizes this contribution."
The Academy also noted that LEDs combined with solar energy hold the promise of bringing light to 1.5 billion people globally who lack access to electricity. Indeed, as we have chronicled in a recent article, LEDs are breathing new life into solar technology (http://bit.ly/1EfG0N8). A speaker at the 2014 Strategies in Light conference back in February also described the advances in LEDs and solar power (http://bit.ly/1kXzh1e).
It's also notable that the Nobel Award to the blue-LED inventors comes as we approach what the United Nations has declared the Year of Light in 2015 (see the article featured in the October issue of LEDs Magazine at http://bit.ly/10qozdC). Saunders added, "It's wonderful that the Nobel Foundation have chosen to commend these three physicists' work on the cusp of the International Year of Light 2015, a global initiative to highlight the importance of light in our lives."
Nakamura in particular has been recognized a number of times previously for his work with the blue LED. He won the 2006 Millennium Technology Prize (http://bit.ly/1x3kh7E), and continues to be involved in the industry and is one of the founders of LED-lamp developer and manufacturer Soraa (http://bit.ly/1x0sk7N).
It's also important to recognize the work in red and other LEDs that preceded the invention of the blue LED. Back in 2012, for instance, GE celebrated the 50th birthday of visible LED lighting (http://bit.ly/1t8qzhe) and the work of the company's researcher Nick Holonyak in creating that LED innovation.
DOE releases long-term report on Minnesota LED bridge lighting
The US Department of Energy (DOE) has published an update on what was one of the first prominent outdoor LED lighting projects installed as part of the agency's Gateway Demonstration program back in 2008. The I-35W freeway bridge in Minneapolis, MN was lit with LED-based fixtures and is among the longest continually-operated SSL installations in the world. After more than 20,000 hours of operation, the luminaires performed to expectations, while high-pressure sodium (HPS) fixtures would have required at least one relamping cycle and most likely additional maintenance procedures.
The luminaires installed on the bridge were The Edge models from BetaLED prior to the acquisition of Ruud Lighting by Cree (http://bit.ly/1zu9g2H). We covered the first DOE Gateway report on the project that was published back in 2009 (http://bit.ly/1tXd8Ga). That first report noted that the LED products offered 13% energy savings relative to HPS lighting along with more uniform illumination across the wide span of the bridge.
The lighting has been periodically monitored over the course of the Gateway Demonstration. The Minnesota Department of Transportation (MnDOT) used a mobile monitoring system developed by the Virginia Tech Transportation Institute to collect seven sets of measurements between April 2009 and October 2011. Through 13,000 operating hours the average illuminance on the roadway dropped from just over 11 lx to just under 10 lx.
The project has provided useful data both relative to the use of LEDs and to lighting issues in general such as dirt depreciation or light losses attributable to dirty optics. Dirt depreciation was 4% after 5000 hours and 12% after 20,300 hours. The DOE noted that LED-based systems are typically specified with an expected 30% in lumen depreciation over the life of the system, and clearly dirt depreciation is a major contributor.
In 2013, the DOE removed the luminaires for an in-depth laboratory analysis of the photometric performance after 20,300 hours of usage. The report notes that although the products were very early-stage SSL products, the photometric performance matched or exceeded what could be expected from HPS lighting while delivering maintenance and energy savings.
Independent of dirt depreciation, the luminaires suffered lumen depreciation of an average 18%. Moreover, the luminaire efficacy declined by 15%. The report also notes a slight unexplained drop in input power over time. The actual output of the LEDs dropped by only 10%, but an issue with the optics/materials added to the overall depreciation.
The report also noted that the CCT of the luminaires dropped by 800K over the course of usage with a corresponding reduction in CRI. Of course, HPS products are far inferior to even early LED-based products in terms of CRI.
Overall, the DOE says that MnDOT has been pleased with the test. The report noted that there were a few issues with the SSL products but that "no lighting installation, conventional or otherwise, is without issues." One LED driver had to be replaced, and MnDOT worked with BetaLED/Cree on the optics material issues in the fixture design.
You can download the original report and the recent Phase II report from the DOE SSL website at http://1.usa.gov/1axM85W.
IEA 4E SSL Annex opines on LED impact on health and environment
The International Energy Agency (IEA) Energy Efficiency End-Use Equipment (4E) Annex, formed to assist governments in promoting LED-based lighting as a means to reduce energy consumption, has published a number of new reports. The latest publications report on the impact of SSL on human health while other recent reports include research on environmental impacts and a review of test labs working with LED-based products.
The IEA 4E SSL Annex was formed in 2010 to advise ten member countries - Australia, China, Denmark, France, Japan, the Netherlands, South Korea, Sweden, the UK, and the US - regarding quality assurance programs for LED-based lighting. In one of its first actions in 2011, the Annex created a document that segmented the SSL market and created performance tiers for products (http://bit.ly/1wuLNvM). The current focus of the Annex is documenting performance criteria, evaluating the robustness of testing standards, and recommending accreditation frameworks.
Over the course of the last month the Annex has released three reports, the most recent of which is focused on the human health impact of SSL. Specifically, the report focused on the impacts of glare, blue-light hazard, flicker, and non-visual effects on the circadian rhythm.
In the area of glare, the Annex recommends that the maximum luminance of all LED lighting products be specified. Moreover, the report states that designers/specifiers should match the luminance to background ratio based on "visual ergonomics criteria." What is clear, however, is that the industry lacks usable glare metrics.
In the area of blue light, the report implies that photobiological standards to which SSL products are tested are largely sufficient to protect the public. Note we had a series of articles on photobiological issues that exhaustively covers the issues and standards (http://bit.ly/1qnDYCc). The Annex also noted that new generations of LEDs are using violet and ultraviolet (UV) emitters and that those products need further scrutiny.
In the area of flicker, the report simply states that it remains a problem for the industry and that no guidelines exist in Europe or the US to limit flicker in LED-based products. The Annex calls the situation unacceptable but makes no definitive recommendation on how to proceed in developing such regulations.
The sections of the report focused on non-visual impact largely cover the same ground on which an interview we published in September was focused (http://bit.ly/1q7GM4G). Clearly, there is more physiological research required on the topic but LEDs offer the unique ability to deliver a tuned spectrum. The health aspects report is on the Annex website at http://bit.ly/13E6B9t.
The lifecycle assessment report is based to a large extent on work done by the DOE. Indeed, we covered the DOE research in a series of articles (http://bit.ly/1tXqEJN). The work revealed that the major impact to the environment relative to LED lighting was energy usage and the greenhouse emissions that accompany generation. Those impacts dwarf any environmental hazards attributable to manufacturing SSL products or retiring the spent product. The Annex lifecycle report is also available on the website at http://bit.ly/1t8yM50.
The Annex research into test laboratories compared the work of 100 laboratories spread around the globe over the course of October 2012 to August 2013. The process involved comparisons of photometric, colorimetric, and electrical parameters associated with a variety of SSL products. More than 50 of the labs were direct and willing participants in the study while others were compared based on existing known test schemes.
The laboratory evaluations will help the test organizations fine-tune their work, and help lighting companies and specifiers/designers understand the areas where special emphasis is needed in characterizing or evaluating SSL products. The full report is on the Annex website at http://bit.ly/10ioLLJ.
DOE again addresses the blue light hazard with LEDs
The DOE has published a report entitled "True Colors" that once again affirms the agency's position on the potential hazard of LED-based lighting attributable to blue energy in the spectral power distribution of SSL products. The study focuses on the relationship between CCT and CRI, and optical safety and photobiological stimulation.
The DOE had previously released a fact sheet on LED lighting and the blue light hazard (http://bit.ly/1vEsIDf). The agency stated at the time that LEDs posed no more danger than legacy sources with similar CCT ratings. Still, some researchers and alarmists continue to speculate that the blue-peak typically seen in the spectral power distribution (SPD) of an LED poses risks to human wellbeing.
In the new report, the DOE fully documents the SPD of LED sources with varying CCT ratings (see figure). The document affirms that there is typically a blue peak in the 450-nm range that is due to the blue emitters used in phosphor-converted white LEDs and that peak is consistent regardless of CCT. Still, the report states that legacy sources with similar CCTs also contain similar percentages of energy in the blue range and pose an equal optical-safety risk even if there is not a blue energy peak in the SPD.
The report also addresses the potential of blue-pump-based LEDs to damage materials such as works of art. The DOE notes that museum curators have already debunked any risk of damage from LED-based lighting. Moreover, the report states that LEDs are less likely to cause damage to artwork than legacy sources due to less energy emitted outside the human sensitivity range - specifically less energy in the ultraviolet (UV) and infrared (IR) regions.
Finally, the DOE addressed the potential effect of LEDs on the photobiological concerns and the human circadian rhythm. The report first notes that how the human physiological system works is still being debated, as we covered recently (http://bit.ly/1q7GM4G). But again the percentage of blue energy in SSL products is similar to that in legacy sources with similar CCTs. The full report is available on the DOE website at http://1.usa.gov/1ogTTqb.
MSSLC indicates moderate LED penetration into roadway lighting
The DOE has released the results of a roadway lighting survey conducted by the agency's Municipal Solid State Lighting Consortium (MSSLC). The survey was meant to shed lighting on the penetration rate of LEDs and the potential for additional energy savings through SSL retrofits.
The MSSLC surveyed 240 organizations including municipalities, counties, state departments of transportation, investor-owned utilities, and municipally-owned utilities. The results show moderate LED penetration and significant opportunities for further savings.
The results indicate that the majority of respondents have some LED-based lighting in their street-lighting inventory, but only 8% considered it the most prominent technology installed. Meanwhile, 82% still say HPS is most prominent. Moreover, 36% still use mercury vapor lights that trail both HPS and LED sources in efficacy.
Indeed, the average age of installed roadway lighting in the survey is 15.3 years with the departments of transportation reporting an even higher 17.6 years. Clearly, there is ample opportunity for SSL deployment and, in fact, we are still in the early stage of the transition to LED sources. Read the full report on the DOE website at http://1.usa.gov/10qRSg7.
The MSSLC is an organization founded to help municipalities and utilities to simplify the transition to LEDs. The organization recently published its v2.0 of a luminaire model specification that can be used to simplify the SSL procurement process (http://bit.ly/1t8IWmb).
EPA begins specification process for Energy Star Luminaires
The US Environmental Protection Agency (EPA) has formally launched the collaborative-revision process that will ultimately lead to an Energy Star Luminaires v2.0 specification. The agency hopes to streamline all aspects of the process, drive lighting efficacy levels higher, and broaden the scope of covered lighting products.
The Energy Star Luminaires v1.1 specification took effect in April 2012 (http://bit.ly/1pvQIMl). In late 2012, the agency made small revisions, establishing the Luminaires v1.2 specification. Both revisions followed the release of Luminaires v1.0 in October of 2011 supplanting the prior Solid State Lighting Luminaires v1.1 spec (http://bit.ly/1tI50aX) and the Residential Light Fixtures V4.2 spec - combining products based on LED and legacy sources.
The intentions of the v2.0 specification are very straightforward. The agency first hopes to simplify the specification requirements as well as the testing and certification process. The EPA has worked with the National Electrical Manufacturers Association (NEMA) to canvass stakeholders in preparation for the revision process. Some areas that may be modified include color angular uniformity, light-source start time, and zonal lumen density.
Meanwhile, expect the efficacy requirements to go up in v2.0. The agency noted that the industry has made notable improvements in efficacy since the v1.0 specification was published, driven primarily by LED sources. The agency will likely set a forward-looking target expected to be reasonable for the final publication of Luminaires v2.0.
Finally, the v2.0 specification will likely include new product types. Some types under consideration include retrofit products for directional and non-directional luminaires, downlight and accent-light products with non-circular beams, and color-tunable luminaires.
Also in news for the larger Energy Star program, the EPA has launched a rebate finder tool online that consumers can use to find special offers and rebates on a variety of products ranging from appliances to lighting (http://1.usa.gov/1uGfsTl). The tool covers residential and commercial products. In the Lighting & Fans category, you can search for types of ceiling fans with and without lights, decorative light strings, retrofit lamps, and light fixtures.
